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鹿茸多肽对兔骨性关节炎软骨细胞金属蛋白酶ｍＲＮＡ表达的影响摘要目的：在家兔膝关节骨性关节炎模型的基础上观察鹿茸多肽对骨性关节炎软骨细胞的影响。
方法：随机分成两组，实验组建立hulth骨性关节炎模型，对照组仅行双侧膝关节切开术，以建立模型。
以正常新西兰大白兔膝关节软骨为正常对照组，以鹿茸多肽为实验药，法滋隆为阳性对照药。
分别进行mtt法检测、sds-聚丙烯酰胺凝胶电泳检测及琼脂糖电泳检测，获取前后软骨细胞核酸中金属蛋白酶表达情况。
结果：鹿茸多肽对骨性关节炎软骨细胞具有促进增殖作用；骨性节炎软骨细胞直接分泌到胞外的金属蛋白酶含量变化不明显；骨性关节炎软骨细胞核酸中金属蛋白酶出现高表达。
结论：骨性关节炎软骨细胞在软骨细胞正常分化及增殖发生改变的过程中，骨性关节炎软骨基质降解可能是金属蛋白酶与其他因子协同作用的结果；鹿茸多肽可促进骨性关节炎软骨细胞增殖，并可抑制骨性关节炎软骨细胞中金属蛋白酶的过度表达，可能对治疗骨性关节炎有较好的作用。
关键词骨性关节炎金属蛋白酶软骨细胞试剂、仪器及实验材料主要试剂：①化学试剂：碳酸氢钠、磷酸氢二钠、硫酸镁、考马斯亮兰、mtt、甘氨酸、tris、sds、temed、二甲基亚砜。
②细胞培养试剂与培养板。
③聚合酶链式反应（pcr）试剂：rna提取试剂盒，rna pcr相关试剂盒。
主要仪器：（略）实验材料：新西兰大白兔，鹿茸多肽，骨肽注射液。
实验方法动物模型及分组：雄性新西兰白兔8只，3～5个月龄，体重2.5～3.5kg，平均2.85kg。
按组间均衡一致的原则随机分为两组，每组4只。
采用内侧副韧带、前后交叉韧带切断并切除内侧半月板hulth 骨性关节炎模型，实验组均行内侧副韧带、前后交叉韧带切断并切除内侧半月板；对照组仅行侧膝关节切开术，但不行前交叉韧带切断并切除内侧半月板术。
mtt法检测鹿茸多肽对软骨细胞生长的影响，sds-聚丙烯酰胺凝胶电泳检测软骨细胞分泌金属蛋白酶，rt-pcr法检测软骨细胞中金属蛋白酶mrna表达。
专利名称：IMPROVED COBALT CATALYST发明人：CARR, John, Frederick,PAKENHAM, Derek 申请号：GB1996001986申请日：19960814公开号：WO97/007124P1公开日：19970227专利内容由知识产权出版社提供摘要：A process for preparing a cobalt (III) complex is described which comprises: (i) treating a divalent cobalt salt of formula CoIIX2/n where n is the valency of an anion X, with up to 15 molar equivalents of ammonia or an amine; (ii) oxidising the resulting amine complex; (iii) converting the oxidised complex to the corresponding carboxylate of formula [CoIII(NR3)5R1COO]X¿2/n? where each R, which may be the same or different, represents hydrogen or an optionally substituted hydrocarbon group and R?1¿represents an alkyl or alkenyl group of 1 to 18 carbon atoms, at a pH above 8.5; and optionally (iv) replacing the X ion by a different anion by a metathetical reaction.申请人：CARR, John, Frederick,PAKENHAM, Derek地址：Oak House Reeds Crescent Watford Hertfordshire WD1 1QH GB,10 Broadwell Close Abbeymead Gloucester GL4 4XX GB,19 St. Michael's Crescent Headingley Leeds LS6 3AL GB国籍：GB,GB,GB代理机构：ELLIS-JONES, Patrick, George, Armine更多信息请下载全文后查看。
高分子物理课程系列辅助资料高分子化学及物理专业英语词汇Polymer chemistry and PhysicsSpecialty English V ocabulary2009年6月brush polymercoiling type polymer5立构规整度Tacticityisotacticity6等规度, 全同立构[规整]度syndiotacticity7间同度，间同立构[规整]度8无规度，无规立构度Atacticity9嵌段block10规整嵌段regular block11非规整嵌段Irregular block12立构嵌段stereoblock13有规立构嵌段Isotactic block14无规立构嵌段atactic block15单体单元monomeric unit16二单元组diad17三单元组triad18四单元组Tetrad19五单元组Pentad20无规线团random coil21自由连接链freely-jointed chain22自由旋转链freely-rotating chain23蠕虫状链worm-like chain24柔性链flexible chain25链柔性chain flexibility26刚性链rigid chain27棒状链rodlike chain28链刚性chain rigidity29聚集aggregation30聚集体aggregate31凝聚、聚集coalescence32链缠结chain entanglement33凝聚缠结cohesional entanglement 34物理缠结physical entanglement 35拓扑缠结topological entanglement36凝聚相condensed phase37凝聚态condensed state38凝聚过程condensing process39临界聚集浓度critical aggregation concentration40线团-球粒转换coil-globule transition41受限链Confined chain42受限态Confined state43物理交联physical crosslinking44统计线团statistical coil45等效链equivalent chain46统计链段statistical segment47链段chain segment48链构象chain conformation49无规线团模型random coil model50无规行走模型random walk model51自避随机行走模型self avoiding walk model52卷曲构象coiled conformation53高斯链Gaussian chain54无扰尺寸unperturbed dimension55扰动尺寸perturbed dimension56热力学等效球thermodynamically equivalent sphere 57近程分子内相互作用short-range intramolecular interaction 58远程分子内相互作用long-range intramolecular interaction 59链间相互作用interchain interaction60链间距interchain spacing61长程有序long range order62近程有序short range order63回转半径radius of gyration64末端间矢量end-to-end vector65链末端chain end66末端距end-to-end distance67无扰末端距unperturbed end-to-end distance68均方根末端距root-mean-square end-to-end distance69伸直长度contour length70相关长度persistence length71主链；链骨架chain backbone72支链branch chain73链支化chain branching74短支链short-chain branch75长支链long-chain branch76支化系数branching index77支化密度branching density78支化度degree of branching79交联度degree of crosslinking80网络Network81网络密度network density82溶胀Swelling83平衡溶胀equilibrium swelling84分子组装，分子组合molecular assembly85自组装self assembly86微凝胶Microgel87凝胶点gel point88可逆[性]凝胶reversible gel89溶胶-凝胶转化sol-gel transformation90临界胶束浓度critical micelle concentration，CMC91组成非均一性constitutional heterogenity, compositionalheterogenity92摩尔质量平均molar mass average93数均分子量number-average molecular weight,number-average molar mass94重均分子量weight-average molecular weight,weight-average molar mass95Z均分子量Z(Zaverage)-average molecular weight,Z-molar mass96黏均分子量viscosity-average molecular weight，viscosity-average molar mass97表观摩尔质量apparent molar mass98表观分子量apparent molecular weight99聚合度degree of polymerization100动力学链长kinetic chain length101单分散性monodispersity102临界分子量critical molecular weight103分子量分布molecular weight distribution，MWD 104多分散性指数polydispersity index，PID105平均聚合度average degree of polymerization 106质量分布函数mass distribution function107数量分布函数number distribution function108重量分布函数weight distribution function109舒尔茨-齐姆分布Schulz-Zimm distribution110最概然分布most probable distribution111对数正态分布logarithmic normal distribution112聚合物溶液polymer solutionpolymer-solvent interaction113聚合物-溶剂相互作用114溶剂热力学性质thermodynamic quality of solvent 115均方末端距mean square end to end distance116均方旋转半径mean square radius of gyration117θ温度theta temperature118θ态theta state119θ溶剂theta solvent120良溶剂good solvent121不良溶剂poor solvent122位力系数Virial coefficient123排除体积excluded volume124溶胀因子expansion factor125溶胀度degree of swelling126弗洛里-哈金斯理论Flory-Huggins theory127哈金斯公式Huggins equation128哈金斯系数Huggins coefficient129χ(相互作用)参数χ-parameter130溶度参数solubility parameter131摩擦系数frictional coefficient132流体力学等效球hydrodynamically equivalent sphere133流体力学体积hydrodynamic volume134珠-棒模型bead-rod model135球-簧链模型ball-spring [chain] model136流动双折射flow birefringence, streaming birefringence 137动态光散射dynamic light scattering138小角激光光散射low angle laser light scattering139沉降平衡sedimentation equilibrium140沉降系数sedimentation coefficient141沉降速度法sedimentation velocity method142沉降平衡法sedimentation equilibrium method143相对黏度relative viscosity144相对黏度增量relative viscosity increment145黏度比viscosity ratio146黏数viscosity number147[乌氏]稀释黏度计[Ubbelohde] dilution viscometer148毛细管黏度计capillary viscometer149落球黏度计ball viscometer150落球黏度ball viscosity151本体黏度bulk viscosity152比浓黏度reduced viscosity153比浓对数黏度inherent viscosity, logarithmic viscositynumber154特性黏数intrinsic viscosity, limiting viscosity number 155黏度函数viscosity function156零切变速率黏度zero shear viscosity157端基分析analysis of end group158蒸气压渗透法vapor pressure osmometry, VPO159辐射的相干弹性散射coherent elastic scattering of radiation160折光指数增量refractive index increment161瑞利比Rayleigh ratio162超瑞利比excess Rayleigh ratio163粒子散射函数particle scattering function164粒子散射因子particle scattering factor165齐姆图Zimm plot166散射的非对称性dissymmetry of scattering167解偏振作用depolarization168分级fractionation169沉淀分级precipitation fractionation170萃取分级extraction fractionation171色谱分级chromatographic fractionation172柱分级column fractionation173洗脱分级，淋洗分级elution fractionation174热分级thermal fractionation175凝胶色谱法gel chromatography176摩尔质量排除极限molar mass exclusion limit177溶剂梯度洗脱色谱法solvent gradient [elution] chromatography 178分子量排除极限molecular weight exclusion limit179洗脱体积elution volume180普适标定universal calibration181加宽函数spreading function182链轴chain axis183等同周期identity period184链重复距离chain repeating distance185晶体折叠周期crystalline fold period186构象重复单元conformational repeating unit187几何等效geometrical equivalence188螺旋链helix chain189构型无序configurational disorder190链取向无序chain orientational disorder191构象无序conformational disorder192锯齿链zigzag chain193双[股]螺旋double stranded helix194[分子]链大尺度取向global chain orientation195结晶聚合物crystalline polymer196半结晶聚合物semi-crystalline polymer197高分子晶体polymer crystal198高分子微晶polymer crystallite199结晶度degree of crystallinity, crystallinitymacromolecular isomorphism 200高分子[异质]同晶现象201聚合物形态学morphology of polymer202片晶lamella, lamellar crystal203轴晶axialite204树枝[状]晶体dendrite205纤维晶fibrous crystal206串晶结构shish-kebab structure207球晶spherulite208折叠链folded chain209链折叠chain folding210折叠表面fold surface211折叠面fold plane212折叠微区fold domain213相邻再入模型adjacent re-entry model214接线板模型switchboard model215缨状微束模型fringed-micelle model216折叠链晶体folded-chain crystal217平行链晶体parallel-chain crystal218伸展链晶体extended-chain crystal219球状链晶体globular-chain crystal220长周期long period221近程结构short-range structure222远程结构long-range structure223成核作用nucleation224分子成核作用molecular nucleation225阿夫拉米方程Avrami equation226主结晶primary crystallization227后期结晶secondary crystallization228外延结晶，附生结晶epitaxial crystallization229外延晶体生长，附生epitaxial growth晶体生长230织构texture231液晶态liquid crystal state232溶致性液晶lyotopic liquid crystal233热致性液晶thermotropic liquid crystal 234热致性介晶thermotropic mesomorphism 235近晶相液晶smectic liquid crystal236近晶中介相smectic mesophase237近晶相smectic phase238条带织构banded texture239环带球晶ringed spherulite240向列相nematic phase241盘状相discotic phase242解取向disorientation243分聚segregation244非晶相amorphous phase 无定形相245非晶区amorphous region246非晶态amorphous state247非晶取向amorphous orientation248链段运动segmental motion249亚稳态metastable state250相分离phase separation251亚稳相分离spinodal decomposition252bimodal decomposition253微相microphase254界面相boundary phase255相容性compatibility256混容性miscibility257不相容性incompatibility258不混容性immiscibility259增容作用compatiibilization260最低临界共溶(溶解)lower critical solution temperature, LCST 温度upper critical solution temperature , UCST 261最高临界共溶(溶解)温度262浓度猝灭concentration quenching263激基缔合物荧光excimer fluorescence264激基复合物荧光exciplex fluorescencelaser confocal fluorescence microscopy 265激光共聚焦荧光显微镜266单轴取向uniaxial orientation267双轴取向biaxial orientation, biorientation268取向度degree of orientation269橡胶态rubber state270玻璃态glassy state271高弹态elastomeric state272黏流态viscous flow state273伸长elongation274高弹形变high elastic deformation275回缩性，弹性复原nerviness276拉伸比draw ratio, extension ratio277泊松比Poisson's ratio278杨氏模量Young's modulus279本体模量bulk modulus280剪切模量shear modulus281法向应力normal stress282剪切应力shear stress283剪切应变shear strain284屈服yielding285颈缩现象Necking 细颈现象286屈服应力yield stress287屈服应变yield strain288脆性断裂brittle fracture289脆性开裂brittle cracking290脆-韧转变brittle ductile transition291脆化温度brittleness(brittle) temperature 292延性破裂ductile fracture293冲击强度impact strength294拉伸强度断裂强度tensile strength breaking strength295极限拉伸强度ultimate tensile strength296抗撕强度tearing strength297弯曲强度flexural strength, bending strength 298弯曲模量bending modulus299弯曲应变bending strain300弯曲应力bending stress301收缩开裂shrinkage crack302剪切强度shear strength303剥离强度peeling strength304疲劳强度fatigue strength, fatigue resistance 305挠曲deflection306压缩强度compressive strength307压缩永久变形compression set308压缩变形compressive deformation309压痕硬度indentation hardness310洛氏硬度Rockwell hardness311布氏硬度Brinell hardness312抗刮性scrath resistance313断裂力学fracture mechanics314力学破坏mechanical failure315应力强度因子stress intensity factor316断裂伸长elongation at break317屈服强度yield strength318断裂韧性fracture toughness319弹性形变elastic deformation320弹性滞后elastic hysteresis321弹性elasticity322弹性模量modulus of elasticity323弹性回复elastic recovery324不可回复形变irrecoverable deformation 325裂缝Crack 龟裂326银纹craze327形变；变形deformation328永久变形deformation set329剩余变形residual deformation330剩余伸长residual stretch331回弹，回弹性resilience332延迟形变retarded deformation333延迟弹性retarded elasticity334可逆形变reversible deformation335应力开裂stress cracking336应力-应变曲线stress strain curve337拉伸应变stretching strain338拉伸应力弛豫tensile stress relaxation339热历史thermal history340热收缩thermoshrinking341扭辫分析torsional braid analysis，TBA 342应力致白stress whitening343应变能strain energy344应变张量strain tensor345剩余应力residual stress346应变硬化strain hardening347应变软化strain softening348电流变液electrorheological fluid349假塑性pseudoplastic350拉胀性auxiticity351牛顿流体Newtonian fluid352非牛顿流体non-Newtonian fluid353宾汉姆流体Bingham fluid354冷流cold flow355牛顿剪切黏度Newtonian shear viscosity 356剪切黏度shear viscosity357表观剪切黏度apparent shear viscosity358剪切变稀shear thinning359触变性thixotropy360塑性形变plastic deformation361塑性流动plastic flow362体积弛豫volume relaxation363拉伸黏度extensional viscosity364黏弹性viscoelasticity365线性黏弹性linear viscoelasticity366非线性黏弹性non-linear viscoelasticity 367蠕变creep368弛豫[作用] Relaxation 松弛369弛豫模量relaxation modulus370蠕变柔量creep compliance371热畸变温度heat distortion temperature 372弛豫谱relaxation spectrum373推迟[时间]谱retardation [time] spectrum 374弛豫时间relaxation time375推迟时间retardation time376动态力学行为dynamic mechanical behavior 377动态黏弹性dynamic viscoelasticity378热-机械曲线thermo-mechanical curve 379动态转变dynamic transition380储能模量storage modulus381损耗模量loss modulus382复数模量complex modulus。
微生物與生化學研究所微生物學組專題討論題目：Fabricate dual-effect liposome for tumor treatment in C26 tumor-bearing mice. 演講人：Peng, Po-Chun 彭柏鈞 R97B47407指導老師：Chen, Chin-Tin 陳進庭副教授演講日期：May 31, 2010演講地點：The 6th Classroom摘要癌症為現代人類主要的死亡原因之一，目前常使用之治療方式中，將化療藥物Doxorubicin (Dox) 包覆於微脂體，形成 Liposomal-Doxorubicin (Lipo-Dox)，雖然能有效降低 Dox副作用，但也減慢藥物釋放速度，使其療效大幅減弱。
而目前新興之癌症治療方式—光動力治療，能針對腫瘤部位，利用光感物質經特定波長光源激發，產生單態氧及自由基對腫瘤細胞進行毒殺。
但是在臨床使用時，因為光源穿透力能力影響，對於腫瘤深處組織無法達到有效毒殺效果。
因此我們將化療藥物 Dox與光感物質 Chlorin e6 (Ce6) 同時包覆於微脂體中，建構出一雙效型微脂體，希望能藉由 Ce6之光動力效應破壞部分癌細胞之外，還能改變微脂體脂雙層通透性，加速化療藥物 Dox從微脂體中釋放，而由釋放出來的 Dox 達到再次毒殺殘存癌細胞之效果，以此種同時結合光動力治療與化學治療效應之雙效型癌症治療模式，改善兩種治療方式各自之缺失，提升對於癌症之治療效益。
本篇研究以薄膜水合法搭配硫酸銨梯度法建構出粒徑為152.9± 37.7 nm之雙效型微脂體 Lipo-Dox-Ce6。
於4℃保存60天後，發現並無明顯藥物滲漏情況，且粒徑也沒有因保存時間延長而改變。
而在37℃ PBS環境中，Ce6及Dox由微脂體中釋放均十分緩慢，顯示此雙效型微脂體進入體液後，應該也能穩定將藥物包覆於微脂體中。
接著檢測 Lipo-Dox-Ce6作用機制，發現經 662 nm光源照射，激發其中的光感物質Ce6產生光動力效應後，能促進Dox釋放，進而使細胞與Dox結合量上升，增強對癌細胞的毒殺效力。
![用于定量监测体内肿瘤氧合的方法和系统[发明专利]](https://img.taocdn.com/s1/m/63aaef3250e2524de4187e99.png)
专利名称：用于定量监测体内肿瘤氧合的方法和系统
专利类型：发明专利
发明人：格雷戈里·詹姆斯·埃克基安,迈克尔·J·奇马,罗伯特·科马克,拉里萨·李,埃胡德·耶路汉姆·施密特
申请号：CN201880029241.5
申请日：20180303
公开号：CN110868910A
公开日：
20200306
专利内容由知识产权出版社提供
摘要：提供了一种氧传感器，该氧传感器用于在部署或植入组织部位时测量溶解氧浓度。
氧传感器包括用于氧的固态造影剂。
氧传感器被配置为当经受基于磁共振的方法时指示组织的溶解氧浓度。
氧传感器可用于标测肿瘤氧合水平并用于近距离放射治疗的适应性计划。
申请人：麻省理工学院,伯莱翰女子医院公司
地址：美国马萨诸塞州
国籍：US
代理机构：北京安信方达知识产权代理有限公司
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专利名称：Positive photoresist thermally stablecompositions and elements having deep UVresponse with maleimide copolymer发明人：Frederick R. Hopf,Michael J.McFarland,Christopher E. Osuch申请号：US07/024875申请日：19870317公开号：US04857435A公开日：19890815专利内容由知识产权出版社提供摘要：Actinic (deep ultraviolet, ultraviolet and visible) light sensitive positive photoresist compositions containing a mixture of an alkali- insoluble photoactive compound capable of being transformed into an alkali-soluble species upon exposure to actinic radiation, in an amount sufficient to render the mixture relatively alkali insoluble and a polymer comprising an amount of --CO--NH--CO-- groups, such as maleimide and especially maleimide-substituted styrene copolymers, sufficient to render the mixture readily alkali soluble upon exposure to actinic radiation are disclosed. The preferred copolymers include maleimide/styrene or &agr;-methylstyrene in a 1:1 molar ratio. The preferred photoactive compound suitable for a positive photoresist composition responsive to deep UV actinic radiation has the formula 18-B in Table I. The present invention also contemplates photosensitive elements and thermally stable photochemically imaged systems based on the actinic light sensitive positive photoresist compositions. The positive photoresist compositions are coated onto a substrate to produce a photosensitive element, which upon exposure to a pattern of actinic radiationof wavelength in the range of about 200-700 nm produces a photochemically imaged system that can be treated with an alkaline developer to form highly resolved patterns, by highly selective removal of exposed areas. After development, preferred embodiments of the photochemically images systems exhibit insignificant changes in the highly resolved features (one micron) in the patterned image upon postbaking at temperatures of about 230° C. and is, thereafter readily stripped. The high thermal stability exhibited by the photochemically imaged systems formed from the positive photoresist compositions of the present invention allows faster processing at higher temperatures, on equipment like plasma etchers and ion implanters; the developed photochemically imaged systems of the present invention retain high resolution, i.e., retain sharp, steep patterned image profiles.申请人：HOECHST CELANESE CORPORATION代理机构：Plottel & Roberts更多信息请下载全文后查看。
高分子专业英语词汇英汉对照关键词：英语高分子词汇英汉对照序号中文英文1 高分子macromolecule, polymer 又称"大分子"。
2 超高分子supra polymer3 天然高分子natural polymer4 无机高分子inorganic polymer5 有机高分子organic polymer6 无机-有机高分子inorganic organic polymer7 金属有机聚合物organometallic polymer8 元素高分子element polymer9 高聚物high polymer10 聚合物polymer11 低聚物oligomer 曾用名"齐聚物"。
12 二聚体dimer13 三聚体trimer14 调聚物telomer15 预聚物prepolymer16 均聚物homopolymer17 无规聚合物random polymer18 无规卷曲聚合物random coiling polymer19 头-头聚合物head-to-head polymer20 头-尾聚合物head-to-tail polymer21 尾-尾聚合物tail-to-tail polymer22 反式有规聚合物transtactic polymer23 顺式有规聚合物cistactic polymer24 规整聚合物regular polymer25 非规整聚合物irregular polymer26 无规立构聚合物atactic polymer27 全同立构聚合物isotactic polymer 又称"等规聚合物"。
28 间同立构聚合物syndiotactic polymer 又称"间规聚合物"。
29 杂同立构聚合物heterotactic polymer 又称"异规聚合物"。
30 有规立构聚合物stereoregular polymer, tactic polymer 又称"有规聚合物"。
更昔洛韦眼用在体凝胶剂的制备及其含量测定尤楠;邵恩颖;刘晨芳【摘要】试验制备了更昔洛韦眼用在体凝胶剂并测定更昔洛韦的含量.采用RP-HPLC法, 色谱柱: Dikma C 18柱(150 mm×4.6 mm, 5 μm); 流动相: V(甲醇):V(水)=10:90;检测波长: 254 nm; 柱温:室温; 流速: 1.0 mL/min.更昔洛韦在10.0～60.0 μg/mL范围内线性关系良好 (r2 = 0.999 5); 更昔洛韦的平均回收率为99.9 %, RSD为0.23 %.该方法简单、快捷, 回收率和重复性良好,可作为更昔洛韦在体凝胶剂质量评价的方法.【期刊名称】《当代化工》【年(卷),期】2010(039)002【总页数】3页(P126-128)【关键词】更昔洛韦;高效液相色谱;在体凝胶剂【作者】尤楠;邵恩颖;刘晨芳【作者单位】东北制药总厂质检处,辽宁,沈阳,110026;沈阳石蜡化工有限公司催化分厂,辽宁,沈阳,110141;东北制药总厂张士制药公司,辽宁,沈阳,110141【正文语种】中文【中图分类】TQ463单纯疱疹病毒性角膜炎是眼科常见的病毒感染性角膜病，易复发、病程迁延、易危害视力[1]。
更昔洛韦（ganciclovir）具有广谱抗病毒活性，主要包括对EB病毒、巨细胞病毒、腺病毒、带状疤疹及HSV-1和HSV-2。
Gcv由于其分配系数相对较低（log p= -1.55）[2]，而严重限制了其作为水溶液形式的局部应用。
因此治疗时需要频繁地给药而且在眼深部组织难以获得有效的药物浓度[3]。
而眼膏和眼用凝胶剂可以改善了抗病毒作用，但是由于这些剂型造成的不舒适和视觉上的损害，患者依从性差[3]。
眼部原位胶化给药系统就是药物以水溶液的形式给药，在滴人结膜囊内时，受到温度、pH值或离子强度的影响，迅速形成凝胶。
这种给药系统可以显著改善药物在结膜囊内的滞留时间，具有给药准确、方便，患者依从性好，不引起视力模糊等特点，同时可提高药物的眼局部生物利用度，是极具前景的新型眼用制剂[4-7]。
Enhanced brain targeting of curcumin by intranasaladministration of a thermosensitive poloxamer hydrogelXi Chen a,b *,Feng Zhi a,c *,Xuefeng Jia c ,Xiang Zhang c ,Rohan Ambardekar e ,Zhengjie Meng d ,Anant R.Paradkar e ,Yiqiao Hu c and Yilin Yang aaModern Medical Research Center,Third Affiliated Hospital of Soochow University,Changzhou,b College of Pharmacy,China PharmaceuticalUniversity,c State Key Laboratory of Pharmaceutical Biotechnology,School of Life Sciences,Nanjing University,d Biotechnology and Pharmaceutical Engineering,Nanjing University of Technology,Nanjing,China and e Institute of Pharmaceutical Innovation,University of Bradford,Bradford,UKKeywordscurcumin;nasal delivery;thermosensitive hydrogelCorrespondenceYilin Yang,Modern Medical Research Center,Third Affiliated Hospital of SoochowUniversity,#185Juqian Road,Changzhou,Jiangsu 213003,China.E-mail:yilinyang.czfph@ Yiqiao Hu,Room 1416,MengminweiBuilding,Nanjing University,Nanjing,Jiangsu 210093,China.E-mail:hu_yiqiao@Anant R.Paradkar,Norcroft Building (ex IPI),3.17,School of Life Sciences Engineering Design and Technology,University of Bradford,Bradford BD71DP ,UK.E-mail:a.paradkar1@ Received September 19,2012Accepted January 6,2013doi:10.1111/jphp.12043*These authors contributed equally to this work.AbstractObjectives The aim of this study was to develop a curcumin intranasal thermo-sensitive hydrogel and to improve its brain targeting efficiency.Methods The hydrogel gelation temperature,gelation time,drug release and mucociliary toxicity characteristics as well as the nose-to-brain transport in the rat model were evaluated.Key findings The developed nasal hydrogel,composed of Pluronic F127and Poloxamer 188,had shorter gelation time,longer mucociliary transport time and produced prolonged curcumin retention in the rat nasal cavity at body tempera-ture.The hydrogel release mechanism was diffusion-controlled drug release,evaluated by the dialysis membrane method,but dissolution-controlled release when evaluated by the membraneless method.A mucociliary toxicity study revealed that the hydrogel maintained nasal mucosal integrity until 14days after application.The drug-targeting efficiencies for the drug in the cerebrum,cerebel-lum,hippocampus and olfactory bulb after intranasal administration of the cur-cumin hydrogel were 1.82,2.05,2.07and 1.51times that after intravenous administration of the curcumin solution injection,respectively,indicating that the hydrogel significantly increased the distribution of curcumin into the rat brain tissue,especially into the cerebellum and hippocampus.Conclusions A thermosensitive curcumin nasal gel was developed with favour-able gelation,release properties,biological safety and enhanced brain-uptake efficiency.IntroductionThe blood–brain barrier (BBB)prevents the transport of almost 98%of all small-molecule and 100%of large-molecule pharmaceuticals from the bloodstream into the central nervous system (CNS).[1]Many drug-delivery strate-gies have been developed to overcome this barrier.Recently,the nasal mucosa has been investigated as a route for direct delivery of therapeutics to the CNS,circumventing the BBB.In addition to that,it enhances the systemic concentration of the drug by avoiding first-pass elimination.[2–5]Unlike most conventional liquid formulations for nasal delivery,bioadhesive nasal gels have high viscosity,which prolongs the drug contact time and releases the drug in a controlledmanner,which results in improved local and systemic bio-availability,reduced dose requirements,and improved patient safety and acceptability.Consequently,bioadhesive nasal gels could be very useful for efficient delivery of drugs used in the treatment of CNS disorders such as brain tumour and Alzheimer’s disease.[6–12]Curcumin,a naturally occurring o-methoxyphenol derivative,extracted from the rhizome Curcuma longa ,has a long history of use in Asia as a spice as well as in traditional therapies.[13]Curcumin has an outstanding safety profile and a number of pleiotropic actions,including anti-inflammatory,antioxidant,antitumoural and antimicrobialAnd PharmacologyJournal of Pharmacy Research Paperactivities,with the potential for neuroprotective activ-ity.[14,15]It has shown excellent efficacy in counteracting neu-ronal dysfunction[16]and in eliminating chemoresistance by sensitizing brain tumours to chemotherapy and radia-tion.[17,18]However,its clinical application has been limited due to its poor aqueous solubility,photosensitivity,rapid hydrolysis at alkaline pH and fast systemic elimination.[19] To be effective as a drug therapy for CNS disorders,curcu-min must be combined with other drugs or new delivery strategies must be developed.[20]In this regard,intranasal delivery seems to be an attractive alternative.[21]The physiological characteristics of the nasal mucosa and nasal mucociliary clearance are the two main considerations in designing nasal formulations.[2,22,23]The strategy to improve nasal drug bioavailability is to increase the drug absorption rate via permeation enhancers[24]or by prolong-ing the drug residence time at the nasal absorption site through hydrogels.[25]Biodegradable,thermosensitive poly-mers have been extensively studied for their utility in for-mulation of thermoresponsive intranasal hydrogels.[8,26–28] Such hydrogels can be dripped or sprayed into the nasal cavity as low-viscosity solutions at room temperature,con-sequently forming more viscous gels when in contact with nasal mucosa.[29]Pluronic F127(PF-127)is one of the most important thermoresponsive hydrogel-forming poloxamers and is widely applied in the biomedicalfield as a topical drug-delivery carrier.[30,31]The block copolymer poloxamer is an important component in thermosensitive hydrogels. Poloxamer consists of blocks of poly(ethylene oxide)(PEO) and propylene oxide(PPO)with a triblock structure:PEO x–PPO y–PEO x.A moderately concentrated solution of PF-127 forms a free-flowing solution at or below ambient tempera-ture and is able to form a gel at body temperature.It can thus be localized in the contact site with sustained release of the drug.PF-127alone has an incipient gelation tempera-ture below25°C and a long gelation time due to the low ratio of PEO to PPO(2.93,w/w,weight/weight),while Poloxamer188(P188)has a higher ratio(3.47,w/w).The addition of P188results in more hydrophilic PEO in the micelle,which increases the incipient gelation temperature and reduces the gelation time.Furthermore,the gelation temperature,also referred to as the sol–gel transition tem-perature,is strongly dependent on the poloxamer type and concentration,the type of solvent and other materials involved in the formulation.[32]The purpose of the present study was to develop a curcu-min mucoadhesive thermosensitive nasal hydrogel capable of undergoing sol–gel transition in the temperature range 32–35°C,thereby allowing a stable liquid state to be main-tained at storage temperature.The hydrogel gelation tem-perature,gelation time,drug release,mucociliary toxicity characteristics and nose-to-brain transport in the rat model were also evaluated.Materials and MethodsAnimalsMale Sprague-Dawley rats weighing about250g were pur-chased from the Shanghai Laboratory Animal Center, Chinese Academy of Sciences(Shanghai,China)and main-tained under standard environmental conditions(tempera-ture25Ϯ1°C;relative humidity70%;12-h light/dark cycle with lights on at6:00am)with free access to food and water.Animal welfare and experimental procedures were carried out in accordance with the Guide for the Care and Use of Laboratory Animals(Ministry of Science and Tech-nology of China,2006)and the related ethical regulations of our university.All the animal experiments were approved by Soochow University Animal Care and Use Committee (SDU-ACUC)and were arranged to minimize suffering and to reduce the number of animals used.The approval was given on30March2012,number SCXK2008_0016. MaterialsCurcumin was purchased from Nanjing Zelang Medical Technology Co.Ltd(Jiangsu,China).All the procedures related to curcumin were performed under dim light in order to prevent its degradation.Emodin was supplied by the National Institute for the Control of Pharmaceutical and Biological Products(Beijing,China).PF-127and P188 were obtained from BASF(Hanover,Germany).PEG400, sodium chloride and benzalkonium bromide(BKB)were purchased from Sigma-Aldrich(St Louis,MO,USA).Except for the acetonitrile and methanol(of HPLC grade;Merck, Darmstadt,Germany),all other chemicals used were ana-lytical reagent grade.All the solutions were prepared using water from a Milli-Q Gradientfiltration system(Millipore, Billerica,MA,USA).Thermosensitive hydrogel preparationThe‘cold’method for preparation of Pluronic gels was adopted.[33]Briefly,different amounts of PF-127and P188 (Table1)were dissolved in sterile distilled deionized water and gently mixed with magnetic stirrers for24h at4°C until all of the Pluronic granules were completely dissolved and a clear solution was obtained.Curcumin(5g)was dis-solved in20ml of an ethanol/PEG400mixture(eth-anol:PEG400=1:1)to form a curcumin solution.The PEG400was part of the curcumin control solution.Then 2ml of curcumin solution was added slowly to the Pluronic solution with continuous stirring.All other excipients such as BKB(0.02%,weight/volume,W/V)and sodium chloride 0.9%(w/v)were added to the mixture.The volume was adjusted with sterile distilled deionized water to achieve a 0.5%(w/v)concentration of curcumin.Xi Chen et al.Enhanced curcumin by hydrogelGelation temperature and gelation time studyThe sol–gel transition temperature (T sol–gel )of the prepared hydrogel was recorded using the test-tube-inverting method.[34,35]Briefly,2ml of hydrogel solution was added to a test-tube (10ml)with a diameter of 1.0cm in a digital circulating water bath (IKA,ETS-D5,Staufen,Germany)at 15°C and sealed with parafilm.The hydrogel was slowly heated,at a rate of 1.0°C/min,from 15°C to the temperature at which the meniscus would no longer move on tilting through 90°.The gelation time of samples at 32°C was determined using the same method.Briefly,the hydrogel solution (2ml)was added to a test-tube (10ml),incubated in a water bath at 32°C and time measurements initiated.The flowability of the sample was observed every 10s by tilting the tubes.The time at which flowing of the samples stopped was taken as the gelation time and the values were recorded.In-vitro release evaluation using the dialysis membrane method and the membraneless diffusion methodThe in-vitro drug release from the hydrogel was studied using the dialysis membrane method and the membraneless diffusion method.For the dialysis membrane method,200m l of liquid hydrogel was introduced into a dialysis membrane bag (Spectrapore,cutoff 1.2–1.4kD,Sigma-Aldrich)and the sealed dialysis bag was incubated in 400ml of release medium (0.8g/l NaCl,3g/l KCl and 0.45g/l CaCl 2,pH 6.8,20%ethanol v/v),maintained at 32°C Ϯ0.5°C and con-stantly stirred at a speed of 50rpm.At 5,10,15,20,25,30,40,50,60,80,120,150,180,210,240,300and 360min,3ml of dissolution medium was withdrawn and the same volume of fresh medium was added.For in-vitro release evaluation using the membraneless diffusion method,a volume of 1ml of the liquid hydrogel at room temperature was put into a pre-weighed empty glass tube (12mm ¥75mm)and then placed in a 32°C water bath until a clear gel formed.The initial weight of each tube plus the gel was recorded.A volume of 1ml ofthe medium (pre-equilibrated at 32°C)was carefully layered over the surface of the gel.The tube was then shaken in a thermostatic shaker (THZ-300,Yiheng,Shang-hai,China)at 32°C and 100rpm.At 10,20,40,60,80,100,120,140and 160min,the release medium was completely replaced by fresh medium,and the weight of the tube plus the gel was recorded to calculate the weight of gel dis-solved.The samples were suitably diluted and measured spectrophotometrically at 426nm (SHIMADZU UV-2450spectrophotometer,Koyoto,Japan).The concentration of the drug was determined from a previously constructed calibration curve.The release experiments were run in triplicate using plain formulations as a blank;the results were averaged.In-vivo mucocilliary transport time evaluationThe in-vivo nasal mucociliary transport time was adopted as per previous reports.[36]For the intranasal administra-tion,the rats were anesthetized with an intra-peritoneal injection of 10%chloral hydrate solution,and 50m l of the hydrogel solution was administered via a polyethylene (PE)10tube attached to a microlitre syringe inserted 0.5cm into right nostril of the rats.The pharyngeal remains of the yellow curcumin were detected by swabbing the oral cavity of the rat with moistened cotton-tipped applicators for 1min at regular time intervals.Curcumin solution (50m l)served as a control and was detected similarly.In-vivo morphological studyThe in-vivo morphological study was carried out as previ-ously described.[37]Briefly,the rats were sedated with an intraperitoneal injection of 10%chloral hydrate solution before nasal administration,and then each rat’s right nostril was treated with 50m l of thermosensitive hydrogel every day.Fourteen days later,the rats were sacrificed and the nasal septum,with the epithelial cell membrane on each side,was carefully separated from the bone.The left nostril was used as a control.The samples were fixed,sectioned and stained by hematoxylin and eosin,and were examined under light microscopy (IX71,Olympus,Tokyo,Japan).Table 1The gelation temperature (T )and gelation time (t )of different hydrogelformulationsXi Chen et al .Enhanced curcumin by hydrogelPharmacokinetic analysis and brain tissue distribution studyFor the intranasal administration,the rats were anesthetized with an intra-peritoneal injection of10%chloral hydrate solution,and the calculated volume of hydrogel solution was administered via a PE10tube attached to a microlitre syringe inserted0.5cm into the right nostril of the rats at a dose of250m g/kg.For the i.v.administration,the curcumin solution was injected(250m g/kg)through the caudal vein. The animals were decapitated and the blood was collected from the trunk.The skull was cut open and the cerebrum, cerebellum,hippocampus and olfactory bulb were carefully excised.The brain tissues were quickly rinsed with saline and blotted withfilter paper to remove the blood taint and macroscopic blood vessels as much as possible.After weigh-ing,the cerebrum,cerebellum,hippocampus and olfactory bulb samples were homogenized.Blood samples were anti-coagulated with sodium citrate and centrifuged at12000g for10min to obtain the plasma.Both plasma and brain tissue homogenates were stored in a deep freezer at-20°C until HPLC analysis.Measurements were repeated on three rats at each time point.Sample preparation and HPLCTwo hundred microlitres of emodin ethanol solution (1mg/l),0.5ml of ethyl acetate and0.5ml of hexane were added to both the500m l plasma samples and500m l brain tissue homogenates(brain tissue:saline=2:1,w/v).The mixture was vortexed for5min and centrifuged at12000g for10min.The organic phase was transferred to a conical tube and evaporated to dryness under a gentleflow of nitrogen at40°C.For the plasma sample,the residue was reconstituted in200m l of acetonitrile and20m l of superna-tant was injected onto the HPLC system.For the brain tissue samples,the residue was reconstituted in200m l of acetonitrile and20m l of supernatant was injected onto the HPLC system after centrifugation at12000g for5min. Samples were quantified using the peak area ratio of curcu-min to emodin.Curcumin content was measured by HPLC (LC-20A and SPD-20A,Shimadzu,Japan)at a wavelength of426nm,and a Hypersil C18ODS column(5m m, 250mm¥4.6mm;Elite,Dalian,China)was used.The mobile phase(acetonitrile:methanol:water,v/v/ v=60:20:20)was delivered at aflow rate of1ml/min at ambient temperature.Statistical analysisStatistical analyses of differences between the various treat-ments were performed using the Kruskal–Wallis test.A0.05 level of probability(P<0.05)was taken as the level of significance.ResultsGelation temperature and gelationtime studyThe gelation temperature(T)and gelation time(t)are two important parameters for in-situ forming of hydrogels.The performance criteria of the nasal-delivery formulations are imposed by the physiological temperature of the nasal cavity(32–35°C[38])and by the mucociliary clearance time (half-life~21min[39]),which correspondingly specify the temperature range and time limits for the sol–gel transition. As displayed in Table1,the gelation temperature and gela-tion time varied with the concentration of both PF-127and P188.Increasing PF-127concentration led to a decrease in gelation temperature and an increase in gelation time,while increasing P188concentration had the opposite effect.The gelation temperatures of batches F2and F6were32Ϯ0.5°C and31Ϯ1°C,respectively,close to the physiological tem-perature of the nasal cavity.The gelation times of F2and F6 were0.2Ϯ0.2and0.4Ϯ0.1min,respectively,well below the time for mucociliary clearance.Since F2had a shorter gelation time,it was selected for further analysis.In-vitro release evaluation using the dialysis membrane method and the membraneless diffusion methodThe drug-release behaviours of curcumin solution and F2 werefirstly measured in vitro by the dialysis membrane method.As evident from Figure1a,the release of curcu-min solution was rapid and almost complete within2h, while the incorporation of drug into the hydrogel signifi-cantly retarded drug release to about80%after6h,sug-gesting that most of the drug remained incorporated in the hydrogel under the study conditions.Consequently,the data obtained from the in-vitro release experiments were analysed by the commonly used Peppas exponential equation:[40]log log log.MMk n tt=+where M t/M is the fraction of released drug at time t,k is a release constant and is dependent on structural and geo-metric characteristics of the drug/polymer system,and n is the release exponent and is indicative of the release mechanism.If n<0.45,the drug is released from the polymer with a Fickian diffusion mechanism.If 0.45<n<0.89,this indicates anomalous or non-Fickian release.If n>0.89,the main mechanism is matrix erosion. The results revealed that the hydrogel had a value of n=0.27,indicating that the major mechanism was diffusion-controlled drug release or Fickian diffusion kinetics.When the curcumin-loaded hydrogel was sepa-Xi Chen et al.Enhanced curcumin by hydrogelrated from the release medium by a dialysis membrane,the dissolution of PF-127and P188wase almost prevented,and diffusion dominated the drug-release mechanism.In contrast,the membraneless model,also used in our study,allowed the release medium solution to directly contact the gel surface and thereby dissolve the gel.As shown in Figure 1b,in the membraneless dissolution experiment the volume of gel gradually decreased and completely disap-peared by the final time point.Several mathematical models,including the Higuchi release model,zero-order release model and first-order release model,were used to describe the kinetic behaviour of curcumin released from the hydrogel in the membraneless diffusion system.The drug-release profile followed the zero-order release model better (R 2=0.9965)than the other two release models.The correlation between gel dissolution and drug release was also investigated.The results showed that the remaining weight percentage of gels also followed zero-order kinetics (R 2=0.9985),and there was a good linear correlation between the percentage of curcumin released and the per-centage of gel dissolved,indicating a distinct polymer dissolution-controlled release mechanism (R 2=0.9910).In-vivo mucoadhesiveness of the nasal in-situ gelsThe hydrogels’in-vivo mucoadhesiveness ability was evalu-ated by measuring the mucociliary transport time,taken as the time for the passage of a coloured dye through the nasal cavity of rats until its appearance in their oropharynx.Cur-cumin is a naturally yellow drug and it could also be used as a dye.Figure 2illustrates that the mucociliary transporttime of the thermosensitive hydrogel is about 67min,which is almost 10-fold higher than that of curcumin solution,which served as a control.In-vivo morphological studyThe safety of the optimized in-situ gel formulation was evaluated by studying the histological changes in the nasal mucosa after administration into the right nostril of experi-mental rats for 14consecutive days (Figure 3).Examination of the dosed (right)and undosed (left)sides of the nasal cavity showed intact ciliated respiratory epithelium and normal goblet cell appearance in both cases.Signs of irrita-tion,such as vascular congestion and subepithelial edema,(a)(b)1008060402001008060402001008060402000040408012016080120160200240280320360Time (min)Time (min)D r u g r e l e a s e d (%)D r u g r e l e a s e d (%)Gel remaining weight (%)hydrogel solutionFigure 1(a)In-vitro drug release kinetics from curcumin thermosensitive hydrogel and curcumin solution using the dialysis-membrane model at 37°C.Data are expressed as mean Ϯstandard deviation (n =3).(b)In-vitro drug release (%)and in-vitro gel dissolution (remaining wt %)from ther-mosensitive hydrogel as a function of time (min),using the membraneless model at 37°C.Data are expressed as mean Ϯstandard deviation (n =3).100806040200SolutionHydrogelT i m e (m i n )P < 0.001Figure 2In-vivo mucociliary transport time of the thermosensitive hydrogel and curcumin solution.Xi Chen et al .Enhanced curcumin by hydrogelwere not observed.Moreover,no severe signs such as the appearance of epithelial necrosis,sloughing of epithelial cells and haemorrhage were detected in any of the rats.These observations validated the safety of the formulation.Drug brain distribution andpharmacokinetic analysis of curcumin The mean brain tissue and plasma concentration–time pro-files of curcumin in male rats following a single dose of the nasal in-situ gel and the i.v.injection of curcumin solution are illustrated in Figure 4.Following administration of the nasal in-situ gel at a dose of 250m g/kg,the respective AUC 0→6h values of curcumin in the cerebrum,cerebellum,hippocampus,olfactory bulb and plasma were 288.50Ϯ25.95ng h/g,295.37Ϯ11.23ng h/g,577.03Ϯ30.29ng h/g,1058.67Ϯ51.73ng h/g and 167.03Ϯ16.57mg h/l (means ϮSE).The AUC 0→6h values of curcumin in the cerebrum,cerebellum,hippocampus,olfactory bulb and plasma fol-lowing an i.v.dose of 250m g/kg were 263.87Ϯ9.82ng h/g,238.37Ϯ7.95ng h/g,464.10Ϯ20.01ng h/g,1159.00Ϯ105.23ng h/g,and 281.97Ϯ50.30mg h/l respectively.The curcumin concentration in the brain by intranasal treat-ment was similar to that by i.v.treatment in the first 2h,but it was higher in the following 4h.The AUC 2→6h values of curcumin in the cerebrum,cerebellum,hippocampus and olfactory bulb were 189.23Ϯ12.34,192.26Ϯ26.47,367.84Ϯ18.64and 698.85Ϯ25.72ng·h/g for intranasal administration,while the AUC 2→6h values of curcumin in the cerebrum,cerebellum,hippocampus and olfactory bulb following i.v.administration were 121.83Ϯ6.45,122.61Ϯ8.84,260.75Ϯ13.87and 572.88Ϯ22.64ng·h/g,respectively.Although the amount of curcumin reaching the brain via intranasal administration was slightly higher than that by i.v.administration after 6h,it was significantlyhigher in the last 4h.The drug-targeting efficiency (DTE)of the i.v.injection or the nasal in-situ gel,calculated as AUC brain /AUC plasma for curcumin,is illustrated in Figure 5.The intranasal administration of the in-situ gel produced significantly higher figures for the DTE in the cerebrum cer-ebellum,hippocampus and olfactory bulb over 0.167–6h than i.v.injection.For example,the DTE for the drug in the cerebrum,cerebellum,hippocampus and olfactory bulb after intranasal administration of the curcumin hydrogel at 6h were 1.82,2.05,2.07and 1.51times that after intrave-nous administration,respectively,which indicated that the hydrogel significantly increases curcumin delivery into the brain.DiscussionIn the past decade,intranasal thermosensitive hydrogels have garnered increasing attention for biomedical and phar-maceutical applications,mainly because of their therapeutic convenience.Hydrogels are liquid-like in vitro ,which sim-plifies accurate dose measurement and nasal administration as a drop or by a spray device.Interestingly,they become semisolid as soon as there is contact with the mucosa,con-sequently prolonging the drug residence time and drug absorption in the nasal cavity.Therefore,determination of the proper gelation temperature and a rapid gelation time are the two main aspects of designing a biocompatible ther-mosensitive hydrogel.The physiological range of the nasal mucosa temperature lies between 32and 35°C,which matches the observed T sol–gel (32°C)for the prepared gel.[38]Considering this,the prepared gel is likely to show a clear viscosity rise following intranasal administration.It is pos-sible to modulate the gelation properties of the hydrogels for intranasal drug delivery by varying the combination of poloxamer mixtures.A thermosensitive and mucoadhesive(a)(b)Figure 3Microscopic photos of normal nasal mucosa (a)and nasal mucosa after treatment with thermosensitive hydrogel for 14days (b).Xi Chen et al .Enhanced curcumin by hydrogelin-situ gel for nimesulide has been developed for rectal administration by mixing poloxamer PF-127and polyethyl-ene glycol (PEG),[41]while a temperature-responsive and biodegradable hydrogel for controlled delivery of human growth hormone was obtained by mixing PV A,PVP k30and PF-127together.[42]It is also crucial to measure the gelation time and mucociliary transport time.The shorter the gelation time,the longer will be the mucociliary trans-port time and hence more drug will be retained on the nasal mucosa.Our results suggest that the hydrogel formulation has a suitable gelation time,which enhances drug retention on the nasal mucosa over plain curcumin solution.Further250200150100500Plasmain ivinivinivin ivin iv0123456C o n c e n t r a t i o n (m g /l )C o n c e n t r a t i o n (n g /g )C o n c e n t r a t i o n (n g /g )C o n c e n t r a t i o n (n g /g )C o n c e n t r a t i o n (n g /g )Time (min)123456Time (min)123456Time (min)0123456Time (min)0123456Time (min)806040200806040200CerebrumHippocampusOlfactory bulbCerebellum150100505004003002001000Figure 4Mean concentration–time profiles of curcumin in the plasma and various brain regions after intranasal and i.v.administration to male rats (n =3).in,in-situ gel;iv,intravenous injection.Concentrations corrected for the differences in doses.Xi Chen et al .Enhanced curcumin by hydrogelto this,histological assessment validated the safety of the formulation over 2weeks;its suitability for long-term clini-cal use still needs to be assessed.The physicochemical properties of the hydrogel network and the drug determine the mechanism(s)by which the loaded drug is released from the cross-linked matrix.Drug release from the hydrogel occurs by two principal mecha-nisms:(i)drug diffusion from the hydrogel during the initial release phase and (ii)release of drug by the erosion of the hydrogel matrix during the later release phase.The diffusion-controlled release mechanism is that the flux goes from regions of high concentration to regions of low con-centration,with a magnitude that is proportional to the concentration gradient.Once a matrix delivery device comes in contact with a surrounding biofluid,a concentra-tion gradient will exist between the dispersed drug within the hydrogel and the ambient fluid.Thus the gradual release of drug from the hydrogel depends on the incorporating efficiency,and its diffusion to the external medium depends on the concentration gradient.In the dissolution-controlled drug-release model,the drug is homogeneously distributedthroughout the polymer matrix.As the polymer matrix dis-solves,drug molecules are released regardless of drug solu-bility in the dissolution media.In the dialysis membrane method,the hydrogel was totally immersed in the stirred release medium,which would facilitate drug release.However,in the membraneless method,the solid hydrogel was at the bottom of a glass tube,with only a small surface area in contact with the release medium.As the polymer matrix dissolved,curcumin was released.Thus the drug-release rate in the membraneless method was lower than that in the dialysis membrane method,especially in the initial phase.The value of n =0.27indicated that the major mechanism was diffusion-controlled drug release or Fickian diffusion kinetics when the dialysis membrane method was used.However,drug release might be hindered by the addi-tional barrier provided by the dialysis membrane,which restricts the dissolution of PF-127and P188.The mem-braneless model allowed the release medium to come into direct contact with the gel surface and thereby dissolve the gel.The drug-release profile in this case followed the zero-order release model (R 2=0.9965).In the nasal cavity,the2.52.01.51.00.50.02.52.01.51.00.50.010864205432100.1670.512460.1670.512460.1670.512460.1670.51246CerebrumCerebellumOlfactory blubHippocampusin ivin ivin ivin ivabbbbaaaaaaaaaaaaaaaaaa aA U C b r a i n /A U C p l a s m aFigure 5Mean brain-to-plasma AUC ratios of curcumin in various brain regions after intranasal and i.v.administration to male rats (250m g/kg.n =3.in,in-situ gel;iv,intravenous injection,b P <0.05,a P <0.01).Xi Chen et al .Enhanced curcumin by hydrogel。
Thermosensitive copolymer with cobalt phthalocyanine and catalytic behavior based on adjustable LCSTWangyang Lu a ,Baoyan Zhao b ,Nan Li a ,Yuyuan Yao a ,Wenxing Chen a,*a Key Laboratory of Advanced Textile Materials and Manufacturing Technology,Ministry of Education of China,Zhejiang Sci-Tech University,Hangzhou 310018,China bZhejiang Textile and Fashion College,Ningbo 315211,Chinaa r t i c l e i n f o Article history:Received 19June 2009Received in revised form 9November 2009Accepted 13November 2009Available online 18November 2009Keywords:PhthalocyanineThermosensitive copolymers N -isopropylacrylamide AcrylamidePhase separationa b s t r a c tThermosensitive polymers with metallophthalocyanine were prepared by immobilizing cobalt tetra(2,4-dichloro-1,3,5-triazine)aminophthalocyanine (Co-TDTAPc)on poly(N -isopropylacrylamide)(PNIPA)and copolymers of N -isopropylacrylamide (NIPA)with acrylamide (AM)(P(NIPA-co-AM))to obtain Co-TD-TAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM).Examination of the thermosensitive behavior of these poly-mers showed that the proportion of AM in Co-TDTAPc–P(NIPA-co-AM)had a significant effect on the low critical solution temperature (LCST)in aqueous solution.The LCST of Co-TDTAPc–P(NIPA-co-AM)was adjustable from 34.5°C to 90.0°C by changing the AM molar fraction from 0%to 40%.The copolymers showed a high level of catalytic activity on the oxidation of 2-mercaptoethanol in the homogeneous phase when the reaction temperature was below the LCST,and the copolymers could be precipitated and recovered by heterogeneous separation when the temperature was above the pared to Co-TDTAPc–PNIPA,the catalytic system with Co-TDTAPc–P(NIPA-co-AM)is able to maintain homogene-ity at a higher temperature due to the higher LCST of the copolymers.In addition,strong salting-out salts,such as NaCl and Na 2SO 4,can decrease the LCST of the copolymers dramatically and obviate the need for more heat to drive the catalytic reaction system to achieve heterogeneous separation.Co-TDTAPc–P(NIPA-co-AM)was stable and remained efficient during repetitive test cycles with no obvious decrease of catalytic activity.Ó2009Elsevier Ltd.All rights reserved.1.IntroductionMetallophthalocyanine derivatives (MtPc),which are structur-ally analogous to the active center of cytochrome P-450,have been used as an effective catalyst for a variety of organic reactions [1–5].As an important class of photosensitizers,MtPc can be used in pho-todynamic therapy for treatment of a range of cancers,macular degeneration,and infectious diseases [6–8],but wider application of MtPc is limited,mainly due to the tendency for aggregation and the difficulty of catalyst recovery and recycling.The aggrega-tion tendency of the dendritic phthalocyanines decreases as the size of the dendrons increases [9–13];however,it is very difficult to realize catalyst recovery and recycling by this method.The strat-egy of immobilizing MtPc on selected insoluble supports (such as activated charcoal,zeolite or clay)has been introduced and used to prepare polymeric MtPc catalysts and thereby to facilitate cata-lyst separation and recycling,which reduces effluent contamina-tion [14–18].Unfortunately,the catalytic activity of these materials is reduced (compared with that of their nonsupportedsoluble counterpart)and,as in the case of photodynamic therapy,if they are not amenable to immobilization of MtPc on an insoluble rigid support,the application cannot be realized.Poly(N -isopropylacrylamide)(PNIPA)is one of the most popular thermosensitive polymers,and undergoes a sharp conformational transition from a water-soluble random coil into water-insoluble globule forms at 32–34°C in aqueous solution [19–22].To obtain MtPc catalysts that have a low aggregation tendency and can be recycled,our group has explored a general approach to the synthe-sis of polymeric MtPc catalysts by introducing a polymerizable N -acrylic carbonyl group into the side chains of cobalt tetraamin-ophthalocyanine (Co-APc)and then copolymerizing with N -isopro-pylacrylamide (NIPA)[23].This copolymer has a high level of catalytic activity in the homogeneous phase and could be recovered by simple heating and heterogeneous separation.The catalytic activity showed a marked decrease when the reaction temperature was above the lower critical solution temperature (LCST)of the copolymer ($32.6°C).Thus,the reaction temperature must be controlled below the LCST to achieve a high level of catalytic activ-ity.However,the environmental temperature in some catalytic applications of MtPc are naturally above this LCST,for instance,in studies of MtPc in the photodynamic therapy field,in which the1381-5148/$-see front matter Ó2009Elsevier Ltd.All rights reserved.doi:10.1016/j.reactfunctpolym.2009.11.002*Corresponding author.Tel./fax:+8657186843251.E-mail address:chenwxg@ (W.Chen).Reactive &Functional Polymers 70(2010)135–141Contents lists available at ScienceDirectReactive &Functional Polymersj o ur na l h om e pa ge :w w w.e ls e v ie r.c o m/lo c a t e/re actreaction temperature must be maintained near the physiological temperature of37°C.In addition,other complicated environmental factors in photodynamic therapy,such as the mixture of salts in bodyfluids,must be taken into account.In the present study,we fo-cus our efforts on developing a novel approach to regulation and control of the LCST of these thermosensitive polymeric MtPc cata-lysts for catalytic applications in a wide range of temperature.Here,thermosensitive polymers with MtPc were prepared by immobilizing highly reactive cobalt tetra(2,4-dichloro-1,3,5-tri-azine)aminophthalocyanine(Co-TDTAPc)[24]onto the homopoly-mer of NIPA or a copolymer of NIPA and acrylamide(AM)in different molar fractions to obtain Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM).We describe the thermosensitive proper-ties and catalytic activities of the water-soluble polymeric catalysts Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM).The copoly-mers were characterized by UV/vis spectra,Fourier transform infrared(FT-IR)spectra,nuclear magnetic resonance(1H NMR), atom absorption spectroscopy(AAS),and dynamic thermogravi-metric analysis(TGA).The LCST of these copolymers was measured by an UV/vis spectrophotometer in a constant-temperature water bath.Considering the importance of environmental factors in the application of MtPc,we focused on investigating the effects of var-ious salts on the LCST of these polymers.The catalytic activity of the polymers was estimated by measuring the efficiency of cata-lytic oxidation on2-mercaptoethanol at different temperatures. Due to the higher LCST of Co-TDTAPc–P(NIPA-co-AM),the temper-ature range for application of these polymers can be enlarged. These copolymers have potential applications in developing new water-soluble polymeric catalysts containing MtPc with thermo-sensitive properties.2.Experiment2.1.MaterialsNIPA(Tokyo Kasei Kogyo Co.,Ltd.)was recrystallized from a1:1 (V/V)mixture of hexane and toluene.AM(Shanghai Lingfeng Chemical reagent Co.,Ltd.Shanghai,China),cobalt chloride hexa-hydrate,urea,and ammonium molybdate were purchased as ana-lytical grade reagents and used as received.Cyanuric chloride (2,4,6-trichloro-1,3,5-triazine,analytical grade)was purchased from Acros.Ammonium persulphate(APS,initiator)was obtained from Aldrich Chemical Co.,Inc.N,N,N0,N0-tetramethylethylenedi-amine(TEMED,accelerator)was purchased from Sigma–Aldrich Co.,Ltd.All the other chemicals were of reagent grade.Water was deionized with a Millipore Milli-Q system.2.2.Synthesis of Co-TDTAPcCobalt tetraaminophthalocyanine(Co-APc)was synthesized from4-nitrophthalic acid,cobalt chloride hexahydrate,and urea as described[25].Co-TDTAPc was prepared by reaction of cyanuric chloride with Co-APc in N,N0-dimethylformamide(DMF)[24].2.3.Synthesis of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)PNIPA and P(NIPA-co-AM)were synthesized essentially as de-scribed by Schild and co-workers but with modifications,and poly-mers were obtained after drying in vacuo[26].Co-TDTAPc–PNIPA was prepared as follows:2.8g of PNIPA was dissolved in80mL of water at room temperature under agitation.Thirty-three milli-gram of Na2CO3was added to this solution.The mixture was stir-red to ensure that all of the solutes had dissolved.Next,140mL of 0.388mmol/L Co-TDTAPc aqueous solution was added rapidly to the above system during the stirring process,which continued for1h before separation and purification.After the reaction,the insoluble and hydrolyzed Co-TDTAPc was eliminated from the solution by centrifugation.The bottle-green supernatant was re-moved by keeping the solution above50°C,and the pellet was dis-solved in100mL of water.The same process was then repeated three times.The resulting solid was dried in vacuo and then dis-solved in50mL of acetone.The solution was centrifuged to remove Co-TDTAPc,which is insoluble in acetone.The polymer was precip-itated in hexane,then dried in vacuo at45°C for48h to yield Co-TDTAPc–PNIPA.In a similar manner,Co-TDTAPc–P(NIPA-co-AM) was synthesized with different molar fractions of AM,and the pre-cipitation and purification process was done by keeping the solu-tion above50°C.When the AM molar fraction was greater than 17%,the copolymer obtained was dissolved in ethanol and then precipitated in hexane because Co-TDTAPc–P(NIPA-co-AM)is insoluble in acetone when the AM molar fraction is greater than 17%.Here the designation X in Co-TDTAPc–P(NIPA-co-XAM)de-notes the AM unit feed mole percentage in the copolymer,as shown in Table1.2.4.Polymer characterizationThe UV/vis spectra of these copolymers in water,ethanol and DMF were recorded with a Hitachi U-3010spectrophotometer.A Thermo solaar M6atomic absorption spectrometer was used for the determination of the cobalt weight fraction in Co-TDTAPc–PNI-PA and Co-TDTAPc–P(NIPA-co-AM).The FT-IR spectra of samples were recorded using a Thermo-Nicolet5700FT-IR spectrometer. 1H NMR spectra were measured on a Bruker AVANCE400 (400MHz)spectrophotometer using DMSO-d6as a solvent and tet-ramethylsilane(TMS)as an internal standard.The cobalt phthalo-cyanine(CoPc)molar fraction in polymers can be calculated according to the cobalt weight fraction.TGA analysis was done with a Perkin–Elmer Pyris1instrument under nitrogen atmo-sphere with aflow rate of100mL/min and a heating rate of 10°C/min.In the solubility test,Co-APc,Co-TDTAPc,PNIPA,Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)(0.01g)were placed into10mL of solvent(water,DMF,ethanol,acetone,tetra-hydrofuran(THF)and chloroform,respectively)and vibrated at 25°C for24h in a thermostatic vibrator.Next,the solution wasfil-tered and the insoluble substrate was collected,dried and weighed. The molecular weight of PNIPA,P(NIPA-co-AM),Co-TDTAPc–PNI-PA,and Co-TDTAPc–P(NIPA-co-AM)was measured by gel perme-ation chromatography(GPC)with three series of aqueous phase columns(Waters Ultrahydrogel250,500and2000, 7.8Â300mm)utilizing a Waters515pump,a Wyatt HELEOS18-angle light scattering detector,and a Wyatt Optilab rEX refractive index detector.H2O was used as the eluent at1mL/min.2.5.LCST measurementThe phase transition of the aqueous polymer solution(1mg/ mL)was detected visually in a closed glass tube and the tempera-ture was controlled by immersion of the glass tube in a constant-temperature water bath.The aqueous solution was adjusted to pH6.7by a diluted aqueous solution of NaOH or HCl.The LCSTs were examined with a Lambda900UV/vis spectrophotometer (Perkin–Elmer)with a constant-temperature water bath by immersion of test tubes containing polymer solutions as a function of temperature.The phase transition was monitored by optical transmittance at500nm through a1-cm sample cell reference against distilled water.The temperature was altered manually, and the solution was allowed to equilibrate for at least5min at each temperature point.LCST is defined as the temperature point at which50%of the absorbance change occurred.The same method136W.Lu et al./Reactive&Functional Polymers70(2010)135–141was used to determine the LCST values of the polymers in the pres-ence of different salts,such as NaCl,Na2SO4,NaBr,and NaSCN. 2.6.Measurement of catalytic activityThe reaction rates of oxidation of2-mercaptoethanol in the presence of the catalyst were determined by measuring the oxygen consumption in the reaction mixture with a gas burette[27].The 2-mercaptoethanol solution was adjusted to pH11.0with NaOH. The system was equipped with a water jacket,and the reaction solution was stirred by a magnetic follower.The oxygen burette, the reactor,and the connection pipe were thermostatically con-trolled,and the temperature of the entire system was regulated by controlling the temperature of the water jacket.The initial reac-tion rate,V0=Àd[HOCH2CH2SH]/d t,was taken from the slope of the tangent line of the concentration of HOCH2CH2SH consumption oxidized by oxygen versus time.The concentration of RSH oxidized by oxygen was calculated from the concentration of consumed oxygen in solution[23].3.Results and discussion3.1.Preparation of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)PNIPA was prepared at room temperature(25°C)by aqueous redox polymerization and a high yield was achievable with further purification by heating.A series of AM-modified P(NIPA-co-AM) copolymers were synthesized via aqueous redox polymerization. Due to the high electrophilic reactivity of2,4-dichloro-1,3,5-tri-azine in Co-TDTAPc[24],Co-TDTAPc can react with imino or amido groups in PNIPA and P(NIPA-co-AM),respectively,in the presence of sodium carbonate in aqueous solution,as shown in -pared with the copolymer of cobalt tetra(N-carbonylacrylic)amin-ophthalocyanine and NIPA(if the weight ratio of CoPc to NIPA was above1%in the solution,an insoluble gel tended to form at room temperature,which would limit its application as a homoge-neous catalyst),the weight ratio of CoPc in this system could be improved without the existence of an insoluble gel because the steric extrusion of the macromolecular chain in PNIPA or P(NIPA-co-AM)can prevent cross-linking between Co-TDTAPc and poly-mers.The molar ratio of CoPc in Co-TDTAPc–PNIPA and in Co-TDTAPc–P(NIPA-co-AM)with different AM molar ratios are given in Table S1.In addition,the weight-average molecular weight (M w)and number-average molecular weight(M n)were measured by GPC combined with18-angle light scattering detector,as shown in Table pared with PNIPA and P(NIPA-co-AM),the molec-ular weight of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM) increased very slightly,indicating that Co-TDTAPc was attached to these polymers but there was seldom cross-linking present in these polymers.For structure characterization and measurement of the thermo-sensitive behavior of polymers,we tested the solubility of Co-APc, Co-TDTAPc,Co-TDTAPc–PNIPA,and Co-TDTAPc–P(NIPA-co-AM)in different solvents,as shown in Table1.The results revealed that Co-APc and Co-TDTAPc were soluble only in strong aprotic sol-vents,such as DMF.Co-TDTAPc immobilized on PNIPA exhibited excellent solubility in most solvents because Co-TDTAPc had little effect on the excellent solubility of PNIPA alone,and the polymer improved the solubility of Co-TDTAPc.However,when Co-TDTAPc was immobilized on P(NIPA-co-AM),the solubility changed with increased AM molar fraction.Co-TDTAPc–P(NIPA-co-AM)was highly soluble in strongly polar solvents,such as water,ethanol, and DMF.Co-TDTAPc–P(NIPA-co-AM)was dissolved selectively in solvents of relatively decreased polarity,such as acetone,THF, and chloroform.These polymers have been characterized by FT-IR,1H NMR,and UV/vis spectroscopy.The absorbance of Co-TDTAPc in FT-IR spectra (Fig.S2)was not marked because the amount of CoPc in Co-TDTAPc–PNIPA was very small(about1–2wt.%).In addition,the 1H NMR of Co-TDTAPc–PNIPA(Fig.S3)and Co-TDTAPc–P(NIPA-co-AM)(Fig.S4)was almost identical to that of PNIPA and P(NIPA-co-AM),respectively,due to the paramagnetism of Co-TDTAPc.Therefore,the UV/vis spectra were used to prove whether Co-TDTAPc was supported on PNIPA or P(NIPA-co-AM).The UV/vis spectra of virgin and Co-TDTAPc-labeled thermosensitive polymers in different solvents are compared in Figs.1and2.We used water, ethanol,and DMF as solvents to determine the solubility of the polymers(Table1).It can be seen in Fig.1that Co-TDTAPc–PNIPA shows an absorption band at$300nm and another at600–700nm,corresponding to the B band and the Q band of metall-ophthalocyanines,respectively[28,29].These absorption bands were not present in the UV/vis spectrum of PNIPA.Since Co-APc and Co-TDTAPc were insoluble in ethanol,it could be confirmed that Co-TDTAPc had been attached to PNIPA.Of course,Co-TDTAPc had also been attached to P(NIPA-co-AM),as shown in Fig.2.As an important catalyst parameter to be evaluated,the thermal stability of phthalocyanine and polymers was investigated by TGA. Fig.S5presents the weight loss curves recorded for Co-TDTAPc, PNIPA,and Co-TDTAPc–PNIPA.The weight loss of Co-TDTAPc occurs at temperatures between230°C and375°C,whichTable1Solubility test of Co-APc,Co-TDTAPc,PNIPA,and Co-TDTAPc–P(NIPA-co-AM)with different AM molar fractions(25°C).Samples H2O DMF Ethanol Acetone THF CHCl3Co-APcÀ+ÀÀÀÀCo-TDTAPc+a+ÀÀÀÀPNIPA++++++ Co-TDTAPc–PNIPA++++++ Co-TDTAPc–P(NIPA-co-1.06AM)++++++ Co-TDTAPc–P(NIPA-co-2.17AM)++++++ Co-TDTAPc–P(NIPA-co-3.23AM)++++++ Co-TDTAPc–P(NIPA-co-3.85AM)++++++ Co-TDTAPc–P(NIPA-co-4.76AM)+++++ÀCo-TDTAPc–P(NIPA-co-9.09AM)+++++ÀCo-TDTAPc–P(NIPA-co-16.67AM)+++++ÀCo-TDTAPc–P(NIPA-co-25.00AM)+++À+ÀCo-TDTAPc–P(NIPA-co-28.57AM)+++ÀÀÀCo-TDTAPc–P(NIPA-co-33.33AM)+++ÀÀÀCo-TDTAPc–P(NIPA-co-38.46AM)+++ÀÀÀCo-TDTAPc–P(NIPA-co-40.00AM)+++ÀÀÀ+,soluble;À,insoluble.a The solution of Co-TDTAPc can be obtained when the fresh sample of Co-TDTAPc was prepared in aqueous solution.W.Lu et al./Reactive&Functional Polymers70(2010)135–141137corresponds to decomposition of the side chains of cobalt phthalo-cyanine.The decomposition of the molecular chain of PNIPA starts from 345°C,while that of Co-TDTAPc–PNIPA starts from 425°C,showing that Co-TDTAPc–PNIPA is more stable than PNIPA at high-er temperature.This can be explained by the fact that phthalocya-nine molecules can form physical cross-linking points in the polymer matrix at high temperature,which can improve the stabil-ity of the polymer.Co-TDTAPc can also improve the stability of P(NIPA-co-AM)due to a similar mechanism.3.2.Thermosensitive behavior of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)Cloud-point temperature measurements have been used to study the effects of the hydrophilic/hydrophobic balance in a series of Co-TDTAPc–P(NIPA-co-AM)copolymers upon the smart thermal responses of these systems in dilute aqueous solution (Fig.S6).Fig.3shows the LCST of aqueous solutions of Co-TDTAPc–P(NIPA-co-AM)with different compositions.With increased AM molar ratio,a pronounced change was observed in the LCSTofFig. 1.UV/vis spectra of PNIPA and Co-TDTAPc–PNIPA in different solvents including:(a)water,(b)ethanol,and (c)DMF.Fig.2.UV/vis spectra of P(NIPA-co-28.57AM)and Co-TDTAPc–P(NIPA-co-28.57AM)in different solvents including:(a)water,(b)ethanol,and (c)DMF.138W.Lu et al./Reactive &Functional Polymers 70(2010)135–141Co-TDTAPc–P(NIPA-co-AM).The increase in the content of the more hydrophilic AM monomer will lead to an obvious increase of the LCST of the system.The results might be expected from the predictions of Taylor and Cerankowski [30]and other studies [31,32]in which the hydrophilic/hydrophobic balance of NIPA-based systems was altered.The phase transition of Co-TDTAPc–P(NIPA-co-28.57AM)is shown in Fig.4.The transparent aqueous solution (A)is trans-formed into a turbid liquid (B)when it is warmed above the LCST of the polymer (55.8°C).This indicates a microphase separation,but without obvious precipitation.Continuous heating causes the system morphology to undergo further changes and results in the formation of a granular deposit (C).As time increases,the precipita-tion process produces a separation between the polymer and the solution (D).With constant homotropic shaking,a shrunken sphere (E)can be observed that makes the system separation easier than it is by filtration or centrifugation.When the phase-separated system is cooled,it returns to the initial homogeneous state (A).3.3.Effect of salts on thermal phase transitionsThe LCST of Co-TDTAPc–PNIPA or Co-TDTAPc–P(NIPA-co-AM)can be affected by various salts,such as Na 2SO 4,NaCl,and NaBr.Fig.S7shows the effect of different salts on the LCST of Co-TDTAPc–PNIPA.As can be seen,at the same concentration of an-ions,SO 2À4is ranked as a strong salting-out ion,Cl Àand Br Àare mildsalting-out ions,and SCN Àis a strong salting-in ion.The results show that the effect of added salts on Co-TDTAPc–PNIPA depends on the kind of anion [33].The effects of different salts on the LCST of Co-TDTAPc–P(NIPA-co-AM)are given in Table 2,where it can be seen that Na 2SO 4decreased the LCST of Co-TDTAPc–P(NIPA-co-AM)dramatically.Due to the higher LCST of Co-TDTAPc–P(NIPA-co-AM),we chose the strong salting-out salt Na 2SO 4to investigate the effect of salt concentration on the LCST of Co-TDTAPc–P(NIPA-co-AM)(Fig.5).Significant decreases in the LCST of Co-TDTAPc–P(NIPA-co-AM)were observed with an increased concentration of Na 2SO 4.This is probably because the existence of Na 2SO 4reduces the hydrogen bond between Co-TDTAPc–P(NIPA-co-AM)and water,destroys the hydration layer in the polymer surface,and causes an increase of hydrophobicity.Therefore,Na 2SO 4can poten-tially be used to precipitate the polymers from the catalytic reac-tion system at a high temperature.3.4.Catalytic activity of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)on oxidation of 2-mercaptoethanolIt is well known that the homogeneous or heterogeneous cata-lytic oxidation of 2-mercaptoethanol by oxygen in the presenceofFig.3.LCST of Co-TDTAPc–P(NIPA-co-AM)as a function of AM molar fraction in monomer feeds (concentration of Co-TDTAPc–P(NIPA-co-AM):1mg/mL,pH6.7).Fig.4.Thermosensitive phase transition of Co-TDTAPc–P(NIPA-co-28.57AM).Table 2Effect of salt on the LCST of Co-TDTAPc–P(NIPA-co-38.46AM)solution (salt concen-tration:0.3168mol/L).Salt Without salt Na 2SO 4NaCl NaBr NaSCN LCST (°C)81.031.058.263.885.0Fig.5.Effect of concentration of Na 2SO 4on the LCST of Co-TDTAPc–P(NIPA-co-38.46AM).W.Lu et al./Reactive &Functional Polymers 70(2010)135–141139CoPc complexes results in the formation of disulfides,according to the oxidation reaction (Eq.1)[34,35].The catalytic activity of Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM)was determined by measuring the amount of O 2consumed.HOCH 2CH 2þOH À!HOCH 2CH 2S ÀþH 2O4HOCH 2CH 2S ÀþO 2þ2H 2O !catalyst2HOCH 2CH 2SSCH 2CH 2OHþ4OH Àð1ÞAccording to our previous report,pH 11is optimal for oxidation on 2-mercaptoethanol catalyzed by CoPc derivatives [34].Fig.6presents the time-dependence of oxygen consumption in 2-mercaptoethanol oxidation catalyzed by Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-28.57AM)in water at pH 11.0and at 25°C or 50°C.The results showed that both Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-28.57AM)have good catalytic activity in aqueous solution at 25°C,based on the homogenous catalytic oxi-dation process.At 50°C,the oxygen consumption rate of the oxida-tion reaction catalyzed by Co-TDTAPc–PNIPA was markedly decreased.In contrast,the rate of oxygen consumption in the pres-ence of Co-TDTAPc–P(NIPA-co-28.57AM)increased markedly.These two catalytic processes present different superficial phe-nomena at 50°C:the solution including Co-TDTAPc–PNIPA was clouded and had some deposits,while the solution including Co-TDTAPc–P(NIPA-co-28.57AM)was transparent and homoge-neous.At 50°C,Co-TDTAPc–PNIPA serves as a heterogeneous catalyst and Co-TDTAPc–P(NIPA-co-AM)serves as a homogeneous catalyst.Some reactions were done at various temperatures to further investigate the temperature-dependence of oxidation of 2-mercap-toethanol catalyzed by these copolymers,as shown in Fig.7.When Co-TDTAPc–PNIPA was chosen as the catalyst,the initial reaction rate V 0increased in the range 20.0–32.0°C,showing that the cata-lytic oxidation of 2-mercaptoethanol is an endothermic reaction,and then a dramatic decline of V 0was observed at 34.0°C.The aqueous solution containing Co-TDTAPc–PNIPA became turbid at temperatures above 32.0°C,which is slightly lower than the LCST of Co-TDTAPc–PNIPA (34.5°C).This is mainly because the LCST of Co-TDTAPc–PNIPA is lowered to pH 11by the addition of alkali [36].Above the LCST,a dramatic decline in the catalytic activity of Co-TDTAPc–PNIPA appeared at 34.0°C.This can be explained in that the catalytic activity of the phthalocyanine molecule was influenced by its microenvironment.When the temperature isabove the LCST,a hydrophobic group can exist on the surface of Co-TDTAPc–PNIPA,and prevent ÀSCH 2CH 2OH,(the hydrophilic group)from coordinating with the active center of CoPc.This is why the catalytic activity decreases on oxidation of 2-mercap-toethanol.Fig.7shows that Co-TDTAPc–P(NIPA-co-AM)has a similar transformation trend.V 0was observed to increase in the range of 20.0to 54.0°C because the oxidation of 2-mercap-toethanol is an endothermic pared with Co-TDTAPc–PNIPA,a dramatic decline of V 0was observed at 56.0°C because the latter has a higher LCST than the former.From the LCST data for Co-TDTAPc–P(NIPA-co-AM)in Fig.3,the LCST of Co-TDTAPc–P(NIPA-co-28.57AM)is 55.8°C.Therefore,the catalytic activity of Co-TDTAPc–P(NIPA-co-AM)is correlated directly with the LCST.A higher reaction temperature is an important factor when trying to achieve a higher catalytic activity.The different AM molar frac-tions in the Co-TDTAPc–P(NIPA-co-AM)can meet the need for a higher reaction temperature by adjusting the LCST.In some catalytic or enzymatic reactions involving phthalocyanine,the temperature can be controlled by adjusting the AM molar fraction.Furthermore,cyclic utilization is essential to evaluation of a catalyst.The results show that the catalytic activity of Co-TDTAPc–P(NIPA-co-AM)was very slightly impaired byfourFig. 6.Oxidation of 2-mercaptoethanol catalyzed by Co-TDTAPc–PNIPA or Co-TDTAPc–P(NIPA-co-28.57AM)in aqueous solution (concentration of CoPc:1Â10À5mol/L;concentration of 2-mercaptoethanol at time zero:0.1mol/L).Fig.7.Temperature-dependence of the initial rate V 0of oxidation of 2-mercap-toethanol catalyzed by Co-TDTAPc–PNIPA or Co-TDTAPc–P(NIPA-co-28.57AM)(concentration of CoPc:1Â10À5mol/L;concentration of 2-mercaptoethanol at time zero:0.1mol/L).Fig.8.Recycling of oxidation of 2-mercaptoethanol catalyzed by Co-TDTAPc–P(NIPA-co-28.57AM)in aqueous solution (concentration of CoPc:1Â10À5mol/L;concentration of 2-mercaptoethanol at time zero:0.1mol/L;50°C).140W.Lu et al./Reactive &Functional Polymers 70(2010)135–141repetitive experiments,as shown in Fig.8,and homogeneous catal-ysis and heterogeneous separation have been realized successfully by simple heating.4.ConclusionA series of water-soluble polymeric catalysts containing CoPc (Co-TDTAPc–PNIPA and Co-TDTAPc–P(NIPA-co-AM))with temper-ature-responsive properties were prepared.The LCST of these poly-meric catalysts with different AM molar fractions cover a wide temperature range.Co-TDTAPc–P(NIPA-co-AM)with a large AM molar fraction can more or less resist the influence of salting-out salts and exists as a transparent solution at high temperature.The copolymers showed a high level of catalytic activity on oxidation of2-mercaptoethanol in the homogeneous phase when the reaction temperature was below the LCST,and could be precipitated and recovered by heterogeneous separation when the temperature was above the LCST.Since the catalytic oxidation of2-mercap-toethanol is an endothermic reaction,the increasing AM content in the copolymer can enhance the catalytic activity of the copolymer via increase of the LCST to maintain homogeneous catalysis at the higher reaction temperature.In addition,the presence of strong salting-out salts,such as Na2SO4,benefits separation of the copoly-mer from the reaction system.Since the LCST of the copolymers is adjustable,we can choose a polymeric catalyst with a certain LCST and control the reaction temperature according to different needs, e.g.,the application of a polymeric catalyst with an LCST above 37°C in photodynamic therapy.These copolymers have potential applications in development of new water-soluble polymeric cata-lysts with thermosensitive properties containing MtPc.AcknowledgementsThis work was supported by theNational Natural Science Foun-dation of China(No.50872124and20574061),Program for Chang-jiang Scholars and Innovative Research Team in University(IRT 0654),and Zhejiang Provincial Natural Science Foundation of China (Y4080341).Appendix A.Supplementary materialSupplementary data associated with this article can be found,in the online version,at doi:10.1016/j.reactfunctpolym.2009.11.002.References[1]C.C.Leznoff,A.B.P.Lever,Phthalocyanines:Properties and Applications,vols.1–4,VCH,New York,1989–1996.[2]H.Shirai,N.Kobayashi,Phthalocyanines–Chemistry and Functions,IPC,Tokyo,1997.[3]N.B.McKeown,Phthalocyanine Materials:Synthesis,Structure and Function,Cambridge University Press,Cambridge,1998.[4]D.Wöhrle,N.Baziakina,O.Suvorova,S.Makarov,V.Kutereva,E.Schupok,G.Schnurpfeil,J.Porphyrins Phthalocyan.8(2004)1390.[5]H.Shirai,H.Tsuiki,E.Masuda,T.Koyama,K.Hanabusa,J.Phys.Chem.95(1991)417.[6]H.Ali,J.E.van Lier,Chem.Rev.99(1999)2379.[7]E.A.Lukyanets,J.Porphyrins Phthalocyan.3(1999)424.[8]C.M.Allen,W.M.Sharman,J.E.van Lier,J.Porphyrins Phthalocyan.5(2001)161.[9]Z.Sheng,X.Ye,Z.Zheng,S.Yu,D.K.P.Ng,T.Ngai,C.Wu,Macromolecules35(2002)3681.[10]A.C.H.Ng,X.-Y.Li,D.K.P.Ng,Macromolecules32(1999)5292.[11]X.-Y.Li,X.He,A.C.H.Ng,C.Wu,D.K.P.Ng,Macromolecules33(2000)2119.[12]T.Ngai,G.-Z.Zheng,X.-Y.Li,D.K.P.Ng,C.Wu,Langmuir17(2001)1381.[13]P.P.S.Lee,T.Ngai,J.-D.Huang,C.Wu,W.-P.Fong,D.K.P.Ng,Macromolecules36(2003)7527.[14]M.Ganschow,D.Wöhrle,G.Schulz-Ekloff,J.Porphyrins Phthalocyan.3(1999)299.[15]K.J.Balkus Jr.,M.Eissa,R.Levado,J.Am.Chem.Soc.117(1995)10753.[16]R.F.Parton,P.E.Neys,P.A.Jacobs,R.C.Sosa,P.G.Rouxhet,J.Catal.164(1996)341.[17]V.Iliev,A.Ileva,L.Bilyarska,J.Mol.Catal.A:Chem.126(1997)199.[18]A.Hirth,A.K.Sobbi,D.Wöhrle,J.Porphyrins Phthalocyan.1(1997)275.[19]Y.Chen,M.Sone,K.Fuchise,R.Sakai,R.Kakuchi,Q.Duan,J.Sun,A.Narumi,T.Satoh,T.Kakuchi,React.Funct.Polym.69(2009)463.[20]X.Z.Zhang,R.X.Zhuo,Langmuir17(2001)12.[21]T.Saitoh,Y.Sugiura,K.Asano,M.Hiraide,React.Funct.Polym.69(2009)792.[22]J.Li,J.Ren,Y.Cao,W.Yuan,React.Funct.Polym.69(2009)870.[23]W.X.Chen,B.Y.Zhao,Y.Pan,Y.Y.Yao,S.S.Lu,S.L.Chen,L.J.Du,J.Colloid Interf.Sci.300(2006)626.[24]W.X.Chen,W.Y.Lu,Y.Y.Yao,M.H.Xu,Environ.Sci.Technol.41(2007)6240.[25]B.N.Achar,G.M.Fohlen,J.A.Parker,J.Keshavayya,Polyhedron6(1987)1463.[26]H.G.Schild,D.A.Tirrell,J.Phys.Chem.94(1990)4352.[27]H.Fischer,G.Schulz-Ekloff,D.Wöhrle,Chem.Eng.Technol.20(1997)462.[28]H.P.Xia,M.Nogami,Opt.Mater.15(2000)93.[29]A.Hadasch,A.Sorokin,A.Rabion,B.Meunier,New J.Chem.22(1998)45.[30]L.D.Taylor,L.D.Cerankowski,J.Polym.Sci.,Polym.Chem.Ed.13(1975)2551.[31]H.Feil,Y.H.Bae,J.Feijen,S.W.Kim,Macromolecules26(1993)2496.[32]M.Shibayama,S.Mizutani,S.Nomura,Macromolecules29(1996)2019.[33]E.Krasovitski,Y.Cohen,H.Bianco-Peled,J.Polym.Sci.Part B:Polym.Phys.42(2004)3713.[34]Y.Pan,W.X.Chen,S.F.Lu,Y.F.Zhang,Dyes Pigm.66(2005)115.[35]M.Sanchez,N.Chap,J.B.Cazaux,B.Meunier,Eur.J.Inorg.Chem.2001(2001)1775.[36]X.M.Liu,L.S.Wang,L.Wang,J.C.Huang,C.B.He,Biomaterials25(2004)5659.W.Lu et al./Reactive&Functional Polymers70(2010)135–141141。
