【作者】 肖荣平；

【导师】 黄剑东； 张汉辉；

【作者基本信息】 福州大学 ， 物理化学， 2010， 博士

【摘要】 光动力治疗(Photodynamic Therapy，简称PDT)是一种新型的肿瘤治疗方法，抗癌光敏剂是光动力治疗的关键因素。临床上使用的光敏剂主要是以Photofrin为代表的血卟啉衍生物，但它们存在有效成分复杂、皮肤光毒副作用大等严重缺陷,因此寻找新型光敏剂的研究工作备受重视。由于具有在光疗窗口吸收强度高、光敏化能力强、暗毒性低和易于化学修饰等特点，酞菁衍生物作为第二代光敏剂的研究已引起广泛的重视。考虑到酞菁锌衍生物的光敏化能力高，白蛋白是水溶性的运载蛋白，而且对某些癌细胞具有靶向性，本学位论文围绕含羧基酞菁锌及其白蛋白共价结合物的制备和光谱性质开展研究，期望为深入探讨抗癌光敏剂的作用机理、提高光敏剂的光敏活性和靶向性提供有益的启示。本学位论文的主要工作和结果概括如下：首先合成了一系列含羧基的取代酞菁锌，进而通过成酰胺键的方式连接含羧基的取代酞菁锌与白蛋白（牛血清白蛋白BSA和人血清白蛋白HSA），制备了十七种高水溶性的、未见报道的酞菁-白蛋白共价结合物，并经过凝胶色谱等方法进行分离纯化，通过红外光谱、荧光光谱、电子吸收光谱和考马斯亮蓝法等手段进行表征。结果表明，酞菁环上取代基的类型、取代位置和羧基的数目对酞菁-白蛋白共价结合物的摩尔组成比没有明显影响。当投料摩尔比为10：1（酞菁：白蛋白）时，获得了摩尔组成比约为6~7：1的共价结合物。比较了含羧基酞菁锌及其白蛋白共价结合物在模拟生理溶液中的光谱性质和存在状态。结果表明，当取代酞菁被共价固定于白蛋白大分子上后，展现出比游离酞菁更为明显的单体特征吸收。羧基在酞菁环上的取代位置，对酞菁与白蛋白结合前后的光谱转变幅度有影响，α位取代比β位取代更有利于光谱向单体方向转变。α位单羧基取代物酞菁1、2、3和α位四羧基取代物酞菁4、5的白蛋白共价结合物在PBS溶液中呈现以单体为主的光谱特征，Q带最大吸收波长位于681~706nm之间。酞菁环上的羧基数量对酞菁及其白蛋白共价结合物光谱性质也有影响，β位八羧基取代酞菁锌8的白蛋白共价结合物在PBS溶液中也显示以单体为主的光谱特征，其Q带最大吸收波长位于677nm附近，而十六羧基取代酞菁锌9与白蛋白形成共价结合物后，则以单体形式存在，其Q带最大吸收波长位于681nm附近，以酞菁计算的摩尔吸光系数约为2.0105mol-1·L·cm-1。研究了模拟生理溶液的pH值变化对含羧基酞菁锌及其白蛋白共价结合物的光谱性质和存在状态的影响。结果表明，水溶液pH值的变化对游离的含羧基酞菁的光谱性质和存在状态有很大影响。总体而言，当溶液为酸性（pH2.0）时，酞菁呈高度聚集的特征吸收（600~800nm之间的吸收峰严重宽化），随着pH值的提高，发生明显的解聚作用（Q带吸收强度增强，峰形逐渐尖锐），这种状况在α位的羧基取代酞菁锌3、4、5和十六羧基取代酞菁锌9上表现得特别明显。但是，当含羧基基团的取代酞菁锌被共价固定到白蛋白网格上之后，体系pH值的变化对所有的酞菁-白蛋白共价结合物中的酞菁Q带特征吸收光谱和存在状态都基本没有影响。这对于设计pH值适应范围宽、具有蛋白质靶向介导的光敏剂具有启发意义。探讨了单取代酞菁2与白蛋白的非共价相互作用，并比较了结合方式（即共价结合与非共价结合）对酞菁的光谱性质和存在状态的影响。结果表明，酞菁2与白蛋白之间存在较强的非共价相互作用，结合常数大约为1.0105mol-1·L。结合位点竞争实验表明，非共价相互作用的结合位点位于人血清白蛋白的亚域ⅠB。酞菁2与白蛋白结合后，无论是共价结合还是非共价结合，均展现出比游离的酞菁更为明显的单体特征吸收，这是一个有利于光动力治疗的性质。共价结合导致酞菁2的单体特征吸收峰红移约5nm，而非共价结合则没有导致红移。相对而言，光动力治疗的作用光谱红移是一个有利的变化，因为波长更长的光能够更好地穿透人体组织。更多还原

【Abstract】 Photodynamic Therapy (PDT) is a new modality for cancer therapy treatment.Anticancer photosensitizer is the key element of photodynamic therapy. The firstgeneraton photosensitizers for clinical use are mainly Hematoporphyrin derivativeswhich represent Photofrin, whereras their gigantic disadvantage are that effectiveingredients are complex, dark cytoxicity is high, etc. Thus it is important to seek newphotosensitizer. The research of phthalocyanines as the second generationphotosensitizer receives extensive interests for their high absorption in photodynamictherapy spectrum, strong photosensitivity, low dark toxicity, and easy to chemicallymodify, etc. It is a hot point in this field this days in researching structure-activityrelationship, action mechanism and effective method to increase photoactivity andtarget tissue selectivity of phthalocyanine type photosensitizer.The dissertation firstly synthesizes a series of carboxy-containing substitutedphthalocyanine zincs, then conjugated these phthalocyanines to albumin (BovineSerum Albumin and Human Serum Albumin) through amide formation way, preparedseventeen high water-soluble and unreported phthalocyanine-albumin covalentconjugates, purified by methods such as gel permeation chromatography, andcharacterized by infra-red spectrum, fluorescence spectrum, electronic absorptionspectrum and Comassic bright blue method, etc. It finds that there are nearly nodifferent effect of molar ratios of phthalocyanine-albumin covalent conjugates onsubstiturion type, substitution position and number of carboxy groups inphthalocyanine cycle. The covalent conjugates are obtained whose molar ratio isabout6~7：1, when10equivalent of phthalocyanine reacts with1equivalent ofalbumin.The dissertation compares carboxy-containing substituted phthalocyanine zincswith their phthalocyanine-albumin covalent conjugates in spectrum property andexistent state in Phosphate buffer solution. It indicates that the conjugates have moreobvious phthalocyanine monomer spectrum characteristic than their corresponding free phthalocyanine, when the substituted phthalocyanine covalently bind to albuminmacromolecule. There are effect of carboxy substitution position in phthalocyanine onspectrum change with conjugation of phthalocyanine and albumin. α positionsubstitution has more phthalocyanine monomer percentage than β positionsubstitution. The covalent albumin conjuagtes of α-substituted phthalocyanine1,2,3and tetra α-substituted phthalocyanine4,5exibit mainly phthalocyanine monomerspectrum characteristic, with Q-band maximum absorption in681~706nmapproximately. The covalent albumin conjuagte of eight carboxy substitutedphthalocyanine zinc8also exibits phthalocyanine monomer spectrum characteristicmainly, with Q-band maximum absorption in about677nm. The covalent albuminconjuagte of sixteen carboxy substituted phthalocyanine zinc9exibits phthalocyaninemonomer spectrum characteristic, with Q-band maximum absorption in about681nm,whose molar extinction coefficient are about2.0105mol-1·L·cm-1.The dissertation investigates the effect of solution pH on spectrum property andexistent state of carboxy-containing substituted phthalocyanine zincs and theirphthalocyanine-albumin covalent conjugates. It finds that the spectrum property andexistent state of free carboxy-containing substituted phthalocyanine change with pHof PBS solution. In general, when solution is acid (pH2.0), the free phthalocyaninedisplays highly aggregated characteristic absorption (the absorption band becomeswide to a great extent). The obvious disaggregation occurs when pH accending(Q-band absorbance becomes higher and sharpper). The situation embodies obviouslyin α substituted carboxy-phthalocyanine3,4,5and sixteen carboxy substitutedphthalocyanine9. But the phthalocyanine Q-band characteristic pectrum property andexistent state in all phthalocyanine-albumin covalent conjugates do not change withsystem pH, when carboxy-containing substituted phthalocyanine covalently bind toalbumin framework. It would inspire the design of the photosensitizer that has highpH capacity and is protein target-mediated.The dissertation also explores the noncovalent interaction with monosubstitutedphthalocyanine2and albumin, compares the effect of conjugation way (covalentconjugation and noncovalent conjugation) on spectrum property and existent state ofsubstituted phthalocyanine. It shows that there is strong noncovalent interactionbetween phthalocyanine2and albumin, and the binding constant is about1.0105mol-1·L. The binding sites competition experiment indicates that the noncovalentinterzction site locates in subdomain ⅠB of human serum albumin. The phthalocyanine conjugated with albumin, no matter covalent conjugate or noncovalentconjugate, both displays more obvious monomer chacteristic absorption thancorresponding free phthalocyanine, which is a property beneficial to photodynamictherapy. Covalent conjugate leads to Q-band maximum absorption of phthalocyanine2red-shift about5nm, while noncovalent conjugate does not cause red-shift.Comparatively, the red-shift of action spectrum for photodynamic therapy is abeneficial change, because the longer wavelength the better for the light permeation tohuman tissue.更多还原