四取代羧基酞菁锌与白蛋白共价结合物的制备与光谱性质

通过成酰胺键的方式制备了一系列含羧基酞菁和白蛋白(牛血清白蛋白(BSA),人血清白蛋白(HSA))之间的共价结合物,所涉及到的酞菁分别是α-四(4-羧基苯氧基)酞菁锌(1)和α-四4-(2-羧基乙基)苯氧基]酞菁锌(3),以及它们相应的β位四取代酞菁锌(化合物2和4).比较了游离酞菁以及它们的白蛋白结合物在磷酸盐缓冲溶液(PBS)中的光谱性质.结果表明,当酞菁被共价固定于白蛋白大分子上之后,展现出比游离酞菁更明显的单体特征吸收,而且结合物中的酞菁光谱特征不受体系pH值变化的影响.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的变化.化合物1和3的白蛋白共价结合物在PBS溶液中甚至呈现出单体形式为主的光谱特征,Q带最大吸收波长分别位于697和706nm附近.

Preparation and Spectroscopic Properties of Covalent Albumin Conjugates of Zinc Phthalocyanines Tetrasubstituted with Carboxyl Moieties

A series of covalently bound albumin (bovine serum albumin (BSA) and human serum albumin (HSA)) conjugates of phthalocyanines functionalized with carboxyls were prepared and resulted in amide bonds. The phthalocyanines are tetra-α-(4-carboxyl phenoxy) phthalocyanine zinc (1) and tetra-α-4-(2-carboxyl-ethyl) phenoxy] phthalocyanine zinc (3) as well as their corresponding tetra-β-substituted counterparts (compounds 2 and 4). The spectroscopic properties of these phthalocyanines and their bioconjugates in phosphate buffer saline solution (PBS) were investigated. The phthalocyanines that are covalently bound to the albumins have a more obvious monomeric absorption characteristic than the corresponding free phthalocyanines. Moreover, the spectroscopic characteristics of the phthalocyanines in the bioconjugates are not affected by solution pH. The substitution position of the carboxyl moieties on the phthalocyanine ring has an effect on the spectroscopic transformation of these macromolecules after conjugation with the albumins. Substitution at the α-position of the phthalocyanine ring leads to more prominent spectroscopic changes than that at the β-position. Both 1-albumin and 3-albumin in PBS show monomeric phthalocyanine spectra with Q-band maxima at about 697 nm and 706 nm, respectively.