Enhanced degradation of cellulose acetate film containing diphenyliodonium salt–benzophenone

Cellulose acetate (degree of substitution 2.45) films containing diphenyliodonium salt and benzophenone were prepared and their degradative behavior was examined under simulated solar exposure. Acetic acid generation from the films under irradiation was greater in the co-presence of diphenyliodonium salt and benzophenone than in the sole presence of diphenyliodonium salt. Photosensitization and free-radical oxidization, which are followed by Brønsted acid generation, were postulated as the mechanism for the observed increase of deacetylation. The patterns of decreased molecular weight were different between the films with the diphenyliodonium salt and those with benzophenone; while the films with the diphenyliodonium salt kept a relatively constant molecular-weight distribution, the polydispersity increased in the films with benzophenone during the degradation. Since the synthesized characteristics of those two different patterns of change in molecular-weight distribution were observed in the co-presence of the diphenyliodonium salt and benzophenone, each additive appeared to act independently to lead to main-chain cleavage of cellulose acetate. Therefore, decrease in the molecular weight of cellulose acetate by diphenyliodonium salt did not seem to be enhanced in the co-presence with benzophenone.     

新型光敏剂二氢卟吩e_6-C_(15)单甲酯荧光光谱特性及其体内分析应用

研究了二氢卟吩e_6-C_(15)单甲酯在不同溶剂体系中的荧光光谱特性,据此建立了检测血浆中二氢卟吩e_6-C_(15)单甲酯的荧光分析法。首先,通过比较分析二氢卟吩e_6-C_(15)单甲酯在甲醇、乙醇、丙酮、乙腈、磷酸盐缓冲液和水六种不同溶剂体系中的荧光光谱特征,考察了溶剂体系对二氢卟吩e_6-C_(15)单甲酯荧光光谱特性的影响,结果发现甲醇和乙腈是比较理想的溶剂体系,而磷酸盐缓冲液优于水溶液。通过进一步考察有机溶剂含量和溶液pH对二氢卟吩e_6-C_(15)单甲酯发射波长和荧光强度的影响,结果表明pH 7.2磷酸盐缓冲液-乙腈(3:7)混合溶液中二氢卟吩e_6-C_(15)单甲酯荧光强度大、性质稳定。采用pH 7.2磷酸盐缓冲液-乙腈(3:7)混合溶液沉淀SD大鼠血浆蛋白,选择498.00和664.05 nm作为激发波长和发射波长,建立的SD大鼠血浆样品中二氢卟吩e_6-C_(15)单甲酯荧光分析法专属性好,灵敏度高,线性范围为0.50~50.00μg·mL~(-1)(R~2≥0.999),批内和批间精密度RSD均小于10%,提取回收率大于90%。该方法简便、快速、可靠,成功地应用于二氢卟吩e_6-C_(15)单甲酯在SD大鼠体内的药代动力学研究。     

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.