To infer changes in the photophysical properties of porphyrins due to complexation with albumin, a combination of Z-scan and conventional spectroscopic techniques was employed. We measured the characteristics of excited states of meso-tetrakis(sulfonatophenyl) porphyrin bound to bovine serum albumin and observed that the binding reduces the intersystem crossing quantum yield and increases the internal conversion one. A reverse saturable absorption process was observed in the nanosecond timescale. These results are important for prediction of the efficiency of this complex in medical and optical applications, because associating porphyrins to proteins enables better accumulation in tumors and improves its stability in optical devices, but at the same time, decreases its triplet quantum yield.

中文翻译：

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牛血清白蛋白（BSA）对中四（磺酰基苯基）卟啉（TPPS4）激发态性质的影响。

为了推断由于与白蛋白络合而引起的卟啉的光物理性质的变化，采用了Z扫描和常规光谱技术的组合。我们测量了与牛血清白蛋白结合的中四（磺酰基苯基）卟啉的激发态特征，观察到结合降低了体系间交叉量子产率并增加了内部转化率。在纳秒时间范围内观察到反向饱和吸收过程。这些结果对于预测该复合物在医学和光学应用中的效率非常重要，因为将卟啉与蛋白质结合可以更好地在肿瘤中蓄积并提高其在光学设备中的稳定性，但同时会降低其三重态量子产率。