4 Enhance PDT by improving the light energy capture efficiency of porphyrin photosensitizers
Porphyrins are widely used in the field of PDT because of their special photosensitive properties. However, porphyrins also have many shortcomings in cancer therapy. For example, porphyrins have low water solubility, which makes it easy for them to aggregate through buildup, leading to electronically excited state bursts, thus reducing the quantum yield of 1O2 and weakening the effectiveness of PDT. In addition, longer wavelengths of red light are generally chosen in PDT, which can easily irradiate deeper tumor tissue and enable photosensitizers to produce photodynamic therapeutic effects. However, the limited tissue penetration and light energy capture efficiency of porphyrin photosensitizers have been the two major obstacles for conventional photosensitizers. Therefore, it is necessary to enhance the tissue penetration and improve the light energy capture efficiency of porphyrin photosensitizers through structural modifications. In addition, indirect excitation of porphyrin photosensitizers using fluorescent donors (fluorescence resonance energy transfer) has been successfully used to address these issues. In this manuscript, we focus on how to enhance the photoenergy capture efficiency of porphyrin photosensitizers, aiming to improve the efficiency of 1O2 production in tumor tissues and enhance the PDT effect of photosensitizers.