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.