4.3 Porphyrin self-assembled nanoparticles enhance light energy capture efficiency to enhance PDT
A major drawback of porphyrin-based photosensitizers is that they easily aggregate through stacking, leading to quenching of electronic excited states, thereby reducing the quantum yield of1O2 and diminish the effectiveness of PDT(Escudero et al. 2006; Helmich et al. 2010; Ji et al. 2018; Lee and Kopelman 2011; Liu et al. 2013). Self-assembly is a natural phenomenon and a powerful method for applying multifunctional nanomaterials to biological applications(Fan et al. 2004; Grzelczak et al. 2019; Liu et al. 2016; Wang et al. 2004; Zhang et al. 2019b). By self-assembling into nanoparticles, porphyrins can effectively address their tendency to aggregate in PDT, efficiently trapping light energy and generating1O2 (Fig. 7). Studies of meso-tetra-4-hydroxyphenylporphyrin (mTHPP) with polyethylene glycol molecules (PEG) have shown that the complexes formed improve the solubility of the porphyrin photosensitizers and reduce their aggregation in the aqueous environment, thus allowing efficient capture of light energy to produce 1O2(Avci et al. 2014; Ding et al. 2011).