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).