Autocatalytic Photodynamic Amplification of PpIX-Conjugated Shell-Cross-Linked (SCL) Micelles via 1O2 Cleaves Cross-Linkers AITranslate

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DOI：https://doi.org/10.1021/acsapm.1c01743

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An important challenge for phototherapy is spatiotemporal controlling of its efficiency while reducing side effects and improving efficacy. Here, we show how to overcome this challenge by autocatalytic photodynamic amplification of protoporphyrin IX moieties (PpIX)-conjugated pH-responsive shell cross-linked (SCL) micelles with a 1O2-cleavable cross-linker. At a neutral pH, self-quenching among photosensitizers and photoinduced electron transfer (PET) process between PpIX and pH-responsive polymers results in low fluorescence emission and 1O2 generation capacity. The protonation of core-formed poly(2-diisopropylaminoethyl methacrylate) (PDPA) blocks triggers partially enhanced emission of PpIX and photodynamic rate at the weakly acidic pH associated with endosomes. More importantly, 1O2 generated by the red-light irradiation breaks the cross-linker and weakens the self-quenching, which further enhances the fluorescence emission and photodynamic efficiency. This self-amplification process simultaneously drives photodynamic therapy, drug release, and endosomal escape.