An intelligent dual stimuli-responsive photosensitizer delivery system with O2-supplying for efficient photodynamic therapy

The effects of photodynamic therapy (PDT) are limited by the hypoxic tumor microenvironment (TME). In this paper, a new type of biocompatible multifunctional photosensitizer delivery system was fabricated to relieve tumor hypoxia and improve the efficacy of PDT. The photosensitizer hematoporphyrin monomethyl ether (HMME) and catalase (CAT) were encapsulated in the pores of mesoporous graphitic-phase carbon nitride nanosheets (mpg-C3N4). Next, hyaluronic (HA) was coated on the surface of the mpg-C3N4 via an amide linkage to construct the tumor-targeting HAase/CAT dual activatable and mpg-C3N4/HMME response photosensitizer delivery system (HA@mpg-C3N4-HMME/CAT). Upon intravenous injection, HA@mpg-C3N4-HMME/CAT shows high tumor accumulation owing to the tumor-targeting HA coating. Meanwhile, CAT within mpg-C3N4 could trigger decomposition of endogenic TME H2O2 to increase oxygen supply in-situ to relieve tumor hypoxia. This effect together with mpg-C3N4/HMME dual response is able to dramatically improve PDT efficiency. The hypoxia status of tumors was evaluated in vivo to demonstrate the success of the O2-supplying. And the in vitro and in vivo results showed the excellent therapeutic effect of the HA@mpg-C3N4-HMME/CAT photosensitizer delivery system. O2-supplying PDT may enable the enhancement of traditional PDT and future PDT design.