Bismuth Sulfide Nanorods with Retractable Zinc Protoporphyrin Molecules for Suppressing Innate Antioxidant Defense System and Strengthening Phototherapeutic Effects.

Abstract

Bismuth (Bi)-based nanomaterials (NMs) are widely used for computed tomography (CT) imaging guided photothermal therapy, however, the photodynamic property is hardly exhibited by these NMs due to the fast electron-hole recombination within their narrow bandgap. Herein, a sophisticated nanosystem is designed to endow bismuth sulfide (Bi₂ S₃ ) nanorods (NRs) with potent photodynamic property. Zinc protoporphyrin IX (ZP) is linked to Bi₂ S₃ NRs through a thermoresponsive polymer to form BPZP nanosystems. The stretching ZP could prebind to the active site of heme oxygenase-1 overexpressed in cancer cells, suppressing the cellular antioxidant defense capability. Upon NIR laser irradiation, the heat released from Bi₂ S₃ NRs could retract the polymer and drive ZP to the proximity of Bi₂ S₃ NRs, facilitating an efficient electron-hole separation in ZP and Bi₂ S₃ NRs, and leading to reactive oxygen species generation. In vitro and in vivo studies demonstrate the promising photodynamic property of BPZP, together with their photothermal and CT imaging performance.