NIR-II sensitive Co9S8/S-CDs@PEG nanocomposites with enhanced multi-enzyme mediated phototherapy

Abstract

Here, Co9S8/S-CDs@PEG (CSCs@PEG) nanocomposites are synthesized by a two-step hydrothermal process. Firstly, sulfur-doped carbon dots (S-CDs) are prepared by using 3-mercaptopropionic acid as a precursor. A region with denser –SH group is regarded as nucleation site on S-CDs for the growth of Co9S8 to induce heterostructure. As-synthesized CSCs@PEG possess great harvest in NIR region and hyperthermia (51.5%, 1064 nm) for photothermal (PTT). Besides, hyperthermia can elevate the thermal energy of nanocomposite to assist low-energy NIR-II irradiation (1064 nm, 1.16 eV), realizing the excitation of Co9S8 (1.46 eV) and reactive oxygen species (ROS) generation for photodynamic therapy (PDT). What's more, CSCs@PEG exhibits GOx-like activity that could consume glucose to elevate H2O2 level and inhibit intracellular energy supply. In addition, they also show mimic peroxidase (POD) and catalase (CAT) characterization, and the tandem multi-nanozye activities endue the enhanced chemotherapy (CDT) and PDT. CSCs@PEG reveals the greater ROS generation and nanozyme activity compared with pure Co9S8@PEG, attributing to the efficient charge separation in heterostructure. The novel biodegradation of CSCs@PEG makes the elimination via feces and urine within 2 weeks. That is associated with PTT/PDT/CDT/starvation therapy to activate immune response for anticancer.