Bioorthogonal chemistry-inspired Cu/5-aminolevulinic acid self-assembled nanoparticles-crosslinked in situ hyaluronic acid hydrogel for chemo-photodynamic tumor therapy

Bioorthogonal chemistry-based cancer therapy greatly reduces the side effects of chemotherapy drugs; however, complicated and expensive procedures limit its clinical application. Disulfiram (DSF), an FDA-approved anti-alcoholic drug, can combine with copper to form a DSF‑copper complex with remarkable tumor-killing effects. Inspired by the bioorthogonal chemistry, we fabricated an in situ crosslinked self-adaptive hyaluronic acid hydrogels (Cu-A/P@PH HGs) via a dynamic boronic ester bond-based reaction between Cu/5-aminolevulinic acid (5-ALA) self-assembled nanoparticles containing PVA (Cu-A/P NPs) and phenylboronic-grafted hyaluronic acid (PH). The prepared Cu-A/P@PH HGs exhibited favorable self-healing performance and ROS-responsive degradation. Upon in situ injection, the Cu-A/P NPs endowed the Cu-A/P@PH HGs with the ability to convert non-toxic DSF into cytotoxic diethyldithiocarbamate (CuET) at the desired tumor site. In addition, under the induction of glutathione (GSH), Cu-A/P NPs gradually released 5-ALA, which was specifically converted into protoporphyrin IX (PpIX) (a photosensitizer) in tumor cells, resulting in irreversible ROS-mediated oxidative damage under 660 nm laser exposure. Our study offers a promising bioorthogonal chemistry-inspired strategy for in situ photodynamic therapy and DSF chemotherapy to treat breast cancer.