Calcium carbonate particle platform for chemodynamic and self-luminescent photodynamic combination antibacterial therapy

The abuse of antibiotics increases antibiotic-resistant bacteria and leads to the ineffectiveness of conventional antibiotics. Therefore, the development of alternative therapeutic strategies for combating antibiotics-resistant bacteria is challenging. In this study, calcium carbonate (CaCO3) was synthesised to load L-012 [chemiluminescence (CL) agent] and Ce6 (photosensitiser), and then, Co2+ (catalyst) doping was performed, yielding the Co@CaCO3/L-012/Ce6 particle system. The Co@CaCO3/L-012/Ce6 particles were exposed to the bacterial infection microenvironment (IME) under low pH and high levels of H2O2, and Co2+, L-012 and Ce6 were released in response to the acidic environment. The released Co2+ decomposed H2O2 to hydroxyl radicals (.OH) via Co2+- mediated chemodynamic therapy (CDT). Simultaneously, the produced .OH reacted with L-012, which induced self-CL illumination as an excitation light source. Subsequently, the self-CL illumination activated Ce6 and generated the singlet oxygen (1O2). The enhanced production of .OH and 1O2 through Co2+-mediated CDT and self-CL illumination-mediated Ce6-induced photodynamic therapy (self-PDT) effectively destroyed the integrity of Staphylococcus aureus (S. aureus) as well as Escherichia coli (E. coli), leading to the induction of the efficient apoptosis of the bacteria. Therefore, the dual -mode CDT/self-PDT system of Co@CaCO3/L-012/Ce6 particles will be an alternative strategy for antibacterial therapy.