Development of a pH-Responsive Co1-XS@Chi-TPP nanoplatform for dual antibacterial and anticancer therapy

Monodisperse Co 1-X S nanospheres were synthesized via a solvothermal method. To enhance their stability and performance, the cobalt sulfide nanospheres were surface-modified using chitosan cross-linked with tripolyphosphate (Chi-TPP). Subsequently, doxorubicin (DOX), a widely used chemotherapeutic drug, was loaded onto the Co 1-X S@Chi-TPP nanoplatforms. The DOX release studies under different simulated conditions demonstrated pronounced pH-responsive behavior, with 63% cumulative release observed in the simulated tumor microenvironment (TME) after 24 h. Kinetic and dynamic light scattering (DLS) analyses revealed that DOX release is mainly diffusion-controlled at physiological pH but accelerated under acidic TME conditions, reflecting the pH-responsive, multiphasic behavior of the nanosystem driven by polymer swelling. The Co 1-X S@Chi-TPP nanoplatforms exhibited antibacterial activity with MIC values of 0.25–4 mg mL -1 for Staphylococcus aureus (Staph.) and 1–4 mg mL -1 for Escherichia coli (E. coli) , and an MBC of 1 mg mL -1 for both strains, indicating their dual functional potential as drug carriers and antimicrobials. The Co 1-X S@Chi-TPP@DOX nanosystem displayed low cytotoxicity toward MCF7 cells at lower concentrations, with an IC 50 of approximately 300 μg mL -1 , suggesting a potentially favorable therapeutic index. The nanosystem demonstrated high blood compatibility and minimal hemolytic activity, supporting a broad therapeutic window for safe and effective DOX delivery .The results demonstrate that Co 1-X S-based nanocarriers can simultaneously enhance the precision and safety of cancer treatments, offering a significant stride toward more successful and less harmful chemotherapeutic strategies. • Uniform Co 1-x S nanospheres were successfully synthesized via a solvothermal method. • Surface modification with Chi-TPP enhanced nanoparticle stability and drug-loading capacity. • Doxorubicin was released up to ∼ 63% under acidic tumor microenvironment conditions. • The nanosystem exhibited antibacterial activity against Staphylococcus aureus. • Low cytotoxicity was observed in MCF-7 cells, with an IC50 of ∼ 350 μg mL -1 .