Synthesis and characterization of nano-cobalt aluminium oxide as a potential antioxidant, biocidal and photocatalytic disinfectant against multi drug-resistant pathogens of public health significance

The present study successfully synthesized nano CoAl2O4 by the solution combustion method, employing sucrose as an ergonomic fuel. The synthesis of CoAl2O4 was confirmed by X-ray diffraction, Raman spectroscopy as well as electron microscopy, and a mean size of 70–80 nm was observed. Besides, the antioxidant, antimicrobial, photocatalytic and antibiofilm potentials of nano CoAl2O4 were evaluated against multi-drug resistant (MDR) bacterial strains. Initially, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CoAl2O4 (µg/mL) were determined to be within the ranges of 62.50–250 and 250–500, respectively. The poultry red blood cell-based hemolysis and secondary cell line-based MTT assays revealed concentration-dependent toxicity with an inhibitory concentration-50 (µg/mL) of 75.0 and 25.0 against MDA-MB468 and HT29 cell lines, respectively. Interestingly, CoAl2O4 was found to generate reactive oxygen species and revealed potential antioxidant properties by DPPH and reducing power assays. Moreover, the synthesized materials permeabilized the membranes of both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and were found to be bactericidal and exhibited antibiofilm activity against the MDR- E. coli strain. The nano CoAl2O4, when treated with the MIC and 1/2X MIC, eliminated MDR-methicillin-resistant S. aureus within 60 and 120 min, respectively, and was found to be an excellent photosensitizer. In short, this study concludes that CoAl2O4 was found to be a promising antimicrobial candidate with antioxidant as well as antibiofilm properties for application in wastewater treatment and therapeutic purposes.