An efficient synthesis, characterization of CuONPs from sulfur atom-containing inorganic salt and Buchanania lanzan Spreng (BLS) bark extract, and its microbial activity

This study reports, for the first time, the green synthesis of copper oxide nanoparticles (CuONPs) using a sulfur-containing inorganic salt and Buchanania lanzan Spreng (BLS) bark extract under ultrasonic irradiation. UV–Vis spectroscopy confirmed the formation of CuONPs by an absorption peak at 292 nm. FESEM images revealed irregular, flake-like, and granular nanoparticles, while EDX analysis confirmed the presence of copper and oxygen. XRD analysis indicated a monoclinic crystal structure with an average crystallite size of 6.9 nm. FTIR spectroscopy showed that the surface of the CuONPs was modified by organic compounds originating from the plant extract, with characteristic absorption bands at 3337 cm−1 (N–H stretching) and 1068 cm−1 (C–O stretching). The observed shifts in the FTIR absorption bands indicated the involvement of these functional groups in the formation and stabilization of the CuONPs. The use of dried BLS bark biomass provides a simple, environmentally friendly, and cost-effective approach for the synthesis of CuONPs. The synthesized nanoparticles exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria, including Staphylococcus aureus (NCIM 5021), Streptococcus mutans (MTCC 497), Bacillus cereus (NCIM 2703), Bacillus subtilis (NCIM 2063), Escherichia coli (NCIM 2832), Salmonella typhi (NCIM 2501), Pseudomonas aeruginosa (NCIM 9027), and Proteus vulgaris (NCIM 2813). The CuONPs showed greater inhibitory activity against Gram-negative bacteria than against Gram-positive bacteria. Furthermore, the nanoparticles exhibited antituberculosis activity against Mycobacterium tuberculosis with an IC50 value of 83.11 µg/mL, compared with 78.94 µg/mL for rifampicin. Overall, the synthesized CuONPs demonstrated significant antimicrobial activity and represent promising broad-spectrum antimicrobial agents.