Synthesis and characterization of Spirulina-mediated titanium dioxide nanoparticles: Antimicrobial activity against multidrug-resistant bacteria

Abstract

Nanotechnology, particularly the use of nanoparticles, has garnered significant interest due to their unique properties and diverse applications, notably in antimicrobial research. This study focuses on the synthesis of titanium dioxide (TiO2) nanoparticles mediated by Spirulina using green synthesis methods and explores their antibacterial effectiveness against multidrug-resistant bacteria, including Methicillin Resistance Staphylococcus aeruginosa, Pseudomonas aeruginosa, E. coli, and Enterococcus faecalis. The synthesis process involved the reduction of a titanium precursor using Spirulina biomass extract. Various characterization techniques, such as UV analysis, SEM imaging, FTIR spectroscopy, EDX analysis, and XRD, were employed to assess the physicochemical properties of the synthesized TiO2 nanoparticles. Results showed a prominent absorbance peak at 322 nm and a band gap energy of 3.850 eV. SEM imaging revealed spherical morphology with aggregation, while XRD analysis indicated 61.4 % crystallinity with anatase phase. FTIR spectroscopy identified functional groups present in the nanoparticles, and EDX analysis confirmed the presence of titanium and oxygen elements. The antibacterial efficacy of Spirulina-mediated TiO2 nanoparticles was evaluated using the Agar well diffusion method against multidrug-resistant bacteria. The nanoparticles exhibited significant inhibitory zones of 22 ±3, 17±4, 11±2, and 15±3 nm at 80 μg/ml against MRSA, P. aeruginosa, E. coli, and E. faecalis, respectively. Minimal microbial inhibition was observed at concentrations of 3.906, 15.625, 15.625, and 31.25 μg/ml for MRSA, Pseudomonas aeruginosa, Enterococcus faecalis, and E. coli, respectively. The minimum bactericidal concentrations (MBC) were found to be 7.812, 31.25, 31.25, and 62.5 μg/ml for the respective bacteria. This study highlights the effectiveness of Spirulina-mediated TiO2 nanoparticles against multidrug-resistant bacterial strains in a bactericidal mode of action. Further research is warranted to investigate the molecular interactions between TiO2 nanoparticles and multidrug-resistant bacteria.