Ciprofloxacin Functionalized Biogenic Gold Nanoflowers as Nanoantibiotics Against Pathogenic Bacterial Strains

Antibiotics are currently being rendered non-functional by the rising incidence of multi-drug resistance amongst pathogenic bacteria. Research has now been focused on developing solutions to this problem by creating new antibiotics and enhancing the functionality of the existing ones.

In the present study, ciprofloxacin was conjugated to biogenic gold nanoflowers (GNFs) from Bacillus subtilis RSB64 by a robust adsorption method under optimized conditions. The resultant drug-nanoflower conjugate was characterized by UV-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR). Addition of ciprofloxacin to gold nanoflowers changed the extinction spectrum towards longer wavelength. The ciprofloxacin-conjugated gold nanoflowers were tested for the drug release statistically. The prepared nanoflower-drug conjugate was subjected to an in vitro microbiological assay against different Gram-positive and Gram-negative bacterial strains to verify the effect of GNF-ciprofloxacin conjugate on the cell growth inhibitory activity of ciprofloxacin.

The GNF-ciprofloxacin conjugates demonstrated enhanced bactericidal activity against Gram-negative bacteria as compared to Gram-positive. The enhancement of the antibacterial activity of the nanoflower-drug conjugate could be attributed to the interaction of the conjugate with phosphate/amine group of the outer membrane of Gram-negative bacterial cell wall making them susceptible to the antibacterial effect of the conjugate.

This study demonstrates the positive attributes of GNF-ciprofloxacin conjugates as a promising antibacterial therapeutic agent against pathogens.