Enhanced antibacterial activity of imipenem immobilized on surface of spherical and rod gold nanoparticles

Pseudomonas aeruginosa is an opportunistic pathogen that has a high resistance to antibiotics and can cause disease in patients with immune deficiency. Therefore, in the present study, the antimicrobial effects of imipenem-functionalized spherical and rod gold nanoparticles (SGNPs and RGNPs) have been investigated on P aeruginosa. Firstly, SGNPs and RGNPs were synthesized by citrate reduction and seed-growth methods, respectively. The SGNPs and RGNPs were conjugated with imipenem (Imp-SGNPs and Imp-RGNPs). The size, potential and morphology of the SGNPs and RGNPs were determined by different techniques including; TEM, DLS and UV-vis spectra. Different concentrations of Imp-SGNPs and Imp-RGNPs were used to determine the bacterial growth rate and minimum inhibitory concentration (MIC) by UV-vis spectrophotometry according to CLSI standard protocol. The results indicated that the drug loading on the surface of SGNPs and RGNPs was 60.5% and 54%, respectively. The Imp-SGNPs and Imp-RGNPs exhibited greater antibacterial activity compared to that of imipenem alone. The highest antibacterial activity of GNPs was observed in the Imp-RGNPs against P aeruginosa. The MIC for 90% inhibition (MIC90) for imipenem, Imp-SGNPs and Imp-RGNPs was determined to be 43 mu g ml(-1), 21 mu g ml(-1) and 5.7 mu g ml(-1), respectively. These results indicated that the new nano-carrier systems with GNPs have great potential for enhanced antibacterial activities.