Silver Nanoparticles Conjugated with Colistin Enhanced the Antimicrobial Activity against Gram-Negative Bacteria

Abstract

Colistin is a potent peptide antibiotic that is effective against Gram-negative bacteria. However, nephrotoxicity limited its clinical use. Silver nanoparticles (AgNPs) have gained attention as a potential antimicrobial agent and nanodrug carrier. The conjugation of antibiotics and AgNPs has been found to increase the activity and decrease drug toxicity. In this study, colistin was conjugated with AgNPs (Col-AgNPs), which was confirmed by Fourier-transform infrared (FT-IR) and energy-dispersive X-ray (EDX) spectra. The optimized Col-AgNPs had the proper characteristics, including spherical shape, monodispersity, nanosized particle, high surface charge, and good stability. The powder X-ray diffraction (PXRD) pattern supported the crystallinity of Col-AgNPs and AgNPs. The drug loading of Col-AgNPs was 11.55 ± 0.93%. Col-AgNPs had higher activity against Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) than AgNPs and colistin. The mechanism of actions of Col-AgNPs involved membrane disruption and genomic DNA damage. The Col-AgNPs and AgNPs were biocompatible with human red blood cells and renal cells at concentrations up to 16 µg/mL. Interestingly, Col-AgNPs exhibited higher cell survival than AgNPs and colistin at 32 µg/mL. Our results revealed that the Col-AgNPs could enhance the antimicrobial activity and cell biocompatibility more than colistin and AgNPs.

Multi-Functional Electrospun AgNO3/PVB and Its Ag NP/PVB Nanofiber Membrane

“…The average particle size of the Ag NPs was estimated using the Debye–Scherrer equation (Equation (2)) [ 42 ]: where D represents the average crystallite size of the Ag NPs, K is the Scherrer constant (with values ranging from 0.9 to 1, accounting for the shape factor), λ is the X-ray wavelength (1.5418 Å), β 1/2 is the width of the XRD peak at half height, and θ is the Bragg angle. Based on the Scherrer equation, the average crystallite size of the Ag NPs was estimated to be approximately 10–20 nm, and the calculated average crystallite size aligned with the grain size range computed by other researchers [ 43 , 44 ].…”

Gold(III) Complexes Activity against Multidrug-Resistant Bacteria of Veterinary Significance

“…Indeed, this provides a promising therapeutic approach for animals infected with CST-resistant Gram-negative pathogens. A plausible explanation for the observed synergy between the gold complexes and colistin would be in the initial binding of the latter to anionic lipid A molecules of Gram-negative bacteria [ 5 , 6 ], leading to a rapid permeabilization of the outer cell membrane that allows improved penetration of the gold(III) complexes [ 39 , 40 ]. In the absence of colistin, the permeability barrier conferred by the outer membrane of Gram-negative bacteria impairs the transfer of gold complexes to the cytoplasm [ 17 ], so that when CST permeabilizes the bacterial outer membrane, the activity of gold(III) complexes is greatly enhanced.…”

Synthesis and Characterization of Paclitaxel-Loaded Silver Nanoparticles: Evaluation of Cytotoxic Effects and Antimicrobial Activity

“…In the study by Muenraya et al, Col-AgNPs were found to have higher activity than AgNPs and colistin against Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa). According to their results, Col-AgNPs can increase antimicrobial activity and cell biocompatibility more than colistin and AgNPs [51]. In their in vitro studies with silver nanoparticles to investigate antimicrobial activity, Rafq et al reported that diferent concentrations of silver nanoparticles were efective against diferent microorganisms, such as bacteria (E. coli, S. aureus, P. aeruginosa, and K. pneumoniae) and fungi (C. albicans) [52].…”