A New Class of Gold Nanoantibiotics- Direct Coating of Ampicillin on Gold Nanoparticles

Abstract

Need for novel, innovative strategies for developing antibiotics is becoming a necessity due to an increasing number of rapidly evolving micro-organismal threats. Antibiotic encapsulated gold nanoparticles (GNPs) are one such strategy showing promise. We report the development of ampicillin encapsulated gold nanoparticles (Amp-GNPs) that possess highly effective, dose dependant antibacterial activity. In this method, ampicillin molecules have been coated on individual GNPs which can then serve as drug carrier devices. Our method for synthesizing Amp-GNPs is an entirely ecofriendly, single step reaction taking place in an aqueous buffer. Following characterization of Amp-GNPs, we find them to be ~15 nm in diameter and spherical in shape. We have tested the antibacterial activity of Amp-GNPs against multiple strains of bacteria, both Grampositive and Gram-negative, and have found Amp-GNPs to be highly efficient against all tested strains. By examining the mechanism of Amp-GNPs antibacterial activity, it was determined that Amp-GNPs disrupt the bacterial cells membrane when coming into contact with the cells, thus disturbing the cell equilibrium, leading to cell lysis or necrosis. Amp-GNPs have been shown to exhibit significant potential and ability to enter the medical field's arsenal to fight infectious disease.

Gold nanoparticles: various methods of synthesis and antibacterial applications

“…These chains were disturbed after entering the bacterial cell, resulting in more scattered AuNPs causing cell lysis. The above finding justified the claim that cationic coated AuNPs are more toxic than anionic coated AuNPs (203). For antibiotics which belong to β-lactam group such as penicillin and cephalorosporin which show antibacterial activity by inhibiting the cell wall synthesis shows quite similar mechanism when they are coated on AuNPs (193).…”

“…Similarly, In 2010 scientists from India and UK utilized the combined reducing and capping ability of a cepholosporin antibiotic cefaclor for the synthesis of 22 nm-52 nm spherical AuNPs (193). Antimicrobial assays against S. aureus and E. coli showed potent (196), ampicillin (203) and vancomycin (197) antibiotic respectively. Reproduced with permission from respective sources.…”

Novel Synthesis of Kanamycin Conjugated Gold Nanoparticles with Potent Antibacterial Activity

“…High water-solubility (50 mg/mL) and absence of delayed toxicity are some of the additional advantages of kanamycin over other actinomycete-derived antibiotics ( Xie et al, 2011 ). Here, we attempt to potentiate the antibacterial activity of kanamycin by designing a unique formulation of kanamycin capped gold nanoparticles (Kan-AuNPs) using a simple, kanamycin-mediated, bio-friendly synthesis that we have developed ( Dakshinamurthy and Sahi, 2012 ; Pender et al, 2013 ). To this end we established and fine-tuned the synthesis protocol by determining the optimum concentrations of nucleating agent [potassium gold (III) chloride (KAuCl 4 )], and reducing agent (kanamycin sulfate) to yield stable, monodispersed Kan-AuNPs.…”

Single-step antibiotic-mediated synthesis of kanamycin-conjugated gold nanoparticles for broad-spectrum antibacterial applications

“…After the determination of MIC by turbidometry assays, the solid agar assays were also performed to obtain visible colony count (Pender et al . 2013). For this 10 μl bacterial suspension from the growth kinetics experiment was mixed with 40 μl saline (0·5% NaCl) and then spread on a sterile nutrient agar plate with the help of a sterile spreader.…”