Preparation, characterization and evaluation of a biopolymeric gold nanocomposite with antimicrobial activity

The present study describes the antimicrobial activity of C-AuNp-Amp (chitosan-capped gold nanoparticles coupled with ampicillin). C-AuNp-Amp was synthesized using the wet precipitation method and characterized using FTIR (Fourier-transform IR) spectroscopy and AFM (atomic force microscopy) techniques. The optimal level of ampicillin concentration that couples with the C-AuNp nanocomposite was determined by using UV-visible spectroscopy. The agar-well diffusion method was used to evaluate the antimicrobial activity, and the broth dilution assay was used to determine the MIC (minimum inhibitory concentration). The size of the ellipsoidal C-AuNp-Amp particles was found to be in the range of 50-100 nm. The FTIR spectrum confirms the bonding between amino groups of chitosan and carboxylic groups of ampicillin. The maximum coupling of ampicillin with C-AuNp was found to be 4.07 mg/10 ml. These results revealed the antimicrobial efficacy of C-AuNp-Amp and a 2-fold increase in activity was achieved when compared with that of free ampicillin. By reducing the antibiotic dosage to 50%, the side effects produced by antibiotics can be minimized.