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 50-100nm. 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.