Antimicrobial Properties of Newly Developed Silver-Enriched Red Onion-Polymer Composites

Abstract

Simple low-cost, nontoxic, environmentally friendly plant-extract-based polymer films play an important role in their application in medicine, the food industry, and agriculture. The addition of silver nanoparticles to the composition of these films enhances their antimicrobial capabilities and makes them suitable for the treatment and prevention of infections. In this study, polymer-based gels and films (AgRonPVA) containing silver nanoparticles (AgNPs) were produced at room temperature from fresh red onion peel extract ("Ron"), silver nitrate, and polyvinyl alcohol (PVA). Silver nanoparticles were synthesized directly in a polymer matrix, which was irradiated by UV light. The presence of nanoparticles was approved by analyzing characteristic local surface plasmon resonance peaks occurring in UV-Vis absorbance spectra of irradiated experimental samples. The proof of evidence was supported by the results of XRD and EDX measurements. The diffusion-based method was applied to investigate the antimicrobial activity of several types of microbes located in the environment of the produced samples. Bacteria Staphylococcus aureus ATCC 29213, Acinetobacter baumannii ATCC BAA 747, and Pseudomonas aeruginosa ATCC 15442; yeasts Candida parapsilosis CBS 8836 and Candida albicans ATCC 90028; and microscopic fungi assays Aspergillus flavus BTL G-33 and Aspergillus fumigatus BTL G-38 were used in this investigation. The greatest effect was observed on Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa bacteria, defining these films as potential candidates for antimicrobial applications. The antimicrobial features of the films were less effective against fungi and the weakest against yeasts.

Keywords: films; gels; nanoparticles; peel; polyvinyl alcohol; red onion; silver.

Figure 1

UV-Vis spectra of experimental samples: red onion extract (Ron); RonPVA hydrogel; and AgRonPVA gel after UV exposure for 0 min, 10 min, 30 min, and 45 min.

Figure 2

UV-Vis spectra of the diluted in distilled water AgRonPVA gels: 4.02 wt.%; 8.41 wt.%; 10.06 wt.%; 100 wt.% (not diluted AgRonPVA gel).

Figure 3

Photographs of fabricated experimental films.

Figure 4

UV-Vis spectra AgRonPVA films obtained from 100 wt.% AgRonPVA gels exposed to UV.

Figure 5

Simulated UV-Vis spectra for differently sized spherical silver nanoparticles in PVA.

Figure 6

XRD pattern red onion PVA films containing silver nanoparticles (AgRonPVA45).

Figure 7

SEM images and EDX analysis results.

Figure 8

Antimicrobial activity of AgRonPVA films containing silver nanoparticles against (a) Staphylococcus aureus ATCC 29213, (b) Acinetobacter baumannii ATCC BAA 747, (c) Pseudomonas aeruginosa ATCC 15442, (d) Candida parapsilosis CBS 8836, (e) Candida albicans ATCC 90028, and (f) Aspergillus flavus BTL G-33 fungus. Numbering of Petri dishes with immersed films: (1) control; (2) AgRonPVA (UV 5 min); (3) AgRonPVA (UV 10 min); (4) AgRonPVA (UV 30 min); (5) AgRonPVA (UV 45 min).