New Generation of Antibacterial Products Based on Colloidal Silver.

Bogdan Pascu,Vasile Gherman,Adina Negrea,Narcis Duteanu,Corneliu Mircea Davidescu,Petru Negrea,Mihaela Ciopec

doi:10.3390/ma13071578

Abstract

The main objective of the present paper is the green synthesis of colloidal silver by ultrasonication starting from silver nitrate and using soluble starch as the reducing agent. Soluble starch has been used during synthesis because it is a cheap and environmentally friendly reactive. Silver colloid has been characterized by physicochemical methods: UV–VIS spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy. This colloidal material was prepared in order to prove and establish its toxicity on heterotrophic bacteria. Toxicity tests were carried out using test cultures with and without silver colloid with different concentrations. This way was possible to establish the minimum silver concentration that presents a toxic effect against used bacteria. Quantitative evaluation of bacterial growth was performed by using the Most Probable Number method. By counting the bacterial colony number, the antibacterial effect was determined for colloidal silver deposited onto the cotton gauze by adsorption. During the present study, we optimized the adsorption specific parameters: solid:liquid ratio, temperature, contact time, colloidal silver concentration. By thermodynamic, equilibrium and kinetic studies, the adsorptive process mechanism was established.

Highlights

Technological development from the last decade lead to extensive usage of colloidal silver in different fields increasing the number of possible applications
Colloidal silver can be obtained by using chemical, physical, photochemical and biological methods
Chemical synthesis consists of the reduction of silver precursors in the presence of some stabilizing agents

Summary

Introduction

Technological development from the last decade lead to extensive usage of colloidal silver in different fields increasing the number of possible applications. A versatile material with multiple uses in textile and medical fields is cotton because it is a soft materialAand has good adsorbent properties. A big problem usagebecause of textile in versatile material with multiple uses in[2,9,10,11]. Textile and medical fields for is cotton it ismaterials a soft the material medicaland field isgood represented the fact [2,9,10,11]. That all A textile materials are exposed severalin viruses has adsorbentby properties big problem for usage of textiletomaterials medical fieldProtective is represented fact that all textile materials are exposed to several virusessuch and layer andthe bacteria [12]. An extensive literature review proved that colloidal silver has a large number of applications: antibacterial agent [3,4], antifungal agent [5], antiviral agent [6], air disinfection [7], water disinfection [3], ground water biological wastewater treatment [8] and surface disinfection (antimicrobial paints, plastic catheters, gel formulation for specific usage, packing paper for food preservation, clinical clothing) [3].

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