γ-Irradiated Chitosan Mediates Enhanced Synthesis and Antimicrobial Properties of Chitosan–Silver (Ag) Nanocomposites

Abstract

Chitosan (CSN) and its derivatives are being exploited for their potential role in agriculture in mitigating environmental stress factors. The present study was aimed to enhance the synthesis of chitosan (CSN)-based silver nanoparticles (Ag NPs) using γ-irradiated chitosan (IR-CSN) and to study the antimicrobial activity of IR-CSN–Ag NPs. The chitosan–silver nanocomposites (CSN–Ag NPs) were prepared by employing the green synthesis method using normal chitosan (high molecular weight (MW), NL-CSN) and oligochitosans (low MW, IR-CSN). The latter was derived by irradiation with γ rays ( 60 Co) at 100 kGy dose to obtain a lower MW (approximately 25 kDa). NL-CSN and IR-CSN (0.0–2.5% w/v) were amalgamated with different concentrations of silver nitrate (0.0–2.5% w/v) and vice versa. The UV–visible spectra displayed a single peak in the range of 419–423 nm, which is the characteristic surface plasmon resonance (SPR) for Ag NPs. The physicochemical properties were assessed using different methods such as transmission electron microscopy (TEM), Fourier transform infrared (FTIR), zetasizer, elemental (CHNS) analysis, etc. The degree of Ag NP synthesis was more in IR-CSN than NL-CSN. The in vitro disc diffusion assay with IR-CSN–Ag NPs exhibited a significantly higher antimicrobial activity against Escherichia coli . Further evaluation of the antifungal activity of IR-CSN and Ag NPs showed a synergistic effect against chickpea wilt ( Fusarium oxysporum f. sp. ciceris ). The study has provided a novel approach for the improved synthesis of CSN–Ag nanoparticle composites using γ-irradiated chitosan. This study also opens up new options for the development and deployment of γ-irradiated chitosan–silver nanocomposites for the control of phytopathogens in sustainable agriculture.

Green Synthesis and Characterization of Silver Nanoparticles / CM-Chitosan-Isopropanol by Gamma Irradiations Method

“…These results agree with the results reported by Hanan et al [53], Shriram et al [14], and M.S.N. Salleh et al [54] for the formation of AgNPs by the reduction of AgNO3.…”

“…Colloidal solution (silver nanoparticles / (CM chitosanisopropanol)) prepared by AgNO3 reduction into positive silver ions (Ag + ) and assisted with the fragmentation of large Ag-NPs during γ-irradiation [14,29]. Figure 2 illustrates the synthesized silver nanoparticles samples.…”

“…Silver nanoparticles can be synthesized by different techniques, such as physical, chemical, and biological method [12]. Documentation of many methods for synthesizing silver nanoparticles are: Electron and gamma (γ)-irradiation, artificial and biological procedures, microwave and ultrasonic processing, laser ablation, photochemical reduction, and so forth [13][14][15].…”

NanoSilver/CS Solutions Optical Characterizations and Some Applications

“…The Ag-NPs/CM CS-isopropanol change the pure yellow colloidal solution from light to dark brown after gamma irradiations (samples (A0-A3). This confirms Hanan et al [57], Shriram et al [58], and M.S.N. Salleh et al [23] to form AgNPs by the reduction of AgNO3.…”

Porous chitosan particles doped by in situ formed silver nanoparticles: Electrorheological response in silicon oil

“…Therefore, noticeable changes in the IR spectra of composite particles are observed. Thus, the Amide I and II bands shift toward lower wavenumbers indicating the interaction of silver nanoparticles with the NH 2 groups of chitosan, 27,66 while the position of the absorption bands C O and C O C does not undergo significant changes. In addition, as the silver content in the samples increases, there is a noticeable increase in intensity of the absorption bands in the region of 1550-1300 cm À1 .…”