Gamma-induced modification of pomegranate extract-capped silver nanoparticles: Physicochemical and antibacterial properties

Le résumé fourni par la source

In this study, silver nanoparticles (AgNPs) were synthesized using pomegranate ( Punica granatum ) peel extract, followed by post-synthesis gamma irradiation at doses of 0 – 60 kGy to investigate gamma-induced modifications of their physicochemical and antibacterial properties. The UV–Vis results indicated that surface plasmon resonance (SPR) intensity progressively increased with increasing gamma dose, suggesting additional reduction of residual Ag + ions and/or improved nanoparticle dispersion following irradiation. However, the SPR peak position and full width at half maximum remained largely unchanged, indicating minimal effects on particle size distribution. TEM analysis further revealed quasi-spherical AgNPs with average particle sizes of approximately 32 – 35 nm, while DLS showed hydrodynamic diameters of 69 – 73 nm and zeta potentials between −32 and −34 mV, confirming good colloidal stability of AgNPs. XRD patterns also demonstrated the characteristic face-centered cubic structure of metallic silver. However, FTIR spectra revealed substantial reductions in absorption bands within the 900 – 1100 cm −1 region for irradiated samples, indicating modification of oxygen-containing functional groups within the phytochemical capping layer, especially those related to C–N and C–O bonds. In addition, antibacterial evaluation against E. coli and S. aureus showed enhanced activity after irradiation, with AgNPs irradiated at 30 kGy (30-AgNPs) exhibiting the lowest MIC and MBC values (156.3 and 156.3, respectively, for E. coli and 312.5 and 312.5, respectively, for S. aureus ). All samples exhibited MBC/MIC ratios of 1 – 2, confirming strong bactericidal behavior. These findings demonstrated that post-synthesis gamma irradiation was able to modify surface chemistry and antibacterial activity of phytochemical-capped AgNPs.

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