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<p>The growing prevalence of antimicrobial resistance and oxidative stress-associated diseases has become a perturbing global health challenge. Inorganic disinfectants and antioxidants have emerged as promising alternatives for combating drug-resistant bacterial infections and mitigating oxidative stress-related ailments. In this study, bioinspired Ag NPs and Ag-Na-activated bentonite nanocomposites (Ag-NaBent NCs) were synthesized using <i>Hagenia abyssinica</i> leaf extract (HALE), and their in vitro antibacterial and antioxidant potency was evaluated. The structural elucidation of synthesized nanomaterials was done using a range of spectroscopic and microscopic techniques. UV–Vis analysis showed characteristic absorption bands at 407 and 426&#xa0;nm and band-gap energies of 2.55 and 2.37&#xa0;eV for Ag NPs and Ag-NaBent NCs, respectively, confirming modified optical properties upon bentonite loading. X-ray diffraction (XRD) analysis confirmed the formation of pure face-centered cubic (FCC) Ag NPs and biphasic Ag-NaBent NCs with crystallite sizes of 15.2 and 10.4&#xa0;nm, respectively. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses confirmed the synthesis of mainly spherical Ag NPs and Ag-NaBent NCs, with average particle sizes of 32.8&#xa0;nm and 26.5&#xa0;nm, correspondingly. X-ray photoelectron spectroscopy (XPS) exhibited the successful reduction of Ag<sup>+</sup> ions to Ag<sup>0</sup> in both pristine Ag NPs and Ag-NaBent NCs. Moreover, zeta potential analysis confirmed the higher (− 61.2&#xa0;mV) colloidal stability and reduced aggregation of aqueous Ag-NaBent NCs relative to Ag NPs (− 31.6 mV). Ag NPs and Ag-NaBent NCs revealed significant in vitro antibacterial activity, with inhibition zones from 18.0 ± 0.2 to 22.5 ± 0.2&#xa0;mm against <i>S. aureus</i> and from 15.2 ±&#xa0;0.3 to 20.2 ± 0.2&#xa0;mm against <i>E. coli</i>. Similarly, Ag-NaBent NCs showed lower MIC/MBC against both <i>S. aureus</i> and <i>E. coli</i> compared with Ag NPs. Furthermore, both materials exhibited considerable antioxidant activity of 69–73%, 64–68%, and 59–63% at 100&#xa0;µg mL<sup>−1</sup> against DPPH, H<sub>2</sub>O<sub>2</sub>, and NO assays, respectively. Overall, the incorporation of Ag NPs into sodium-activated bentonite significantly enhanced particle stability, antibacterial performance, and antioxidant activity.</p> Graphical abstract <p></p>

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Bioinspired synthesis of silver nanoparticles and silver nanoparticles impregnated activated bentonite: evaluation of antibacterial and antioxidant activities

  • 期刊论文

  • 发表日期：

    2026年7月28日

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  • Enyew Amare Zereffa,
  • Heledana Aderajew Hailu,
  • Neeraj Kumar Gupta,
  • Susmila Aparna Gaddam,
  • Venkata Subbaiah Kotakadi,
  • Temesgen Achamo Orshiso

摘要

The growing prevalence of antimicrobial resistance and oxidative stress-associated diseases has become a perturbing global health challenge. Inorganic disinfectants and antioxidants have emerged as promising alternatives for combating drug-resistant bacterial infections and mitigating oxidative stress-related ailments. In this study, bioinspired Ag NPs and Ag-Na-activated bentonite nanocomposites (Ag-NaBent NCs) were synthesized using Hagenia abyssinica leaf extract (HALE), and their in vitro antibacterial and antioxidant potency was evaluated. The structural elucidation of synthesized nanomaterials was done using a range of spectroscopic and microscopic techniques. UV–Vis analysis showed characteristic absorption bands at 407 and 426 nm and band-gap energies of 2.55 and 2.37 eV for Ag NPs and Ag-NaBent NCs, respectively, confirming modified optical properties upon bentonite loading. X-ray diffraction (XRD) analysis confirmed the formation of pure face-centered cubic (FCC) Ag NPs and biphasic Ag-NaBent NCs with crystallite sizes of 15.2 and 10.4 nm, respectively. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses confirmed the synthesis of mainly spherical Ag NPs and Ag-NaBent NCs, with average particle sizes of 32.8 nm and 26.5 nm, correspondingly. X-ray photoelectron spectroscopy (XPS) exhibited the successful reduction of Ag+ ions to Ag0 in both pristine Ag NPs and Ag-NaBent NCs. Moreover, zeta potential analysis confirmed the higher (− 61.2 mV) colloidal stability and reduced aggregation of aqueous Ag-NaBent NCs relative to Ag NPs (− 31.6 mV). Ag NPs and Ag-NaBent NCs revealed significant in vitro antibacterial activity, with inhibition zones from 18.0 ± 0.2 to 22.5 ± 0.2 mm against S. aureus and from 15.2 ± 0.3 to 20.2 ± 0.2 mm against E. coli. Similarly, Ag-NaBent NCs showed lower MIC/MBC against both S. aureus and E. coli compared with Ag NPs. Furthermore, both materials exhibited considerable antioxidant activity of 69–73%, 64–68%, and 59–63% at 100 µg mL−1 against DPPH, H2O2, and NO assays, respectively. Overall, the incorporation of Ag NPs into sodium-activated bentonite significantly enhanced particle stability, antibacterial performance, and antioxidant activity.

Graphical abstract