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<p>The escalating threat of multidrug-resistant pathogens and aggressive malignancies demands sustainable alternatives to conventional therapeutics. Aligning with the One-Health approach, this study establishes an eco-friendly green nanotechnology platform utilising the unexploited marine unicellular cyanobacterium <i>Synechocystis pevaleikii</i> to biosynthesise stable, multifunctional silver nanoparticles (<i>Sp</i>-AgNPs). The synthesis using a 100&#xa0;mg/10 mL aqueous biomass extract and 1 mM silver nitrate (AgNO<sub>3</sub>) at 40&#xa0;°C was visually confirmed by a green-to-brown colour transition. Comprehensive physical mapping revealed a sharp UV-visible surface plasmon resonance peak at 441&#xa0;nm. FTIR spectroscopy identified a robust bio-organic capping matrix composed of proteins, carbohydrates, and polyphenols. Crystallographic analysis (P-XRD and SAED) confirmed a highly pure, face-centered cubic lattice with an average core crystallite size of 24.6&#xa0;nm. FESEM and TEM imaging demonstrated spherical, polydisperse morphologies with a core size distribution of 11–56&#xa0;nm and a mean particle diameter of 51 ± 1.2&#xa0;nm. EDX validated elemental purity with 84.80 wt% silver. DLS measurements had a mean hydrodynamic diameter of 103.6&#xa0;nm, while a highly negative zeta potential of − 21.43 mV excellent colloidal stability. In biological evaluations, <i>Sp</i>-AgNPs demonstrated broad-spectrum antibacterial efficacy, producing zones of inhibition of 16&#xa0;mm against <i>Escherichia coli</i> and 14&#xa0;mm against <i>Arthrobacter globiformis</i>, with highly potent MIC values of 6.25&#xa0;µg/mL and 12.5&#xa0;µg/mL, respectively. Quantitative microtiter assays confirmed substantial dose-dependent antibiofilm activity, achieving up to 93% (<i>A. globiformis</i>) and 77% (<i>E. coli</i>) eradication at peak concentrations. Furthermore, the nanostructures exhibited exceptional free-radical scavenging capacity with an IC<sub>50</sub> value of 9.2&#xa0;µg/mL. Most crucially, <i>Sp</i>-AgNPs displayed powerful selective cytotoxicity against the breast cancer MCF-7 cell line, yielding an IC<sub>50</sub> value of 12.09&#xa0;µg/mL in MTT assays. Confocal microscopy (Calcein-AM/PI and Annexin V-PI) confirmed that this cytotoxicity is driven by robust intracellular reactive oxygen species overproduction, triggering targeted cellular death.</p> Graphical abstract <p></p>

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Evaluating antibacterial, antioxidant and apoptosis-mediated anticancer activities of green-synthesised silver nanoparticles using unicellular cyanobacterium Synechocystis pevaleikii

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月5日

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  • Sagar Patra,
  • Sanjana Sabat,
  • Anusha Srivastava,
  • Ajit Kumar Bishoyi,
  • Rabindra Nath Padhy

摘要

The escalating threat of multidrug-resistant pathogens and aggressive malignancies demands sustainable alternatives to conventional therapeutics. Aligning with the One-Health approach, this study establishes an eco-friendly green nanotechnology platform utilising the unexploited marine unicellular cyanobacterium Synechocystis pevaleikii to biosynthesise stable, multifunctional silver nanoparticles (Sp-AgNPs). The synthesis using a 100 mg/10 mL aqueous biomass extract and 1 mM silver nitrate (AgNO3) at 40 °C was visually confirmed by a green-to-brown colour transition. Comprehensive physical mapping revealed a sharp UV-visible surface plasmon resonance peak at 441 nm. FTIR spectroscopy identified a robust bio-organic capping matrix composed of proteins, carbohydrates, and polyphenols. Crystallographic analysis (P-XRD and SAED) confirmed a highly pure, face-centered cubic lattice with an average core crystallite size of 24.6 nm. FESEM and TEM imaging demonstrated spherical, polydisperse morphologies with a core size distribution of 11–56 nm and a mean particle diameter of 51 ± 1.2 nm. EDX validated elemental purity with 84.80 wt% silver. DLS measurements had a mean hydrodynamic diameter of 103.6 nm, while a highly negative zeta potential of − 21.43 mV excellent colloidal stability. In biological evaluations, Sp-AgNPs demonstrated broad-spectrum antibacterial efficacy, producing zones of inhibition of 16 mm against Escherichia coli and 14 mm against Arthrobacter globiformis, with highly potent MIC values of 6.25 µg/mL and 12.5 µg/mL, respectively. Quantitative microtiter assays confirmed substantial dose-dependent antibiofilm activity, achieving up to 93% (A. globiformis) and 77% (E. coli) eradication at peak concentrations. Furthermore, the nanostructures exhibited exceptional free-radical scavenging capacity with an IC50 value of 9.2 µg/mL. Most crucially, Sp-AgNPs displayed powerful selective cytotoxicity against the breast cancer MCF-7 cell line, yielding an IC50 value of 12.09 µg/mL in MTT assays. Confocal microscopy (Calcein-AM/PI and Annexin V-PI) confirmed that this cytotoxicity is driven by robust intracellular reactive oxygen species overproduction, triggering targeted cellular death.

Graphical abstract