Antimicrobial &amp; anticancer activities of extracellular silver nanoparticles biosynthesised by <i>Haloferax</i> sp SNP6

Background & objectives Nanotechnology-based therapeutics offer promising strategies for treating infectious diseases and cancer. Silver nanoparticles (AgNPs), in particular, exhibit strong antimicrobial and anticancer properties. Biologically synthesized AgNPs are preferred for their safety and environmental compatibility. Haloferax species, known for their extremophilic nature, present a novel biosynthetic platform. This study aimed to evaluate the antimicrobial and anticancer activities of extracellular AgNPs biosynthesized by Haloferax sp SNP6 and assess their effects on selected human cancer cell lines. Methods Initially, the extracellular silver NPs were biosynthesized using Haloferax sp SNP6. These nanoparticles were then characterized using several techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and UV spectroscopy. The purpose of these analyses was to confirm the formation, size, shape, and functional groups associated with the Ag-NPs. Their antimicrobial efficacy was tested against several pathogenic bacteria and fungi using standard microbiological methods. The cytotoxic effects were assessed on human cancer cell lines (breast and cervical) and compared with those on a non-cancerous human cell line. Results The biogenic Ag-NPs via Haloferax sp exhibited significant antimicrobial activity against Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC 6633), Pseudomonas aeruginosa (ATCC 90274), Staphylococcus aureus (ATCC 6538), Aspergillus niger, and Candida albicans (ATCC 10221), which possessed clear zones of 18±1.1, 28±1.7, 24±1.3, 18±1.2, 0, and 27±2.0, respectively. The biogenic Ag-NPs via Haloferax sp (Hal-AgNPs) demonstrated potent cytotoxic effects on cancer cell lines, with lower IC50 values indicating higher efficacy and minimal toxicity toward non-cancerous cells. The NPs presented a unique combination of size, stability, and surface characteristics, contributing to their biological activities. The TEM image of Hal-AgNPs demonstrated semi-spherical-shaped particles ranging from 2 to 14 nm, and XRD proved that the Hal-AgNPs are crystalline. Interpretation & conclusions The observed findings of this study suggest a dual functionality of the biosynthesized silver nanoparticles (Hal-AgNPs) as antimicrobials and anticancer agents highlighting their potential as therapeutic agents, especially in treating drug-resistant infections and cancer.