Famotidine-conjugated green silver nanoparticles as a selective anticancer and antibacterial nanomedicine.

Despite extensive interest in green silver nanoparticles, translating them into selective nanomedicines with minimal off-target toxicity remains a major challenge. Here, we report for the first time the green synthesis of famotidine-conjugated silver nanoparticles (BR@AgNPs-FAM) and demonstrate their potential to be transformed into a selective anticancer and antibacterial nanomedicine. Structural analyses confirmed the presence of a stable core with an approximate size of 6 nm and successful surface functionalization with famotidine. Critically, we show that BR@AgNPs-FAM selectively kills gastric (AGS) and prostate (PC-3) cancer cells with IC₅₀ values of 8.5 and 13.4 µg/mL, while sparing healthy human dermal fibroblasts (IC₅₀ > 320 µg/mL), yielding exceptional selectivity indices of 37 and 24. Importantly, enhanced anticancer selectivity does not impair antimicrobial performance; rather, BR@AgNPs-FAM exhibits more than a twofold increase in antibacterial efficacy, achieving MIC values as low as 7.81 µg/mL against Bacillus cereus. This nanoplatform also demonstrates measurable antioxidant activity (DPPH IC₅₀ = 23.2 µg/mL). These findings establish famotidine functionalization as an effective strategy to convert green silver nanoparticles into a nanomedicine with selective activity against cancer cells and concurrent antibacterial action.