Silver-Zinc oxide nanocomposites: a green approach to mitigate herpes simplex virus type 1 challenges

Herpes simplex virus type 1 (HSV-1) remains a significant global health challenge due to its high prevalence, recurrent infections, emergence of drug-resistant viral strains, and adverse effects associated with conventional antiviral therapies. In this study, silver–zinc oxide nanocomposites (Ag–ZnONPs) were synthesized using Nigella sativa extract and evaluated for antiviral activity against HSV-1 alongside ZnONPs, AgNPs, and calcined Ag–ZnONPs (Ag–ZnONPs-K). Characterization confirmed nanoparticle formation with sizes of ~ 35–50 nm and zeta potentials ranging from − 15.5 to − 25.5 mV. Cytotoxicity assays showed CC50 values of 700 µg/mL (ZnONPs), 35 µg/mL (AgNPs), and 80 µg/mL (Ag–ZnONPs-K), while Ag–ZnONPs showed no cytotoxicity within the tested range. In post-treatment assays, Ag–ZnONPs achieved 95% viral inhibition at 120 µg/mL (SI = 12), comparable to ZnONPs (97% at 300 µg/mL, SI = 13) and higher than AgNPs (83% at 25 µg/mL). These results demonstrate strong in vitro antiviral activity of Ag–ZnONPs against HSV-1, particularly in post-infection conditions.