Hydrothermally Grown ZnO Nanowires on Silicon and Quartz: Multifunctional Coatings with Enhanced Antiviral Activity against SARS-CoV-2

The relentless emergence of viral threats, such as SARS-CoV-2, has underscored the critical demand for materials that can emulate the multifunctionality and adaptability found in nature's most resilient systems. Zinc oxide nanowires (ZnO NWs), synthesized via a two-step hydrothermal process on silicon (Si) and quartz (Qtz) substrates, exhibit a remarkable convergence of properties reminiscent of biological defense mechanisms─combining photoreactivity, antibacterial, and antiviral actions within a single nanostructured platform. Detailed morphological and structural analyses confirm the formation of highly crystalline, vertically aligned nanowires (Si: 45 ± 3 nm diameter, 1.28 ± 0.02 μm length, 110 ± 5 μm^-2 density; Qtz: 50 ± 4 nm, 1.32 ± 0.05 μm, 90 ± 5 μm^-2) with strong <i>c</i>-axis texturing. Photocatalytic performance, assessed through methylene blue (MB, 10 μM) degradation demonstrates Si/ZnO NWs: 99.2% (UVA, 365 nm, 180 min) vs 42.3% photolysis; Qtz/ZnO NWs: 98.5%; solar: 98.8%/97.2% vs 69.6% photolysis. Antibacterial assays against <i>Pseudomonas putida</i> (<i>P. putida</i>) show complete growth suppression under UVA (365 nm, 17 mW/cm², 10 min) vs substantial growth on bare substrates. Most notably, antiviral efficacy against SARS-CoV-2 Wuhan D614G demonstrates >2 log TCID₅₀/mL reduction: Si/ZnO (5.7 → 3.0 log), Qtz/ZnO (5.8 → 3.3 log) under low-power UVA (395 nm, 600-640 μW/cm², 20 min) vs minimal reduction on bare substrates (5.3-5.5 log). By uniting these synergistic properties─99% pollutant degradation, complete bacterial suppression, >99% viral inactivation─hydrothermally grown ZnO NWs manifest as a class of adaptive, multifunctional materials, establishing their potential as multifunctional antiviral surface coatings for high-contact environmental applications.