Bioactive Antiviral Black Organic Coatings Functionalized with Silver–Silica and Silver–Zirconium for Cytocompatible Biomaterial Surfaces Against Human Coronavirus

Bioactive antiviral biomaterial coatings capable of rapidly inactivating respiratory viruses while preserving cytocompatibility are highly desirable for development protective and high-contact biomedical materials. Here, we engineered black (Bl) organic coatings functionalized with two silver (Ag)-based inorganic additives—nano (n) Ag supported on colloidal silica (SiO2) and Ag-substituted zirconium phosphate—to develop multifunctional antiviral biomaterial surfaces. Their antiviral efficacy was evaluated against human coronavirus (HCoV) 229E, a model enveloped respiratory coronavirus, together with their cytocompatibility toward human keratinocytes (HaCaT) and human lung fibroblasts (MRC-5) cells. The morphology and elemental composition of the coatings were characterized using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Antiviral performance was quantified by a neutral red uptake cytopathic (NRU-CPE) infectivity assay following 30 and 60 min of virus–surface contact. Coatings functionalized with nAg supported on SiO2 reduced infectious virus recovery by 2.2–5.3 log10, whereas coatings containing Ag-substituted zirconium phosphate achieved reductions of 1.9–4.7 log10, depending on additive loading and exposure time. Interestingly, the unmodified black organic coating also reduced viral infectivity, indicating that both the coating matrix and Ag-based functionalization contribute to the overall antiviral performance. Importantly, all functionalized coatings maintained cell viability above the ISO 10993-5 acceptance threshold (≥70%), demonstrating excellent cytocompatibility.