Virucidal Efficacy of Laser-Generated Copper Nanoparticle Coatings Against Model Coronavirus and Herpesvirus

High-efficiency antiviral surfaces can be effective means to fight against viral diseases such as the recent Covid-19 pandemic. Copper and copper oxides, as well as their nanoparticles (Cu NPs) and coatings, are among the effective antiviral materials having internal and external biocidal effects on viruses. In this work, stable Cu NP colloids were produced via femtosecond laser ablation of the metal target in water containing sodium citrate. Raman spectroscopy and X-ray diffraction studies confirmed that the 32 nm mean size nanoparticles are mixtures of mainly metallic copper and copper (I) oxide Cu2O. Polyvinyl butyral was utilized as the binding agent for the spray-coated Cu NPs. The virucidal efficacy of such coatings containing different Cu content ranging from 2.9 at.% to 11.2 at.%. was confirmed against animal-origin coronavirus containing RNA, the agent of avian infectious bronchitis (IBV), and herpesvirus containing DNA, the agent of bovine herpesvirus (BoHV-1) infection. It was demonstrated that after a short time of exposure, the Cu NPs-based coatings do not have a toxic effect on the cell cultures while demonstrating a negative effect on the biological activity of both model viruses that was confirmed by quantification of the viruses via the determination of tissue culture infectious dose (TCID50) virus titre and their viral nucleic acids via determination of threshold cycle (Ct) employing real-time polymerase chain reaction analysis. The assays showed that the decrease in TCID50 virus titre and increase in Ct values correlated with Cu content in Cu NPs-based coatings for both investigated viruses. Contact with coatings decreased IBV and BoHV-1 numbers from 99.42% to 100.00% and from 98.65% to 99.96% respectively. These findings suggest that Cu NPs show inhibitory effects leading to the inactivation of viruses and their nuclei regardless of the presence of a viral envelope.