Transparent Surface Coatings that Kill Antimicrobial-Resistant Bacteria within Minutes and Inactivate the COVID-19 Virus

Pathogens can be transferred between solids and humans, and cause diseases. Apart from any loss of life, these diseases cost millions of dollars to be treated. A method of decreasing the disease spread is to use surface coatings that rapidly inactivate or kill pathogens. Transparent coatings are particularly desired for such a purpose. Not only do they visually preserve the solid object, they are also necessary for certain applications, touch screen and cell phone covers, for example. We have developed two transparent surface coatings that inactivate pathogens within minutes. We used polydopamine (PDA) as the adhesive layer in the coatings. PDA has the advantage that its monomer can be sprayed in order to cover all surfaces of a solid object, and then it makes a conformal film on it. We prepared our first coating (PDA/Cu₂O) by depositing a suspension that contained both PDA’s monomer and Cu₂O particles. Then the monomer self-polymerized and bound the Cu₂O particles to the surface. For our second coating (PDA/Cu), we first prepared a PDA layer, and then grew a layer of copper via electroless deposition. We deposited a very thin layer of copper to maintain the transparency of the coating. The PDA/Cu₂O coating kills methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) by 96.82% and <i>Pseudomonas aeruginosa</i> (<i>P. aeruginosa</i>) by 99.94%, within 10 minutes, and inactivates 99.88% of SARS-CoV-2 (COVID-19 virus) within 1 hr. The PDA/Cu coating kills MRSA by 99.18% and <i>P. aeruginosa</i> by &gt;99.99%, within 10 minutes, and inactivates 99.98% of SARS-CoV-2, within 1 hr.