The highly contagious COVID-19 pandemic has highlighted the potential of indirect contact transmission of respiratory viruses, whereby viruses were expelled from infected person via respiratory droplets, then reside and survive on abiotic surfaces for an extended period. Touching of such contaminated surfaces(fomites) would then transfer to vulnerable orifices on the face, resulting infection. Initially, efforts had been placed to continuously disinfect common surfaces, but this is not effective in the long term due to cost and human error. Material scientists have been trying to design the most effective antiviral surfaces that comprises many perks and non-toxic to other organisms using different technologies, including antimicrobial peptides, heavy metals, and physical/chemical modifications.
Herein, inspired by insect wings (and other topologies found in nature), we fabricated single side polished p- type 100 mm silicon wafers using Samco RIE-101iPH inductively coupled plasma (ICP) assisted reactive ion etching tool. The following process parameters were used: etchant gases SF6/O 2 with respective flow rates of 35/45 sccm, process pressure of 1 Pa, ICP power of 150 W, and RIE bias power of 15 W. This resulted formation of black silicon (black-Si) that has nanopillars topography with proven high bactericidal activity, non-toxic to mammalian cells and not prone to corrosion.
In this study, human parainfluenza virus type 3 (hPIV-3) droplets were incubated on black-Si and non-fabricated smooth silicon wafers for an hour at ambient environment in dark. We show that after incubation, black-Si is capable of high degree interaction and damage of human parainfluenza virus type 3 (hPIV-3) particles as assessed via RT-qPCR (98.4% reduction) and plaque assay (95.4% reduction) in comparison to smooth silicon wafers. In addition, electron microscopy depicted changes in morphology of the hPIV-3 particles, illustrating irreversible physical damage. These findings set the precedent for further development in antiviral surface to combat indirect contact transmission of respiratory viruses as well as being applied in hospital settings to combat viral nosocomial infections.