This research’s overall goal is to converge the field of biochemistry, membranes, and aerosol science to develop functionalized materials that can deactivate the SARS-CoV-2 virus upon contact, both in novel mask and enclosed environment filter applications. Specifically, this research is aimed at investigating the air flux and nanosized aerosol particle capture of existing commercial membranes, in addition to evaluating the effect of enzyme functionalization of membrane material on the spike glycoprotein (SGP) of the SARS-CoV-2 virus. The SGP facilitates host cell infection via cell membrane fusion and the denaturation of the SGP has been proven to lead to the loss of the coronavirus’ ability to infect its host. Subtilisin is a highly stable serine protease enzyme and was determined to successfully denature the SGP in solution phase by the disappearance of the protein denaturation peak at 40°C, quantified via Differential Scanning Calorimetry (DSC). Commercial membranes commonly used for water filtration applications (microfiltration, ultrafiltration, and nanofiltration membranes) were evaluated for air filtration application. Based on porosity, thickness, pore size, and air flux, polyvinylidene difluoride (PVDF) microfiltration membranes with average pore diameter of 100 nm were selected. The air flux of this PVDF membrane and a commercial N95 mask was found to be 1.36E+5 and 1.2E+6 L/m<sup>2</sup>/hour, respectively, at human breathing pressure (0.08 bar). PVDF membranes were functionalized with poly(methacrylic acid) (PMAA) to enhance the enzyme functionalization capacity and to increase moisture capture/retention of the membrane, thus decreasing the loss of enzymatic activity when exposed to a dry air environment over time. The peak relative frequency of permeate diameter distribution of aerosolized polystyrene latex (PSL) particles (100 nm average diameter) was found to be 38, 68, and 91 nm for PMAA-PVDF membranes, N95 masks, and surgical masks, respectively. PMAA-PVDF membranes with a weight gain of 2% after polymerization were further functionalized with Subtilisin via a batch solution immobilization method. The enzyme-functionalized membranes’ ability to deactivate the SGP at near-dry conditions was confirmed and quantified using Sypro Orange, a fluorescent dye that binds to hydrophobic regions of the protein.

Enzyme-functionalized membrane masks and filters for aerosol capture and spike glycoprotein denaturation for SARS-CoV-2 deactivation

ACS Spring 2022

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