Hybrid polymer/ionic liquid electrospun membranes with tunable surface charge for virus capture in aqueous environments

Although electrospun-based membranes may be engineered as efficient platforms for the capture of biomolecules in aqueous environments, the capability of such membranes to selectively capture viruses and proteins is often limited due to poor and constrained surface affinity for molecular bonding. In order to generate more efficient electrospun-based membranes, fine-tuning Van der Waals and ionic interactions is required to control chemical affinities with such contaminants and support advanced remediation solutions. Here, diallydimethylammonium chloride and poly(acrylonitrile) electrospun nanofibres were developed to enhance the adsorption of specific contaminant molecules compared to equivalently shaped pristine poly(acrylonitrile) nanofibre membranes. The results showed that the incorporation of the ionic liquid improved contact with water by forming super-hydrophilic nanofibres with narrow diameters and smaller pore size distributions, while also significantly changing the surface charge of the material and shifting the isoelectric point of the surface from 3 to 4.4. The specific surface area of the membranes was also increased by up to 4 times upon ionic liquid loading, which was found to support efficient coronavirus capture and filtration efficiency. This new strategy represents a promising way to control surface properties of virus filtration membranes towards efficient and targeted remediation solutions.

Impact of Wearing on Filtration Performance of Electrostatic Filter Face Masks.

Certified disposable respirators afford important protection from hazardous aerosols but lose performance as they are worn. This study examines the effect of wear time on filtration efficiency. Disposable respirators were worn by CSIRO staff over a period of 4 weeks in early 2020. Participants wore the respirator masks for given times up to eight hours whilst working in laboratory/office environments. At that time COVID-19 precautions required staff to wear surgical (or other) masks and increase use of hand sanitizer from dispenser stations. Results obtained from a test group of ten individuals without health preconditions show an increasing number of masks failing with wear time, while the remainder continue to perform nearly unaffected for up to 8 h. Some masks were found to retain filtration performance better than others, possibly due to the type of challenge they were subjected to by the wearer. However, the rate and extent of decay are expected to differ between environments since there are many contributing factors and properties of the aerosol challenge cannot be controlled in a live trial. Penetration and variability increased during wear; the longer the wear time, the more deleterious to particle removal, particularly after approximately 2 h of wear. This behavior is captured in a descriptive statistical model based on results from a trial with this test group. The effectiveness of the masks in preventing the penetration of KCl particles was determined before and after wearing, with the analysis focusing on the most penetrating particles in a size range of 0.3-0.5 µm diameter where respirator masks are most vulnerable. The basic elements of the study, including the approach to filter testing and sample sanitization, are broadly applicable. Conclusions also have applicability to typical commercially available single-use respirator masks manufactured from melt blown polypropylene as they are reliant on the same physical principles for particle capture and electrostatic enhancement was comparable for the particle size range used for detection.

The Effect of Sanitizing Treatments on Respirator Filtration Performance.

The potential for alcoholic vapors emitted by common sanitizing treatments to deteriorate the (electrostatic) filtration performance of disposable respirator masks has been investigated. Reports in the literature and some standard test methods provide a confusing and ambiguous picture concerning the relevance of this effect. Four different types of exposure were investigated in this study to clarify the effect of alcoholic vapor emissions on respirator masks. These included exposure to saturated vapors, use of hand sanitizers, cleaning of table surfaces and sanitization of masks by spraying them with alcohol-containing solutions. Methods employed were designed to be as real-world oriented as possible while remaining reproducible. Filtration performance and deterioration effects on exposure to the different treatments were determined on three different types of certified commercial respirator masks-a P2 and two KN95 masks. This study provides substantial evidence that disposable respirator masks with an accepted performance rating are seriously compromised from an exposure to saturated alcoholic vapors, can tolerate a one-off spray treatment with an alcoholic solution and retain their attested protection under the influence of alcoholic vapors from the use of hand sanitizer or spray sanitizer. Considering the range of vastly different outcomes obtained from the four treatments investigated, it seems prudent to assess in each case the specific effects of alcoholic solution treatments and vapors on respirator masks before use.