Copper-impregnated three-layer mask efficiently inactivates SARS-CoV2.

The present study investigates the potential of SARS-CoV-2 inactivation by a copper sulfide (CuS) incorporated three-layer mask design. The mask consisted of the outer, middle, and inner layers to give comfort, strength, shape, and safety. The outer layer contained a total of 4.4% CuS (w/w) (2.2% CuS coated & 2.2% CuS impregnated) nylon fibers and the middle entrapment area contain a total of 17.6% CuS (w/w) impregnated nylon. No CuS was present in the inner layer. The antiviral efficacy assessment revealed, CuS incorporated mask is highly effective in inactivating SARS-CoV-2 within 30 min exposure. After, 1h and 2 h exposure, near-complete elimination of virus were observed by cytopathy, fluorescence, and viral copy number. The antiviral activity of the mask material was derived by incorporated solid-state CuS. Noticeably, the antiviral activity of CuS against SARS-CoV-2 was in the form of solid-state CuS, but not as Cu2+ ionic form derived by dissolved CuSO4. The kinetics of droplet entrapment revealed, that the three-layered mask almost completely block virus-containing droplet pass-through for short exposure periods of 1-2 min, and 80% efficacy for longer exposure times of 5-10 min. We also demonstrated the incorporated CuS is evenly distributed all over the fibers assuring the uniformity of potential antiviral activity and proves, CuS particles are not easily shed out of the fabric fibers. The inactivation efficacy demonstrated against SARS-CoV-2 proves that the CuS incorporated three-layer mask will be a lifesaver during the present intense global pandemic.

pH-Responsive assembly of metal nanoparticles and fluorescent dyes by diblock copolymer micelles.

Hybrid assemblies consisting of metal nanoparticles (NPs) and fluorophores are quite interesting because the intrinsic properties of fluorophores can be engineered in the assembled structure. In this regard, we utilized the self-segregation properties of block copolymer micelles to organize metal NPs and fluorophores simultaneously in a specific arrangement. From the viewpoint of assembly methods, we first encapsulated Au NPs in the PS cores of polystyrene-block-poly(acrylic acid) (PS-PAA) micelles. Then, positively charged fluorescent dyes of rhodamine 123 (R123) were bound to the negatively charged PAA coronas by electrostatic interactions. Since carboxylic acid in the PAA block is a weak acid, the degree of R123 binding to PS-PAA micelles can be adjusted by varying the pH of the solution. Therefore, by changing the pH, we were able to control the assembly and disassembly of R123 molecules to PS-PAA micelles and the corresponding change in the fluorescence signal.