Nano silver antimicrobial spray-coated textiles effective against SARS-CoV-2

In response to the battle against SARS-CoV-2, an eco-friendly process is used to produce highly concentrated suspensions of silver nanoparticles (Ag NPs) applied on textiles with antiviral and antibacterial properties suitable for the engineering of facemasks and protective textiles. Ag NPs were synthesized at room temperature reducing a solution of AgNO3 by means of hydroxyethyl cellulose (HEC) which acts also as capping agent. The reduction synthesis was catalyzed by NaOH according to the patented procedure [1]. The Ag-HEC NPs dispersion was added to poly(vinyl alcohol) (PVA) dissolved at a concentration of 1.0 wt/vol % in water with 1:1 volume ratio. The resulting dispersion was deposited on three different types of fabric: 1) spunbonded non-woven polypropylene (PPNW); 2) polyamide (PA 6,6) fabric; and 3) ISO 105 F04 polyethylene terephthalate (PET) fabric. The coated fabrics were then oven dried at 80 °C for 2 min. Anti-SARS-CoV-2 and antibacterial activities of each coated fabric were tested. Stability of the functionalized samples against washing and abrasion was also assessed. The virus activity on Ag-HEC-loaded fabrics was reduced by about 33% when compared with the untreated substrates, pointing out that despite Ag NPs were immobilized on a textile support the antiviral action capability was still exerted. Antibacterial tests were performed on Ag-HEC coated fabrics after abrasion or laundering cycles, for testing washing and mechanical resistance. The results showed a substantial, and in some cases complete, reduction of Escherichia coli after 1 hour, also after the treatments simulating the use. These results, comparable to our previous ones obtained on nanofibers coated filter media [2], further confirmed the strong adhesion of AgHEC to the treated fabrics, leading to efficient antibacterial activity after washing. The design of this Ag-based nanotechnology seems to be very efficient in the battle against microorganims.