6.5. Challenges to LbL Nanocoating as an Antiviral Measure
It is seen from the literature that LbL nanocoating has been successful against many microorganisms, however, it has not seen significant testing against viruses. It is uncertain how long a surface will remain efficient in trapping viruses, and regular replacement of the materials is probable. Recently [160] it was shown that self-cleaning reusable face masks could be manufactured by coating the textile with hydrophobic silicon dioxide over etched pores of the mask.
On the other hand, it was shown that superhydrophilic chitosan/carboxymethylcellulose LbL coating of silicone ophthalmic devices encouraged the flow of tears and prevented bacterial biofilm formation. The devices also contained antibacterial agents that were released and contributed to the overall effect [195]. Perhaps polysaccharides can be employed in the same way, however, they might require chemical modification. It is also not established if hydro- or hydrophilic coatings will be the most effective.
It has been illustrated that orthopedic implants could be coated with drug-containing niosomes that prevented bacterial adhesion to the implant [196]. Other antibacterial coatings almost always contained antibacterial drugs. Antiviral drugs are not so abundant and other agents might have to be included in the LbL polysaccharide films. These are yet to be identified.
There are no studies that have reported the saturation load that these coatings might accommodate. The disposal of materials that have come in contact with viruses is of concern and protocols for handling this waste should be developed. Not only do they contribute to waste production [197], but also possibly to accumulation of a virus at the place of disposal. Antibacterial textiles have been utilized to manufacture sportswear, underwear, bedding, mattresses, wound dressings, and hospital gowns [198]. These items need laundering in order to reuse and pollute water sources, potentially leading to the accumulation of viruses in the water [199]. Perhaps a disposable product is a better alternative than a reusable product such as illustrated for disposable towels and baths that prevent the accumulation of skin bacteria in patients under nursing care [200].
Clearly many challenges need to be addressed to ensure the effectiveness of these coatings against viruses. The way has, however, been paved by, for example, successful antibacterial and antifungal applications in many settings where humans are exposed to many different surfaces.