Synthesis and characterization of n-phosphonium chitosan and its virucidal activity evaluation against coronavirus.

Despite the worldwide vaccination effort against COVID-19, the demand for biocidal materials has increased. One promising solution is the chemical modification of polysaccharides, such as chitosan, which can provide antiviral activity through the insertion of cationic terminals. In this study, chitosan was modified with (4-carboxybutyl) triphenylphosphonium bromide to create N-phosphonium chitosan (NPCS), a quaternized derivative. The resulting NPCS samples with three degrees of substitution (15.6 %, 19.8 % and 24.2 %) were characterized and found to have improved solubility in water and alkaline solutions but reduced thermal stability. The particles zeta potential exhibits positive charges and is directly correlated with the degree of substitution of the derivative. In virucidal assays, all NPCS samples were able to inhibit 99.999 % of the MHV-3 coronavirus within 5 min at low concentrations of 0.1 mg/mL, while maintaining low cytotoxicity to L929 cells. In addition to its potential application against current coronavirus strains, NPCS could also be valuable in combating future pandemics caused by other viral pathogens. The antiviral properties of NPCS make it a promising material for use in coating surface and personal protective equipment to limit the spread of disease-causing viruses.

Study of chitosan with different degrees of acetylation as cardboard paper coating.

The biodegradability of chitosan is significant for packaging systems. Another relevant property of chitosan is its degree of acetylation (DA), which affects other properties, such as crystallinity and hydrophobicity. The DA can be modulated by chitin deacetylation or even chitosan reacetylation. The novelty of this paper is the application of reacetylated chitosan as a coating for cardboard paper surfaces to improve the barrier and mechanical properties of the paper. Chitosan with 2% DA was reacetylated to yield chitosan with 48% DA. Both samples were applied as cardboard paper coating, and the coated materials were characterized. The paper-film system of chitosan with 2% DA had better water barrier and mechanical resistance. Heterogeneous deacetylation of chitin reduced the solubility of chitosan because molecular groups were distributed in blocks, increasing the hydrophobicity of the polymer.