Regioselective synthesis of quaternized cellulose nanocrystals and its antibacterial properties in clinical isolates of methicillin-resistant Staphylococcus aureus

Quaternized cellulose nanocrystals (CNCs) were prepared by chloroacetylation and subsequent reaction with tertiary amines. The chloroacetylation of CNCs and quaternary ammonium-modified CNCs were characterized by the analysis of FTIR and solid-state NMR spectroscopies. Chloroacetylation of CNCs was found to be highly regioselective. CNCs can be chemically modified to tailor their properties to improve dispersion in the polymer matrix, which expands the application of CNCs as reinforcing materials. Biological evaluation of the ammonium-modified compounds was conducted using the disc diffusion test, minimum bactericidal concentration, and bacterial killing pattern for methicillin-associated multidrug-resistant clinical isolates of Staphylococcus aureus, one of the most problematic bacterial human pathogens. Results showed that the CNC with alkyl chains with 16 carbons had more antibacterial properties than that of 10 carbons against all tested clinical isolates of Staphylococcus aureus regardless of antibiotic resistance or sensitivity. This finding suggests that the ammonium-modified CNCs may be applicable to treat Staphylococcus aureus infections.