Effect of Chitosan-Coated Nanostructured Lipid Carrier on Escherichia coli Biofilms

Antimicrobial delivery systems are useful tools to control biofilm growth on abiotic surfaces such as urinary catheter. The present study examined whether nanostructured lipid carriers coated with chitosan (NLC-chitosan) affected the growth of uropathogenic biofilms of Escherichia coli . NLC-chitosan was prepared using the emulsion and sonication method, and further characterized with respect to particle size, polydispersity index, and zeta potential. After determining the minimum inhibitory and bactericidal concentrations, E. coli biofilms were grown on catheter specimens (following a preliminary study in which E. coli was found to adhere better to the catheter surface than glass slide and plate). At the 48, 72, 96, and 120 h of growth, they were exposed to 0.9% NaCl solution (negative control), 0.12% chlorhexidine solution (positive control), or NLC-chitosan (final chitosan concentration of 0.28%). After 24 h of treatment, the biofilms were collected to analyze their bacterial viability. NLC-chitosan preparation had bimodal particle size distribution with mean size of 292.9 ± 2.5 nm and polydispersity index of 0.24 ± 0.03 and positive zeta potential (+19.1 ± 0.2) indicating the nanoparticle coating by chitosan. Compared with the control groups, NLC-chitosan affected bacterial viability of biofilms at all ages studied ( p <0.05). NLC-chitosan can effectively control the growth of young and mature biofilms of uropathogenic E. coli .