Chitosan‐based rechargeable long‐term antimicrobial and biofilm‐controlling systems

Abstract

Chitosan, a natural cationic polymer, strongly binds anionic antibiotics (e.g., rifampin) through the formation of ionic complexes. The new system shows sustained rifampin release, leading to potent antimicrobial and biofilm-controlling functions against gram-positive bacteria including Staphylococcus epidermidis and Staphylococcus aureus, which are responsible for a wide range of medical device-related infections, for longer than 30 days. Moreover, the released drugs can be recharged to further extend antimicrobial durations. Drug release mechanisms and potential applications of the new system are also discussed.

pH Effects on solubility, zeta potential, and correlation between antibacterial activity and molecular weight of chitosan

“…Some studies concluded that the antibacterial activities of chitosans increased as their MWs decreased (Cao & Sun, 2009;Ganan, Carrascosa & Martinez-Rodriguez, 2009); whereas, some reports demonstrated that larger MW chitosans have higher antibacterial activity (Lin et al, 2009;No et al, 2002b;Qin et al, 2006). In order to clarify the equivocal argument mentioned above, a comprehensive study was conducted in this study by investigation of the combined effects of pH, temperature and MW on antibacterial activity of chitosan.…”

“…However, we found equivocal results in terms of the correlation between the antibacterial activity and the MWs of chitosans. Some studies showed that the antibacterial activities of chitosans increased as the MW decreased, such as (Cao & Sun, 2009) and demonstrated that the chitosan activity increased with the MW. In the present study, we found that the correlation between the antibacterial activity and the MW of chitosans was affected by pH.…”

Biomaterials immobilized with chitosan for rechargeable antimicrobial drug delivery

“…With further increase in drug binding time, drug content on the film only increased slightly. This phenomenon can be explained by the specific interactions between CS and the drug as described in our previous work15 and others' study 30. The enhanced drug binding capability of the CS‐immobilized PU could be attributed to the introduction of functional groups on the resulting films that could form hydrogen bonds, dipole–dipole interactions, and ionic interactions with rifampin.…”

“…Previously we reported a chitosan‐based rechargeable antimicrobial system to achieve long‐term biofilm‐controlling effects 15. Chitosan is a poly‐β (1‐4)‐ D ‐glucosamine that is derived from chitin, a linear N ‐acetyl‐β(1‐4)‐ D ‐glucosamine that exists in the exoskeleton of marine shells of crustaceans 16.…”

“…We found that chitosan, being cationic, could strongly absorb anionic antimicrobial drugs and then slowly release the drugs to achieve antimicrobial and biofilm‐controlling effects for weeks. The released drugs could be repeatedly recharged to resume drug release, leading to long‐term protection 15…”