Chemists improve antibacterial properties of chitosan films with iron and new chitin derivative

Chemists at RUDN University, in collaboration with colleagues from Belarus, have enhanced the effectiveness of antibacterial chitosan films for medical and food industry applications. They achieved this by incorporating iron-based nanoparticles and a novel chitin derivative into chitosan nanoparticles. The results of their research were published in the BioTech journal.

Antibacterial films find utility in medicine for wound healing, burn treatment, and drug delivery, as well as in food packaging to prolong shelf life. Chitosan, a natural polymer typically derived from crab shells, is a commonly used material for crafting such films due to its inherent antibacterial properties. However, the chemists discovered that iron-based nanoparticles could serve as valuable additives to boost chitosan’s performance.

“Chitosan holds a unique position among polymers due to its exceptional environmental, biological, and chemical characteristics. Its environmental advantage lies in its biodegradability, as this natural polymer readily breaks down in soil or water. From a chemical standpoint, chitosan is a linear polymer with abundant opportunities for chemical modification thanks to its free amino group,” explained Andrey Kritchenkov, Ph.D., from the Department of Inorganic Chemistry at RUDN University.

The researchers synthesized chitosan nanoparticles with varying iron concentrations, ranging from 2% to 15%. They assessed the antibacterial efficacy of the resulting films in vitro, targeting gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria. In such evaluations, the critical parameter is the size of the inhibition zone where bacterial growth and reproduction cease.

Credit: Russian Foundation for Basic Research

The team pinpointed the optimal iron nanoparticle concentration to be 10%. At this level, the suppression zone for Staphylococcus aureus measured 16.8 mm, and for E. coli, it reached 11.2 mm. In comparison, pure chitosan films achieved inhibition zones of 12.7 mm for Staphylococcus aureus and 9.2 mm for E. coli. During their investigation, the chemists also generated a novel water-soluble chitin derivative. When added to chitosan with 10% iron, it further enhanced the mechanical and antibacterial properties of the film. The suppression zone for Staphylococcus aureus expanded to 19.6 mm, and for E. coli, it reached 14.2 mm.

“We have developed chitosan-based films fortified with varying iron concentrations. Iron nanoparticles have enhanced both the mechanical strength and antibacterial properties of these films. Moreover, we have introduced a new chitin derivative that amplifies their mechanical and antimicrobial characteristics. Additionally, we have confirmed that the principal mechanism behind the films’ antibacterial action is the disruption of bacterial cell membranes,” noted Anton Egorov, a research intern at RUDN University.

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