Preparation, characterisation and antibacterial properties of thermoplastic chitosan/nano ZnO composites

ABSTRACT

This study prepares thermoplastic chitosan/nano ZnO (CZ) composites by thermomechanical treatment in an internal mixer. Dilute hydrochloric acid aqueous solution is used as the destructuring agent of chitosan and solvent of nano ZnO. Fourier transform infrared spectroscopy and scanning electron microscopy confirm the chitosan–ZnO interaction. The crystallinity and UV transmittance of the composites decreases, while their thermal stability increases due to the addition of nano ZnO. The antibacterial activity of the CZ composites is examined in terms of their inhibitory and bactericidal effects against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. Improved antibacterial properties are obtained for the CZ composites, compared to pure chitosan sheet. Gram-positive bacteria (S. aureus and B. subtilis) are more sensitive to the antibacterial activity of the CZ composites than Gram-negative bacteria (E. coli). This work provides a simple method to prepare chitosan-based materials and obtains CZ composites with improved antibacterial activities, which can be applied in agriculture and food safety.

KEYWORDS:

• Thermoplastic chitosan
• nano ZnO
• antibacterial activity

Acknowledgments

The authors would like to express their appreciation from the project supported by National Natural Science Foundation of China (grant no. 51903077); Foundation of Hubei Provincial Department of Education (grant no. Q20173008); Research Start-up Funding of Hubei University of Education; Foundation of Open Project of State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics; Special Funding of Prevention and Cure of COVID-19 from Hubei University of Education (grant no. 20XGZX23).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Hubei Provincial Department of Education [Foundation of Hubei Provincial Department of Education]; National Natural Science Foundation of China [51903077]; Research Start-up Funding of Hubei University of Education; Foundation of Open Project of State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics; Special Funding of Prevention and Cure of COVID-19 from Hubei University of Education [20XGZX23].