Essential oil-loaded chitosan/zinc (II) montmorillonite synergistic sustained-release system as antibacterial material

Abstract

Tea tree oil (TTO) is a broad-spectrum natural antimicrobial agent. Its application is limited due to its volatile property. To reduce its volatility and improve its sustained-release performance, a synergistic sustained-release system was prepared. Montmorillonite (Mt) was ion-exchanged with sodium ions (Na⁺) and zinc ions (Zn²⁺), then organically modified with cetyl trimethyl ammonium bromide (CTAB) and chitosan (CS) to improve its sustained release performance. The results indicated that Mt was exfoliated, but still maintained its ordered layer structure. The surface of CS-Zn-OMt was rough, because some pores and surfaces were filled. The addition of Zn²⁺ increased the loading of CS (37.8 − 40.8%) and induced more uniform distribution of CS on Mt. Also, CS-Zn-OMt achieved a high loading capacity for TTO and the loading value was 222.0 mg*g⁻¹. Furthermore, the release studies showed that CS-Zn-OMt exhibited sustained-release behavior due to the release from the outer layer of CS and the Mt channel simultaneously. The results of antibacterial test showed that the addition of CS inhibited the drift of Mt and showed good antibacterial performance because of strong effective drug-carrier interaction. The developed system can be potentially applied for the delivery of volatile essential oils for antibacterial infection.

Graphical Abstract

Keywords:

• Chitosan
• montmorillonite
• zinc
• tea tree oil
• antibacterial

Conflict of interest

The authors declare that they have no competing interests.

Additional information

Funding

The authors gratefully appreciate the financial support from Science Technology Program of Guangzhou, China (Grant No. 201903010011), Innovation Team of Modern Agricultural Industry Technology System of Guangdong Province (Grant No. 2019KJ140), Innovation Team Project by the Department of Education of Guangdong Province (Grant No. 2018KCXTD015), Science and Technology Planning Project of Guangdong Province (2016A020210066).