Facile Mechanical-Induced Functionalization of Hexagonal Boron Nitride and Its Application as Vehicles for Antibacterial Essential Oil

Herein, we report a novel type of functionalized hexagonal boron nitride (h-BN) materials as vehicles for the delivery of volatile tea tree oil (TTO) to address the challenges in bacterial infection by killing germs without using antibiotics. For the sake of improving aqueous dispersity, biocompatibility, and effective utilization, h-BN was simultaneously exfoliated and functionalized via mixed ball milling with polysaccharide (carboxymethyl cellulose, CMC) and soy protein isolate (SPI). The CMC-SPI-assisted mechanical-induced method endowed the resultant good and stable aqueous dispersity. The mechanical force-induced exfoliation and noncovalent bonding between CMC and SPI incorporated into boron nitride nanosheets (BNNS) promoted the curling and peeling of BNNS surfaces and formed orderly layered nanochannels, which provided the nanoconfinement effect as vehicles for TTO retention and transportation. Such vehicles achieved a high loading capacity for TTO with a value of 359 mg g(-1) and exhibited a long-term sustained-release behavior fitting with the Korsmeyer-Peppas release kinetics model indicative of the Fick diffusion mechanism, owing to the hydrogen bond, pi-pi stacking, and hydrophobic interactions as well as the strong interfacial interaction between vehicles and essential oils. Furthermore, we also demonstrated the proof of concept for the antibacterial activity of TTO-loaded CMC-SPI-BNNS vehicles through larger inhibition zones and a higher minimal inhibitory concentration (MIC) value against Escherichia coli (E. coli) compared to pure TTO, indicating that CMC-SPI-BNNS protects the active ingredient and exhibits a more excellent effect. Overall, this study provides a facile method for simultaneous exfoliation and functionalization of boron nitride materials with intriguing properties that can be an effective and promising approach for the delivery of volatile essential oils for antibacterial infection.