Bifunctional peppermint oil nanoparticles for antibacterial activity and fluorescence imaging

Essential oil from peppermint plants was used to prepare luminescent nanoparticles via a simple, one-step, thermal synthesis process. The peppermint oil nanoparticles (NPs) had a narrow particle size distribution (1.5 ± 0.5 nm) with prominent blue emission under UV irradiation. Photoluminescence (PL) spectra of the peppermint oil NP dispersion exhibited characteristic emission peaks when excited from 350 to 540 nm. The characteristic fragment from GC/MS shows the peppermint oil contains various components with antimicrobial activities. These components underwent conversion while forming the NPs via heat treatment. Transmission Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS) were used to characterize the NP chemical composition, and revealed that functional groups, such as C=O, C-O, and -CH, were present on the NP surfaces, which could act as fluorescent emissive traps. Additionally, the NPs exhibited strong antimicrobial efficiency and demonstrated good fluorescent emission during bacteria imaging, making them good candidates as antibacterial agents and multifluorescence tracers for bacterial disease treatment.