Facile preparation of artemisia argyi oil-loaded antibacterial microcapsules by hydroxyapatite-stabilized Pickering emulsion templating

Artemisia argyi oil (AAO)-loaded antibacterial microcapsules with hydroxyapatite (HAp)/poly(melamine formaldehyde) (PMF) hybrid shells were facilely prepared by oil-in-water (O/W) Pickering emulsion templating. AAO-in-water emulsions were stabilized using HAp nanoparticles as the particulate emulsifier. The hybrid shells were fabricated by in situ polymerization of melamine formaldehyde pre-polymer (pre-MF) at the interface of the O/W Pickering emulsions. The prepared microcapsules were characterized in terms of size, morphology, component and thermal stability using scanning electronic microscope (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), respectively. Moreover, both in vitro release and antimicrobial activity of the microcapsules were also evaluated. The results showed that the AAO-loaded microcapsules with HAp/PMF shells had a spherical shape and a rough surface. The microcapsules maintained excellent performances in the thermal stability, controlled release activity, antimicrobial effect and long-term antimicrobial activity. The release curves of AAO from the microcapsules could be well described by Higuchi kinetic model. The microcapsules may find applications as antibacterial agents in the areas of textiles, leather, rubber and coatings. In situ polymerization based on Pickering emulsion droplets opens up a new route to prepare a variety of hybrid microcapsules with a core-shell structure.