Rambutan-liked Pickering emulsion stabilized by cellulose nanocrystals for enhancing anti-bacterial activity and anti-inflammatory effect of Chimonanthus nitens Oliv. essential oil.

Owing to volatility and poor water solubility, the medical application of Chimonanthus nitens Oliv. essential oil (CEO) in the fields of medicine was strictly limited. To tackle this problem, a novel CEO loaded rambutan-liked Pickering emulsion (CEO-RPE) with a spiky surface was effectively designed by coating with carboxymethyl cellulose sodium modified cellulose nanocrystals (CCN) as stabilizer. The effect of CCN concentration on the formation and stabilization of CEO-RPE was investigated. The results showed that CEO-RPE stabilized by 1 % CCN had a smaller droplet size and exhibited a rambutan-liked surface, and was stabilized against concentrated salt and high pH condition due to the steric barrier of CCN that covered in the droplet surface. Subsequently, the antibacterial performance of CEO-RPE was investigated against E. coli, S. aureus, P. aeruginosa, and S. pneumoniae by determining the minimum inhibitory concentration (MIC). The results showed that the CEO-RPE exhibited higher antibacterial activity compared to CEO, which could be attributed to its effective adhesion to the cell membrane of bacteria. In addition, the results of anti-inflammatory experiments showed that CEO-RPE also exhibited strong anti-inflammatory effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats. Therefore, the CCN stabilized rambutan-liked Pickering emulsion seemed to be a promising strategy to increase the antibacterial and anti-inflammatory activity of CEO.

Sponge-liked Silica Nanoporous Particles for Sustaining Release and Long-Term Antibacterial Activity of Natural Essential Oil.

To improve the sustained release and long-term antibacterial activity of Chimonanthus nitens Oliv. essential oil (CEO), novel sponge-liked nanoporous silica particles (SNP) were synthesized via the soft template method, which was employed as a biocompatible carrier to prepare spong-liked nanoporous silica particles loading with CEO (CEO-SNP) through physical adsorption. The structure and properties of the samples were characterized via N2 adsorption/desorption measurements, thermogravimetry (TGA), Fourier transform infrared, SEM and TEM. The result showed that the SNP exhibited an excellent loading capability of CEO up to 76.3%. The thermal stability and release behavior of the CEO were significantly improved via the physical adsorption of the SNP materials. The release profile of CEO was in accordance with the first-order kinetic model, which meant that the release mechanism was drug Fick's diffusion. The antibacterial evaluation results demonstrated that the CEO-SNP exhibited strong antibacterial activity against S. aureus, E. coli and P. aeruginosa. The antibacterial results have shown that the CEO-SNP could destroy the cell structure of bacteria, and result in the generation of oxidative stress and the release of nucleic acid. After storage of 30 d at 25 °C, the CEO-SNP still had the stronger antibacterial activity towards S. aureus, E. coli and P. aeruginosa in comparison with CEO. Therefore, the sponge-like silica nanoporous particles seemed to be a promising carrier for long-term stability and antibacterial delivery of CEO.

Fabrication and antibacterial evaluation of peppermint oil-loaded composite microcapsules by chitosan-decorated silica nanoparticles stabilized Pickering emulsion templating.

Novel peppermint oil (PO)-loaded composite microcapsules (CM) with hydroxypropyl methyl cellulose (HPMC)/chitosan/silica shells were effectively fabricated by PO Pickering emulsion, which were stabilized with chitosan-decorated silica nanoparticles (CSN). The surface modification of chitosan could improve the hydrophobicity of silica nanoparticles and favor their adsorption at the oil-water interface of PO Pickering emulsions. The microcapsule composite shells were formed dependent on the electrostatic adsorption of HPMC and CSN, and further subjected to spray-drying. The peppermint oil-loaded composite microcapsules with 100% HPMC as wall material (PO-CM@100%HPMC) seemed to be optimum formulation based on the prolonged release, acceptable entrapment efficiency (89.1%) and drug loading (25.5%). The PO-CM@100%HPMC could remarkably prolong the stability of PO. Moreover, the PO-CM@100%HPMC had a long-term antimicrobial activity (85.4%) against S. aureus and E. coli even after storage for 60 days. Therefore, the Pickering emulsions based microcapsules seemed to be a promising strategy for antibacterial application for PO.