Preparation and Antibacterial Activity of Thermo-Responsive Nanohydrogels from Qiai Essential Oil and Pluronic F108.

Essential oils (EOs) have been used in cosmetics and food due to their antimicrobial and antiviral effects. However, the applications of EOs are compromised because of their poor aqueous solubility and high volatility. Qiai (Artemisia argyi Levl. et Van. var. argyi cv. Qiai) is a traditional Chinese herb and possesses strong antibacterial activity. Herein, we report an innovative formulation of EO as nanohydrogels, which were prepared through co-assembly of Qiai EO (QEO) and Pluronic F108 (PEG-b-PPG-b-PEG, or PF108) in aqueous solution. QEO was efficiently loaded in the PF108 micelles and formed nanohydrogels by heating the QEO/PF108 mixture solution to 37 °C, by the innate thermo-responsive property of PF108. The encapsulation efficiency and loading capacity of QEO reached 80.2% and 6.8%, respectively. QEO nanohydrogels were more stable than the free QEO with respect to volatilization. Sustained QEO release was achieved at body temperature using the QEO nanohydrogels, with the cumulative release rate reaching 95% in 35 h. In vitro antibacterial test indicated that the QEO nanohydrogels showed stronger antimicrobial activity against S. aureus and E. coli than the free QEO due to the enhanced stability and sustained-release characteristics. It has been attested that thermo-responsive QEO nanohydrogels have good potential as antibacterial cosmetics.

Nanocellulose hyperfine network achieves sustained release of berberine hydrochloride solubilized with ß-cyclodextrin for potential anti-infection oral administration.

Berberine hydrochloride (BBH) has been used to treat diarrhea and other gastrointestinal diseases, however its therapeutic efficacy is compromised because of poor aqueous solubility and dissolution. In this work, BBH was solubilized with ß-cyclodextrin (ß-CD) in aqueous solution through formation of the BBH/ß-CD inclusion complex (IC), which was confirmed by the combination of different techniques including FT-IR, XRD, DSC, 1H NMR and 1H NOESY. The aqueous solubility of BBH at 25 °C was increased by ca. 102% in the presence of 16 mM ß-CD. BBH/ß-CD IC-loaded bacterial cellulose (BC) hydrogels (denoted as BC/IC) were prepared by physical absorption method, resulting in higher drug loading capacity (DLC) than BC/BBH hydrogels. In vitro drug release showed that sustained drug release was achieved at different pH conditions simulating the gastrointestinal fluids by BC/IC hydrogels due to the hyperfine network of BC matrix. Furthermore, in vitro anti-bacterial test demonstrated the BC/IC hydrogels induced effective bacterial inhibition. Together with the good biocompatibility and edibility of the BC matrix, these BC/IC hydrogels appear to be promising candidates of oral administration medicine against gastrointestinal infections.

Supramolecular hydrogels based on poly (ethylene glycol)-poly (lactic acid) block copolymer micelles and α-cyclodextrin for potential injectable drug delivery system.

A supramolecular hydrogel system was prepared by the host-guest interaction between the α-cyclodextrin (α-CD) and poly (ethylene glycol) (PEG) chains of the poly (ethylene glycol)-block-poly (lactic acid) (PEG-b-PLA) micelles. The formation of inclusion complex (IC) crystals between α-CD and the PEG chains of the micelles was verified by different techniques. Rheological studies indicated that the gelation kinetics and the mechanical strength of the hydrogels could be modulated by the α-CD concentration. Also, the shear-thinning and self-healing properties of the hydrogels were confirmed. Doxorubicin (DOX) could be encapsulated into the hydrogels via the micelles and be released from the hydrogels sustainably, with the release rate dependent on the α-CD concentration. The released DOX showed higher inhibition efficacy against HeLa cells compared with the free drug. These attractive features, together with the superior biocompatibility, make the present hydrogels an potential injectable drug delivery system for tumour treatment.