Meifeng Liu,Weichi Chen,Xingyu Zhang,Pengwen Su,Feng Yue,Shaoqun Zeng,Song Du
Madecassoside (MA) exhibits excellent therapeutic effects in wound healing and scar management. However, its high hydrophilic nature and low permeability through skin tissue limits its topical application. Liposomes are widely used to deliver drugs due to their high structural similarity and biocompatibility with cell membranes. However, normal liposome formulations are too fluid to maintain sufficient adhesion to the wound surface. In this study, in order to make an MA formulation conducive to topical administration, poly(ethylene glycol)-poly( ε -caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE), a biodegradable and temperature-responsive copolymer material, was synthesized and applied to improve the adhesion properties of MA liposomes. The mean particle size of the PECE-modified MA liposomes was 213.43±4.68 nm, and the zeta potential was −23.80±15.37 mV under the optimal conditions of EPC (egg yolk lecithin) to PECE at a mass ratio of 1:1. Additionally, PECE-modified MA liposomes maintained a hydrogel state for better adhesion until the temperature reached 43°C. Furthermore, the PECE-modified MA liposomes showed superior wound contraction effects relative to the MA liposomes in second-degree burn experiments using a rat model. These results indicated that PECE-modified MA liposomes have better surface adhesion performance and healing effects than unmodified MA liposomes.
Development of efficient ocular drug delivery systems was still a challenging task. The objective of this article was to develop a thermosensitive PEG–PCL–PEG (PECE) hydrogel and investigate its potential application for ocular drug delivery of diclofenac sodium (DIC). PECE block polymers were synthesized by coupling MPEG-PCL co-polymer using IPDI reagent, and then its sol–gel transition as a function with temperature was investigated by a rheometer. The results showed that 30% (w/v) PECE aqueous solution exhibited sol–gel transition at approximately 35 °C. In vitro release profiles showed the entrapped DIC was sustained release from PECE hydrogels up to 7 days and the initial drug loading greatly effect on release behavior of DIC from PECE hydrogels. MTT assay results indicated that no matter PECE or 0.1% (w/v) DIC-loaded PECE hydrogels were nontoxic to HCEC and L929 cells after 24 h culturing. In vivo eye irritation test showed that the instillation of either 30% (w/v) PECE hydrogels or 0.1% (w/v) DIC-loaded PECE hydrogels to rabbit eye did not result in eye irritation within 72 h. In vivo results showed that the AUC0–48 h of 0.1% (w/v) DIC-loaded PECE hydrogels exhibited 1.6-fold increment as compared with that of commercial 0.1% (w/v) DIC eye drops, suggesting the better ophthalmic bioavailability could be obtained by the instillation of 0.1% (w/v) DIC-loaded PECE hydrogels.
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