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A series of star and linear polymers based on a poly(ethylene oxide) core and poly(diethylene glycol ethyl ether acrylate) outer arms were synthesised by atom-transfer radical polymerization. The polydispersity of the polymers were low, showing good control of initiation and growth. They all showed lower critical solution (LCST) behaviour, and at 3...
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Emulgels are amphiphilic semi-solid that can control the delivery of drugs showing different polarities. The use of a polymeric matrix in the hydrophilic portion leads to a higher thermodynamic stability system. Emulgels composed of poloxamer 407 (P407) and a bioadhesive polymer has shown improved contact time and adhesiveness on the site of administration, which can lead to an increase in the bioavailability of drugs. This work studied the effect of three different bioadhesive polymers, namely Carbopol 974P (C974P), polycarbophil (PCB) and poly(vinyl methyl ether-alt-maleic anhydride) (PMV/MA), on physicochemical characteristics of emulsion systems containing P407 and Amazonian andiroba oil. This oil is utilized as emollient, humectant and antioxidant. A factorial design 3⁴ was utilized, and the physicochemical stability was investigated. The mechanical textural and rheological properties of the most stable formulations were evaluated for selection of potential emulsion systems. According to the texture profile and softness analyses, the selected formulations were mainly influenced by the type and amount of bioadhesive polymer, increase of andiroba oil, and P407 content. All formulations displayed pseudoplastic flow behavior and viscoelasticity. Bioadhesion assays in ear porcine skin showed the formulations as being equally bioadhesive. Transmission electron cryomicroscopy (Cryo-TEM) analysis showed well-structured micelles, with a size < 200 nm. The use of C974P (0.20%, w/w) and P407 (17.5%, w/w) constitutes a good strategy to produce emulgel systems for local administration of Andiroba oil from 4 to 8% (w/w).
3D printing hydrogel is attractive to fabricate biomimetic scaffolds for skin repair. However, hydrogels that can be directly 3D printed with excellent mechanical properties are still limited. Here, a dual crosslinked hydrogel based on dynamic oxime crosslinking and hydrophobic interaction is developed for direct extrusion printing. We apply aminooxy terminated Pluronic F127 (AOP127) and oxidized dextran (ODex) as materials. At a lower temperature (ca. 16 °C), AOP127 and ODex form hydrogel with oxime binding for extrusion printing. At higher temperature (37 °C), the PPO segments of AOP127 physically associate, forming the second crosslinking to toughen the hydrogel. The hydrogel exhibits excellent thermosensitivity and self-healability. By 3D printing of AOP127-ODex-15% hydrogel, the obtained scaffolds show high toughness and excellent cytocompatibility. After coated with fibroin, the composite constructs showed adhesion and proliferation of skin cells. The present hydrogel is promising for fabrication of tough scaffold with natural polysaccharides and synthetic polymers.
