The mechanical and biological properties of polycarbonate-modified F127 hydrogels after incorporating active pendent double-bonds

- The lower critical gelation concentration and thermo-sensitivty of hydrophobic modified F127 was produced.
- A physical-chemical dual-crosslinked hydrogel was fabricated using a quantitative Michael addition reaction.
- The dual-crosslinked hydrogel shows high storage modulus and nice stability.
- The dual-crosslinked hydrogel can conjugate RGD to improve its biocompatibility.

The design and synthesis of a novel polyether-ester injectable hydrogel with a low gelation concentration and biological compatibility is important in tissue engineering. PTMC-F127-PTMC and PTMAc-F127-PTMAc block copolymers were synthesised via the ring-opening polymerisation of trimethylene carbonate (TMC) or copolymerisation of TMC and 2-methyl,2-methylacrylate,1,3-bimethylene (Ac) using F127 as the macro-initiator, and the structure was confirmed using 1H NMR and GPC. The properties of the diluted copolymer solution were studied via 1H NMR, a pyrene-fluorescence probe method and dynamic light scattering. The results showed that the introduction of short-chain polycarbonate decreased the critical micelle concentration (CMC) of the copolymer by an order of magnitude and significantly increased the diameter of the aggregate particles compared with the F127. Furthermore, the introduction of PAc segements increased this tendency. The gelation behaviour of the copolymer solution showed that this polyether-ester polymer hydrogel still retained the characteristics of the thermo-sensitive Sol-Gel transition, and the critical gelation concentration (CGC) decreased to 4-6% (15% was achieved using only F127). A physical-chemical dual-crosslinked hydrogel was fabricated using a quantitative Michael addition reaction between the double bonds in the PTMAc-F127-PTMAc copolymer and the thiols in dithiothreitol (DTT). The storage modulus (G′) of this dual-crosslinked hydrogel was three times greater than that of the simple physical crosslinked hydrogel (from 200 Pa to 630 Pa). Degradation experiments in vitro showed that the mass loss of the dual-crosslinked hydrogel at eight weeks was 20% compared with greater than 50% in the purely physically crosslinked sample. After further enhancements using the RGDC peptide, the PTMAc-F127-PTMAc hydrogel got significantly improved the adhesion and spread of mouse embryonic fibroblasts cells (NIH/3T3), which indicated the potential of this injectable hydrogel for applications in biomedical engineering.

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