Citations

AbstractGraphene oxide (GO) is an attractive material that can be utilized to enhance the modulus and conductivities of substrates and hydrogels. To covalently cross‐link graphene oxide sheets into hydrogels, abundant cross‐linkable double bonds were introduced to synthesize the graphene‐oxide‐tris‐acrylate sheet (GO‐TrisA). Polyacrylamide (PAM) nanocomposite hydrogels were then fabricated with inherent covalently and permanently cross‐linked GO‐TrisA sheets. Results showed that the covalently cross‐linked GO‐TrisA/PAM nanocomposite hydrogel had enhanced mechanical strength, thermo stability compared with GO/PAM hydrogel maintained mainly by hydrogen bonding between PAM chains and GO sheets. In vitro cell study showed that the covalently cross‐linked rGO‐TrisA/PAM nanocomposite hydrogel had excellent cytocompatibility after in situ reduction. These results suggest that rGO‐TrisA/PAM nanocomposite hydrogel holds great potential for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1247–1257, 2018.

AbstractTo investigate the effect of sustained bone morphogenetic protein‐2 (BMP‐2) release kinetics on bone formation in poly(propylene fumarate) (PPF) scaffolds, different poly(lactic‐co‐glycolic acid) (PLGA) microspheres were used as delivery vehicles. All PPF scaffolds had the same 75% porous structure, while the degradation rate of the embedded PLGA microspheres was changed to tailor BMP‐2 release by varying the lactic‐to‐glycolic acid (L:G) ratio in the copolymer. Four PLGA microsphere formulations with 50/50, 65/35, 75/25, and 85/15 L:G ratios and varying in vivo degradation rates were fabricated. The in vitro and in vivo BMP‐2 release kinetics were determined by analyzing radiolabeled 125I‐BMP‐2. Biological activity of released BMP‐2 was tested using a W20‐17 cell culture model in vitro and a subcutaneous rat model in vivo. Corresponding outcome parameters were defined as capacity to increase the in vitro AP activity in weekly consecutive cell cultures over 14 weeks and the in vivo bone formation after 7 and 14 weeks. The PLGA/PPF composites showed similar biological activity and BMP‐2 release profiles in vitro. In vivo, PPF/PLGA 85:15 composite released significantly less BMP‐2 per time point in the first weeks. Micro‐CT and histological analysis after 7 and 14 weeks of implantation showed bone formation, which significantly increased over time for all composites. No significant differences were seen between the composites. Overall, the results of this study show that small differences in BMP‐2 sustained release had no significant effect on BMP‐2 osteogenic efficacy in PPF/PLGA composites. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 477–487, 2018.

Chemically crosslinking GOa and CNTpega followed by in situ reduction fabricated a conductive rGOa–CNTpega–OPF hydrogel that strongly stimulated neurite growth.

AbstractScaffolds with porous structures are highly applicable for tissue engineering and regenerative medicine. In the present study, 3‐dimensional poly(propylene fumarate‐co‐caprolactone) [P(PF‐co‐CL)] scaffolds were fabricated from a P(PF‐co‐CL)–dioxane‐water ternary system through thermally induced phase separation (TIPS). Cloud points of P(PF‐co‐CL) in dioxane‐water solutions increased with increased solute concentration, but increased dioxane composition decreased cloud point. Among 3 polymer concentrations (4, 8, and 12 wt%), 8 wt% P(PF‐co‐CL) scaffolds exhibited the best pore interconnectivity, with large, regular sized pores. Scaffolds were formed in 3 solutions with different dioxane‐water ratios (74/26, 78/22, and 82/18 wt/wt); the 78/22 wt/wt scaffold had finger‐shaped patterns with better interconnectivity than scaffolds from the other two ratios. Higher dioxane‐water ratios resulted in a larger contact angle and thus less wettability for the fabricated scaffold, while scaffolds fabricated from higher concentrations of P(PF‐co‐CL) or high dioxane‐water ratios had better biomineralization after soaking in simulated body fluid. In vitro cell viability testing showed the scaffolds had good biocompatibility with both bone and nerve cells. The results indicate that the polymer concentration and solvents ratio significantly affect the formation of porous structures, and optimum processing parameters were found to be 8% polymer concentration and 22% to 24% water content. These porous P(PF‐co‐CL) scaffolds fabricated via TIPS may be useful in various tissue engineering applications © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 226–235, 2017.

A combined method by in situ crosslink polymers under phase separation condition was developed for tunable 3-D porous scaffolds fabrication.