Miller, Alan Lee

Biomimetic biomaterials require good biocompatibility and bioactivity to serve as appropriate scaffolds for tissue engineering applications.

AbstractThree‐dimensional structural scaffolds have played an important role in tissue engineering, especially broad applications in areas such as regenerative medicine. We have developed novel biodegradable porous poly(propylene fumarate)‐co‐poly(lactic‐co‐glycolic acid) (PPF‐co‐PLGA) scaffolds using thermally induced phase separation, and determined the effects of critical parameters such as copolymer concentration (6, 8, and 10 wt %) and the binary solvent ratio of dioxane:water (78/22, 80/20, 82/18 wt/wt %) on the fabrication process. The cloud‐point temperatures of PPF‐co‐PLGA changed in parallel with increasing copolymer concentration, but inversely with increasing dioxane content. The compressive moduli of the scaffolds increased with greater weight composition and dioxane:water ratio. Scaffolds formed using high copolymer concentrations and solvent ratios exhibited preferable biomineralization. All samples showed biodegradation capability in both accelerated solution and phosphate‐buffered saline (PBS). Cell toxicity testing indicated that the scaffolds had good biocompatibility with bone and nerve cells, which adhered well to the scaffolds. Variations in the copolymer concentration and solvent ratio exercised a remarkable influence on morphology, mechanical properties, biomineralization, and biodegradation, but not on the cell viability and adhesion of the cross‐linked scaffolds. An 8 to 10 wt % solute concentration and 80/20 to 82/18 wt/wt dioxane:water ratio were the optimum parameters for scaffold fabrication. PPF‐co‐PLGA scaffolds thus possess several promising prospects for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2507–2517, 2018.

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.

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.

An extracellular stable micelle with a folate conjugated surface, a crosslinked core and pH-sensitive hydrolysable bonds was developed for cancer targeted drug delivery.