Miller, A. Lee

Strain-promoted alkyne–azide cycloaddition (SPAAC) click chemistry was applied for the rapid conjugation of nanoparticles, proteins, and siRNA-micelles to ultrasound microbubbles.

Abstract Incorporation of hydroxyapatite (HA) into polymer networks is a promising strategy to enhance the mechanical properties and osteoinductivity of the composite scaffolds for bone tissue engineering. In this study, we designed a group of nanocomposite scaffolds based on cross‐linkable poly(propylene fumarate) (PPF) and 30 wt % strontium‐hydroxyapatite (Sr‐HA) nanoparticles. Four different Sr contents [Sr:(Sr + Ca), molar ratio] in the Sr‐HA particles were studied: 0% (HA), 5% (Sr5‐HA), 10% (Sr10‐HA), and 20% (Sr20‐HA). Two‐dimensional (2D) disks were prepared using a thermal crosslinking method. The structure and surface morphology of different Sr‐HA and PPF/Sr‐HA composites were characterized using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). To detect cellular responses in vitro, MC3T3‐E1 cells were seeded and cultured on the different PPF/Sr‐HA composite disks. Cell morphology after 24 h and 5 days were imaged using Live/Dead live cell staining and SEM, respectively. Cell proliferation was quantified using an MTS assay at 1, 4, and 7 days. Osteogenic differentiation of the cells was examined by alkaline phosphatase (ALP) staining at 10 days and quantified using ALP activity and osteocalcin assays at 7, 14, and 21 days. The sizes of the HA, Sr5‐HA, Sr10‐HA, and Sr20‐HA particles were mainly between 10 × 20 nm and 10 × 250 nm, and these nanoparticles were dispersed or clustered in the composite scaffolds. in vitro cell studies showed that the PPF/Sr10‐HA scaffold was significantly better than the other three groups (PPF/HA, PPF/Sr5‐HA, and PPF/Sr20‐HA) in supporting MC3T3‐E1 cell adhesion, proliferation, and differentiation. PPF/Sr10‐HA may, therefore, serve as a promising scaffold material for bone tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 631–642, 2019.

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.

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.

Novel crosslinkable self-assembled PPF–PLGA–PEG nanoparticles with fluorescent RhB probes and FA ligands for targeted cancer imaging and potential drug delivery.