Injectable Electrical Conductive and Phosphate Releasing Gel with Two-Dimensional Black Phosphorus and Carbon Nanotubes for Bone Tissue Engineering

Abstract

Injectable hydrogels have unique advantages for the repair of irregular tissue defects. In this study, we report a novel injectable carbon nanotube (CNT) and black phosphorus (BP) gel with enhanced mechanical strength, electrical conductivity, and continuous phosphate ion release for tissue engineering. The gel utilized biodegradable oligo­(poly­(ethylene glycol) fumarate) (OPF) polymer as the cross-linking matrix, with the addition of cross-linkable CNT-poly­(ethylene glycol)-acrylate (CNTpega) to grant mechanical support and electric conductivity. Two-dimensional (2D) black phosphorus nanosheets were also infused to aid in tissue regeneration through the steady release of phosphate that results from environmental oxidation of phosphorus in situ. This newly developed BP-CNTpega-gel was found to enhance the adhesion, proliferation, and osteogenic differentiation of MC3T3 preosteoblast cells. With electric stimulation, the osteogenesis of preosteoblast cells was further enhanced with elevated expression of several key osteogenic pathway genes. As monitored with X-ray imaging, the BP-CNTpega-gel demonstrated excellent in situ gelation and cross-linking to fill femur defects, vertebral body cavities, and posterolateral spinal fusion sites in the rabbit. Together, these results indicate that this newly developed injectable BP-CNTpega-gel owns promising potential for future bone and broad types of tissue engineering applications.

Conductive Hydrogels with Dynamic Reversible Networks for Biomedical Applications

“…[169] To mimic the physiological microenvironment of bone, Liu et al reported injectable CNTs and black phosphorus (BP)-containing DCH with enhanced mechanical strength, electrical conductivity, and continuous phosphate ion release for tissue engineering. [170] The DCH utilized a biodegradable oligo-(poly-(ethylene glycol) fumarate) (OPF) polymer as the crosslinking matrix, with the addition of cross-linkable CNT-poly(ethylene glycol)-acrylate (CNTpega) to grant network formation and electroconductivity. BP nanosheets were incorporated to aid bone regeneration through the steady release of phosphate (through the environmental oxidation of phosphorus in situ).…”

Advance of Electroconductive Hydrogels for Biomedical Applications in Orthopedics

“…Synchronously, the MC3T3-E1 could continue to release vancomycin for 28 days, a promising material for osteomyelitis and bone regeneration. Also, scientists have recently synthesized new injectable CNT and black phosphorus (BP) gels, seen in Figure 4 [4]. e gels employed biodegradable oligo(poly(ethylene glycol) fumarate) (OPF) polymer as the crosslinked substrate, with the addition of a cross-linked CNTpoly(ethylene glycol)-acrylate (CNTpega) to provide mechanical support and electrical conductivity.…”

“…e natural polymers cover fibrin, hyaluronic acid, chitosan, gellan, gelatin, collagen, alginate, and others. In contrast, the synthetic polymers include polylactide (PLA), poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(lactic-co-glycolic acetic acid) (PLGA), polycaprolactone (PCL), poly(glycerol sebacate), and polyurethane (PU) [2][3][4][5][6]. Most of these polymers are nonconductive.…”

“…e addition of various conductive active materials will produce advanced composite material of EHs with controlled conductive phase morphology. In recent years, the clinical medicine domain of electroactive cell and tissue engineering has seen an in-depth development and extensive application of EHs, such as skin, muscle, nerve, heart, bone, and cartilage [4,[18][19][20].…”

“…Figure4: Schematic demonstration of the novel injectable gel with continuous phosphate ion release and electrical responsiveness to promote cell osteogenesis and bone regeneration[4]. Copyright © 2020 American Chemical Society.…”