Dicalcium Phosphate Coated with Graphene Synergistically Increases Osteogenic Differentiation In Vitro

Three-dimensional porous reduced graphene oxide/hydroxyapatite membrane for guided bone regeneration

The guided bone regeneration (GBR) membrane is intended to provide sufficient space for alveolar bone regeneration and meanwhile prevent the invasion of gingival epithelium. In this study, three-dimensional porous reduced graphene oxide/hydroxyapatite (3D rGO/HA) membrane with two different sides was prepared using a two-step electrochemical method. One side of this composite membrane facing the bone defect was formed by 3D porous rGO with HA deposited on the frame of the 3D structure, and the other side of the membrane presented a dense 2D rGO surface to prevent the invasion of the gingival epithelium. The morphology, phase composition, and physical properties of the 3D rGO/HA composite membrane were characterized. Then the cell morphology, viability, and proliferation of pre-osteoblasts (MC3T3-E1 cells) on the 3D porous structure surface of membranes were evaluated and alkaline phosphatase (ALP) secretion as an indication of osteogenic differentiation was also investigated. Meanwhile, cell morphology, viability, and proliferation of HUVEC and L929 cells on the dense structure surface were examined. Finally, a cranial defect model of rat was employed to evaluate the effect of 3D rGO/HA as a GBR membrane in vivo. The results revealed the 3D rGO/HA membrane had good biocompatibility for MC3T3-E1 and HUVEC cells and could significantly enhance ALP secretion. Furthermore, this membrane also promoted the repair of calvarial defects in vivo. These results demonstrated that 3D porous rGO/HA composite membrane with a porous side and another dense side represents great application potential as an ideal GBR membrane.

Potential of Carbon-Based Nanocomposites for Dental Tissue Engineering and Regeneration

While conventional dental implants focus on mechanical properties, recent advances in functional carbon nanomaterials (CNMs) accelerated the facilitation of functionalities including osteoinduction, osteoconduction, and osseointegration. The surface functionalization with CNMs in dental implants has emerged as a novel strategy for reinforcement and as a bioactive cue due to their potential for mechanical reinforcing, osseointegration, and antimicrobial properties. Numerous developments in the fabrication and biological studies of CNMs have provided various opportunities to expand their application to dental regeneration and restoration. In this review, we discuss the advances in novel dental implants with CNMs in terms of tissue engineering, including material combination, coating strategies, and biofunctionalities. We present a brief overview of recent findings and progression in the research to show the promising aspect of CNMs for dental implant application. In conclusion, it is shown that further development of surface functionalization with CNMs may provide innovative results with clinical potential for improved osseointegration after implantation.

Reduced graphene oxide coating enhances osteogenic differentiation of human mesenchymal stem cells on Ti surfaces

BACKGROUND

Titanium (Ti) has been utilized as hard tissue replacement owing to its superior mechanical and bioinert property, however, lack in tissue compatibility and biofunctionality has limited its clinical use. Reduced graphene oxide (rGO) is one of the graphene derivatives that possess extraordinary biofunctionality and are known to induce osseointegration in vitro and in vivo. In this study, rGO was uniformly coated by meniscus-dragging deposition (MDD) technique to fabricate rGO-Ti substrate for orthopedic and dental implant application.

METHODS

The physicochemical characteristics of rGO-coated Ti (rGO-Ti) substrates were evaluated by atomic force microscopy, water contact angle, and Raman spectroscopy. Furthermore, human mesenchymal stem cells (hMSCs) were cultured on the rGO-Ti substrate, and then their cellular behaviors such as growth and osteogenic differentiation were determined by a cell counting kit-8 assay, alkaline phosphatase (ALP) activity assay, and alizarin red S staining.

RESULTS

rGO was coated uniformly on Ti substrates by MDD process, which allowed a decrease in the surface roughness and contact angle of Ti substrates. While rGO-Ti substrates significantly increased cell proliferation after 7 days of incubation, they significantly promoted ALP activity and matrix mineralization, which are early and late differentiation markers, respectively.

CONCLUSION

It is suggested that rGO-Ti substrates can be effectively utilized as dental and orthopedic bone substitutes since these graphene derivatives have potent effects on stimulating the osteogenic differentiation of hMSCs and showed superior bioactivity and osteogenic potential.

Recent advancement in biomedical applications on the surface of two-dimensional materials: from biosensing to tissue engineering

As biosensors and biomedical devices have become increasingly important to everyday diagnostics and monitoring, there are tremendous, and constant efforts towards developing and improving the reliability and versatility of such technology. As they offer high surface area-to-volume ratios and a diverse range of properties, from electronic to optical, two dimensional (2D) materials have proven to be very promising candidates for biological applications and technologies. Due to the dimensionality, 2D materials facilitate many interfacial phenomena that have shown to significantly improve the performance of biosensors, while recent advances in synthesis techniques and surface engineering methods also enable the realization of future biomedical devices. This short review aims to highlight the influence of 2D material surfaces and the properties that arise due to their 2D structure. Using recent (within the last few years) examples of biosensors and biomedical applications, we emphasize the important role of 2D materials in advancing developments and research for biosensing and healthcare.

Investigating the mechanical behavior of hydroxyapatite-reduced graphene oxide nanocomposite under different loading rates

In this study, the hydroxyapatite (HA)-reduced graphene oxide (rGO) nanocomposite was investigated for its mechanical properties. The nanocomposite used in this study was made in two stages. The HA-rGO powders were first synthesized by hydrogen gas injected hydrothermal method, and then consolidated by spark plasma sintering. HA-rGO nanocomposite was subjected to Vickers indentation experiments with different loading rates. Various analyzes have been used in this study, including x-rays diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, fast fourier transform, and inverse fast fourier transform. The findings of this study showed that the HA in this nanocomposite was reinforced with rGO sheets coated with HA. As the loading rate increased, the slope of the curves in the elastic region was increased, indicating that the elastic modulus was increased. Also, the contact depth at higher loading rates was increased. Plastic deformation was higher at higher loading rates and the hardness had increased. As the loading rate increased from 300 mN to 1 N, the hardness and elastic modulus increased with more slope than when the loading rate changed from 1 N to 2 N. The presence of rGO sheets had partially controlled the HA brittleness.

Graphene Oxide Reinforcing Genipin Crosslinked Chitosan-Gelatin Blend Films

This study was targeted towards the synthesis and characterization of new chitosan–gelatin biocomposite films reinforced with graphene oxide and crosslinked with genipin. The composites’ mode of structuration was characterized by Fourier Transform Infrared spectroscopy and X-ray diffraction, while morphology and topography were investigated by scanning electron microscopy, nano-computer tomography and profilometry. Eventually, thermal stability was evaluated through thermogravimetrical analysis, mechanical properties assessment was carried out to detect potential improvements as a result of graphene oxide (GO) addition and in vitro enzyme degradation was performed to discern the most promising formulations for the maturation of the study towards in vivo assays. In accordance with similar works, results indicated the possibility of using GO as an agent for adjusting films’ roughness, chemical stability and polymer structuration. The enzymatic stability of chitosan–gelatin (CHT-GEL) films was also improved by genipin (GEN) crosslinking and GO supplementation, with the best results being obtained for CHT-GEL-GEN and CHT-GEL-GEN-GO3 (crosslinked formulation with 3 wt.% GO). Yet, contrary to previous reports, no great enhancement of CHT-GEN-GEL-GO thermal performances was obtained by the incorporation of GO.

Graphene-Based Nanocomposites as Promising Options for Hard Tissue Regeneration

Tissues are often damaged by physical trauma, infection or tumors. A slight injury heals naturally through the normal healing process, while severe injury causes serious health implications. Therefore, many efforts have been devoted to treat and repair various tissue defects. Recently, tissue engineering approaches have attracted a rapidly growing interest in biomedical fields to promote and enhance healing and regeneration of large-scale tissue defects. On the other hand, with the recent advances in nanoscience and nanotechnology, various nanomaterials have been suggested as novel biomaterials. Graphene, a two-dimensional atomic layer of graphite, and its derivatives have recently been found to possess promoting effects on various types of cells. In addition, their unique properties, such as outstanding mechanical and biological properties, allow them to be a promising option for hard tissue regeneration. Herein, we summarized recent research advances in graphene-based nanocomposites for hard tissue regeneration, and highlighted their promising potentials in biomedical and tissue engineering.