Novel Reduced Graphene Oxide/Zinc Silicate/Calcium Silicate Electroconductive Biocomposite for Stimulating Osteoporotic Bone Regeneration

Abstract

In the absence of external assistance, autogenous healing of bone fracture is difficult due to impaired regeneration ability under osteoporosis pathological conditions. In this study, a reduced graphene oxide/zinc silicate/calcium silicate (RGO/ZS/CS) conductive biocomposite with an optimal surface electroconductivity of 5625 S/m was prepared by a two-step spin-coating method. The presence of lamellar apatite nanocrystals on the surfaces of the biocomposite suggests that it has good in vitro biomineralization ability. The silicon and zinc released from the biocomposite induced a significant increase in the osteogenesis of mouse bone mesenchymal stem cells (mBMSCs). Furthermore, alkaline phosphatase activities were further promoted when 3 μA direct current was applied to stimulate the mBMSCs that were cultured on the RGO/ZS/CS surface. However, electrical stimulation failed to further upregulate the osteogenesis-related gene expression. Moreover, RGO/ZS/CS extracts were found to suppress the receptor activator of nuclear factor-κB ligand-induced osteoclastic differentiation of mouse leukemic monocyte macrophages (RAW264.7 cells). Although the zinc ions in the RGO/ZS/CS extracts showed an inhibitory role in human umbilical vein endothelial cell (HUVEC) proliferation, dilutions of the RGO/ZS/CS extracts (1/16, 1/32, and 1/64) promoted HUVEC proliferation, and their angiogenesis-related gene expression was also upregulated. On the basis of the results of the in vitro angiogenesis model, more interconnected tubes formed when the above dilutions of RGO/ZS/CS extracts were added to ECMatrix. The new RGO/ZS/CS electroconductive biocomposite has potential to be used for stimulating osteoporotic bone regeneration.

From Dermal Patch to Implants—Applications of Biocomposites in Living Tissues

“…However, in the presence of the biocomposite extracts with different dilution ratios, mesh-like circle structures were observed, indicating that HUVEC proliferation increased and expression of angiogenesis-related genes was promoted. These results indicated that the electroconductive biocomposite developed by Xiong et al [15] demonstrated superior in vitro osteogenesis and angiogenesis performances, displaying a large potential for stimulating osteoporotic bone regeneration. Although promising, application of this biocomposite to osteoporotic fracture healing will require further in vitro and in vivo studies, moving beyond the seeding of cells at the surface of the scaffolds.…”

“…Considering that bone defects may also arise from diseases such as osteoporosis (predominant disease due to the aging population), Xiong et al [15] explored the development of an electroconductive biocomposite for stimulating bone regeneration under osteoporosis conditions. Previous promising results have demonstrated that silicate-based biomaterials are able to be used in the enhancement of osteoporotic bone regeneration [16][17][18][19][20].…”

“…Previous promising results have demonstrated that silicate-based biomaterials are able to be used in the enhancement of osteoporotic bone regeneration [16][17][18][19][20]. Consequently, the biocomposite developed by Xiong et al [15] was composed of different silicates organized in three layers-a calcium silicate (CS) substrate base, a zinc silicate (ZS) middle layer and a reduced graphene oxide (RGO) top layer. Zinc and silicon are key trace elements in the bone, known to enhance bone regeneration [21,22].…”

“…In addition to allowing growth of MC3T3 cells when cultured on the discs-shaped cement, these cells displayed high levels of ALP, illustrating that the biocomposite was osteoinductive and supported cell differentiation. Reprinted with permission from Reference [15]. (d) Fabrication process of 3D-orinted scaffolds using a low temperature process.…”

“…Nanohydroxyapatite and glycol chitosan [10] Hydroxyapatite and polymeric blend (fibroin, chitosan and agarose) [11] Calcium silicate, zinc silicate and graphene oxide [15] Collagen, silk fibroin and dECM [26] Boron nitride and boron trioxide [28] Nanohydroxyapatite, calcium sulfate and bioactive molecules [32] Orthopedic Implants PEEK and graphene oxide [39] CFRPEEK, nanohydroxyapatite, carboxymethyl, chitosan and bone forming peptide [41] Polyphenylene sulfide and nanohydroxyapatite [42] Polyimide and tantalum pentaoxide [43] Hydroxyapatite, ceria nanoparticles and silver nanoparticles [44] Wound Healing Polycaprolactone and gelatin [54] Chitosan, polyethylene oxide and fibrinogen [57] Collagen, alginate and silver nanoparticles [60] Polyurethane, keratin and silver nanoparticles [63] Collagen and dextran [65] Tissue Engineering Fibrin, alginate and genipin [68] PEDOT, chitosan and gelatin [70] Polycaprolactone, silk fibroin and carbon nanotubes [71] Silk fibroin and melanin [78] Polycaprolactone and collagen [82] Gelatin, alginate and fibrinogen [88] Collagen type I and gelatin methacryloyl [89] Author Contributions: Conceptualization, K.P.V., A.B., and A.S.; writing-original draft preparation, K.P.V. ; writing-review and editing, K.P.V., A.B., and A.S.; supervision, A.B.…”