Biomineralization inspired engineering of nanobiomaterials promoting bone repair.

A biomineralization processes is disclosed for engineering nanomaterials that support bone repair. The material was fabricated through a hot press process using electrospun poly(lactic acid) (PLA) matrix covered with hybrid composites of carbon nanotubes/graphene nanoribbons (GNR) and nanohydroxyapatite (nHA). Various scaffolds were devised [nHA/PLA, PLA/GNR, and PLA/nHA/GNR (1 and 3%)] and their structure and morphology characterized through Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), and Atomic force microscope (AFM). Moreover, thorough biocompatibility and toxicity studies were performed. Here, in vivo studies on toxicity and cytotoxicity were conducted in aqueous dispersions of the biomaterials at concentrations of 30, 60, and 120 µg/mL using the Allium cepa test. Further toxicity studies were performed through hemolysis toxicity tests and genotoxicity tests evaluating the damage index and damage frequencies of DNAs through comet assays with samples of the animals' peripheral blood, marrow, and liver. Additionally, the regenerative activity of the scaffolds was analyzed by measuring the cortical tibiae of rats oophorectomized implanted with the biomaterials. Biochemical analyzes [glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), urea, calcium, phosphorus, and alkaline phosphatase (ALP)] were also performed on blood samples. The results suggested a toxicity and cytotoxicity level for the GNR biomaterials at a concentration of 60 and 120 µg/mL, but non-toxicity and cytotoxicity for the 30 µg/mL concentration. The scaffolds obtained at a concentration of 0.3 mg/cm2 were not toxic in the hemolysis test and demonstrated no cytotoxicity, genotoxicity, and mutagenicity in the blood, marrow, and liver analyzes of the animals, corroborating data from the biochemical markers of GPT, GOT, and urea. Tissue regeneration was performed in all groups and was more pronounced in the group containing the combination of nHA/GNR (3%), which is consistent with the data obtained for the calcium, serum phosphorus, and ALP concentrations. Consequently, the study indicates that the engineered nanobiomaterial is a promising candidate for bone tissue repair and regenerative applications. STATEMENT OF SIGNIFICANCE: The scientific contribution of this study is the engineering of a synthetic hybrid biomaterial, in nanoscale by a pressing and heating process. A biodegradable polymeric matrix was covered on both sides with a carbonated hybrid bioceramic/graphene nanoribbons (GNR), which has hydrophilic characteristics, with chemical elements stoichiometrically similar to bone mineral composition. The nanomaterial displayed promising bone regeneration ability, which is the first example to be used in an osteoporotic animal model. Moreover, detailed biocompatibility and toxicity studies were performed on the nanomaterials and their compositions, which is of great interest for the scientific community.

Carbon Nanomaterials for Treating Osteoporotic Vertebral Fractures.

PURPOSE OF REVIEW: To identify the use of carbon nanomaterials in bone regeneration and present new data on the regenerative capacity of bone tissue in osteopenic rats treated with graphene nanoribbons (GNRs). RECENT FINDINGS: The results show that the physical and chemical properties of the nanomaterials are suitable for the fabrication of scaffolds intended for bone regeneration. The in vitro tests suggested a non-toxicity of the GNRs as well as improved biocompatibility and bone mineralization activity. Here, for the first time, we evaluated the potential of GNRs in remodeling and repairing bone defects in osteoporotic animal models in vivo. Interestingly, bone mineralization and the initiation of the remodeling cycle by osteoclasts/osteoblasts were observed after the implantation of GNRs, thus implying healthy bone remodeling when using GNRs. This study, therefore, has opened our perspectives and certainly calls for more attention to the use of carbon nanomaterials for a wide range of osteoporosis applications.