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.

High loads of nano-hydroxyapatite/graphene nanoribbon composites guided bone regeneration using an osteoporotic animal model.

BACKGROUND: It has been difficult to find bioactive compounds that can optimize bone repair therapy and adequate osseointegration for people with osteoporosis. The nano-hydroxyapatite (nHAp)/carbon nanotubes with graphene oxides, termed graphene nanoribbons (GNR) composites have emerged as promising materials/scaffolds for bone regeneration due to their bioactivity and osseointegration properties. Herein, we evaluated the action of nHAp/GNR composites (nHAp/GNR) to promote bone regeneration using an osteoporotic model. MATERIALS AND METHODS: First, three different nHAp/GNR (1, 2, and 3 wt% of GNR) were produced and characterized. For in vivo analyses, 36 Wistar rats (var. albinus, weighing 250-300 g, Comissão de Ética no Uso de Animais [CEUA] n.002/17) were used. Prior to implantation, osteoporosis was induced by oophorectomy in female rats. After 45 days, a tibial fracture was inflicted using a 3.0-mm Quest trephine drill. Then, the animals were separated into six sample groups at two different time periods of 21 and 45 days. The lesions were filled with 3 mg of one of the above samples using a curette. After 21 or 45 days of implantation, the animals were euthanized for analysis. Histological, biochemical, and radiographic analyses (DIGORA method) were performed. The data were evaluated through ANOVA, Tukey test, and Kolmogorov-Smirnov test with statistical significance at P<0.05. RESULTS: Both nHAp and GNR exhibited osteoconductive activity. However, the nHAp/GNR exhibited regenerative activity proportional to their concentration, following the order of 3% >2% >1% wt. CONCLUSION: Therefore, it can be inferred that all analyzed nanoparticles promoted bone regeneration in osteoporotic rats independent of analyzed time.

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.

Análise do potencial cariogênico e erosivo de diferentes marcas de leite fermentado / Analysis of the cariogenic and erosive potential of different brands of fermented milk

A dieta, quando realizada de forma inadequada, passa a ser um fator determinante para a ocorrência de cárie e erosão dentária, principalmente levando em consideração o aumento do consumo de alimentos e bebidas industrializadas por crianças e adolescentes. No presente estudo avaliaram- -se as propriedades bioquímicas dos leites fermentados encontrados em um supermercado da zona leste de Teresina, PI. Foram analisadas 36 amostras de 6 marcas comerciais diferentes, por meio das propriedades de pH endógeno e Sólidos Solúveis Totais (SST). As análises foram submetidas ao teste Kolmogorov-Smirnov e a análise da variância pela ANOVA, seguida de pós-teste Tukey para a comparação entre os grupos, no programa Minitab 16. As marcas analisadas apresentaram valor de pH que variaram de 3,13 a 3,68. Todas apresentaram valores de pH abaixo do valor considerado crítico para o processo de desmineralização do esmalte (5,5). Em relação aos sólidos solúveis totais, os valores oscilaram entre 5,93 e 11,2. Com os dados obtidos, pode-se sugerir que, se essas bebidas forem ingeridas com frequência, podem apresentar tanto um potencial cariogênico como erosivo. É de fundamental importância que os profissionais de saúde estejam cientes e alertem seus pacientes sobre os riscos que esses alimentos podem oferecer à saúde bucal dos mesmos.(AU)

Diet, when performed in inadequate ways, becomes a determining factor for occurrence of caries and dental erosion, mainly when taking into consideration the increasing consumption of industrialized foods and beverages by children and adolescents. This study aimed to evaluate the biochemical properties of fermented milks found in a supermarket in the eastern zone of Teresina-PI. Thirty-six samples from six different commercial brands were analyzed through their endogenous pH and Total Soluble Solids (TSS) properties. To analyze the data, Kolmogorov-Smirnov test and analysis of variance by ANOVA, followed by a Tukey post-test for comparison between the groups in the Minitab 16 program were performed. The analyzed brands presented pH values ranging from 3.13 to 3.68. All of them presented pH values below those considered critical for the enamel (5,5). The TSS data ranged from 5.93 to 11.2. With the data obtained, it can be suggested that if those drinks are frequently ingested, it can present both cariogenic and erosive potential. It is important that health professionals be aware and alert their patients about the risks that those sort of beverage can offer to their oral health.

Avaliação da atividade antioxidante total de chás comercializados em sachês / Evaluation of the total antioxidant activity of tea commercialized in saches

Os Antioxidantes são substancias que retardam o aparecimento de alterações oxidativas tanto nos seres vivos como nos alimentos. Quimicamente, são compostos aromáticos que contém em sua estrutura, pelo menos, um grupamento hidroxila. Estes podem ser naturais ou sintéticos, sendo o último amplamente utilizado na indústria alimentícia como conservante. O consumo de alimentos ricos em antioxidantes, como chás, vinhos e frutos foi relacionado com a baixa incidência de doenças degenerativas. Assim, objetivou-se neste estudo investigar a atividade antioxidante de chás processados frente ao DPPH (1,1-Diphenyl-2-picryl- hydrazyl). Para tanto, selecionaram- se 05 tipos de chá processados, comercializados no comercio formal da cidade de Teresina, Piauí, Brasil. A determinação da Atividade Antioxidante Total (AAT) se deu a partir dos extratos etanólicos obtidos das amostras com leituras em espectrofotômetro a 517nm. Os resultados revelam uma distribuição da ATT nas amostras variando de 19 a 84%. Observou-se, ainda, que o Boldo do Chile registrou a maior média dentre os demais. De uma forma geral, os chás são uma boa fonte de antioxidantes.(AU)