Papers by Author: Antonella M. Rossi

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Authors: C.A.S. Souza, Renata M. Souto, Ana Paula V. Colombo, Antonella M. Rossi, Maria Helena M. Rocha-Leão
Abstract: Chlorhexidine (CHX), a cationic antiseptic, is an antimicrobial agent with many applications. In this work, the antimicrobial action of CHX associated with hydroxyapatite (HA) was evaluated for treating oral infections. Based on the determination of MIC (6,25 mg/mL HACHX), the material showed growth inhibition of E. faecalis for up to 08 days.
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Authors: E. Barros, J. Alvarenga, Gutemberg Alves, B. Canabarro, G.V.O. Fernandes, Antonella M. Rossi, J.M. Granjeiro, M. Calasans-Maia
Abstract: The objective of this study was to investigate the in vitro and in vivo biological responses to carbonate apatite (cHA) in comparison to hydroxyapatite (HA). Spheres (400<ø>500 μm) of both materials were synthesized under 5°C (cHA) and 90°C (HA) and not sintered. The in vitro cytocompatibility was determined by the XTT assay, according to ISO 10993-5:2009, after exposure of MC3T3-E1 cells to the materials extracts. Ethics Commission on Teaching and Research in Animals approved this project (CEPA/NAL 193/10) and, subsequently, the biomaterials were grafted in the subcutaneous tissues of mice (n=15). After 1 and 3 weeks, five animals of each group were killed for samples removal containing biomaterials and surrounding tissues for histological examination. Semi-serial (5-μm thick) sections were cut and stained with Hematoxylin and Eosin (HE) and the presence of inflammatory infiltrates and biomaterials resorption were evaluated. The experimental group of 3 weeks didn’t show the presence of spheres of both biomaterials and few spheres were observed after 1 week. Histological analysis showed the granulation tissue around the biomaterials with the presence of multinucleated giant cells. After 3 weeks it was observed the presence of fibrous tissue around biomaterials and few inflammatory cells. No signals of tissue necrosis were observed in both groups in all experimental studied periods. Nanostructured carbonate apatite spheres are cytocompatible, biocompatible and present initial biosorption on the subcutaneous comparable to stoichiometric HA, indicating its suitability for further studies on regenerative medicine.
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Authors: Monica Calasans-Maia, Silvia R. A. Santos, Antonella M. Rossi, José Mauro Granjeiro
Abstract: The study aimed the evaluation of the effect of osseous repair in the synthetic hydroxyapatite cylinder (HA) implanted in rabbit’s tibia. Fifteen adult animals, weighing around 2.5 and 3.0 Kg, sourced by the Fluminense Federal University Animal Lab were anesthetized with spinal anesthesia, and two perforations were created in right tibia and filled with cylinders (2 x 6 mm) of HA. The animals were killed after 28 days for evaluating the HA cylinder through attenuated total reflection infrared microscopy (ATR-FTIR). The two fragments of tibia with the cylinder were collected and fixed in alcohol 70° prior to dehydration in successive alcohol solutions and then impregnated and embedded in methyl-methacrylate. Not stained neither pasted to lamina, sections of 200 µm thickness were analyzed in a Shimadzu IRPrestige-21 Automatic Infrared Microscope (AIM-8800) with ATR Objective Mirror (ATR-8800M). Prior to implantation, HA cylinder was characterized by X-Ray diffraction (XRD), Attenuated Total Reflection- Infra Red microscopy (ATR-FTIR) and X-Ray Fluorescence (XRF). After the implantation, the spectrum of the ATR-FTIR at the interface to neoformed bone was acquired. The hydroxyapatite synthesized was crystalline and stoichiometric with Ca/P ratio of 1.66, becoming carbonated after 28 days of implantation. We conclude that attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) is a useful tool for biomaterial evaluation and able to detect the modification of the chemical HA cylinder pattern occurred probably by ions migration in the biological environment.
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Authors: C.L. Jardelino, Esther R. Takamori, Silvia R. A. Santos, Antonella M. Rossi, José Mauro Granjeiro
Abstract: Porous granules without organic residues were produced from bovine medular anorganic bone. Sample showed carbonate content and crystalline order similar to natural bone. The cytotoxicity of anorganic bovine xenograft (Ossĕus®) was valuated from fibroblasts (1.5x104/cm2) cultured in serial diluted extract (0 – 100%) of Ossĕus plus 10% of fetal bovine serum (FBS). Pure extract (100%) reduced in 15% the number of viable cells (p<0.05, ANOVA, Tukey test) indicating very low cytotoxicity. Samples were implanted in the subcutaneous tissue of mice in order to evaluate tissue reaction. An organized connective tissue in contact to the granules was observed nine weeks after implantation. The anorganic bovine xenograft (Ossĕus®) was biocompatible and its behavior and osteoconduction potential should be evaluated in bony defects.
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Authors: Elena Mavropoulos, Nilce C.C. da Rocha, Maria Helena M. Rocha-Leão, Antonella M. Rossi
Abstract: Adsorption experiments of bovine serum albumin on hydroxyapatite previously annealed at temperatures up to 1100°C was performed at 37°C and phosphate buffer, pH 6.0. Kinetic process was very efficient and irreversible for low phosphate buffer concentration. Thermal treatment contributed to the decrease of bovine serum albumin immobilization indicating that sorption process depended on HA specific surface area and the number of surface active sites. However, it was verified that particle size was also an important parameter for bovine serum albumin immobilization.
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Authors: Zhen Hong, Alexandre Mello, L. Luan, Marcos Farina, L.R. Andrade, C.L. Ferreira, S. Paik, B. Deng, J.G. Eon, J. Terra, Antonella M. Rossi, Donald E. Ellis, J.B. Ketterson
Abstract: Crystalline hydroxyapatite thin coatings have been prepared using a novel opposing RF magnetron sputtering approach at room temperature. X-ray diffraction (XRD) analysis shows that all the principal peaks are attributable to HA, and the as-deposited HA coatings are made up of crystallites in the size range of 50-100nm. Fourier transform infrared spectroscopy (FTIR) studies reveal the existence of phosphate, carbonate and hydroxyl groups, suggesting that HA coatings are carbonated. Finally, in vitro cell culture experiments have demonstrated that murine osteoblast cells attach and grow well on the as-sputtered coatings. These results encourage further studies of hydroxyapatite thin coatings prepared by the opposing RF magnetron sputtering approach as a promising candidate for next-generation bioimplant materials.
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Authors: G.V.O. Fernandes, J.A. Cortês, B.R. Melo, Antonella M. Rossi, J.M. Granjeiro, Mônica Diuana Calasans-Maia, Gutemberg Alves
Abstract: Hydroxyapatite (HA) is one of the most employed materials for bone therapy due to its structural similarity with bone, its biocompatibility and physicochemical properties. Additionally, HA performance may be improved by ionic substitution of calcium with divalent bioactive metallic cations such as zinc. In this context, zinc incorporation into HA have been well studied, in spite of conflicting results regarding its biocompatibility: while previous reports on in vitro cytocompatibility have described 5% zinc containing HA (ZnHA) as slightly cytotoxic, this material presented an excellent response on in vivo studies. In order to bring more information on ZnHA biocompatibility, we performed a multiparametric assay evaluating sequentially on the same cells three different viability parameters: mitochondrial activity (XTT), membrane integrity (Neutral Red) and cell density (Crystal Violet Dye Exclusion test). Additionally, we intended to complement the existing data on ZnHA in vivo performance, by assessing its ability to affect the arrangement of collagen fibers on the grafted area, an important indicative of bone maturation. MC3T3-E1 cells were exposed to 24-hours extracts of ZnHA or stoichiometric HA on culture medium (DMEM) and cell viability was assayed. ZnHA was very cytocompatible, since the levels of viable cells on all 3 tests were similar to the HA and polystyrene (negative control) extracts, but significantly higher than cells treated with 4% phenol (positive control). For the in vivo studies, critical size defects in rats calvaria were filled with HA or ZnHA granules. The histological evaluation after 30 and 180 days revealed an increase along time. Event tough ZnHA is cytocompatible the presence of Zn was unable to alter the interaction between collagen fibers and the mineral bone phase, as compared to stoichiometric HA.
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Authors: Ingried Russoni Lima, Silvia R. A. Santos, D.L. Santiago, Antonella M. Rossi, José Mauro Granjeiro
Abstract: Hydroxyapatite (HA) and apatite based biomaterials are important for bone replacement. Different apatites could be produced by substituting calcium, phosphate or hydroxyl groups, resulting in new materials with different physical, chemical and biological properties. In this work we investigate the biological compatibility of apatites modified by divalent cations in cultured mammalian cells using Balb/c 3T3 fibroblasts cell line. Modified apatites, Ca9.5M0.5(PO4)6(OH)2 (M=Fe, Zn, Cu, Co, Sr, V e Pb) and Ca10(VO4)6(OH)2 were produced and characterized by FTIR, XRD and XRF. Extracts of each metal-modified apatites (0.1mg/mL of Dulbeco Modified Eagle Medium – DMEM without serum) were obtained. Cells (3x104) were exposed for 24 h/37C to the pure extract (100%). Afterwards, the number of viable cells was determined in a hemocitometer. The number of viable cells in the absence of any extract was taking as 100%. SHA didn’t present any toxicity while phenol killed 82% of the cells. In the presence of pure extract of Fe-HA or Sr- HA an increase of 70% and 20%, respectively, in the number of relative cells was observed. On the other hand, the number of residual cells after treatment with the pure extract of Pb+2, Zn+2, Co+2, and (VO4)3- was73, 65, 48, and 21%, respectively. In conclusion, cells response was strongly dependent on the metal that substitutes calcium or phosphate. Further studies are required to better understand the biological effect of these substitutions.
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Authors: H. Valiense, G.V.O. Fernandes, B. Moura, J. Calasans-Maia, A. Alves, Antonella M. Rossi, J.M. Granjeiro, M. Calasans-Maia
Abstract: The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group), on osseous repair of non-critical size defect in rat calvaria. Spheres (400<ø>500μm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sintered. Fifteen rats Wistar were submitted to general anesthesia and two perforations (4mm each) were made, one in each parietal bone, for implantation of cHA (left side) and HA spheres (right side). After 1, 3 and 6 weeks, five animals of each group were killed and the two fragments with the biomaterial were collected from the calvaria. The bone blocks with biomaterial were demineralized and 5μm thick semi-serial sections were done for histological analysis. The experimental group of 6 weeks did not show the presence of spheres of both biomaterials and few spheres were observed after 1 and 3 weeks. Histological analysis showed the connective tissue repairing the surgical defect after 1 week and newly formed bone after 3 weeks of surgery. Thus, we concluded both materials are biocompatible, promote osteoconduction and in all studied periods the biomaterials showed to be resorbable.
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