Papers by Author: A.C.B.M. Fook

Abstract: There is a growing need for new biomaterials that can gain predictable and controlled tissue response, this is, that as bone graft substitutes should initiate new bone formation, after which they should get reabsorbed and replaced by bone tissue. This combination aims to improve the mechanical properties, degradation rates and absorption rates of biocompatibility and biodegradability. The aim of this study was to propose a synthetic route in which the HA was obtained by reaction of precipitation directly on evaluating the influence of chitosan biopolymer in the middle of precipitation in the characteristics of hydroxyapatite obtained. XRD analysis revealed the presence of HA phase with low crystallinity. In the FTIR analysis identified the characteristic bands of hydroxyapatite, as well as bands that characterize an interaction between chitosan and hydroxyapatite, as the band around 1050cm^-1. SEM analysis of the biocomposites chitosan/HA, showed a dispersion of HA particles in chitosan, revealing a homogenous material and microporous.

Abstract: The application of a hybrid composite consisting of biopolymer and calcium phosphate, similar morphology and properties of natural bone, may be a way to solve the problem of the fragility of ceramics without reducing its mechanical properties, retaining the properties of biocompatibility and high bioactivity. This work aims at the preparation and characterization of three-dimensional scaffolds composite HA / biopolymers (chitosan and gelatin). The freeze-drying technique was employed in this study to obtain these frameworks and partial results showed the effectiveness of this method. This involved the study of structural, chemical and morphological frameworks, in order to direct the research suggested the application. The X Ray Diffraction (XRD) and infrared spectroscopy and Fourier transform (FTIR) results confirmed the formation of hydroxyapatite (HA) phase and the presence of characteristic bands of HA and biopolymers in all compositions. The microstructure of the scaffolds study conducted by Scanning Electron Microscopy (SEM) revealed the formation of longitudinally oriented microchannels with interconnected pores. In all compositions the porous scaffolds showed varying sizes and mostly larger than 100μm, and is therefore considered materials with potential for application in bone tissue engineering.

Abstract: This study aimed to develop porous hydroxyapatite scaffold for bone regeneration using the replica of the polymeric sponge technique. Polyurethane sponges were used with varying densities to obtain the scaffolds. The results indicate the porous HA scaffolds developed in this study as potential materials for application as bone substitutes to have high porosity (> 70%), chemical composition, interconnectivity and pore sizes appropriate to the bone regeneration.

Abstract: In bioscience, there are several apatites constituteds by differents compositions. In the biological environment, apatites are found in bones and teeth of vertebrates with Ca/P ration from 2.0 to 0.5. It is not easy to determine the exact proportion of Ca2 + and PO43- in solution in the preparation of the process. In this study, apatites with Ca/P ration 1.0, 1.67 and 2.0 were prepared by direct reaction in an solution of H3PO4 in a suspension of Ca(OH)2, of same molarity, evalueting the crystallinity of CPP, Hap e TeCP with 1 mol/l, 3 mol/l and 5 mol/l. The samples characterized by X-ray diffraction (XRD) were compared with the standard of reference of the data base JCPDS. The composition of calcium phosphate for the differents molarity studied, resulted in a combination of phases with the exception of hydroxyapatite Ca/P ration 1.67 at concentrations 1 mol/l and 3 mol/l. But the diffractograms revealed that the increased molarity provided a decrease of some peaks of reflection of calcium phosphates with Ca/P ration 1.67. However, for the Ca/P ration 1.0 increasing the concentration, showed an increase of crystallinity of calcium phosphates. The FTIR confirmed the presence of phosphates in the spectrums around 1045 cm-1. The calcium phosphates obtained through direct reaction showed Ca/P ration is related with the technique employed, consolidating it in the preparation of these bioceramics.

Abstract: Calcium carbonate (CaCO3) is a ceramic of strong economic potential, given the versatility of its application in industry in many different areas. Protective shells of marine snails of the Brazilian coast were analyzed in this study, to verify the content of calcium carbonate available in this type of material. The samples were collected at Bessa´s Beach located in the João Pessoa’ coast Capital of Paraíba state, northern Brazil. The collection occurred during the month of February 2008; the sample was processed into powder and it was examined by X-ray Fluorescence (XRF), X-ray diffraction (XRD) and Infrared Spectroscopy with Fourier Trasformating (FTIR). The material was also submitted to heat treatment at 110°C and characterized by same techniques. The results confirmed the presence of a high content of calcium carbonate in the samples (over 95%,) which has not changed with the heat treatment used. It was presents the morphologies calcite and aragonite with prevalence of the second, both showing high levels of crystallinity. From the results obtained, calcium carbonate of the coast Paraíba has a potential application like bioceramic.