Priscila Ferraz Franczak

Characterization of Three Calcium Phosphate Microporous Granulated Bioceramics

The calcium phosphate microporous bioceramics, and hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) biphasic compositions, in the granular form of microporous biomaterials, are research themes and present potential biomedical applications in rebuilding and repairing maxillofacial bone and tooth structure and in orthopedic applications. This is associated with microstructural characteristics of biocompatibility and bioactivity and osteoconductivity properties that these biomaterials offer when applied in vivo or in simulated environment. Another differential point of these biomaterials is the solubilization capacity that they present when applied in the biological environment. These compositions of calcium phosphates (hydroxyapatite matrix and/or β-tricalcium phosphate) allow for the gradual release of calcium and phosphate ions for the biological environment, which are absorbed and promote the formation of new bone tissue. These materials are also promising in applications in the field of traumatology as in the repair of traumatized bone tissue and drugs controlled release and bone structure treatments. The favorable results of these biomaterials as bone reconstruction matrix and drugs controlled release are associated with crystallographic characteristics, morphology, surface and solubility that these biomaterials present when in contact with body fluids. This work aimed to describe three types of calcium phosphate microporous granulated biomaterials. The biomaterials used were provided by the Biomaterials Group from Universidade do Estado de Santa Catarina - UDESC and are: hydroxyapatite, β-tricalcium phosphate and biphasic composition 60% hydroxyapatite/40% β-tricalcium phosphate. The Scanning Electron Microscopy technique (SEM) was used for carrying out the morphological characterization and microstructure studies of granulated biomaterials. The X-Ray Diffractometry (XRD) served for characterization of crystalline phases. Arthur Method was used for determining open porosity and hydrostatic density of biomaterials. The BET technique served to support determination of the surface area of microporous granulated biomaterials. The results are encouraging and show that these biomaterials present promising morphological characteristics and microporous microstructure as wettability and capillarity. These characteristics may contribute to biomaterial osteointegration by new tissue, bone formation and mineralization process.

Characterization of Different Nanostructured Bone Substitute Biomaterials

The present research paper centers on physicochemical characterization of six nanostructured alloplastic bone substitutes developed at Santa Catarina State University (UDESC Brazil). In addition to identifying the main phases, the focus was to measure the morphological and microstructural features, which are believed to be crucial for controlling and guiding biological and molecular events. The studied samples exhibited rounded granules measuring 200μm 10(PO4)6(OH)2] was found as main phase for HAp, BCP and HAp/Al2O3 biomaterials. For HAp/TiO2n, HAp/SiO2n and β-TCP, the major phase was beta tricalcium phosphate [Ca3(PO4)2-β]. The results demonstrate that the presence of a second phase of nanometer order, at a hydroxyapatite bioceramic matrix, may modify the surface diffusion of the grains and the phase transformation kinetics of hydroxyapatite and beta tricalcium phosphate at temperatures up to 1100°C.

Synthesis and Characterization of Three Hydrated Calcium Phosphates Used as Biocement Precursors

Calcium phosphates biocements are biomaterials that present crystallographic and mineralogical characteristics similar to human skeletal structure. This has led to the development of new calcium phosphates biomaterials for biomedical applications, especially biomaterials for repairing defects and bone reconstruction. Calcium phosphates biocements are a promising alternative in biomedical applications, for they are easy to mold, they have good wettability, hydration and hardening capacity during its application in biological environment. This work aimed at the synthesis of hydrated calcium phosphates powder, precursor to late biocements development. Three calcium phosphates compositions were produced via CaCO3/phosphoric acid reactive method in the ratios Ca/P = 1,5; 1,6 e 1,67 molar. The presented results are associated to hydrated powder morphology and synthesis process control. Field Electronic Microscope helped with the morphological characterization of the powders, Fourier Transformed Infrared Spectroscopy (FTIR) gave support to the identification of H2O e PO43- grouping vibrational bands and x-ray diffractometry (XRD) served on crystallographic characterization of hydrated calcium phosphates. The work showed that for the different powder compositions the hydrated calcium phosphate phase is formed by clustered fine particles. This demonstrated that the chosen synthesis method permits the obtaining nanoparticles of hydrated calcium phosphates, precursors for later biocement production.

Elaboration of a triphasic calcium phosphate and silica nanocomposite for maxillary grafting and deposition on titanium implants

Abstract A hydroxyapatite and tricalcium phosphate nanocomposite containing 5% silica was developed for dental applications. The biomaterial was prepared by one-step synthesis via the wet route. The resulting dry material consisted of hydrated calcium phosphate agglomerates with sizes of up to 200 μm. The presence of silica was found to lower the phase transformation temperature of the calcium phosphates and increase the open porosity of the biomaterial compared to that of hydroxyapatite. The hydrated calcium phosphate transformed into hydroxyapatite (HA) and beta tricalcium phosphate (TCP) at approximately 682 °C. After 2 h of calcination at 900 °C, the volume ratios of HA and TCP in the nanocomposite were 84 and 16%, respectively. The open porosity in the triphasic nanocomposite and in the HA was 46.35% and 41.52%, respectively, after 3 h of sintering at 1 100 °C. Samples of grade 2 titanium were sandpapered and etched with an acid solution of HCl/H2SO4 prior to deposition of the calcined nanocomposite. The particles were deposited homogeneously and reduced the contact angle of the titanium surface.

Hydration study from different calcium phosphate biocements with microstructure and nanostructure.

Important features of biocements include easy molding and good wettability, hydration, and setting time during its application in biological tissue. Interest in calcium phosphate biocements is directly related to its characteristics of bioactivity, biocompatibility, and crystallographic similarity to bone apatite. This experimental study aimed to understand hydration behavior of calcium phosphate biocements with microstructure and nanostructure, with molar ratios Ca/P = 1.5; 1.6; 1.67; and 1.7 and hydration times of 5 and 30 min. The hydration tests were performed on the same solid/liquid ratio for the four Ca/P compositions. The morphology was observed via scanning electron microscopy and phases were identified with help from X-ray diffraction. The biocements showed similar effects of hydration and gelling for the periods of 5 and 30 min. The results show that these biocements can offer favorable wettability, hydration, and easy molding during the surgical procedure, which could be an innovation in implant fixation and bone tissue repair.

Synthesis and Characterization of a Hydrated Calcium Phosphate Matrix and Biphasic Compositions with MgO and α-Al2O3

The calcium phosphate bioceramics are characterized by chemical and crystallographic similarity with the human skeleton. The wet synthesis method was used in the preparation of hydrated calcium phosphate nanostructured powders and biphasic compositions of calcium phosphate matrix. This study aimed the synthesis and characterization of a hydrated calcium phosphate matrix in the ratio Ca/P 1.67 molar and two biphasic compositions of hydrated calcium phosphate matrix, with 1% MgO and 5% α-Al2O3. Scanning Electron Microscopy (SEM) helped with the powders morphological characterization, X-ray diffractometry (XRD) served for crystallographic characterization of powders and Fourier Transformed Infrared Spectroscopy (FTIR) gave support to the identification of H2O, CO32- and PO43- grouping vibrational bands. The work showed that the presence of 1% MgO inside the hydrated calcium phosphate matrix provided brushite formation and the presence of 5% α-Al2O3 in the matrix provided the hydrated calcium phosphate powder.

Synthesis and Characterization of Nanostructured Calcium Phosphates: Colloidal Suspension Rheological Study

Calcium phosphates bioceramics are a broad class of biomaterials, known by properties like biocompatibility and bioactivity in living tissues. The aim of this paper was the synthesis by wet method and characterization of nanostructured calcium phosphate powders in the Ca/P ratio of 1.67molar and rheological evaluation of the colloidal suspension during the synthesis: suspension viscosity with variable shear rate. Morphological characterization was performed for the hydrated nanostructured calcium phosphate powder by scanning electron microscopy with field effect, crystallography by X-Ray diffractometry, chemical characterization by Fourier Transformed Infrared Spectroscopy. The results demonstrated that varying the shear rate has a direct influence on the viscosity values according to time. This result may contribute to the development of a synthesis methodology for nanostructured calcium phosphate powders.

Part II - Microstructural and Physical of Calcium Phosphate Biomaterials Obtained from Natural Raw Materials

Calcium phosphate bioceramics obtained from raw materials are potential bone substitutes in orthopedic and dental applications. Calcium phosphates attained from calcareous shells using wet methods provide an interconnected microporous framework, shown to be promising and contribute to cell adhesion and proliferation. This study aimed to characterize three different calcium phosphate ratio compositions: (i)1.4, (ii)1.6 and (iii)1.7 molar, sintered for 2 hours at 1100°C and 1200°C. Scanning electron microscopy field effect [FEG] and confocal were used to assess microstructural characterization and Arthur method to determine open porosity. FEG and confocal analyses showed good grain coalescence, sinterability and well defined interfaces for all Ca/P molar at 1100°C and 1200°C. Open porosity and hydrostatic density exhibit better results when using Ca/P molar ratio (iii)1.7 at 1100°C. The results showed that open porosity is related to Ca/P ratio and by temperature. As the Ca/P increases so does the open porosity. Inversely occurs for temperature. As the temperature increases the porosity decreases and in parallel, the grain size increases.

Synthesis and Characterization of a Nanostructured Matrix of Hydrated Calcium Phosphate

Bone reconstruction biomaterials are topics of interest in dentistry, orthopedics, scientific, commercial. The most popular bone repairing and reconstruction biomaterials are calcium phosphates. The demand for biomaterials is associated with the chemical and crystallographic characteristics of the human bone apatite. The wet synthesis method is common in the production of nanostructured powders of hydrated calcium phosphates, providing nanoparticles with sizes less than 50nm. This study aimed to synthesize and characterize hydrated calcium phosphate powders in the molar ratio of Ca/P = 1.67. After calcination at temperature 900°C/2h, these powders provide nanostructured hydroxyapatite matrix. The characterization studies were performed with Scanning Electron Microscopy, X-rays diffraction and Infrared Spectroscopy by Fourier Transform. The results show that the synthesis method provides hydrated calcium phosphate powders formed by aggregated and agglomerated nanoparticles. The thermal treatment of hydrated calcium phosphate powder led to formation of hydroxyapatite matrix.

Synthesis and Characterization of Hydrated Calcium Phosphate: Precursors for Obtaining Biocements

Calcium phosphates biocements are biomaterials that present crystallographic and mineralogical characteristics similar to human skeletal structure. This has led to the development of new calcium phosphates biomaterials for biomedical applications, especially biomaterials for repairing defects and bone reconstruction. Calcium phosphates biocements are a promising alternative in biomedical applications, for they are easy to mold, they have good wettability, hydration and hardening capacity during its application in biological means. This work aimed at the synthesis of hydrated calcium phosphates powder, through a simple reactive method, which will be the basis for the production of calcium phosphate biocimentos with self-setting reaction. Three calcium phosphates compositions were produced via CaCO3/phosphoric acid reactive method in the ratios Ca/P = 1,5; 1,6 e 1,67 molar. The presented results are associated to hydrated powder morphology and synthesis process control. Scanning Electron Microscopy (SEM) helped with the morphological characterization of the powders, the laser analysis method was used for determining particle size and the Fourier Transformed Infrared Spectroscopy (FTIR) gave support to the identification of H2O e PO43- grouping vibrational bands. The work showed that for the different powder compositions the hydrated calcium phosphate phase is formed by clustered fine particles. This demonstrated that the chosen synthesis method permits the obtention of hydrated calcium phosphates, precursors for later biocement production.