Porous HA ceramics were prepared by using NH4 HCO3/PVA as pore-formed material along with biological glass as intensifier, and these ceramics were immersed in Locke's Physiological Saline and Simulate Body Fluid (SBF). The changes of phase composition, grain size and crystallinity of porous HA ceramics before and after immersion were investigated by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The biological activity was evaluated. The porous HA ceramics showed various degrees of decomposition after immersion in the two solution systems, but there was no evident change in respect to crystallinity. Besides, the impact of different degrees of solution systems on the change of grain size and planar preferred orientation was observed. The TCP phase of the ceramics immersed in Locke's Physiological Saline decomposed and there was no crystal growth on the surface of ceramics; however, the grain size of ceramics immersed in SBF became refined in certain degree and the surface of ceramics took on the new crystal growth.
Bicarbonates ; chemistry ; Biomimetic Materials ; chemical synthesis ; chemistry ; Ceramics ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Polyvinyl Alcohol ; chemistry ; Porosity

The macroporous structure of human bone allows the ingrowth of the soft tissues and organic cells into the bone matrix, profits the development and metabolism of bone tissue, and adapts the bone to the change of load. There is great requirement for artificial biomimic porous bioactive ceramics with the similar structure of bone tissue that can be used clinically for repairing lost bone. Fine hydroxyapatite (HAp) powder produced by wet chemical reaction was mixed with hydrogen peroxide (H2O2), polyvinyl alcohol, methyl cellulose or other pores-making materials to form green cake. After drying at low temperature (below 100 degrees C) and decarbonizing at about 300 degrees C-400 degrees C, the spongy ceramic block was sintered at high temperature, thus, macroporous HAp bioceramic with interconnected pores and reasonable porosity and pore-diameter was manufactured. This kind of porous HAp bioceramics were intrinsically osteoinductive to a certain degree, but its outstanding property was that they can absorb human bone morphogenetic proteins and other bone growth factors to form composites, so that the macroporous HAp bioactive ceramic has appropriate feasibility for clinical application. From the point of biomedical application, the recent developments in synthesis and characteristics investigation of macroporous HAp are reviewed in this paper.
Biocompatible Materials ; chemical synthesis ; chemistry ; Bone and Bones ; Ceramics ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Hot Temperature ; Humans ; Porosity ; Powders

Present study used dip-coating techniques to fabricate ultrathin nano-HA coating on titanium in organic sol-gel of Ca (NO3)2. 4H2O and PO(CH3)3 and inorganic sol-gel of Ca (NO3)2. 4H2O and (NH4)2HPO4. Scanning electron microscope (SEM) and grazing-incidence X-ray diffraction (XRD) were used to observe the morphology and distribution of crystallite size (D) and lattice strain (epsilon) of ultrathin nano-HA coating. After heated at 400 degrees C, the apatite structure of coatings on titanium began to appear. At heating temperature of 400 degrees C-600 degrees C, the effect of heating temperature on D and epsilon of both coatings was obvious. Precursor types significantly affected the particle diameters of nano-HA coatings, which were 25-40 nm for organic sol-gel and about 100 nm for inorganic sol. The thickness of ultrathin nano-HA coatings was 2.5 microm for organic sol-gel and 5 microm for inorganic sol and morphology of interfaces between coating and titanium was intact and homogenous.
Coated Materials, Biocompatible ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Gels ; Nanostructures

Oligopeptide T2, a kind of PA (Peptide Amphiphile) molecule, which could build up nano-fiber by self-assembly was designed and synthesized in this study. And the double-diffusion gel system was applied on this molecule to investigate its biomineralization features in vitro. The results showed that T2 could obviously reduce the hydroxyapatite (HA) formation period. And HA was found to possess the characteristics of non-crystalline by analysis of X-ray diffraction (XRD) and scanning electronic microscopy (SEM). These findings point to the conclusion that the negatively charged zone in T2 might make this molecule have the function of promoting HA biomineralization in vitro. And the mechanism responsible for the procession of HA biomineralization needs further research.
Biocompatible Materials ; chemical synthesis ; chemistry ; Bone Substitutes ; chemistry ; Calcification, Physiologic ; Durapatite ; chemistry ; Oligopeptides ; chemical synthesis ; chemistry

Hydroxyapatite (HA) has been earmarked as suitable for implantation within the human of its chemical makeup to human bone. In this paper, HA powders were synthesized via the precipitation method where phosphoric acid (H3PO4) was titrated into calcium hydroxide solution [Ca(OH)2]. Two parameters such as temperature and stirring rate were identified as factors that influenced the amount and purity of HA powder. Phase identification of the synthesized powder was done using X-Ray Diffraction (XRD). The results show that HA phase can be synthesized from this titration process of Ca(OH)2 and H3PO4 with yield amount of HA powder around 45 - 61 grams but with less than hundred percent purity. In order to study the effect of heat treatment to HA crystals structure, HA powder was calcined at 850 degrees C for 2 hours. It's found that the degree of crystallinity increases after calcination because of lattice expansion when the materials were heated at higher temperature
Biocompatible Materials/*chemical synthesis ; Calcium Hydroxide ; Durapatite/*chemical synthesis ; Phosphoric Acids ; Precipitation ; X-Ray Diffraction

An electrochemical co-deposition technique has been developed to prepare a hydroxyapatite (HAP)/organic polymer composite coatings on Ti surface as new biomaterial of hard tissue. The composite coating of organic polymer and calcium phosphate is formed by adding a water soluble polymer of the ethylene series to NH4H2PO4-Ca (NO3)2 solution when conducting an appropriate electrochemical co-deposition experiment. The XRD, SEM, XPS, SIMS and nano indent measurements were performed to characterize the morphology, composition, structure and surface stiffness of the composite coating. It was found that the morphology and surface hardness of the coatings showed a remarkable modification when introducing a minor polymer to HAP coating, and the bonding force between the coating and metal substrate was distinctly increased. The incorporation of minor organic polymer into the HAP compound at molecular level will improve the mechanical properties and morphology of the composite coatings, and this may be helpful to raising its bio-activity.
Coated Materials, Biocompatible ; chemical synthesis ; Durapatite ; chemical synthesis ; Electrochemistry ; Materials Testing ; Titanium ; X-Ray Diffraction

Hydroxyapatite (HAP) formation on the surface of the degradable polyamides implant by a coating technology was studied. A suspension of HAP-glutin-acetic acid was prepared and brushed on the surface of the implant at room temperature. Scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FT-IR) were employed to study the composition and the microstructure of the coating. The results obtained indicate that the main composition of coating is crystal HAP, its structural formula is Ca10(PO4)6(OH)2. So the coating has bioactivity. The coating has also small pores, which can stimulate bone regrowth and adsorption of other bioactive materials or mediine. This technology is an effective method to improve medical performance of the polyamides implant.
Bone Substitutes ; Coated Materials, Biocompatible ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Nylons ; Prostheses and Implants

OBJECTIVETo synthesize nanometer hydroxyapatite (HAP) by sol-gel method from Ca (NO3)2.4H2O and PO (CH3O)3 with water and ethanol as solvents and to study the factors that can affect the formation of sol-gel, including the type of solvents, amount of solvents, pH value, as well as properties under the condition of low temperature combustion of dried gel.

METHODSThe viscosities of sol were determined on WU viscosimeter. TG-DTA was used to analyze the thermal procedure of dried gel by increasing temperature. Characterization of the dried gel and powder after combustion were evaluated by X-ray diffraction and infrared spectrum. The morphology of the powder was observed by transmission electron microscopy.

RESULTSStable and homogeneous gel could be obtained at appropriate pH value when ethylene glycol was added into solvent. The dried gel had the feature of low temperature combustion. HAP powder with particle size of 50 nm was directly prepared.

CONCLUSIONNanometer HAP powder with uniform particle size can be synthesized by sol-gel method.

OBJECTIVETo investigate the variation of the corrosion resistance of micro-arc oxidation film on titanium by electrochemical methods in simulated body fluid.

METHODSMicro-arc oxidation film was formed on the titanium surface using micro-arc oxidation. The morphology was observed with scanning electron microscopy (SEM) and the phase composition was analyzed using X-ray diffraction (XRD). Polarization curves and electrochemical impedance spectroscopy (EIS) in simulated body fluid were examined with electrochemical methods.

RESULTSOn the titanium surface with micro-arc oxidation, the film consisted of many volcanic micropores. The film formed was a titanium dioxide (TiO(2)) with peaks for both anatase and rutile phases. In addition, hydroxylapatite was also observed. The self-corrosion potential and self-corrosion current density of titanium with micro-arc oxidation film were -0.255 V and 0.80 microA/cm(2) respectively, while those of untreated titanium were -0.358 V and 0.55 microA/cm(2). Electrochemical impedance spectroscopy confirmed the model of equivalent circuits reasonable.

CONCLUSIONSThe results of electrochemical examinations indicate that micro-arc oxidation film increases the corrosion resistance of titanium.

The hydroxyapatite (HA) powder surface modified with silane coupling agent was used to prepare HA/epoxy composite. It was found that silane has greatly improved the dispersion of HA in epoxy. The composite has good in vitro bioactivity and biocompatibility with 40 wt% HA, and the flexural modulus is close to that of natural bone, but its strength is lower than that of natural bone. So the composite needs further reinforcement in some way or other.
Biocompatible Materials ; chemical synthesis ; chemistry ; Bone Substitutes ; chemical synthesis ; chemistry ; Durapatite ; chemical synthesis ; chemistry ; Epoxy Resins ; chemical synthesis ; chemistry ; Humans ; Materials Testing