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The use of artificial biomaterials has been acclaiming potential therapeutic scope in diverse clinical applications. This review started with the description of the basics of biomaterials, and desirable properties, which are the prerequisites to understand biomaterials. The orthopedic biomaterials, their classification and the importance of calcium phosphate (CaP) materials for hard-tissue applications were utterly discussed. Furthermore, among the various CaP biominerals, the importance of hydroxyapatite (HAP) and its synthesis techniques was comprehensively reviewed. The sol–gel route for the synthesis of HAP nanoparticles and deposition of coatings were systematically studied. Among the metallic substrates, Ti6Al4V alloy remained the focus of this study. Moreover, several film pre-preparation methods were also given due importance. The importance of other surface modification techniques, especially in the context of Ti6Al4V substrates, was also discussed. Among several coating techniques to deposit CaP coatings, special attention was paid to the spin and dip coating techniques. In addition to monolithic HAP coatings, reinforced and antimicrobial HAP coatings were also reviewed from broad perspectives. Therefore, this review provides an in-depth insight into the preparation and properties of apatitic nanoparticles and their coatings for orthopedic and dental applications.

This article documents the outcome of treatment of intraosseous ganglia and simple bone cysts of the carpal bones by curettage and injectable calcium phosphate bone cement (CPC) grafting. The patients consisted of five men and three women. One had a cystic lesion in the scaphoid, one in the hamate, and five in the lunate. Curettage of the lesions was performed, and CPC was injected into the cavity. Five patients were diagnosed with a ganglion and three with a simple bone cyst. Among the five patients with wrist pain, the pain disappeared completely in four. Radiographs showed apparent partial absorption of CPC in four patients and no absorption in other four. There were no recurrence of tumours and no other complications were encountered. We conclude that calcium phosphate bone cement is a useful material for repairing bone defect after curettage of an intraosseous ganglion or bone cyst of a carpal bone.

Distal radius fracture alignment and stabilization can be a surgical challenge in the face of severe comminution and bone loss. We describe a technique using a calcium phosphate/sulfate bone cement, as an adjunct to internal fixation. This bone cement is biocompatible, osteoconductive, and sets quickly with an isothermic reaction. The use of bone cement eliminates the need for primary autologous bone grafting and allows for easier reduction and retention of reduction at the time of surgery. Bone cement is employed for the following purposes in comminuted fractures: (1) to fill a void due to lost or crushed cancellous bone, (2) to hold larger unstable fragments while hardware is placed, and (3) to retain fragments too small to take hardware. Available bone cements, studies involving the use of bone cement for distal radius fractures, indications, and surgical technique will be reviewed.

Polyethylene oxide-block-polymethacrylic acid (PEO-b-PMAA) copolymer was employed as template for the controlled precipitation of calcium phosphate from aqueous solution at different pH values. Two interesting superstructures of an organized inorganic/organic hybrid material were characterized by electron microscopy. At pH of 4, a nested structure was obtained, which consists of hybrid nanofilaments. The fibers originate from a core of similar size to the primary polymer aggregates, suggesting that cooperative interactions at a local level between dissolving calcium phosphate clusters and disassembling polymer units could be responsible for the highly anisotropic nature of the secondary growth process. At pH of 9, a fractal induced growth morphology was obtained through the mineralization process. Such calcium phosphate/polymer nanohybrids with complex morphologies are interesting and may find application as novel ceramics precursors, reinforcing fillers, or biomedical implants.

Biodegradable porous materials can serve as a scaffold in tissue engineering. In this work, highly porous nano-calcium phosphate (NCP)/poly(L-lactic acid)(PLLA) composites were prepared by a thermally induced phase separation technique. Five calcium phosphates with different biodegradation rate were selected, i.e. amorphous calcium phosphate, α-tricalcium phosphate, β-tricalcium phosphate and biphasic α/β-tricalcium phosphate. The results showed that the NCP particles could be homogenously incorporated into pore walls; the composites had a porosity of ~90%, and a pore size of ~200 μm. From the point of view of materials science, the obtained porous NCP/PLLA composites demonstrate to have a capability of applying in bone tissue engineering.

Different forms of calcium-phosphate (Hydoxyapatite, α-TCP, β-TCP, CDHA) minerals are found to be major component of bone tissue. Development of calcium-phosphate (CaP) based fibrous microstructures is of significant research interest worldwide owing to its improved mechanical properties and higher interconnectivity. Here we represent a method for single step sintered wet-spun Fibers of calcium phosphate from avian egg shells for biomedical applications.

Raw egg shell powder was mixed with chitosan solution and Phosphoric acid. The mixture is milled in a ball mill overnight and then filtered. The slurry was de-aired using 100 microliter 1-octanol per 100 ml of slurry as antifoaming and wet spun in coagulation bath. Fiber was dried overnight and sintered at different temperatures for microstructure and phase analysis. Both green and sintered Fibers were physico-chemical characterized by SEM, EDX, XRD, TGA, DSC, FTIR, and stereo-zoom microscopy. The fibers obtained in this procedure are found to have highly porous interconnected structures which can provide good cell adhesion and therefore can be used for bioactive scaffold making.

Purpose: Plasmid loading into scaffolds to enhance sustained release of growth factors is an important focus of regenerative medicine. The aim of this study was to build gene-activated matrices (GAMs) and examine the bone augmentation properties. Methods: Generation 5 polyamidoamine dendrimers (G5 dPAMAM)/plasmid recombinant human bone morphogenetic protein-2 (rhBMP-2) complexes were immobilized into beta-tricalcium phosphate (β-TCP)/type I collagen porous scaffolds. After cultured with rat mesenchymal stem cells (rMSCs), transfection efficiencies were examined. The secretion of rhBMP-2 and alkaline phosphatase (ALP) were detected to evaluate the osteogenic properties. Scanning electron microscopy (SEM) was used to observe attachment and proliferation. Moreover, we applied these GAMs directly into freshly created segmental bone defects in rat femurs, and their osteogenic efficiencies were evaluated. Results: Released plasmid complexes were transfected into stem cells and were expressed, which caused osteogenic differentiations of rat mesenchymal stem cells (rMSCs). SEM analysis showed excellent cell attachment. Bioactivity of plasmid rhBMP-2 was maintained in vivo, and the X-ray observation, histological analysis and immunohistochemistry (IHC) of bone tissue demonstrated that the bone healing in segmental femoral defects was enhanced by implantation of GAMs. Conclusions: Such biomaterials offer therapeutic opportunities in critical-sized bone defects.

Collagen and noncollagenous proteins have an important role in the formation of mineral constituent of bone matrix. In this research, the morphology and phase characteristics of calcium phosphate nanoparticles in presence of collagen were investigated. The synthesis reaction was initiated by mixing H₃PO₄ as phosphorous source and CaCl₂ as calcium source and type I collagen. Collagen concentration in suspension and Ca to P ratio was 1% and 1.67, respectively. The samples (with collagen and without collagen), were heat treated at 600°C and characterized by X-Ray diffraction (XRD), Fourier transformation infrared (FTIR) and scanning electron microscopy (SEM). More smaller and flake-like shape particles were observed in the SEM images of sample synthesized in the presence of collagen compared to the control sample which was constituted of larger granular particles. The XRD results revealed that the synthesized mineral powders with collagen were composed of hydroxyapatite and octacalcium phosphate. P–O and OH characteristic peaks were identified in FTIR spectra. In hybrid sample, the shift of amides band, revealed the electrostatic interactions between calcium phosphate ions and carboxyl or amino groups of collagen fibrils. The Ca to P molar ratio for sample with collagen was 1.9. It was found that the sample synthesized in the presence of collagen has a similar microstructure to natural bone.

A major aim of gene therapy is the efficient and specific delivery of therapeutic gene into the desired target tissues. Development of reliable vectors is a major challenge in gene therapy. The aim of this study is to develop calcium phosphate nanoparticles as novel non-viral vectors for the gene delivery system. Calcium phosphate nanoparticles were prepared by water-in-oil microemulsion method with a water to surfactant molar ratio, Wo $=$ 2–10.

This paper studies the design and synthesis of ultra-low size, highly monodispersed DNA doped calcium phosphate nanoparticles of size around 100nm in diameter. The structure of DNA-calcium phosphate nanocomplex observed by TEM was displayed as a shell-like structure. This study used pEGFP as a reporter gene. The encapsulating efficiency to encapsulate DNA inside the nanoparticles was greater than 80%. In the MTT test, both calcium phosphate nanoparticles and DNA-calcium phosphate nanocomplex have no negative effect for 293T cells. By gel electrophoresis of free and entrapped pEGFP DNA, the DNA encapsulated inside the nanoparticles was protected from the external DNaseI environment. In vitro transfection studies in 293T cell-line, the DNA-calcium phosphate nanocomplex could be used safely to transfer the encapsulated DNA into the 293T cells and expression green fluorescent protein. The characteristic of DNA-calcium phosphate nanocomplex to deliver DNA belongs to slow release. The property of DNA-calcium phosphate nanocomplex was fit in the requirement of non-viral vectors for the gene delivery system.

A calcium phosphate coating over porous chitosan sponges was produced by a process based on phosphorylation, Ca(OH)₂ treatment and SBF immersion. Porous chitosan sponges were prepared first by dissolving chitosan powder in acetic acid, and then freeze-drying. The obtained porous sponges were washed with ethanol containing sodium hydroxide. Sponges not subjected to the sodium hydroxide treatment were easy to dissolve in water. Sponges were phosphorylated by using urea and phosphoric acid in DMF solution. Phosphorylated chitosan sponges was soaked in saturated Ca(OH)₂ solution at ambient temperature, which lead to the rapid formation of calcium phosphate coatings and were found to stimulate the growth of a calcium phosphate coating on their surfaces after soaking in SBF solution. The mechanism of formation of the calcium phosphate coatings on the chitosan sponges must involve a diffusion of the phosphorus ion from the interior of the sponges, so creating a sufficiently high local concentration of ions at the surface to facilitate precipitation of calcium phosphate from the soaking medium.

Bone formation was investigated by ectopic implantation of bioresorbable macroporous calcium phosphate (CMP) matrices combined with rat marrow cells of the athymic mouse. CMP matrices used were macroporous with about 200 μm pore size. CMP matrices were soaked in the subcultured rat marrow cell suspension adjusted to 5 × 10⁷ cells/ml for 30 minutes and then implanted into subcutaneous sites of an athymic mouse. The matrices recovered after 4 and 6 weeks and then uncalcified ground sections were prepared for histological examination. Osteogenesis could be observed in the pore regions at 4 weeks after implantation without fibrous encapsulation. This study thus suggested that the composite grafting of macroporous calcium metaphosphate matrices with marrow derived mesenchymal cells may be useful for repair massive bone defects.

A composite, composed of biphasic calcium phosphate, BCP (60% hydroxyapatite, HA + 40% β-tricalcium phosphate, β-TCP) granules and a hydrophilic polymer (hydroxy-propyl-methyl cellulose, HPMC) was developed as an injectable bone substitute (IBS). The composite was prepared by incubating for 6 and 12 months a mixture of 60% BCP powder (w/w) and 40% HPMC. The composite was then steam sterilized and non-sterilized composite served as control. The interaction between ceramic crystals and polymer and the effect of sterilization were investigated using scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HrTEM). Results: SEM demonstrated the degradation of ceramic in the composite after incubation. HrTEM demonstrated the presence of a dissolution zone, about 13 nm, associted with the HA crystal surfaces. Precipitated globular microcrystals (2-3 nm in diameter) represented the first zone of interaction between HA crystals and the polymer. Under this zone, the inter-reticular distances of HA lattice planes appeared enlarged by 1.2% [from 0.817 to 0.827 nm for (100) lattice planes]. The enlargement of lattice planes could be due to HPO₄ incorporation in the newly formed apatite crystal lattice. In β-TCP crystals, dissolution took place on several nanometers. Conclusion: This study demonstrated that interaction between hydrophilic polymer and calcium phosphate ceramic occurs only on very thin layer (several nanometers).

Process related variability on plasma sprayed HA coatings have shown significant influence on the coating characteristics. The coatings were generated from wet precipitated HA powders which were subsequently produced by the plasma spraying technique. The effects of spraying standoff distance and particle size ranges on the tensile bond strength, phase composition and microstructural characteristics of the spheroidized HA (SHA) coating were investigated. XRD and SEM analysis revealed a substantial increase in the amount of amorphous and other undesirable calcium phosphate phases in the coatings as the spray distance increases. It was found that a well-defined splat structure with a maximum adhesion strength was obtained with SHA 20˜45 μm powders using a spray distance of 10 cm at a net energy of 12 kW. The presence of microstructural defects and the amount of melting served to affect the structural integrity of the coating.

Biodegradable calcium metaphosphate (CMP) sol was prepared and then coated on Ti6A14V substrates by spin-coating technique. In order to investigate the effect of hydrolysis time of (OC₂H₅)₃P on the reaction with Ca(NO₃)₂4H₂O, the P-precursor was pre-hydrolyzed for 1, 5, and 10 hours before the reaction with the Ca-precursor. At least above 5 hours of pre-hydrolysis of P-precursor were required to obtain β -CMP. The CMP coated specimens were dried at 70, 100, and 130°C, respectively and then heat-treated at 630°C for 3 hours with and without holding at 476°C for 2 hours. It has been found that the drying temperature of the CMP coated specimens was one of the most important factors affecting the homogeneity of the coating layer. The optimum drying temperature was 70°C, and the CMP coated layer with holding at 476°C during firing was homogeneous and had fewer cracks, compared with that of sample without holding.