The effects of phosphorylated chitin (P-chitin) on the tissue responses to two kinds of calcium phosphate cements (CPCs) were investigated using experimental rabbits. One of them consisting of monocalcium phosphate monohydrate, calcium oxide, 1 m phosphate buffer (pH: 7.4) and different amounts of P-chitin (CPC-I or P-CPC-I) with relatively neutral initial pH was filled as paste into tibial defects of the rabbits for 1, 4, 12 and 22 weeks. The other kind of cement made from dicacium phosphate dihydrate/calcium hydroxide/1m Na2HPO4/different amounts of P-chitin (CPC-II or P-CPC-II) with relatively higher initial pH was implanted as prehardened cylinders into the radial defects of the rabbits for the same periods. Pure CPC-I and CPC-II were used as controls. Histological and histomorphological studies were performed on thin un-decalcified and decalcified sections. Three different bone formation types in the resorption lacuna of the P-CPCs were found during this study. The biodegradation rate of the P-CPCs had a negative relationship with the P-chitin content. Most of the low P-chitin-containing samples were bioabsorbed in 16 weeks, while the high P-chitin-containing samples disappeared in 22 weeks. The newly formed bone was identified with back scattered scanning electron microscopy and X-ray energy-dispersive spectrometry. The results show that with P-chitin component in a certain range, the P-CPCs are biocompatible, bioabsorbable and osteoinductive and could be used as promising candidates of bone repair materials.

A biomimetic calcium phosphate coating is expected to enhance the bioactivity and bone inductivity of human implants. This study presents a very simple, highly effective biomimetic method to obtain a calcium phosphate coating on a titanium substrate. Using NaH2PO4, a stable solution was prepared with high calcium and phosphate ion concentrations. This solution turned to a supersaturated calcification solution (SCS) when NaHCO3 was added. The addition of NaHCO3 elevated the pH value of the solution gradually and steadily. A uniform coating approximately 40 mm thick was found on the substrates after 24 h immersion. The compositions of the coatings were adjustable from hydroxyapatite (HA) to HAydicalcium phosphate dihydrate (DCPD). The calcium phosphate deposits were investigated by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) spectroscopy.

Ion beam assisted deposition (IBAD) has been successfully used to produce a dense ultra-adherent and pinhole-free hydroxyapatite (HAp) layer on alumina substrates. After deposition the HAp-coated alumina was immersed in 20 ppm and 100 ppm AgNO3 solution to carry out the ion exchange between Ag1 and Ca21 in HAp. An obvious antimicrobial effect against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis was observed in the samples treated with 20 ppm AgNO3 solution. In contrast to this, the untreated samples did not show any bactericidal effect. Scanning electron microscopy (SEM) studies showed that Ag-rich phases were homogeneously distributed on the surface. X-ray diffraction (XRD) demonstrated that the surface structure in the samples without Ag was HAp, whereas with Ag it is HAp and AgCaP. The minimum inhibitory concentration of AgNO3 was measured to be 1.302 mg/ml. The release of Ag1 ions from the Ag-HAp

The modulation function of proteins was studied during biomineralization in vitro. Morphological development of calcium carbonate precipitation in collagen solutions at different concentrations has been examined using scanning electron microscope. X-ray diffraction is used to determine the polymorph of calcium carbonate crystals. Its data indicate that only calcite crystals are formed. The experimental results also show that the calcite growth is more and more inhibited as collagen is increasing in concentration. A simple crystal model is employed to explain these phenomena. Different crystal planes with different affinities to collagen play a crucial role in changing the morphology of calcite crystals.

The structure and crystallographic orientation of different layers (the cone layer, palisade layer and the crystal layer) in ostrich eggshells were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM) with selected area electron diffraction (SAED). It is found that the degree of 001 preferred orientation enhanced from inner to outer ostrich eggshells. A crystallographic orientation regulation was observed for the first time. The adjacent 1-5 calcite crystals with the same three-dimensional orientation are proposed to form a crystalline cluster with the size of several microns. The a-axes in the neighboring clusters orient from several degrees to tens of degrees.