Amorphous calcium phosphate, a precursor phase of the bone mineral in vertebrates, is limited owing to its instability. A simple wet-chemical precipitation method was developed in this study to prepare stable and nanosized amorphous calcium phosphates doped with citrate using orthophosphoric acid, anhydrous critic acid, and anhydrous calcium chloride as the raw materials in an alcohol system at room temperature. The structure of the obtained nanosized amorphous calcium phosphate doped with citrate was evaluated by an X-ray diffraction analysis, Fourier transform-infrared spectroscopy, X-ray photoelectron spectrometry, high-resolution transmission electron microscopy and selected area electron diffraction. In addition, Ca and P ions release profile was investigated in the simulated bodily fluid solution for two weeks, and the biological performance was evaluated using in vitro mineralization and cell viability studies. The results demonstrated that the synthetic specimens in the presence of citrate had a similar structure, and their dimensions were in the nanoscale. Furthermore, the specimens possessed excellent apatite mineralization ability in simulated bodily fluid solution and a stimulatory effect on the cell viability of mouse bone-marrow stem cells. The S0.050 specimen displayed the maximum amount of Ca (152.5 ppm) and P (81 ppm) ions release at the third day and the best bioactivity and cell viability. Based on all of the results, it was concluded that the stability and bioactivity of nanosized amorphous calcium phosphates were improved by doping with citrate. Thus, bone graft substitutes could potentially be modified by the addition of citric acid to affect their performance in bone repair and regeneration.

Microcapsules were prepared using the complex coacervation method with nanoanatase TiO2 as the core material, gelatin/Arabia gum as the wall material. Then the obtained microcapsules were finished to the PP nonwovens to investigate the photocatalytic properties to the nonwovens. The breaking strength decrease of the finished polypropylene nonwoven after irradiated with the artificial UV lamp was the optimization evaluation index, and the four factors including finishing temperature, adhesive concentration, microcapsule concentration and finishing time were used to design the experimental scheme using the second order orthogonal rotation combination design. The data were processed with SAS software, the obtained optimal finish process is: finishing temperature is 22°C, adhesive concentration is 75g/L, microcapsule concentration is 36g/L, and finishing time 25min.