Abstract Bioavailability of calcium in food is not high. Calcium ions can react with the organic acids such as oxalic acid and phytic acid in the food to form insoluble salt. Calcium phosphorylated inulin (CaPInu) was developed as a new potential functional food. Inulin was chemically modified by importing charged group using esterification with phosphate mixture in order to chelate calcium. Two equivalence points of the introduced phosphate groups were estimated to be around 3.85 and 8.76 by potentiometric titration. The structural characterization indicated that C6-OH in the chemical structure of phosphorylated inulin was located in the outside of the sugar ring and its steric hindrance was relatively small and esterification was performed with phosphate easily. CaPInu could stimulate the growth of Bifidobacteria and decrase pH in vitro fermentation. Low pH in colon is benefit to the dissolution of calcium. Mice fed CaPInu diet had a higher serum calcium and femur weight compared with the control diet.

A multi-layer scaffold that incorporates bioglass, phosphatidylserine and steroidal saponins loaded collagen microparticles was prepared in this study. Combinatorial processing techniques involving porogen leaching protocol and freeze-drying were used. Drug distribution and microstructure could be controlled mainly by the concentrations of drug-loaded collagen microparticles and porogen as well as freezing temperature for different layers of the scaffolds. Morphological observation, measurement of swelling properties, examination of drug release kinetics, and analysis of cell bioactivity showed that the resultant scaffolds had highly interconnected pores, gradient drug distribution and graded porous micro-architecture, similar swelling ratio for different layers, better drug release kinetics in view of lower initial release and slower average release rate compared to the scaffolds with homogeneous structure, as well as approving support of cell ingrowth. This study suggests that the optimized scaffolds have promising potential for applications in bone tissue engineering.

Steroidal saponins are the major pharmacological constituents of ophiopogon japonicus which have been used to treat bone and joint diseases, nerve damage, and hematischesis for hundreds of years in China. The objective of this study was to investigate the therapeutic potential of collagen microspheres loaded with steroidal saponins as an inducer factor for skeletal defects using an in vitro model. The collagen - steroidal saponins composite microspheres were prepared using a water-in-oil-in-water emulsion/solvent evaporation technique. SEM micrographs showed that spherical particles with diameters of tens micrometers were successfully produced. Release kinetics was characterized by an initial burst release reducing to a linear release over the first 8 days. MTT assay showed that the cells attached on composite microspheres were more in comparison with pure collagen microspheres and stimulated significantly higher level of alkaline phosphatase than the counterpart. Moreover, composite microspheres possess osteoinductive activities as demonstrated by the ability to induce cells to commit to crystals in contact coculture. The present finding suggests that sustained delivery of steroidal saponins may be very effective in improving the osteogenic potential of collagen microspheres and the composite microspheres are useful for tissue-engineering applications.