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Silk fibroin from a domesticated mulberry silkworm, Bombyx mori, is the most widely used in biomaterial design. We report for the first time the preparation of a relatively smooth (granule free) film of the nonmulberry Samia cynthia ricini fibroin for comparative evaluation of its cell-supporting properties against those of the B. mori fibroin film. The granule formation on the S. c. ricini fibroin film was successfully prevented by facilitating proper rearrangement of the protein molecules, as monitored by FT-IR, by dialysis through a stepwise decrease in the urea concentration in the dialysis media. The lower contact angle of the S. c. ricini fibroin film, compared to the B. mori fibroin film, corresponds well to its lower hydrophobic/hydrophilic amino-acid ratio and grand average of hydropathicity (GRAVY). L929 murine fibroblast cells on the granule-free S. c. ricini fibroin films exhibited greater proliferation and spreading rates than those on the B. mori fibroin films, possibly attributable to its higher content of hydrophilic and positively charged amino acids. It further suggests that fabrication, modification and/or engineering of S. c. ricini fibroin may provide a better biomaterial scaffold design than the more commonly used B. mori fibroin.

A composite of 70/30 poly(lactic acid)/hydroxyapatite was systematically prepared using various amounts of glycidyl methacrylate as reactive compatibilizer or Joncryl ADR®-4368 containing nine glycidyl methacrylate functions as a chain extension/branching agent to improve the mechanical and biological properties for suitable usage as internal bone fixation devices. The effect of glycidyl methacrylate/Joncryl on mechanical properties of poly(lactic acid)/hydroxyapatite was investigated through flexural strength. Cell proliferation and differentiation of osteoblast-like MC3T3-E1 cells cultured on the composite samples were determined by Alamar Blue assay and alkaline phosphatase expression, respectively. Result shows that flexural strength tends to decrease, as glycidyl methacrylate content increases except for 1 wt.% glycidyl methacrylate. With an addition of dicumyl peroxide, the flexural strength shows an improvement than that of without dicumyl peroxide probably due to the chemical bonding of the hydroxyapatite and poly(lactic acid) as revealed by FTIR and NMR, whereas the composite with 5 wt.% Joncryl shows the best result, as the flexural strength increases getting close to pure poly(lactic acid). The significant morphology change could be seen in composite with Joncryl where the uniform agglomeration of hydroxyapatite particles oriented in poly(lactic acid) matrix. Addition of the epoxy functional compatibilizers at suitable percentages could also have benefits to cellular attachment, proliferation, differentiation and mineralization. So that, this poly(lactic acid)/hydroxyapatite composite could be a promising material to be used as internal bone fixation devices such as screws, pins and plates.

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A series of TiO2 modified hydroxyapatite composites (HA/TiO2) with different compositions were prepared. Phase formations and morphologies of the obtained HA/TiO2 composite were characterised using X-ray diffraction and SEM, and their photocatalytic activities were also determined by decomposition of methylene blue solution. Filter cloths were prepared by depositing the composite on polyester non-wovens via pad dry cure, and their filtering effectiveness was examined by photocatalytic activity measurement and bactericidal test. Hydroxyapatite/TiO2 composites were successfully prepared and exhibited photocatalytic properties. With increasing ratio of anatase titania in the HA/TiO2 composite from 20 to 30 and 50%, photocatalytic activity of composite material increased such that HATi5050 composite exhibited the highest photocatalytic activity. Non-woven filters coated with HA/TiO2 composites also exhibited good photocatalytic activities. Less difference in photocatalytic activity between HATi7030 and HATi5050 coated non-woven filters was observed, compared to that in powder form. The filter coated with HA/TiO2 composite exhibited good bactericidal effect.