Materials Science Forum Vol. 685

Abstract: As a naturally-occurring trace element, boron involves many life processes including embryogenesis, bone growth and maintenance, immune function and psychomotor skills. Thus, the low chemical durable glass based on 3-fold coordination boron network former shows potential in delivering boron for bone health. However, its high dissolution rate may result in cytotoxicity. The addition of strontium seems to be an effective approach not only inhibits its rapid degradation, but delivers strontium as a ‘drug’ to enhance the ability of bone formation. Thus, strontium-incorporated borosilicate shows special role in bone regeneration, in particular in women past menopause.

Abstract: Scanning electron microscope (SEM) observation showed that femur bone is a kind of bioceramic composite consisting of hydroxyapatite layers and protein matters. The hydroxyapatite layers are further composed of hydroxyapatite fiber sheets. The observation also showed that the hydroxyapatite fiber sheets possess very thin fiber shape. The thickness of the hydroxyapatite fiber sheets is within nanometer scale. The mechanism of the high fracture strength of the bone was investigated based on the microstructural characteristics of the hydroxyapatite fiber sheets and the theory of fracture mechanics. The result reveals that the thin fiber shape of the hydroxyapatite fiber sheets endows the bone with high fracture strength.

Abstract: The effect of poly(L-lactide-co-glycolide)/bioactive glass (PLGA/BG) on cell attachment, proliferation and differentiation of L929 fibroblastic cells was investigated. The results of in-vitro cytotoxicity test indicated that the cells cultured in extract of PLGA/BG and on the surface of composite showed normal growth and proliferation. The cell proliferation and alkaline phosphatase (ALP) activity of fibroblast were significantly improved after 3 and 7 days of culture on PLGA/BG films in comparison with PLGA films. It can be concluded that the addition of bioactive glass into PLGA stimulates the proliferation and differentiation of fibroblastic cells. Therefore, PLGA/BG composites have a promising biological response as a potential biomaterial in medical field.

Abstract: A new poly(ester amide)s (PEA) derived from L-lactic acid and α-alanine have been synthesized by melting copolymerization with p-toluenesulfonic acid (TSA) with stannous chloride (SnCl₂) as catalyst. The products were analyzed by NMR, FT IR techniques. The effects of the content of α-alanine (L-Ala) on the copolymers structure were studied. Being the phosphate buffered saline (pH=7.2) as the degradation solution, the degradation rate speed up with the increasing the content of the α-alanine.

Abstract: The PDLLA(DL-Poly lactic acids)/HA(Hydroxyapatite) composite and pure PDLLA control were implanted in bone for test. Using fluorescent pictures of tetracycline double label and advanced image analysis system, the trend of bone-formation rate for the implanting region of PDLLA/HA composite was obtained via morphometry measurement of the slices labeled with tetracycline. The investigation and calculation results show that, the formation rate of new bone is stable and high (reaches 2.044μm/day) in the early stage of implantation for the PDLLA/HA composite, demonstrating the advantageous capability of bone formation for the composite. The formation rate of new bone seems to decrease continuously with time, and then the bone formation and bone decomposition tend towards equilibration. Namely, the dynamic balance of bony tissue’s metabolism is maintained.