Solution’s Effect On Collagen’s Structures And Preparation Of Collagen/Hydroxyapatite Composite Fibers

One important field in biomaterials research is the preparation of collagen and hydroxyapatite composites. They are organic and inorganic component of natural bones. The artificial composites can simulate natural bones on components and structures, so they are potential to be used as bone repair materials. This thesis makes researches on three fields below:1. Research of collagen solution properties1、Type I collagen was soluted in HAc, H3PO4, HCl, PBS phosphorous buffer solution, HFIP and HAc-NaAc of which pH value equals 3.0. Circular dichroism results show that when collagen concentration is 1mg/mL, HAc and H3PO4 cause least change to collagen structure while pH value is 3.0 and so does HCl while pH value is 2.5. The collagen structure is more influenced if pH values decrease. PBS solutions with various concentrations show no exact effect to collagen structure. HFIP causes serious denaturation effect to different concentrations of collagen. It shows that collagen soluted by HAc-NaAc which pH=3.0 does not have obvious change in structure. CDNN was used to evaluate collagen second structure contents after being soluted to the three inorganic acids with different pH values. FT-IR results conclude that different acids have various effect to collagen structure. Zeta potential tests show that all three acids have the least effect to collagen structure while pH value equals to3.0.2. Preparation of Hydroxyapatite with controllable morphologiesHydroxyapatite of long-rod and short-rod shapes were prepared by chemical precipitation. XRD, SEM and TEM were used to characterize the products. The determinant factors of their morphology and size were explored by controlling experiment conditions. To the long-rod shape, the products may mix with TCP and OCP if the aging time is shorter than 6h, and the HAP particles would grow extremely large if the aging time is longer than 24 h, which is not good to the further electrospinning. The more PVP are used in preparation, the better order degree ofshort-rod shape HAP’s morphology performs.3. Preparation of composite fibers by electrospinningThe prior HAP were composited with collagen and composite fibers were created by electrospinning. According to the results of SEM and TEM, the fibers’ diameter reduces while the voltage increases and enlarges while the receiving distance increases. The short-rod HAP distributes randomly in the fibers, and the long-rod HAP could only arranges in orientation. The increasing content of short-rod HAP show no obvious difference to fiber morphology and diameter. The increasing content of long-rod HAP causes the increase to the fibers. The circular dichroism test imply that the collagen’s native structure are not damaged in the electrospinning.