A Study Of Hydroxyapatite Base Biomaterials Prepared Via Electrospinning Technique And Its Properties

Because of its excellent biocompatibility and ability to adsorb bioactive molecules onto its surface, synthetic hydroxyapatite(Ca5(PO4)3OH, Hap) is widely used in biomedical engineering.Among the different Hap products with various structures, nanosized Hap, which has a grain size of less than 100 nm in at least one direction, has high surface activity and an ultra-fine structure,has drawn considerable interest as a novel biomaterial. Over the past decades, many methods have been used to prepare Hap nanoparticles. The purpose of this study is to prepare different forms of Hap by using a variety of methods, in order to developingthe applications of Hap.First, by using hydrothermal method with sodium citrate and cetyl trimethyl ammonium bromide as an additive, effect of citrate and(or) CTAB on the growth of Hap in a thermal aqueous solution was developed in the study. Plate-like Hap crystals of 200~500nm in length and20~50nm in width were synthesized in the presence of sodiumcitrate, which grew along with(002). Needle-like Hap crystals were obtained in the presence of CTAB and Hap nanorods with diameter of 10~20nm, length-diameter ratio of 5 were prepared under the regulation of sodiumcitrate and CTAB. The orient direction of needle- and rod-like Hap kept the same plane of(130) no matter whether citrate existed. All results suggested the effect of CTAB(macormolecule)as a soft template would be the main template despite the minormolecule(citrate) existed.Hap nanoscale fibers were produced by combining electrospinning and a sol-gel system.The fibers were composed of carbonated Hap. Highly interconnected solid and porous Hap fibers with diameters between 80 and 110 nm and crystal sizes between 20 and 40 nm can be produced.Decreasing the concentration of sol in the solvent system led to Hap fibers with smaller diameters. The amount of protein adsorbed onto Hap fibers decreased as the gel concentration and the temperature of heat treatment increased. The sustained release of BSA from Hap nanofibers were observed over18 days. And the result of cell co-culture indicated Hap fibers inhibited the growth of cells while promoted the expression of ALP.In order to explore a new method to organic-inorganic composite material, Ca P precursor sol and poly(lactide- glycolide) copolymer(PLGA) composite fibers were prepared byelectrospinning, and then followed by in situ bimineralization. PLGA-Ca P fiber composite was successfully fabricated with a uniform distribution of Ca and P elements. The addition of Ca P sol led in inter-tangles, branches of fiber and increasing the diameters of the composite fibers. An alkaline treatment by ammonia was applied to realize the in situ bimineralization of PLGA-Ca P composite. Afrer alkaline treatment, Hap with low crystallinity appeared and the mechanical properties of the fibers were increased, but the elongation at break were decreased. The cell experiments showed, PLGA/Hap composite fibers were provided to be a promotion for MC3T3 growth and ALP expression.