Papers by Author: Hua Nan Wang

Abstract: In the paper, ampicillin-loaded alginate(ALG) microspheres covered with chitosan (CS) were firstly prepared by emulsification/internal gelation method. These microspheres were mixed with n-HA/CS composite and then were fabricated into porous scaffold carrying micropheres by gas-foaming together with phase-separation. their properties were characterized by the methods of scanning electronic microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and inversed microscope. The drug releasing rate and entrapment efficiency were tested by spectrophotometry at 203 nm. The results show that the porous scaffold carrying microspheres has good property of slow drug releasing rate. The research will offer a new kind of degradable porous scaffold with good property of controlled drug release for bone or cartilage repairing.

Abstract: Scaffold in bone tissue engineering must have a three-dimensional (3-D) interconnected porous structure acting as a template for bone tissue regeneration, and material fabricating the scaffold must be biocompatible and can provide structural support during bone growth and remodeling at the same time. In this paper, a method of phase separation and particle leaching combined (PS/PL) was used to prepare porous scaffold of nano-hydroxyapatite and polyamide6 (n-HA/PA6) composite. The results show that the scaffold prepared by PS/PL has not only interconnected macropores of 100~300 μm, but also micropores on the walls of macropores, and PS/PL scaffold is more interconnective in compare with phase separation (PS) scaffold. When the porosity of the scaffold is about 79%, its compressive strongth is about 3.27 MPa, that is similar to the human cancellous bone(2~10MPa). Ethanol has some effect on hydrogen bonds, but fabricating method will not change the chemical component of the composite. The porous scaffold is prospect for bone tissue engineering.

Abstract: Nano-hydroxyapatite/polyamide66/chitosan composite (n-HA/PA66/CS) was prepared by a co-precipitation method, and was characterized by TG/DTG, TEM, IR, XRD and Universal mechanical testing machine. TEM test showed that some rod like crystals were formed and distributed uniformly into polymer matrix, with a size of about Φ30nm×80nm. IR and XRD analysis showed that some chemical bonds and electrostatic interaction existed between n-HA and polymers. TG/DTG curves indicated that the composites possessed a talent of high heat-resistance. The compressive strength of composite changed with different content of three compounds, the maximum compressive strength of composite (70MPa) could be acquired.

Abstract: Nano-hydroxyapatite/polyamide66 (n-HA/PA66) composite scaffolds are prepared using phase separation and phase separation in combination with particle leaching, and both the composite powder and paste are used as starting materials. The composite is characterized by IR and XRD. The micro-architecture of the scaffolds is observed by SEM, and the mechanisms that the formation of the porous structure follows have been investigated preliminarily. The results show that scaffold prepared by phase separation in combination with particle leaching method using composite powder as starting material possesses controllable porosity and interconnectivity, as well as good mechanical strength comparable to human cancellous bone, suitable for being the tissue-engineered scaffold for load-bearing bone repair. Furthermore, scaffold made by phase separation using composite paste as starting material exhibits an anisotropy both in morphology and mechanical properties, which indicates the potential of guiding cell seeding, distribution and new tissue formation in preferential direction.

Abstract: The compatibility efficiency on different compatibilizer for nano-hydroxyapatite (n-HA) reinforced polyamide 66 (PA66) and high density polyethylene (HDPE) blends at a composition of 40/42/18 as functionalized biomaterial was investigated by mechanical properties testing and scanning electron microscopy (SEM). The results showed that mechanical properties of compatibilized blends were much improved by the compatibilizers of maleic anhydride grafted polyethylene (PE-g-MAH) and ethylene/methacrylic acid ionomer-sodium ion (ION) compared with the uncompatibilized blends. Blends had peak mechanical values of different compatibilizer. Both PE-g and ION formed adhesion during melt mixing and stabilized the morphology and significantly reduced the size of dispersed PE phase. PE-g gave the blends with PE spheres ranging from 1 to 4µm and ION with well-dispersed spheres with an average diameter of 1µm. The more enlarged interphase of the blends containing ION reduced the lower interfacial energy to increase the miscibiliy of the blends. Consequently, ION had better contribution to rigidity properties than PE-g for n-HA/PA/PE blends.