Polymer Matrix Composites Of Hydroxyapatite Nanoparticles And Its Application In Bone Tissue Engineering Scaffolds

Tissue engineering is the technology of remodeling of living organisms in vitro and involves architecture of artificial cellular scaffolds, which mimic extracellular matrix. Recently biopolymer materials have been used for tissue engineering and other biomedical applications. Hydroxyapatite (HA) is the main inorganic component of bones and teeth having biocompatibility for biomedical applications. Bone itself is a composite consisting of HA nanorods embedded in the collagen matrix. Hence, from the perspective of anti-bionics, rod-like HA has much more excellent function for bone cells growth than the ball-like HA., Since the mechanical properties, brittleness, toughness of HA is poor, restricted it used as material of tissue engineering scaffold, so, preparation of polymer-based composite materials is an effective way to overcome HA shortcomings.Hydroxyapatite (HA) nanoparticles with rod-like morphologies and controllable size have been synthesized successfully by a low-temperature hydrothermal method with N-[(2-hydroxy-3-trimethylammonium)propyl]chitosan chloride (HTCC) used as a template. HTCC was prepared by reacting chitosan (CS) with glycidyltrimethylammonium chloride (GTA). The synthesized HA was characterized using X-ray diffraction (XRD), Fourier transform infrared spectrograph (FTIR) and Transmission electronmicroscopy (TEM). The results indicated that the obtained HAp was rod-like monocrystals, the size and morphology can be modulated by pH of solution, hydrothermal temperature and the ratio of quaternary ammonium in HTCC to PO43-. HTCC is able to regulate the nucleation and crystal growth in the formation of HA and can be removed completely after HA formation. HTCC can be well incorporated to the phosphate anion by the charge and stereochemical complementarity. Moreover, the macromolecular effect of HTCC is another assignable factor to modulate the nucleation and crystal growth.The nanocomposites composed of hydroxyapatite (HA) and N-carboxyethylchitosan (NCECS) were successfully synthesized by in situ precipitation. The effect of molar ratio of glucosamine in NCECS to [Ca2+] on the crystallization, size, size distribution and aggregation morphology of the NCECS/HA nanocomposites was investigated. Fourier transform-infrared spectroscopy (FTIR) indicates that the chemical bond has formed between NCECS and HA in the nanocomposites. X-ray diffraction (XRD) shows that the crystallization of HA was retarded in the NCECS/HA nanocomposites significantly. Transmission electron microscopy (TEM) results indicate that NCECS/HA nanocomposites show regular spheric morphology with a diameter ranging from 10~40 nm. The mechanism of preparation of NCECS/HA nanocomposites in situ precipitation was discussed. NCECS/HA nanocomposite not only has the excellent dispersibility in neutral aqueous solution, but also has both the bioactivity of NCECS and the osteoconductive of HA, which make it have potential applications in the control release of bone growth factors and bone therapeutic drugs.N-carboxyethylchitosan/nano-hydroxyapatite (NCECS/HA) composite films were fabricated and their potential applications in guiding bone regeneration were investigated in terms of their in vitro cellular activity. Fourier ransform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to investigate the structure and composition of the composite film. Field Emission scanning electron microscopy (FESEM) revealed that HA nanoparticles were dispersed homogeneously in NCECS matrix. The composite film has sufficient mechanical properties for tissue engineering scaffold. The composite film was found to have better cartilage cell adhesion and growth than pure NCECS film.N-Maleic Acyl-Chitosan (NMCS) is a biocompatible amphiphilic chitosan derivatives. The functional carboxylic groups provide the possibility to obtain physically crosslinked NMCS hydrogel by calcium ion (Ca2+). From the crosslinking point, the hydroxyapatite (HA) crystal nucleates and grows. As a result, mineralization of N-Maleic Acyl-Chitosan hydrogel scaffold (NMCS/HA) was successfully obtained in situ. FT-IR, XRD and SEM results indicateds that HA crystal structure with the low degree of crystallinity. SEM reveals that HAs on the NMCS hydrogel surface demonstrate regular cuboid-like (~12μm×2μm×4μm) morphology, while that HAs inside the hydrogel show flower-like morphology. The porous mineralized NMCS hydrogel scaffolds may have great potential in bone tissue engineering applications.PLA is an ideal scaffold for tissue engineering of synthetic biological materials. Prepared of PLA/HA composite scaffolds by different methods, such as solution electrospinning, solution casting salt leaching and blend salt leaching method. The purpose is to prepare an ideal scaffold for bone tissue engineering.