Biomimetic Immersion Growth of Hydroxyapatite Layer on Biomedical Polymer

• Main Authors: Meng-Hui Chi, 紀孟慧
• Other Authors: Ju-Liang He
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/9xtyh5

碩士 === 逢甲大學 === 材料科學所 === 100 === Polyetheretherketone (PEEK) possesses an elastic modulus resembling human cancellous bone, radiolucence and non-toxicity to cells. Consequently, it is widely applied today as implant material for spinal interbody fusion cages. However, its bio-inertness and hydrophobic surface properties provide poor bone cell adhesion and growth, thereby unsatisfactory osseointegration when implanted into human bodies. Shortening the recognition period for osteoblast cells to attach and grow on an implant and enable bone tissues and the implanted material to form a firm bone joint has become an important research subject. On the other hand, hydroxyapatite (HA) with its composition close to human bone exhibits excellent osteoconductivity and makes it an excellent bone bonding material. A combinatorial method involving an arc ion plating (AIP) technique (which is popular for application in coating industry due to its high ionization rate, high ion energy, low temperature process, and strong film adhesion) and biomimetic immersion method (which is a low cost and low temperature process) dual-technique of surface modification was employed in this research to prepare HA layer on PEEK material at low temperature. For comparison, a pre-coated interlayer by using arc ion plated titanium metal (Ti), anatase-rich titanium dioxide (A-TiO2) and rutile-rich titanium dioxide (R-TiO2) coatings were carried out, respectively which were then immersed in simulated body fluid (SBF) at room temperature for inducing HA layer growth. Experimental results show that a crystallinic Ti, A-TiO2, and R-TiO2 coating can be respestively deposited on PEEK substrate by low temperature AIP technique. After a long period of 28 days SBF immersion, a bone-like crystallinic carbonate-incorporated hydroxyapatite (CO32––HA) layer with corresponding stoichiometry of Ca/P molar ratio was able to form on A-TiO2/PEEK and R-TiO2/PEEK specimen, and amorphous/nano-crystallinic Ca-deficient apatite layer was grown on Ti/PEEK specimen. On the contrary, an amorphous Ca-deficient apatite layer was found on bare PEEK substrate after the same SBF immersion period, confirming the bio-inertness of the bare PEEK. Overall to say, the R-TiO2/PEEK specimen exhibit superior ability to induce HA formation due most likely to negatively charged –OH− groups on R-TiO2 coating surface. This corresponds well with the fact that the largest decrease in Ca and P concentration in the SBF was observed when on R-TiO2/PEEK specimens. In addition, the liberation of Ti ion-free was also undetectable in any of the specimens after a long SBF immersion period. Furthermore, the osteoblast compatibility of bare PEEK substrate and interlayered specimen in terms of cell adhesion, cell proliferation and cell differentiation were ranked as R-TiO2/PEEK＞A-TiO2/PEEK＞Ti/PEEK＞PEEK, significantly correlated positively with the degree of HA layer formation.