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Photo-luminescent hydroxyapatite coatings through a bio-mimetic process

Ren-Jei Chung 1Huai-Yu Cheng 1Hsiao-Wei Wen 3Ming-Fa Hsieh 2Tsung-Shune Chin 1

1. Department of Materials Science and Engineering, National Tsing Hua University (NTHU), 101, Sec 2, Kuang-Fu Road, Hsinchu 30013, Taiwan
2. Department of Biomedical Engineering, Chung Yuan Christian University (CYCU), 200, Chung Pei Road, Chung-Li 32023, Taiwan
3. Department of Food Science, National Ilan University (NIU), 1, Sec. 1, Shen-Lung Road, I-Lan, Ilan 26047, Taiwan

Abstract

Hydroxyapatite (HAp) is the major inorganic component in natural bones and has been widely studied and prepared in many forms for orthopedic and dental applications. In this study, we successfully manufactured crystallite HAp on to Si(100) through a bio-mimetic process. The deposition of hydroxyapatite two-dimensional films on Si substrate was carried out using a supersaturated solution containing Ca2+ and PO43- ions. All chemicals used were of analytical grade. The calcium ion and phosphate ion sources were hydrated Ca(NO3)2.4H2O and (NH4)2HPO4 respectively. All preparations were done at room temperature, i.e. 298K. In the previous studies, stimulated body fluid (SBF) was commonly used to produce the HAp coatings through a series of bio-mimetic processes. However, the precursor ions of SBF are complex and usually lead to a surface of specific crystalline with incisive edges, neither a uniform plane. Here we used a simplified precursor to insure pure and uniform HAp coatings. GIA-XRD diffraction pattern insured the crystalline structure of HAp coatings. FE-SEM images showed that the coatings were composed of granular islands of HAp with a roughness of 50nm after two days immersion. FTIR data showed that functional groups of HAp increased with the immersion days of preparation. And the absorption wavelength between 1420cm-1-1480cm-1 belonging to CO32- implied the existence of carbonated HAp. XPS results indicated that there were two kinds of binding structures of Ca2+ cation.Pulsed He-Cd laser with a wavelength of 325nm was used as the excitation sources of the photo-luminescent measurement with a scan rang from 350nm-900nm. Results showed that the coatings emitted specific light with a peak value of 465nm and 515nm. The intensity of emitting light was greater with the coatings were thicker. And a blue shift phenomenon was also observed. The PL properties can be useful in in situ bio-imaging or bio-chip application associated with bio-optical electronics.

 

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Related papers

Presentation: Oral at E-MRS Fall Meeting 2006, Symposium J, by Ren-Jei Chung
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-17 08:26
Revised:   2009-06-07 00:44