XPS survey spectra of (a) coating 5 modified surface and (b) coating 5/BMP-2 modified surface.

<p>The atomic concentration of C, N and O are 77.3%, 4.55% and 18.22% on the coating <b>5</b> modified surface and 65.0%, 9.5% and 25.5% on the coating <b>5</b>/BMP-2 modified surface. The N composition significantly increased due to immobilization of BMP-2.</p

IRRAS characterization of (a) coating 5 modified surface and (b) coating 5/BMP-2 modified surface.

<p>Both of the modifications were on a gold-coated silicon substrate. Three significant peaks, which are characters of asymmetric stretching bands of NHS ester C = O were detected as 1770, 1739, and 1716 cm^-1 in S1(a). Peaks at 1217 cm^-1 and 1072 cm^-1 were attributed to N-O and C-O stretch, respectively. In S1 (b), peak of N-O (1207 cm^-1) and C-O (1067 cm^-1) stretch were reduced and one of the C = O peak (1716 cm^-1 in (a) and 1709 cm^-1 in (b)) strongly reduced after immobilization of BMP-2. The characterization peaks of BMP-2 appeared on the bands around 3247 cm^-1 for N-H and 3490 cm^-1 for O-H.</p

QCM analysis of coating 5 modified surface.

<p>Curve (a) is the result of BMP-2 solution injected and flowing through coating <b>5</b> modified surface, and at the end of the measurement, the amount of BMP-2 adsorption on coating <b>5</b> modified surface is 6.04·10⁻¹² mol cm^-2. Curve (b) is the result of BMP-2 solution injected and flowing through parylene C-modified surface, and at the end of the measurement, the amount of BMP-2 adsorption on parylene C surface is 3.81·10⁻¹² mol cm^-2. Curve (c) is the result of BMP-2 solution injected and flowing through PEG5000 modified surface, and at the end of the measurement, only 1.62·10⁻¹⁴ mol cm^-2 of BMP-2 adsorbed on the surface. Curve (d) is the result of BMP-2 primary antibody solution injected and flowing through coating <b>5</b>/BMP-2 modified surface, and at the end of the measurement, the amount of BMP-2 primary antibody adsorption on coating <b>5</b> modified surface is 2.43·10⁻¹² mol cm^-2. Curve (e) is the result of BMP-2 primary antibody solution injected and flowing through coating <b>5</b> modified surface, and at the end of the measurement, the amount of BMP-2 primary antibody adsorption on coating <b>5</b> modified surface is 2.35·10⁻¹² mol cm^-2.</p

Relative gene expression of (a) Alpl (gene marker of ALP) and (b) Bglap3 (gene marker of osteocalcin).

<p>The effect of coating <b>5</b>/BMP-2 modified, coating <b>5</b> modified and unmodified surface on relative mRNA expression was assayed on days 0, 4, 7, 11, and 14. The asterisks indicate significant differences (*P<0.05 and **P<0.01) between coating <b>5</b>/BMP-2 modified, coating <b>5</b> modified and unmodified surface at each time point.</p

Sustained Immobilization of Growth Factor Proteins Based on Functionalized Parylenes

Protein molecules immobilized on biomaterial surfaces are performed based on oriented conjugation or replaced mimicking peptides. The sustainable immobilization of growth factor proteins using functionalized parylene coatings is demonstrated in this study. Site-specific and nonspecific immobilization approaches are realized to conjugate bone morphogenetic protein (BMP-2). The binding affinities and conformational changes of BMP-2 are confirmed by QCM and SPR characterizations. Osteoinduction of stem cells is examined by ALP activity on the BMP-2 modified surfaces. Finally, immobilizations and equally sustained biological functions of vascular endothelial growth factor (VEGF) and a mimicking peptide of KLTWQELYQLKYKG (QK) are also examined and confirmed