| Summary: | 碩士 === 國立臺灣大學 === 化學工程學研究所 === 96 === Polyelectrolyte multilayers (PEMs) are widely used for biomedical applications. The layer-by-layer (LbL) deposition of PEM films has emerged as a very robust and versatile tool. Surface modification by layer-by-layer (LbL) deposition allows coating substrates with complicated geometries and incorporating a wide variety of materials into the films, such as natural polymer and peptide. Cell- (RGD) and heparin-binding site (LHRRVKI) bind the receptors presented on the cell membrane and initiates receptor-mediated signal transduction and promotes cell adhesion, proliferation and differentiation. The aim of this study is to investigate the influence of the prptide-modified PEM films built up at different pH on the behaviors of osteoblast-like cells, MG-63 and primary osteoblasts from rat calvariae.
Poly (allylamine hydrochloride) (PAH) and poly (acrylic acid) (PAA) solution were assembled onto TCPS and PS by LbL technique with five bilayers ((PAH/PAA)5) in different deposition solusion. Then, the peptide-grafted PAH was adsorbed on the films as the topmost layer. First, MG-63 cells were seeded onto the PEM films and cell proliferation, alkaline phophatase (ALP) activity and matrix mineralization were studied to test the effect of peptide-modified PEM films. The MG-63 cells adhered and proliferated well on the PEM films with RGD. The level of matrix mineralization on the 2.0-RGD was higher than on the 6.5-RGD. The results showed that the cell function of MG-63 cells was influenced by the films assembled at different pH of deposition solution and the adsorption of PAH-RGD on the PEM films enhanced the cell proliferation and differentiation.
Next, the peptide-grafted PAH, PAH-RGD and PAH-LHRRVKI or mixtures of the two in the ratios of 50:5 (mimetic peptide surfaces I), 50:10 (mimetic peptide surfaces II) and 50:50 (mimetic peptide surfaces III), were adsorbed on the PEM films built up at different pH. The primary osteoblasts isolated from rat calvariae were seeded on the PEM films, and cell proliferation, alkaline phophatase (ALP) activity and matrix mineralization were studied to observe the behaviors of primary osteoblasts on the peptide-modified PEM films. The cells on the films built up at pH 2.0 with mixtures of peptide-conjugated PAH were adhered and proliferated better than on the films built up at pH 6.5. The cells on the films built up at pH 2.0 with mixtures of peptide-conjugated PAH deposited more calcium salt than on the homogeneous surfaces and the films built up at pH 6.5 with mixtures of peptide-conjugated PAH. Therefore, the results demonstrated that incorporating both cell- and heparin-binding motifs on the films assembled at pH 2.0 improved the cell proliferation and matrix mineralization.
These studies support the potential of PEM films for surface modification of biomaterial, and point to a novel perspective for peptide functionalization that can lead to an improvement of biocompatibility and promote cell function.
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