Peptide ormosils as cellular substrates

Abstract

Peptide-functionalized thin films exhibit significant potential for integration into implantable devices and cell-based technologies. A new type of neuroactive peptide-modified silica was developed using sol–gel reaction chemistry to produce thin films from four different peptide silane precursors. Peptide silanes containing binding sequences from laminin (YIGSR and KDI), fibronectin (RGD), and EGF repeats from laminin and tenascin (NID) were produced using standard solid-state FMOC peptide synthesis conditions and the covalent attachment of 3′-(aminopropyl)trimethoxysilane (APTMS), using carbonyldiimadazole (CDI) as a linking molecule. Precursor formation was confirmed with MALDI-MS. Thin films were produced by dip-coating using the peptide precursors combined with hydrolyzed tetramethoxysilane. Atomic force microscopy indicated that the surface topography was not affected by low concentrations of peptide precursor (0.0025 mol%), but higher concentrations of peptide precursor (0.01 mol%) resulted in features that were 50–75 nm in height. The height features observed were consistent in size with previously determined topographical morphology supportive of neuronal cell lines. The surfaces were biologically active and modulated the phenotype of the embryonic carcinoma stem cell line, P19. Combinations of the peptide silanes resulted in altered cell types after retinoic acid treatment. More neurons were observed on RGD/YIGSR and RGD/YIGSR/NID surfaces compared to tetramethoxysilane (TMOS) controls. More supporting cells were observed compared to collagen coated tissue culture plates. In addition, neurites were significantly longer on the peptide ormosils compared to controls. This work demonstrates a novel method for producing biologically active peptide ormosils using peptide-modified precursors.