Cellular adhesion and growth on solid-state surfaces is the central theme in the development of cell-based biosensors and implantable medical devices. Suitable interface techniques must be applied to construct stable and well-organized thin films of biologically active molecules that would control the development of neuronal cells on chips.
Peptides such as RGD fragments, poly-
L-lysine (PLL), or basal lamina
proteins, such as
laminin or
fibronectin, are often used in order to promote cellular adhesion on surfaces. In this paper we describe the characterization of several self-assembled monolayers (
SAMs) for their ability to anchor a
laminin-derived synthetic
peptide,
PA22-2, a
peptide known to promote neuronal attachment and stimulate neurite outgrowth. We have evaluated the immobilization of
PA22-2 onto
16-mercaptohexadecanoic acid, 4-maleimide-N-(11-undecyldithio)butanamide, and 2-(maleimide)ethyl-N-(11-hexaethylene oxide-undecyldithio)acetamide SAM functionalized Au substrates. The neuronal attachment and outgrowth have been evaluated in embryonic mouse hippocampal neuron cultures up to 14 days in vitro. Our results show that differences in the cell morphologies were observed on the surfaces modified with various
SAMs, despite the minor differences in chemical composition identified using standard characterization tools. These different cell morphologies can most probably be explained when investigating the effect of a given SAM layer on the adsorption of
proteins present in the culture medium. More likely, it is the ratio between the specific
PA22-2 adsorption and nonspecific medium
protein adsorption that controls the cellular morphology. Large amounts of adsorbed medium
proteins could screen the
PA22-2 sites required for cellular attachment.