Enhanced Osteoblast Adhesion to Epoxide-Functionalized Surfaces

As an alternative to expensive extracellular matrix (ECM) proteins generally applied as coatings in Petri dishes used for cell binding, an innovative system based on epoxide-functionalized monolayers capable of protein binding is proposed. Since cells bind to material surfaces through proteins, protein-binding surfaces should also promote cell binding. Here we investigate how the cell-binding properties of an epoxide-functionalized surface compares with ECM protein gel coated surfaces and tissue culture polystyrene control surfaces. Glass surfaces are functionalized with glycidoxypropyltriethoxysilane (GOPS), which results in an epoxide-functionalized surface capable of binding proteins through an epoxide–amine reaction. Advancing contact angle measurements and atomic force microscopy measurements confirm the formation of a homogeneous GOPS monolayer. This monolayer is micropatterned with fluorescein-labeled ECM protein gel by microcontact printing (µCP). Confocal laser scanning microscopy (CLSM) shows accurately transferred ECM protein gel micropatterns. Osteoblasts that are seeded on these micropatterned substrates show a clear preference for adhering to the epoxide-functionalized areas. The morphology of these cultured osteoblasts is needle-like with high aspect ratios. As controls, osteoblasts are cultured on GOPS-functionalized surfaces, unstructured ECM protein gel surfaces, and tissue culture polystyrene (TCPS). The GOPS surfaces demonstrate a drastic increase in cell adhesion after 2 h, whilst the other tests show no adverse effects of this surface on the osteoblasts as compared to ECM and TCPS. CLSM shows healthy cell morphologies on each surface. It is demonstrated for the first time that epoxide groups outperform ECM protein gel in cell adhesion, thereby providing new routes for cost-effective coatings that improve biocompatibility as well as exciting, new methodologies to control and direct cell adhesion.