pH-dependent modulation of fibroblast adhesion on multilayers composed of poly(ethylene imine) and heparin.

Adhesion of tissue cells is a prerequisite for their growth and differentiation but prevents also apoptosis. Here the layer-by-layer technique (LbL) was used to design multilayer structures of poly(ethylene imine) (PEI) and heparin (HEP) on glass as model biomaterial to control the adhesion of primary human dermal fibroblasts. Distinct surface features like wettability, charge and lateral structures were controlled by changing the pH value of the HEP solution during multilayer assembly to acidic, neutral or alkaline values. While plain terminal layers were rather cytophobic, the pre-adsorption of serum or fibronectin (FN) caused a distinct change in cell morphology in dependence on the pH setup. The effect of serum was more prominent on PEI layers probably due to their positive surface charge, whereas the effect of FN was more pronounced on HEP terminated multilayers possibly due to its ability to bind FN specifically. Those layers which hampered cell adhesion also inhibited growth of human fibroblasts under serum conditions. Conversely, on layers where cell adhesion was increased also an elevated growth and, thus, metabolic activity was observed.