Blood cell adhesion on sensor materials studied by light, scanning electron, and atomic-force microscopy.

Unwanted interactions of biomedical sensors with surrounding tissues, body fluids, and cells are one of the most crucial problems affecting their long-term stability. In vivo processes were simulated in a computer-controlled bioreactor connected to a flow chamber system. Optical sensor materials were inserted into a parallel-plate chamber and monitored by light microscopy in order to get information about the number of adhered cells. Tests with thrombocyte-enriched plasma show that novel phosphorylcholine (PC)-polymer-coated sensors appear to be more bioinert, and thus demonstrate better haemocopatibility in comparison with untreated glass sensors. The influence of different materials on the morphology of adhered cells was investigated by off-line methods such as scanning electron microscopy (SEM) and atomic-force microscopy (AFM). SEM showed a reduction in the number of adhered thrombocytes and the lack of any fibrin network on the PC-polymer-modified glass surface, in contrast to the pure glass surface. AFM gives topographical information, and the calculated contact areas and cell volumes indicate smaller interactions between cells and sensor material in the case of PC-polymer-coated sensors.