Protein adsorption to planar electrochemical sensors and sensor materials *

In electrochemical sensing devices, aimed for acute and chronic in vivo application, the active surface of the sensor is often negligible compared to the overall surface area of the device in contact with the biological host. Consequently, to minimize the perturbation of an implanted sensor on the in vivo environment the chemical composition and surface texturing of the complete device (the active sensor, sensor substrate, and “accessories”) have to be considered. In our work, the adsorption of three abundant proteins (albumin, IgG, and fibrinogen) was determined quantitatively on untreated and modified sensor substrates and sensing membrane surfaces. In this study, a flexible polyimide-based material (Kapton®) was used as sensor substrate with or without an amorphous diamond-like carbon (DLC) or an amorphous oxygen-containing DLC (o-DLC) coating. The ion-sensitive membranes were cast from high-molecular-weight (HMW) or carboxylated poly(vinyl chloride) (PVC) and were doped with increasing concentrations of highly hydrophilic poly(ethylene oxide) (PEO). The potentiometric characteristics of the potassium-selective membranes cast with up to 6 % PEO were the same as those without PEO. However, the PEO-modified PVC membranes elicited a large amount of protein adsorption, especially in terms of albumin.