Poly(ethylene glycol) is a hydrophilic molecule used among others, to passivate surfaces and prevent non-specific adsorption of proteins . The ability to protect from fouling highly depends on the surface density and mutual orientation of PEG molecules . PEG can be also crosslinked to form a hydrogel with poly(ethylene glycol) diglycidyl ether frequently being the starting material . It is nontoxic, biocompatible, stable under sterilization and for this reason it is often used to immobilize enzymes on implantable sensors . In case of syringaldazine modified electrodes PEGDE increased the capacitance of the sensors, but both reduction and oxidation peaks were clearly visible. Slow decrease in signal was observed with each subsequent scan, and no signal from syringaldazine could be detected after a week long incubation in the cell culture medium.