Advanced antifouling zwitterionic layer based impedimetric HER2 biosensing in human serum: Glycoprofiling as a novel approach for breast cancer diagnostics

There are two key novel components presented here behind identification of potential novel breast cancer (BCa) diagnostic approach: 1. application of photoimmobilizable zwitterionic hydrogels resisting non-specific protein adsorption for preparation of the biosensor interfaces and 2. integration of lectins (carbohydrate recognizing proteins) within biosensors to evaluate changes in the glycan profile of HER2 protein on the molecular level. A disposable, electrochemical biosensor based on screen printed carbon electrodes (SPCEs) with a deposited hydrogel layer was applied for covalent attachment of antibodies for a specific interaction with HER2. In the subsequent step, HER2 molecules were in situ glycoprofiled using lectins. The impedimetric immunosensor was able to detect HER2 down to 5 pg mL(-1) (approximate to 77 fM) with a minimal non-specific protein adsorption. The biosensor was then combined with lectins to glycoprofile HER2 in two serum samples (one from a healthy, high BCa risk woman and the other from a woman with a 2nd stage BCa). The results obtained by the glycoprofiling via the impedimetric biosensor were successfully verified by independent lectin-based enzyme-linked immunosorbent assays (ELISA). To our best knowledge it is a very first biosensor applying zwitterionic polymeric hydrogelmodified interface for glycoprofiling of a cancer biomarker.