Electro-switchable biosurface
An electro-switchable biosurface is a biosensor that can be used in conjunction with alternating or fixed electrical potentials in order to affect change in the structure and position (movement) of charged biomolecules such as DNA, RNA or oligopeptides bound to the biosurface. This is especially pronounced when the biomolecule has rigidity in its structure such as double stranded DNA. In turn, the changes caused by electrical potentials can be used to affect the biological function of the biomolecule by revealing or changing the access to molecular targets. Label free molecular interaction. The biomolecule (for instance double  stranded DNA) bound to the biosurface can be used to tether a label free target in a label free interaction model. By applying a variable or alternating potential to the biosurface, the biomolecules can be moved systematically. In turn the movement can be measured in real time using time-resolved fluorescence spectroscopy of the fluorescence quenching of an attached fluorescent marker molecule. By analyzing the speed of the biomolecule as it is dragged through the buffer solution by the electric field, the binding of a ligand can be measured in real time. Since the speed of the biomolecule and a  bound ligand depend on their hydrodynamic friction the method can be used to measure the size of the biomolecule and/or of the ligand. This can also be directly applied to detect conformational changes of the biomolecule and/or the ligand. It competes with technologies including surface plasmon resonance. Recently, electrical stimulus has also been utilized to influence the binding between a protein and its ligand which could be incorporated into smart surfaces for controlled molecular release.