Electro-switchable biosurface

An electro-switchable biosurface is a biosensor that is based on an electrode (often gold) to which a layer of biomolecules (often DNA molecules) has been tethered.

An alternating or fixed electrical potential is applied to the electrode which causes changes in the structure and position (movement) of the charged biomolecules.

SAM can be used as surface layers for nanoparticles, e.g. in MRI contrast agents, they can protect metal films from corrosion, and have many other applications in electrochemistry and nanoscience.

Due to its molecular structure, double stranded DNA molecules are negatively charged and rigid.

In static mode, the potential applied to the electrode is fixed, keeping the DNA molecule in an upright position.

The static mode can also be used to measure the activity of enzymes like polymerases that influence the structure of the DNA molecule.

[11] In dynamic mode, the potential applied to the electrode is oscillating, thus the DNA molecule switches between the upright and the horizontal position.

The image shows a schematic depiction of the static measurement mode, in which the electrode potential is negative and the DNA molecule is in an upright position. Additionally, it shows the dynamic measurement mode with an oscillating DNA molecule due to an alternating potential being applied to the electrode. Thirdly, it shows a DNA molecule that is elongated by an enzyme, whereby the distance of the dye from the electrode surface increases.
Electro-switchable biosurfaces equipped with DNA strands can be used to analyze the binding of an analyte to a ligand, conformations or enzymatic activity. V = voltage applied to the electrode.