Protein and DNA Electronic Biosensors

Protein and DNA
Electronic Biosensors

Electronic Transfer Mechanisms

Life processes are governed by an intricate orchestration of biochemical events. A goal of our current research is to understand these processes in terms of molecular interactions and to develop molecular-based methods to investigate. Ligand-receptor thermodynamics, ligand trafficking, receptor-mediated cell response, and cell adhesion and migration are pertinent examples.

The interactions between a small molecule and a large biomolecule are determined by forces such as ionic contacts, hydrogen bonding, dipole-dipole alignment, van der Waal’s forces, and hydrophobic interactions. Electrochemistry of redox-modified monolayers is highly sensitive to these forces. We use electrochemical methods to probe ligand-receptor interactions and to ultimately develop electronic protein biosensors.

Crystal structure of a biotinyalated Iron complex bound to Avidin. Electron transfer measurements reveal the nature of the binding in solution.
Crystal structure of a biotinyalated Iron complex bound to Avidin. Electron transfer measurements reveal the nature of the binding in solution.

 

Electronic Detection of Proteins

Redox-active self-assembled monolayers (SAMs). SAMs provide an excellent platform for investigating electron transfer kinetics. Using a well-defined bridge, a redox center can be positioned at a fixed distance from the electrode and electron transfer kinetics probed using a variety of electrochemical techniques. SAMs offer an ideal environment to study the outer-sphere interactions of redox species. The composition and integrity of the monolayer and the electrode material influence the electron transfer kinetics and can be investigated using electrochemical methods.

Exploiting this architecture we have developed a reagentless protein biosensor platform that is capable of detecting a large number of targets depending on the capture ligand employed.

Mechanism of electronic protein detection.  The metal complex in the absence of the target protein does not transfer electrons from the electrode to the Ru complex. Upon target binding the local dielectric and reorganization change as a result of the exclusion of water molecules and an electronic signal is acquired.
Mechanism of electronic protein detection. The metal complex in the absence of the target protein does not transfer electrons from the electrode to the Ru complex. Upon target binding the local dielectric and reorganization change as a result of the exclusion of water molecules and an electronic signal is acquired.

Chemistry at Northwestern University