Hamers Group Research Projects
Understanding the electrical properties of biological molecules, and using electrical response as a way of detecting biological binding events.
Most existing biosensors use fluorescence or other optical means of detection. We are investigating the electrical properties of biologically-modified surfaces as a means of achieving real-time, label-free detection of biological molecules.
In these experiments, we modify a surface of silicon, diamond, or other material with a biological molecule such as DNA. We then measure the electrical properties of the surface and how these change when the biomolecularly-modified surface interacts with other biomolecules in solution. By combining high-quality surface chemistry with electronic detection, it should be possible to monitor for a variety of biological agents continuously and in real time.
There are several key components to this work. First, it is necessary to have very high-quality surface chemistry. Our laboratory is equipped with a variety of state-of-the-art surface analysis methods such as core-level photoemission spectroscopy, Fourier-transform infrared spectroscopy, and atomic force microscopy that we use to optimize the various stages of biochemical modification of the surface. Once the surface chemistry is optimized, we use electrochemical impedance spectroscopy to measure the electrical properties of biologically-modified surfaces and how these change when exposed to other biomolecules.
For example, we link DNA to surfaces of silicon and/or conductive diamond thin films. When these biologically-modified surfaces are exposed to DNA molecules in solution having the complementary sequence, the electrical impedance of the interface changes. Control experiments using non-complementary sequences generate no response. Thus, we conclude that the changes in electrical properties are a direct result of the biomolecular binding at the surface. Similar effects are observed with biotin binds with the protein avidin.
The overall change in electrical response can arise from a number of different physical mechanisms. Ongoing experiments are aimed at understanding the molecular origin of the electrical signals, understanding the relationship between the electrical response and the biomolecular structure at the interface, and optimizing conditions to achieve maximum sensitivity and reliability as a means for biomolecular analysis.