Services

We offer services for measuring chemicals in biosystems with our state-of-the-art technology and professional research personnel. We have the capabilities to measure a variety of neurochemicals and their metabolites and precursors, as well as amino acids by utilizing several methodologies.

In Vivo ElectroChemistry

In vivo electrochemistry relies on the fact that certain compounds can undergo oxidation (electron loss) or reduction (electron gain) reactions at a given applied potential. During such a reaction, the number of molecules of a substance is directly related to the number of electrons detected. Moreover, these reactions can be reliably detected on millisecond time scales, and on small surfaces. In our laboratory, we take advantage of the principles of electrochemistry in order to detect a variety of electroactive compounds in the brain. The FAST-16 (Fast Analytical Sampling Technology) system, developed at the Center for Microelectrode Technology (CenMeT), allows us to accuately detect compounds such as dopamine, norepinephrine, serotonin, and nitric oxide with high sensitivity (< 10 nM) and on a short (< 1 s) time scale. We have developed a ceramic-based microelectrode array (MEA) that incorporates advances and flexibility in site patterning. (Burmeister, et al., 2000, 2001, 2002.) for rapid measurements of L-glutamate (Glu) choline (Ch) and acetylcholine (ACh) in brain tissue. The new designs have platinum recording sites of varying geometries and recording site placements allowing for a wide range of recording configurations.

Measurements are carried out on carbon fiber microelectrodes or MEAs, the dimensions of which (carbon fiber - ca. 100 x 30 mm; MEA- 1 cm long, affording spatial resolution as low as 10-300 microns)are small enough to penetrate the extracellular space of the brain with only minimal tissue disruption. A small potential (0.9 V relative to a standard AgCl reference) is applied to the surface of the electrode, thereby causing oxidation of the electroactive species at the surface of the electrode. The current generated by this reaction is converted to an actual concentration change (for example, on a mM scale), based on standard curves generated prior to each experiment. These signals can be generated many times per second and are typically displayed every second, so that a "real time" assessment of the electrochemical signal can be seen. The signal parameters obtained in these recordings, such as peak height and time to decay, can be used to define properties of neuronal release and reuptake. For example, it is possible to detect dopamine release in several brain regions using a variety of known physiological stimuli. Moreover, agents that are known to affect release or reuptake, such as amphetamine or cocaine, will alter the parameters of the electrochemical signal. In this way, it is possible to study the dynamic processes of neuronal function in the intact animal.

Key Benefits

• Accurate In vivo detection of compounds such as l-glutamate, dopamine, norepinephrine, serotonin, and nitric oxide.
• with high sensitivity ( <0.2 uM Glu, < 10 nM DA
• on a short (< 1 s) time scale.