Professor, Analytical Chemistry

B.S. 1986, Iowa State University
Ph.D. 1990, Indiana University
Postdoctoral: 1990-1992, Miles, Inc.

Email: jebaur@ilstu.edu
Phone: (309)438-2663
Office: 215 Science Laboratory Building

For more details, recent publications, and up-to-date project information, visit the Baur Group Website.

Chemical nanosensors and microsensors are valuable tools for investigating complex biological systems. These tiny sensors, which have active sensing elements between 100 nm and 10 µm wide (about 1/1000th to 1/10th the diameter of a hair), can measure very small changes in concentration in real time with very high spatial resolution. Such advantages can be exploited in two ways. First, a chemical image can be created by systematically measuring the concentrations of chemical species as a function of sensor location. A technique that we extensively employ, Scanning Electrochemical Microscopy (SECM) (click here for a primer on SECM), is based upon this principle. Second, transient and localized changes in the concentration of a chemical species can be monitored in real time using a stationary sensor. This is principle serves as the basis of several techniques (such as amperometry and fast-scan voltammetry) for real-time monitoring dynamic biological systems.

5 µm microsensor

Our research is aimed at combining these two powerful approaches into a single instrument, the Biological Scanning Electrochemical Microscope (BioSECM), particularly for investigating neurotransmitter release from cultured neurons during growth and neurodegeneration. One significant advantage of the BioSECM over other methods for investigating these systems is that topographical and chemical imaging can take place simultaneously. This means that structure-function relationships of neurons (or model neurons) can be studied.

Schematic Diagram of the BioSECM Imaging Process

Because of the interdisciplinary nature of this research, students from both biology and chemistry (or biochemistry) are needed. Those with an interest or aptitude in instrumentation (e.g. electronics, computer hardware, and computer programming), cell culture, or nanotechnology will find this research particularly rewarding.

In order to realize the potential of the BioSECM, substantial improvements in the instrumentation and the sensor must be achieved. These improvements, along with brief descriptions of the biological applications of the instrument, are summarized below.

Instrument Improvement
In order to use the SECM for high-resolution chemical and topographical imaging of biological samples, we must develop our own hardware, software, and techniques. We have recently developed a method for imaging cultured model neurons directly in the growth media, a critical step toward our long-term goal of measuring release during neuronal development. However, this goal can only be achieved if the BioSECM is adapted to function under incubation conditions (i.e. 37°C, 5% CO₂ atmosphere), and so we are presently developing an incubation chamber suitable for this purpose.

BioSECM image (left) of a cultured model neuron recorded with a 5 µm microsensor

Sensor Development
The sensor is the heart of the SECM. It provides the specificity necessary for chemical imaging, and its size determines the spatial resolution of the technique. For this reason, a primary thrust of our research is the development of new chemically selective nanosensors and microsensors. Presently, we are working to modify carbon nano-ring sensors so that they are capable of imaging neurotransmitter release and imaging cell morphology with high resolution. We are also developing multifunctional sensors that will be capable of imaging multiple species simultaneously.

Applications
       Neurodevelopment and synaptogenesis. One distinct advantage of the BioSECM is its capability for imaging both cell morphology and neurotransmitter release. We wish to investigate how neurotransmitter release, both its time course and spatial distribution, changes during neuronal growth and the formation of synapses with other cells, a process known as synaptogenesis. By studying these processes, we can learn fundamental mechanisms involved in neuronal development.

        Neurodegeneration. The types of microsensors and nanosensors used for the BioSECM are also capable of producing short-lived chemical species that are known exert oxidative stress on cells. These reactive oxygen species (predominately superoxide, O₂^-, hydroxyl radical, •OH, and hydrogen peroxide, H₂O₂) are suspected of playing a role in neurodegenerative diseases such as Alzheimer’s Disease and Parkinson’s Syndrome. We plan to use the BioSECM to apply a local dose of the reactive oxygen species and then image changes in morphology and neurotransmitter release. In this way the role of reactive oxygen species in neurodegeneration can be investigated, and potential therapies evalutated.

Simultaneous detection of neurotransmitter release (black) and cell morphology (red)