There is an acute need for the development of a new class of microarray biosensors that are sufficiently versatile, selective, sensitive and reliable to allow investigation of the time-dependent neurochemical events of ethanol administration in multiple regions of the brain. Currently, the preferred method for monitoring neurotransmitters in vivo real time is fast-scan cyclic voltammetry (FSCV) and the preferred microelectrode material is carbon fiber. We propose development of the next generation electrode material, boron-doped ultrananocrystalline diamond (BD-UNCD) that offers superior sensitivity and specificity, fast response time, low background currents, long-term stability and resistance to fouling as compared to carbon fibers. The goal is to develop chronically implantable UNCD microarray electrodes for long-term (i.e., months to years) recording of multiple neurochemicals, especially if human compatible.
The specific aims of this project are to: (i) develop a reliable, scalable and mass-producible UNCD microarray that exhibits micro or nano electrode electrochemical behavior (i.e. higher signal-to-noise ratio) using cyclic voltammetry and dopamine (the most widely studied neurotransmitter), (ii) demonstrate glutamate detection on a modified UNCD microelectrode and (iii) demonstrate the unique advantages of UNCD microarrays by measuring two neurochemicals (dopamine and glutamate with flow injection analysis and in an anesthetized rat brain) i.e. multiplexing, which is an important step towards multiple neurochemical detection at a single site. As a proof-of-concept, the electrodes will be used to measure the two neurochemicals down to physiological concentrations. The proposed microarray chemical/biosensor could potentially be used for simultaneous measurement of dopamine, glutamate and many other important neurotransmitters in multiple brain regions. If this project is successful, it will accomplish key NIH mission goals, specifically: 1) UNCD's bioinertness, low pseudo capacitance and high selectively due to its surface chemistry will greatly enhance "in vivo voltammetry";2) UNCD/parylene passivation is novel and completely "biocompatible" for chronic neurochemical sensing;3) application of UCND and nanometer thick insulators will greatly advance the way in which probes are fabricated for "nanotechnologies'in general;and 4) UNCD can be easily modified with enzymes, antibodies and oligonucleotide probes through photochemical or electrochemical means for "biosensors". A recent sensor market report suggests that the medical sensing market will reach $10.9 billion in 2012. Based on a letter of support from a leading neurophysiological microelectrodes and instrumentation company, the expected annual sales for this product at FHC Inc., would be "at least $10-15 million" and would be expected to exceed this number many-fold over the broader neuroscience market. Also, a greater understanding of real-time sensing of neurotransmitters from this project would enable alternative applications for the technology, including: low-cost, point-of-use, portable sensors for toxins, metabolites and disease biomarkers.
This project will develop a microarray biosensor technology using ultrananocrystalline diamond electrodes to further advance the neuroscience field (brain function and the effects of ethanol administration). Its versatility, sensitivity and reliability are ideally suited for real-time, chronic measurement of multiple neurochemicals and brain activity mapping.