Electrochemical/Optical Nanoprobes for High-Resolution Chemical Analysis at Neuronal Microenvironment

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

This award supports development of an instrument that combines near-field scanning optical microscopy (NSOM) and scanning electrochemical microscopy (SECM) with the goal of localizing specific chemicals at the surface of single neurons. Signal transmission in the central nervous system is mediated by specific chemical messengers; thus the measurement of concentration distributions of chemical species in neuronal microenvironments is critically important to improving understanding of neurotransmission and brain function. Because signaling events occur at highly localized areas whose dimensions are less than several hundred nanometers, commonly used electrochemical and optical techniques are limited by electrode size (>1 micron) and by the wavelength of light. In addition, neuronal processes are highly complicated chemical events, so that simultaneous monitoring of various analytes by the combination of two or more techniques is frequently required. Synchronization of the spatial-temporal resolution of the techniques, however, is so difficult that the observed events usually lack one-to-one correspondence. The approach to be taken will overcome these difficulties through development of nanoprobes that can serve as both a light source and also an electrode. The multi-functionality allows for electrochemical and optical measurements at the same time and same location. This project explores the use of selectively etched optical fibers as a basis of electrochemical/optical nanoprobes. The etching technique allows for reproducible fabrication of optical fibers with a tip diameter of less than 10 nm. By taking advantages of the sharp fibers, electrochemical/optical nanoprobes with an active area of 100 nm in diameter will be designed and constructed. Once constructed, the tips will be tested for near-field optical imaging of single neuronal vesicles using electrochemical regulation of the probe - sample distance. The project will provide an opportunity for training of both undergraduate and graduate students in an interdisciplinary environment and, if successful, lead to new technology that can be exploited broadly in neuroscience and cell biology.