Robert C. Dunn
Analytical Chemistry: Optical Spectroscopy/Microscopy, Fiber Optics, Optical Sensors, X-ray Microscopy.
Professor Dunn's research interests involve the application of novel optical techniquesto the study of bioanalytical and biophysical problems. One area which he is currently workingin is that of near-field scanning optical microscopy. This emerging technique allows one tomeasure the optical properties of a system with single molecule sensitivity and nanometric spatialresolution. Because of diffraction effects, conventional optical techniques have a spatialresolution limit of approximately half the wavelength of the light used or about 250 nm. Innear-field optical microscopy, however, this limit can be overcome. In this technique, aspecially fabricated optical fiber is used to funnel light down to a small point less than 90 nmin diameter. Sub diffraction limit spatial resolution results from positioningthis spot of light in close proximity to the sample surface (approximately 10 nm) such thatdiffraction effects do not degrade the resolution. The resulting resolution, therefore, is only afunction of the near-field fiber tip diameter and not the wavelength of the light used. Near-fieldfiber optic probes with diameters less than 90 nm can easily and reproducibly be manufacturedin Prof. Dunn's lab.
The unique capabilities of this technique are being utilized to study a range of biologicallyrelevant systems. In particular, the dynamics and microscopic structure of membranes are acurrent area of interest within the group. These studies are aimed at elucidating the microscopicproperties of biological membranes at ambient conditions, in hopes of better understanding theirrole in cellular and subcellular processes.
Another active area of research in the lab deals with the development of fiber optic basedchemical sensors. This project is exploring the possibility of measuring pH and O2 using sensors based on near-field fiber optic probes. These sensors couldpotentially provide enhanced spatial and temporal resolution over designs currently beingutilized. The ultimate goal of this project is to produce optical sensors or sensor arrays capableof the in vivo monitoring of one or more analytes with submicron resolution.