Undergraduate Research Opportunities in the Bohn Group

Label-free Optical Chemical Biosensors 

This project targets the development of a novel integrated nanoscale chemical sensor using a low-cost nanofabrication technique.  The sensing mechanism uses surface plasmon enhanced transmission through a nanostructured metallic feature, the Au nanocapillary array membrane (NCAM).  We are especially interested in developing low-cost, robust routes to highly parallel arrays of sensor elements, for example, using nanosphere lithography as an alternative to focused ion beam milling or electron beam lithography.  The sensor will be tuned to a specific bioanalyte by Au-thiol self assembled monolayer chemistry.  Incorporating the sensor into a microfluidic device will leverage the advantages of fast diffusive transport and digital sample control with nanoscale detection volume offered by the Au-NCAM.  The effectiveness of the integrated sensor will be explored by quantifying sensitivity, accuracy, and limits of detection. 

Single Molecule Reaction Dynamics 

Our interest in reactive molecules under conditions of confinement or crowding leads us to explore the dynamics of single molecules executing fundamental chemical events that either create, alter or destroy high efficiency fluorescence.  Typical systems currently being studied at the single molecule level are enzyme dynamics in single nanopores, DNA ligation and cleavage reactions and molecules executing Brownian motion in structured environments, such as stimulus-responsive materials.  Specific experiments executed by undergraduates include using fluorescence intensity to follow reaction product formation and fluorescence correlation spectroscopy to measure transport properties. 

Chemical Imaging 

Our interest in chemical imaging seeks to combine 2D and 3D approaches to generating spatial maps of molecular functional groups.  Generally, these experiments are conducted in parallel either with another imaging modality, e.g. imaging mass spectrometry, or with sophisticated methods of nanostructure development, such as self-limiting electrochemical growth of atom-scale junctions.  The goal is to correlate information from several disparate approaches to yield unique insight into the structure-function relationship in complex nanostructures.  These  experiments make extensive use of a commercial confocal Raman imaging microscope, and a second-harmonic optical coherence tomography microscope is under construction.