Quantitative Label-Free Investigations of Biorecognition

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With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Joel Harris and his research group at the University of Utah are developing a new microscopy technique to investigate the mechanisms of reactions involving biological molecules employed in therapeutic applications and clinical diagnostics. The measurements are carried out on surfaces that mimic the structure of cell membranes, so that the response can be related to the action of these molecules in biologically- and clinically-relevant systems. In most investigations of this type, emission of light from a dye label is used to monitor the reactions of the biological molecules of interest. In some instances the dye label can interfere with the interactions of interest. The approach being developed by the Harris group avoids the need for the label, and therefore the associated complications. The fundamental information derived from these investigations should advance understanding and development of new biologically-derived pharmaceuticals (biologics) and more selective clinical diagnostic assays. The group is also extending the tools to studies related to cultural heritage science, and communicating the science to a broad audience through outreach to a local fine arts museum. The program is training graduate students, undergraduates, and postdoctoral associates in microscopy and bioanalytical chemistry, topics that are relevant to advancing U.S. science and technology. Additional science education and outreach comes through development of Chemistry-under-the-Microscope exercises in undergraduate chemistry labs.The measurement innovation in this project is the application of confocal-Raman microscopy to measure biorecognition reactions within individual porous particles modified with lipid bilayers. Raman spectroscopy is a label-free method that can report the structure and interactions of proteins. A major limitation of Raman is the low sensitivity resulting from small scattering cross sections. In this work, this limitation is overcome by enhancing the surface area that can be interrogated within a small detection volume through use of porous silica particle supports. The internal surfaces of these particles are modified with lipid bilayers and used as substrates for investigating biorecognition reactions relevant to protein-lipid interactions and bioassay applications. With calibration using internal standards, confocal Raman microscopy can provide both structural information and assessment of absolute surface coverages for biomolecules involved in interfacial reactions. This research is generating new understanding of biomolecule association, stoichiometry, and structure that govern peptide-lipid membrane interactions and protein biorecognition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.