Development of Multi-Parametric/Multimodal Spectroscopy Apparatus for Characterization of Functional Interfaces

With increasing interest in functional interfaces, it becomes increasingly important to characterize chemical structures and biomolecules on surfaces in a quantitative fashion, and to test their proper allocation orientation, conformation, activities, stability, etc. This research integrates several synergistic surface characterization spectroscopy methods such as surface plasmon, fluorescence, and electrochemical spectroscopies into one new surface analytics, to enhance the power and capabilities of interface characterization sensing techniques. Since currently there is no such instrument available, the main objective of this proposal is to develop a multi-parametric/multimodal spectroscopy system (MPMS) for simultaneous application of these surface-mediated optical techniques. Electrochemical Proximity Assay (ECPA) is taken as a research model, which is a flexible method with high potential for quantitation of a variety of proteins in clinical laboratory settings or at the point-of-care. With fluorescent labels (green circle in figure) and methylene blue (blue circle in figure) incorporated into the DNA strands, the process of ECPA can be real-time monitored by fluorescent, electrochemical and SPR signals simultaneously. Among the steps of ECPA, SPR should generate signal upon assembly of each step, surface fluorescence will only change upon assembly of the labeled piece, while electrochemical signal will only change upon addition of the methylene blue (MB) labeled DNA strand. In this way, the SPR signal will thus give a non-biased view of all steps of assembly, fluorescence will give us the power to label and monitor specific portions, and electrochemistry will allow high sensitivity and quantitative characterization of surface coverage. Therefore, the MPMS system will allow an unprecedented level of fundamental understanding of the dynamics of the ECPA process.