Label-free SERS detection of proteins via carbohydrate conjugated nanoparticles
Martin, Sharon Janille Hurley
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Carbohydrates may be found inside or on the surface of cells. Understanding the structure and role carbohydrates play in regulating these processes is of great importance. This can be done by the development of carbohydrate detection methods. Surface enhanced Raman spectroscopy (SERS) can be used as a label free biosensing technique which yields a chemically sensitive signature of the analyte molecule. Carbohydrates were immobilized by copper (Cu) free click chemistry reactions to develop carbohydrate nanoparticles for detection and differentiation of proteins by SERS. Galectin proteins were detected with 95-100% sensitivity and specificity. Two galectin proteins were differentiated by SERS with 85-100% sensitivity and specificity. Then we demonstrate that sialylated carbohydrates can be immobilized to SERS substrates using Cu free click chemistry reactions. This created a sialylated carbohydrate sensing surface that was used to detect influenza hemagglutinin. Using SERS we were also able to detect H1N1 and H7N9 hemagglutinin binding to sialylated carbohydrates and differentiate H7N9 and H1N1 hemagglutinin. These findings demonstrate that SERS can be used as a label free method to detect biomolecular interactions.