Dielectrophoresis-enabled surface enhanced Raman scattering of glycine modified on Au-nanoparticle-decorated polystyrene beads in micro-optofluidic devices

Abstract

The Raman spectra of glycine, an amino acid, trapped on the surface of polystyrene (PS) beads decorated with Au nanoparticles (AuNPs) through carbodiimide method are reported. The Raman spectra indicate that both amino and carboxylate groups are bound to the surface of the PS beads. Dielectrophoresis enabled the aggregation of the AuNP-decorated PS beads, which captured glycine onto an Au electrode; bound glycine withstood 20 times irrigation process using an ultrapure water. In the case of dielectrophoresis-induced aggregation of the AuNP-decorated PS beads without modification to molecular recognition, the Raman spectra of glycine decreased with washing time. This method enabled us to detect glycine at 100mM by a simple procedure using a fiber-type, simple Raman spectrometer. This platform enables the easy Raman detection of amino acids such as RGD motif via alternative peptide coupling using carbodiimide method.