Surface-enhanced Raman spectroscopy competitive binding biosensor development utilizing surface modification of silver nanocubes and a citrulline aptamer

Brian M. Walton; George W. Jackson; Nicolaas Deutz; Gerard Cote

doi:10.1117/1.JBO.22.7.075002

21 July 2017 Surface-enhanced Raman spectroscopy competitive binding biosensor development utilizing surface modification of silver nanocubes and a citrulline aptamer

Brian M. Walton, George W. Jackson, Nicolaas Deutz, Gerard Cote

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Journal of Biomedical Optics, Vol. 22, Issue 7, 075002 (July 2017). https://doi.org/10.1117/1.JBO.22.7.075002

Abstract

A point-of-care (PoC) device with the ability to detect biomarkers at low concentrations in bodily fluids would have an enormous potential for medical diagnostics outside the central laboratory. One method to monitor analytes at low concentrations is by using surface-enhanced Raman spectroscopy (SERS). In this preliminary study toward using SERS for PoC biosensing, the surface of colloidal silver (Ag) nanocubes has been modified to test the feasibility of a competitive binding SERS assay utilizing aptamers against citrulline. Specifically, Ag nanocubes were functionalized with mercaptobenzoic acid, as well as a heterobifunctional polyethylene glycol linker that forms an amide bond with the amino acid citrulline. After the functionalization, the nanocubes were characterized by zeta-potential, transmission electron microscopy images, ultraviolet/visible spectroscopy, and by SERS. The citrulline aptamers were developed and tested using backscattering interferometry. The data show that our surface modification method does work and that the functionalized nanoparticles can be detected using SERS down to a 24.5 picomolar level. Last, we used microscale thermophoresis to show that the aptamers bind to citrulline with at least a 50 times stronger affinity than other amino acids.

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Brian M. Walton, George W. Jackson, Nicolaas Deutz, and Gerard Cote "Surface-enhanced Raman spectroscopy competitive binding biosensor development utilizing surface modification of silver nanocubes and a citrulline aptamer," Journal of Biomedical Optics 22(7), 075002 (21 July 2017). https://doi.org/10.1117/1.JBO.22.7.075002

Received: 8 March 2017; Accepted: 30 June 2017; Published: 21 July 2017

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