Abstract
A nanoplasmonic biosensor for highly-sensitive, single-step detection of protein biomarkers is presented. The principle is based on the utilization of the optical scattering properties of gold nanorods (GNRs) conjugated to bio-recognition molecules. The nanoplasmonic properties of the GNRs were utilized to detect proteins using near-infrared light interferometry. We show that the antibody-conjugated GNRs can specifically bind to our model analyte, Glucose Transporter-1 (Glut-1). The signal intensity of back-scattered light from the GNRs bound after incubation, correlated well to the Glut-1 concentration as per the calibration curve. The detection range using this nanoplasmonic immunoassay ranges from 10 ng/mL to 1 ug/mL for Glut-1. The minimal detectable concentration based on the lowest discernable concentration from zero is 10 ng/mL. This nanoplasmonic immunoassay can act as a simple, selective, sensitive strategy for effective disease diagnosis. It offers advantages such as wide detection range, increased speed of analysis (due to fewer incubation/washing steps), and no label development as compared to traditional immunoassay techniques. Our future goal is to incorporate this detection strategy onto a microfluidic platform to be used as a point-of-care diagnostic tool.
Highlights
Immunoassays have been used in research and clinical settings over the past five decades to quantify biomolecules of various sizes, chemical and physical properties [1]
The working principle of optical coherence tomography (OCT) is related to the capture and analysis of light backscattered from sample, we are interested in preferentially scattering nanoparticles [12]
The extinction spectra of the gold nanorods (GNRs) is characterized by two peaks, the larger/dominant peak corresponding to the longitudinal surface plasmon resonance, and the shorter peak obtained at a lower wavelength corresponding to the axial surface plasmon resonance
Summary
Immunoassays have been used in research and clinical settings over the past five decades to quantify biomolecules of various sizes, chemical and physical properties [1]. Noble metal nanostructures are of great interest for optical imaging due to their remarkable capacity to absorb and scatter light at visible and near-infrared (NIR) regions, due to the conversion of photon energy to surface plasmon resonance [5,6]. These optical properties depend on nanoparticles size, shape, and dielectric environment, enabling their application as novel imaging and sensing probes [7]. OCT for gold nanorod (GNR) detection relies on the local surface plasmon resonance effect caused by the incident OCT light [12,13]. Glut-1 overexpression is linked to increased proliferative activity, energy requirements, aggressive behavior, and poor prognosis [25,26]
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