Label-Enhanced Surface Plasmon Resonance: A New Concept for Improved Performance in Optical Biosensor Analysis

Abstract

Surface plasmon resonance (SPR) is a well-established optical biosensor technology with many proven applications in the study of molecular interactions as well as in surface and material science. SPR is usually applied in the label-free mode which may be advantageous in cases where the presence of a label may potentially interfere with the studied interactions per se. However, the fundamental challenges of label-free SPR in terms of limited sensitivity and specificity are well known. Here we present a new concept called label-enhanced SPR, which is based on utilizing strongly absorbing dye molecules in combination with the evaluation of the full shape of the SPR curve, whereby the sensitivity as well as the specificity of SPR is significantly improved. The performance of the new label-enhanced SPR method was demonstrated by two simple model assays: a small molecule assay and a DNA hybridization assay. The small molecule assay was used to demonstrate the sensitivity enhancement of the method, and how competitive assays can be used for relative affinity determination. The DNA assay was used to demonstrate the selectivity of the assay, and the capabilities in eliminating noise from bulk liquid composition variations.

Identification of C3b-Binding Small-Molecule Complement Inhibitors Using Cheminformatics

“…Thus, to address this question, we developed a Label-Enhanced SPR (LE-SPR)-based competition assay. LE-SPR allows for real-time interaction monitoring of analytes which have previously been labeled with a dye that absorbs strongly and has an anomalously high refractive index at the SPR measurement wavelength (43, 44). In the case of a small molecule competition assay, LE-SPR holds two significant advantages over conventional SPR.…”

“…In the case of a small molecule competition assay, LE-SPR holds two significant advantages over conventional SPR. First, the LE-SPR signal is virtually independent of refractive index changes and thus the large bulk signal changes associated with small differences in DMSO concentrations between samples are eliminated (43, 44). Second, the presence of non-dye-labeled interacting analytes (such as our C3b-binding small molecules) do not contribute to the LE-SPR signal.…”

“…The arbitrary units of the epigram are enhanced resonance units (eRU), which are defined to correspond with approximately 1 RU (i.e. conventional SPR unit) of B23 labeling dye (43, 44). To obtain a K D , the resulting epigrams were then fit to a kinetic 1:1 Langmuir binding model using BiaEvaluation Software v3.0.…”

Effect of Diffusion Limitations on Multianalyte Determination from Biased Biosensor Response

“…While in most electrochemical systems, the electrode noise and signal trend elimination are practically impossible, a comprehensive study of the background current provides valuable insight for analytical system design [19–21]. …”

Visualization of submicron Si-rods by SPR-enhanced total internal reflection microscopy

“…Growing use of SPR has stimulated research focused on developing new SPR-related techniques: label-enhanced SPR, surface plasmon fluorescence spectroscopy, SPR microscopy (SPRM), also referred to as SPR imaging (SPRI), etc. [4][5][6][7][8][9][10][11][12]. SPRM was first to demonstrate by B. Rothenhäusler and W. Knoll for imaging of low-contrast samples with high lateral resolution [13].…”