Droplet-based label-free detection system based on guided-mode resonance and electrowetting-on-dielectric for concentration measurement

This paper presents a compact spectral detection system for common fluorescent and colorimetric assays. This system includes a gradient grating period guided-mode resonance (GGP-GMR) filter and charge-coupled device. In its current form, the GGP-GMR filter, which has a size of less than 2.5 mm, can achieve a spectral detection range of 500–700 nm. Through the direct measurement of the fluorescence emission, the proposed system was demonstrated to detect both the peak wavelength and its corresponding intensity. One fluorescent assay (albumin) and two colorimetric assays (albumin and creatinine) were performed to demonstrate the practical application of the proposed system for quantifying common liquid assays. The results of our system exhibited suitable agreement with those of a commercial spectrometer in terms of the assay sensitivity and limit of detection (LOD). With the proposed system, the fluorescent albumin, colorimetric albumin, and colorimetric creatinine assays achieved LODs of 40.99 and 398 and 25.49 mg/L, respectively. For a wide selection of biomolecules in point-of-care applications, the spectral detection range achieved by the GGP-GMR filter can be further extended and the simple and compact optical path configuration can be integrated with a lab-on-a-chip system.

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Characterisation of Antibodies Against the Active Conformation of Gαi1 Using the SRU-BIND® Label-Free Detection System

Label-Free Technologies for Drug Discovery ◽

10.1002/9780470979129.ch17 ◽

2011 ◽

pp. 255-268

Author(s):

Melanie Leveridge ◽

Chun-Wa Chung ◽

Trevor Wattam

Keyword(s):

Detection System ◽

Active Conformation ◽

Label Free ◽

Label Free Detection

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Quantification of Neuropeptide Y with Picomolar Sensitivity Enabled by Guided-Mode Resonance Biosensors

Sensors ◽

10.3390/s20010126 ◽

2019 ◽

Vol 20 (1) ◽

pp. 126 ◽

Cited By ~ 3

Author(s):

Mohammad G. Abdallah ◽

Joseph A. Buchanan-Vega ◽

Kyu J. Lee ◽

Brett R. Wenner ◽

Jeffery W. Allen ◽

...

Keyword(s):

Neuropeptide Y ◽

Near Infrared ◽

Single Point ◽

High Sensitivity ◽

Quantitative Detection ◽

Label Free ◽

Sensor Surface ◽

Detection Range ◽

Guided Mode ◽

Guided Mode Resonance

Assessing levels of neuropeptide Y (NPY) in the human body has many medical uses. Accordingly, we report the quantitative detection of NPY biomarkers applying guided-mode resonance (GMR) biosensor methodology. The label-free sensor operates in the near-infrared spectral region exhibiting distinctive resonance signatures. The interaction of NPY with bioselective molecules on the sensor surface causes spectral shifts that directly identify the binding event without additional processing. In the experiments described here, NPY antibodies are attached to the sensor surface to impart specificity during operation. For the low concentrations of NPY of interest, we apply a sandwich NPY assay in which the sensor-linked anti-NPY molecule binds with NPY that subsequently binds with anti-NPY to close the sandwich. The sandwich assay achieves a detection limit of ~0.1 pM NPY. The photonic sensor methodology applied here enables expeditious high-throughput data acquisition with high sensitivity and specificity. The entire bioreaction is recorded as a function of time, in contrast to label-based methods with single-point detection. The convenient methodology and results reported are significant, as the NPY detection range of 0.1–10 pM demonstrated is useful in important medical circumstances.

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