A quantitative diffraction-based sandwich immunoassay

Goh, Jane Betty; Tam, Pui Lam; Loo, Richard W.; Goh, M. Cynthia

doi:10.1016/s0003-2697(02)00634-6

Cited by 64 publications

(52 citation statements)

References 11 publications

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“…The dotLab system uses a plastic consumable, the dotLab Sensor, with an integrated prism situated below the flow channel so that the light source interrogates the diffraction grating without passing through the bulk solution. Previous studies suggest that this total internal reflection scheme allows for 95% of the laser intensity to be measured, whereas in a nontotal internal reflection set-up only 5% is measured (4 ). Moreover, with this configuration, our system monitors biomolecule binding in real time and in complex media.…”

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confidence: 99%

“…Infection with HPV is ubiquitous and is often resolved by the host. High-risk HPV infections leading to cervical cancer require the production of both HPV E6 and E7 oncoproteins (1)(2)(3)(4)(5). Thus, an assay capable of detecting high-risk HPV E6 from cervical swab samples may have a high positive predictive value and may help to accurately identify women at increased risk of progression to cancer.…”

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confidence: 99%

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Diffractive Optics Technology: A Novel Detection Technology for Immunoassays

Borisenko

Tam

et al. 2006

Clinical Chemistry

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There is an increasing need for high-sensitivity immunoassays that can be used in point-of-care patient testing of complex media. For example, analytes such as the natriuretic peptides and recently discovered sepsis markers are found in blood in very low picomolar concentrations (1, 2 ). Although advances have been made in the use of fluorescent, chemiluminescent, and other labels to measure markers at lower detection limits, background interference from biological samples and detection instrumentation remains problematic. Optical biosensors offer the promise of label-free real-time measurements, but their application to quantification of analytes in complex media is impaired by higher detection limits and is susceptible to changes in refractive indices or nonspecific surface binding. Moreover, the costliness of these devices has largely prohibited bedside implementation. In this report, we detail the use of a novel diffractive optics technology (dot™) that takes advantage of the inherent properties of diffractive optics to deliver a cost-effective, portable, robust, optical biosensor that detects analytes at picomolar concentrations in complex media.In the dotLab TM System, coherent light striking a nonrandom pattern of capture molecules on the dotLab Sensor creates constructive and destructive interferences that produce a well-defined diffraction image. As molecules bind to the capture molecules, the height of the diffraction pattern is increased, which in turn increases the diffraction efficiency and the diffractive order intensity. A photodiode monitors the intensity of the diffractive order, which is correlated to analyte concentrations. Because diffraction is inherently self-referencing, the transduction of binding events is dependent on the initial pattern, and an increase in diffractive order intensity will occur only if molecules bind exclusively to the patterned capture reagents. Therefore, nonspecific binding to both the patterned and nonpatterned regions will not affect the signal, a characteristic that offers an important advantage over other optical biosensor systems in which any surfacebinding event will cause an increase in signal.Previous diffraction-based immunosensors have used silicon wafer chips that were in contact with analytecontaining solutions and required washing and drying before analysis by a simple reader (3 ). The dotLab system uses a plastic consumable, the dotLab Sensor, with an integrated prism situated below the flow channel so that the light source interrogates the diffraction grating without passing through the bulk solution. Previous studies suggest that this total internal reflection scheme allows for 95% of the laser intensity to be measured, whereas in a nontotal internal reflection set-up only 5% is measured (4 ). Moreover, with this configuration, our system monitors biomolecule binding in real time and in complex media.We tested the beta prototype of the dotLab instrument, which incorporates the core dot technology in an integrated package intended for in-house and con...

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Diffractive Optics Technology: A Novel Detection Technology for Immunoassays

Borisenko

Tam

et al. 2006

Clinical Chemistry

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“…Shortly thereafter, Bailey et al [10] showed that gold-labeled oligonucleotides could be used to detect DNA hybridization in a diVraction sensing experiment. In our original paper, we speculated that using even larger labels would further enhance sensitivity [9]. In the current study, rather than simply using a larger label, we showed through the use of secondary enzymatic ampliWcation with a precipitating substrate that we can improve the limit of detection by 4000-fold in a diVraction-based sandwich immunoassay.…”

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confidence: 67%

“…The direct and gold-labeled experiments were conducted as previously described [9]. For the enzyme ampliWcation experiments the following procedure was used.…”

Section: Methodsmentioning

confidence: 99%

“…In these past examples, the binding interactions were measured directly without using any label for either the analyte or the capture molecule. Recently, we showed that the limit of detection in a diVraction-based sensing experiment can be reduced more than 40-fold by using a gold-conjugated secondary antibody in a diVraction-based sandwich immunoassay [9]. Shortly thereafter, Bailey et al [10] showed that gold-labeled oligonucleotides could be used to detect DNA hybridization in a diVraction sensing experiment.…”

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An enzyme-amplified diffraction-based immunoassay

Loo

Tam

Goh

et al. 2005

Analytical Biochemistry

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Sensing Diffraction Gratings of Antigen‐Responsive Hydrogel for Human Immunoglobulin‐G Detection

Yang

Wang

2010

Macromol. Rapid Commun.

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Sensing diffraction gratings of antigen-responsive hydrogel were developed for human immunoglobulin-G (H-IgG) detection. The IgG-sensing gratings were fabricated by soft lithographic duplication of photoinduced surface relief gratings on azo polymer films to the hydrogel surfaces. The quantitative detection of H-IgG was achieved by detecting modulation of the diffraction efficiency when the gratings were exposed to antigen solutions. The gratings showed high sensitivity and specificity for the H-IgG detection. The detection could be performed at a reasonably fast rate with good reusability. In the process, no fluorophore labeling or additional signal enhancement was required.

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A quantitative diffraction-based sandwich immunoassay

Cited by 64 publications

References 11 publications

Diffractive Optics Technology: A Novel Detection Technology for Immunoassays

Diffractive Optics Technology: A Novel Detection Technology for Immunoassays

An enzyme-amplified diffraction-based immunoassay

Sensing Diffraction Gratings of Antigen‐Responsive Hydrogel for Human Immunoglobulin‐G Detection

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