The BioCD is a spinning biochip that uses quadrature laser interferometry to detect captured protein on the disc surface. We describe the detection limits of protein binding on this optical biosensor. The fundamental ...
The BioCD is a spinning biochip that uses quadrature laser interferometry to detect captured protein on the disc surface. We describe the detection limits of protein binding on this optical biosensor. The fundamental metrology limit is 1 picometer for a single 100-micron diameter spot. Under assay conditions for prostate specific antigen, we can detect 25 pg/ml at 10 assays per disc.
We describe a set of methods to enable fully automated analysis of a novel label-free spinning-disc format microarray system. This microarray system operates in a dual-channel mode, simultaneously acquiring fluorescen...
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(纸本)9780819469847
We describe a set of methods to enable fully automated analysis of a novel label-free spinning-disc format microarray system. This microarray system operates in a dual-channel mode, simultaneously acquiring fluorescence as well as interferometric signals. The label-free interferometric component enables the design of robust gridding methods, which account for rotational effects difficult to estimate in traditional microarray image analysis. Printing of microarray features in a Cartesian grid is preferable for commercial systems because of the benefits of using existing DNA/protein printing technologies. The spinning disc operation of the microarray requires spatial transformation of Cartesian microarray features, from the reader/scanner frame of reference to the disc frame of reference. We describe a fast spatial transformation method with no measurable degradation in the quality of transformed data, for this purpose. The gridding method uses frequency-domain information to calculate grid spacing and grid rotation. An adaptive morphological segmentation method is used to segment microarray spots with variable sizes accurately. The entire process, from the generation of the raw data to the extraction of biologically relevant information, can be performed without any manual intervention, allowing for the deployment of high-throughput systems. These image analysis methods have enabled this microarray system to achieve superior sensitivity limits.
The BioCD is a spinning biochip that uses quadrature laser interferometry to detect captured protein on the disc surface. We describe the detection limits of protein binding on this optical biosensor. The fundamental ...
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Molecular interferometric imaging (MI2) is a common-path interferometric imaging technique for detecting protein binding to surfaces. The experimental metrology limit is 10 pm/pixel longitudinal resolution at 0.4-mu m...
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Molecular interferometric imaging (MI2) is a common-path interferometric imaging technique for detecting protein binding to surfaces. The experimental metrology limit is 10 pm/pixel longitudinal resolution at 0.4-mu m diffraction-limited lateral resolution, corresponding to 1.7 attogram of protein, which is only 8 antibody molecules per pixel, near to single-molecule detection. The scaling mass sensitivity at the metrology limit is 5 fg/mm. We demonstrate a protein microarray application in a 128-multiplex immunoassay. Assay applications include prostate specific antigen (PSA) at a detection limit of 60 pg/mL and the cytokine interieukin-5 (IL-5) at a detection limit of 50 pg/mL. Real-time binding assays using MI2 enable the study of reaction kinetics of antibodies exposed to antigen, and the binding of antibody Fc regions to protein G.
Background: We describe a direct-detection immunoassay that uses high-speed optical interferometry on a biological compact disc (BioCD). Methods: We fabricated phase-contrast BioCDs from 100-mm diameter 1.1-mm thick b...
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Background: We describe a direct-detection immunoassay that uses high-speed optical interferometry on a biological compact disc (BioCD). Methods: We fabricated phase-contrast BioCDs from 100-mm diameter 1.1-mm thick borosilicate glass disks coated with a 10-layer dielectric stack of Ta2O5/SiO2 that serves as a mirror with a center wavelength at 635 nm. The final layer is a lambda/4 layer of SiO2 onto which protein patterns are immobilized through several different chemical approaches. Protein on the disc is scanned by a focused laser spot as the disc spins. Interaction of the light with the protein provides both a phase-modulated signal and a local reference that are combined interferometrically to convert phase into intensity. A periodic pattern of protein on the spinning disc produces an intensity modulation as a function of time that is proportional to the surface-bound mass. The binding of antigen or antibodies is detected directly, without labels, by a change in the interferometric intensity. The technique is demonstrated with a reverse assay of immobilized rabbit and mouse IgG antigen incubated against anti-IgG antibody in a casein buffer. Results: The signal increased with increased concentration of analyte. The current embodiment detected a concentration of 100 ng/L when averaged over similar to 3000 100-micron-diameter protein spots. Conclusions: High-speed interferometric detection of label-free protein assays on a rapidly spinning BioCD is a high-sensitivity approach that is amenable to scaling up to many analytes. (c) 2006 American Association for Clinical Chemistry.
An alternative polymerase chain reactor (PCR) driven by electrokinetic flow was developed and tested. A single straight microchannel and a double-T intersection were designed for injection of DNA samples and thermal c...
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We have developed a high-speed interferometric optical assay called the BioCD. It is a spinning disk on which antibody molecules are printed that test for specific proteins in biological samples. The class of the BioC...
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