Force Discrimination for Enhanced Biosensor Specificity of Micro-Retroreflector Assays

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In nearly all diagnostic/bioanalytical methods other than mass spectrometry, what is actually detected is a label of some sort, and the sensitivity and simplicity of detection of this label limits assay performance. Non-specific interactions between the label and assay surfaces can also hinder results and lead to false-positives. This work introduces magnetic particles as labels in assays based on microfabricated retroreflectors. The magnetic properties of the particles can also be used to discriminate against non-specific interactions. The detection surface is composed of arrays of microfabricated retroreflector tetrads. Retroreflectors return light directly to its source and are readily detectable with inexpensive optics. A detector tetrad is composed of four retroreflectors; one assay retroreflector decorated with antibodies is surrounded by three always-on reference reflectors without antibodies. The assay can easily detect the presence of a single particle bound to the surface. One or two Rickettsia conorii bacteria have been shown to hold down a 1.0 µm magnetic particle coated with rabbit polyclonal anti-Rickettsia antibodies, supporting the possibility of detecting a single target pathogen with this assay.

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Journal: TechConnect Briefs
Volume: 2, Nanotechnology 2009: Life Sciences, Medicine, Diagnostics, Bio Materials and Composites
Published: May 3, 2009
Pages: 185 - 188
Industry sectors: Medical & Biotech | Sensors, MEMS, Electronics
Topics: Chemical, Physical & Bio-Sensors, Diagnostics & Bioimaging
ISBN: 978-1-4398-1783-4