The recently developed bio-barcode assay for the detection of nucleic acid and protein targets without PCR has been shown to be extraordinarily sensitive, showing high sensitivity for both nucleic acid and protein targets. Two types of particles are used in the assay: (i) a magnetic microparticle with recognition elements for the target of interest; and (ii) a gold nanoparticle (Au-NP) with a second recognition agent (which can form a sandwich around the target in conjunction with the magnetic particle) and hundreds of thiolated single-strand oligonucleotide barcodes. After reaction with the analyte, a magnetic field is used to localize and collect the sandwich structures, and a DTT solution at elevated temperature is used to release the barcode strands. The barcode strands can be identified on a microarray via scanometric detection or in situ if the barcodes carry with them a detectable marker. The recent modification to the original bio-barcode assay method, utilizing DTT, has streamlined and simplified probe preparation and greatly enhanced the quantitative capabilities of the assay. Here we report the detailed methods for performing the ligand exchange bio-barcode assay for both nucleic acid and protein detection. In total, reagent synthesis, probe preparation and detection require 4 d.
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C.A.M. acknowledges HSARPA, NIH Pioneer Award, NIH NIAID, AFOSR, Doris Duke Charitable Foundation, NSF/NSEC and NCI. H.D.H: This work was performed while on appointment as a U.S. Department of Homeland Security (DHS) Fellow under the DHS Scholarship and Fellowship Program, a program administered by the Oak Ridge Institute for Science and Education (ORISE) for DHS through an interagency agreement with the U.S. Department of Energy (DOE). ORISE is managed by Oak Ridge Associated Universities under DOE contract number DE-AC05-06OR23100. All opinions expressed in this paper are the author's and do not necessarily reflect the policies and views of DHS, DOE or ORISE.
The authors declare no competing financial interests.
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Hill, H., Mirkin, C. The bio-barcode assay for the detection of protein and nucleic acid targets using DTT-induced ligand exchange. Nat Protoc 1, 324–336 (2006). https://doi.org/10.1038/nprot.2006.51
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