title: Tethered-bead, immune sandwich assay.
abstract: We describe a proof-of-principle, immune sandwich assay in which immune complexes link micron-size beads via DNA tethers to a sensor surface. The number of tethered beads, counted using low-magnification microscopy, provides a measure of the concentration of analyte. The prototype assay was sensitive to pM concentration of analyte. In theory, the assay could be sensitive to sub-fM analyte because beads attached via single-immune complexes and DNA strands form tethers, and tether formation in the absence of analyte is extremely rare. The limiting step at present is binding of streptavidin at the end of DNA to biotin on capture beads. Potential advantages of this type of sensor are discussed.
authors: Department of Mechanical and Aerospace Engineering, George Washington University, Washington, DC, USA; Laboratory of Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Building 50, Room 3316, 9000 Rockville Pike, Bethesda, MD 20902, USA. Electronic address: jesilver@gwu.edu.
authors: Jonathan
authors: J
authors: Silver
authors: Department of Electrical and Computer Engineering, George Washington University, Washington, DC, USA.
authors: Zhenyu
authors: Z
authors: Li
authors: Laboratory of Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Building 50, Room 3316, 9000 Rockville Pike, Bethesda, MD 20902, USA.
authors: Keir
authors: K
authors: Neuman
mesh_terms: D000936:Antigen-Antibody Complex / Q000737:chemistry / Q000302:isolation & purification*; D015374:Biosensing Techniques / Q000379:methods*; D001710:Biotin / Q000737:chemistry; D004247:DNA / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D007118:Immunoassay / Q000379:methods*; D019809:Streptavidin / Q000737:chemistry
chemical_list: D000936:Antigen-Antibody Complex; D001710:Biotin; D004247:DNA; D019809:Streptavidin
keywords: DNA tethers; Flow-mediated DNA extension; Opto- microfluidics; PSA immunoassay; Single-molecule immunoassay; Tethered-bead immunoassay