Basic Information

Abstract Number: 900 - 3
Author Name: David R Walt - Tufts University
Session Title: Pittsburgh Analytical Chemistry Award
Event Type: Awards
Event Title: High Sensitivity Analysis Using Single Molecule Arrays

Presider Name:Jane Chan
Affiliation:Bechtel Bettis, Inc.

Date: Tuesday, March 19, 2013
Start Time: 08:10 AM (Slot #3)
Location: 114

Abstract Content

Digital measurements, based on counting single molecules, provide high sensitivity because the signals where a molecule is present can be readily distinguished from the signals where a molecule is absent. We employ microspheres covered with capture antibodies or DNA capture probes. Single protein or DNA molecules are captured on an excess number of microspheres such that there is either one or zero molecules per microsphere. After capture of the protein or DNA molecule, a detection antibody or DNA probe forms a sandwich complex with the bound analyte molecule. An enzyme label is then attached to each detection entity. Individual beads are then sequestered in microwells, and the microwells are sealed in the presence of a fluorogenic substrate solution. If an enzyme is present on the bead, it catalyzes the formation of a large number of fluorescent molecules that can be readily detected within the femtoliter volume of the sealed microwell. The number of fluorescent microwells provides a digital readout of the number of molecules in the sample solution. This method has been used to detect both nucleic acids and proteins at very low concentrations. Proteins can be detected at concentrations more than a thousand times lower than ELISAs, enabling unique diagnostic capabilities.