3,628 research outputs found
Digital detection of biomarkers for low-cost, high-sensitivity diagnostics
We have demonstrated Interferometric Reflectance Imaging Sensor (IRIS) with the ability to detect single nanoscale particles. By extending single-particle IRIS to in-liquid dynamic imaging, we demonstrated real-time digital detection of individual viral pathogens as well as single molecules labeled with Au nanoparticles. With this technique we demonstrate real-time simultaneous detection of multiple targets in a single sample, as well as quantitative dynamic detection of individual biomolecular interactions for reaction kinetics measurements. This approach promises to simplify and reduce the cost of rapid diagnostics.Accepted manuscrip
Effects of initial compression stress on wave propagation in carbon nanotubes
An analytical method to investigate wave propagation in single- and double-
walled carbon nanotubes under initial compression stress is presented. The
nanotube structures are treated within the multilayer thin shell approximation
with the elastic properties taken to be those of the graphene sheet. The
governing equations are derived based on Flugge equations of motion. Frequency
equations of wave propagation in single and double wall carbon nanotubes are
described through the effects of initial compression stress and van der Waals
force. To show the effects of Initial compression stress on the wave
propagation in nanotubes, the symmetrical mode can be analyzed based on the
present elastic continuum model. It is shown that the wave speed are sensitive
to the compression stress especially for the lower frequencies.Comment: 12 pages, 4 figure
Beating the reaction limits of biosensor sensitivity with dynamic tracking of single binding events
The clinical need for ultrasensitive molecular analysis has motivated the development of several endpoint-assay technologies capable of single-molecule readout. These endpoint assays are now primarily limited by the affinity and specificity of the molecular-recognition agents for the analyte of interest. In contrast, a kinetic assay with single-molecule readout could distinguish between low-abundance, high-affinity (specific analyte) and high-abundance, low-affinity (nonspecific background) binding by measuring the duration of individual binding events at equilibrium. Here, we describe such a kinetic assay, in which individual binding events are detected and monitored during sample incubation. This method uses plasmonic gold nanorods and interferometric reflectance imaging to detect thousands of individual binding events across a multiplex solid-phase sensor with a large area approaching that of leading bead-based endpoint-assay technologies. A dynamic tracking procedure is used to measure the duration of each event. From this, the total rates of binding and debinding as well as the distribution of binding-event durations are determined. We observe a limit of detection of 19 fM for a proof-of-concept synthetic DNA analyte in a 12-plex assay format.First author draf
Nanoparticle Classification in Wide-field Interferometric Microscopy by Supervised Learning from Model
Interference enhanced wide-field nanoparticle imaging is a highly sensitive
technique that has found numerous applications in labeled and label-free
sub-diffraction-limited pathogen detection. It also provides unique
opportunities for nanoparticle classification upon detection. More specif-
ically, the nanoparticle defocus images result in a particle-specific response
that can be of great utility for nanoparticle classification, particularly
based on type and size. In this work, we com- bine a model based supervised
learning algorithm with a wide-field common-path interferometric microscopy
method to achieve accurate nanoparticle classification. We verify our
classification schemes experimentally by using gold and polystyrene
nanospheres.Comment: 5 pages, 2 figure
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