32 research outputs found
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
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
Digital microarrays: single-molecule readout with interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the simultaneous quantification of tens of thousands of different biomolecular species. The mediocre sensitivity and limited dynamic range of traditional fluorescence microarrays compared to other detection techniques have been the technology’s Achilles’ heel and prevented their adoption for many biomedical and clinical diagnostic applications. Previous work to enhance the sensitivity of microarray readout to the single-molecule (“digital”) regime have either required signal amplifying chemistry or sacrificed throughput, nixing the platform’s primary advantages. Here, we report the development of a digital microarray which extends both the sensitivity and dynamic range of microarrays by about 3 orders of magnitude. This technique uses functionalized gold nanorods as single-molecule labels and an interferometric scanner which can rapidly enumerate individual nanorods by imaging them with a 10× objective lens. This approach does not require any chemical signal enhancement such as silver deposition and scans arrays with a throughput similar to commercial fluorescence scanners. By combining single-nanoparticle enumeration and ensemble measurements of spots when the particles are very dense, this system achieves a dynamic range of about 6 orders of magnitude directly from a single scan. As a proof-of-concept digital protein microarray assay, we demonstrated detection of hepatitis B virus surface antigen in buffer with a limit of detection of 3.2 pg/mL. More broadly, the technique’s simplicity and high-throughput nature make digital microarrays a flexible platform technology with a wide range of potential applications in biomedical research and clinical diagnostics.The authors wish to thank Oguzhan Avci and Jacob Trueb for thoughtful comments and suggestions regarding numerical optimization of the optical system. This work was funded in part by a research contract with ASELSAN, Inc. and the Wallace H. Coulter Foundation 2010 Coulter Translational Award. (ASELSAN, Inc.; Wallace H. Coulter Foundation Coulter Translational Award)Accepted manuscrip
A digital microarray using interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the
simultaneous quantification of tens of thousands of different biomolecular
species. The mediocre sensitivity and dynamic range of traditional fluorescence
microarrays compared to other techniques have been the technology's Achilles'
Heel, and prevented their adoption for many biomedical and clinical diagnostic
applications. Previous work to enhance the sensitivity of microarray readout to
the single-molecule ('digital') regime have either required signal amplifying
chemistry or sacrificed throughput, nixing the platform's primary advantages.
Here, we report the development of a digital microarray which extends both the
sensitivity and dynamic range of microarrays by about three orders of
magnitude. This technique uses functionalized gold nanorods as single-molecule
labels and an interferometric scanner which can rapidly enumerate individual
nanorods by imaging them with a 10x objective lens. This approach does not
require any chemical enhancement such as silver deposition, and scans arrays
with a throughput similar to commercial fluorescence devices. By combining
single-nanoparticle enumeration and ensemble measurements of spots when the
particles are very dense, this system achieves a dynamic range of about one
million directly from a single scan
A digital microarray using interferometric detection of plasmonic nanorod labels
DNA and protein microarrays are a high-throughput technology that allow the simultaneous quantification of tens of thousands of different biomolecular species. The mediocre sensitivity and dynamic range of traditional fluorescence microarrays compared to other techniques have been the technology's Achilles' Heel, and prevented their adoption for many biomedical and clinical diagnostic applications. Previous work to enhance the sensitivity of microarray readout to the single-molecule ('digital') regime have either required signal amplifying chemistry or sacrificed throughput, nixing the platform's primary advantages. Here, we report the development of a digital microarray which extends both the sensitivity and dynamic range of microarrays by about three orders of magnitude. This technique uses functionalized gold nanorods as single-molecule labels and an interferometric scanner which can rapidly enumerate individual nanorods by imaging them with a 10x objective lens. This approach does not require any chemical enhancement such as silver deposition, and scans arrays with a throughput similar to commercial fluorescence devices. By combining single-nanoparticle enumeration and ensemble measurements of spots when the particles are very dense, this system achieves a dynamic range of about one million directly from a single scan.First author draf
Polarization enhanced interferometric imaging
https://patentimages.storage.googleapis.com/1e/21/aa/dee6cbdf9a3542/US11428626.pdfPublished versio
A spatially uniform illumination source for widefield multi-spectral optical microscopy
Illumination uniformity is a critical parameter for excitation and data
extraction quality in widefield biological imaging applications. However,
typical imaging systems suffer from spatial and spectral non-uniformity due to
non-ideal optical elements, thus require complex solutions for illumination
corrections. We present Effective Uniform Color-Light Integration Device
(EUCLID), a simple and cost-effective illumination source for uniformity
corrections. EUCLID employs a diffuse-reflective, adjustable hollow cavity that
allows for uniform mixing of light from discrete light sources and modifies the
source field distribution to compensate for spatial non-uniformity introduced
by optical components in the imaging system. In this study, we characterize the
light coupling efficiency of the proposed design and compare the uniformity
performance with the conventional method. EUCLID demonstrates a remarkable
illumination improvement for multi-spectral imaging in both Nelsonian and
Koehler alignment with a maximum spatial deviation of ~1% across a wide
field-of-view
Interferometric detection and enumeration of viral particles using Si-based microfluidics
Single-particle interferometric reflectance imaging sensor enables optical visualization and characterization of individual nanoparticles without any labels. Using this technique, we have shown end-point and real-time detection of viral particles using laminate-based active and passive cartridge configurations. Here, we present a new concept for low-cost microfluidic integration of the sensor chips into compact cartridges through utilization of readily available silicon fabrication technologies. This new cartridge configuration will allow simultaneous detection of individual virus binding events on a 9-spot microarray, and provide the needed simplicity and robustness for routine real-time operation for discrete detection of viral particles in a multiplex format.This work was supported in part by a research contract with the ASELSAN Research Center, Ankara, Turkey, and in part by the European Union's Horizon 2020 FET Open program under Grant 766466-INDEX. (ASELSAN Research Center, Ankara, Turkey; 766466-INDEX - European Union's Horizon 2020 FET Open program)First author draf
Rapid mapping of digital integrated circuit logic gates via multi-spectral backside imaging
Modern semiconductor integrated circuits are increasingly fabricated at
untrusted third party foundries. There now exist myriad security threats of
malicious tampering at the hardware level and hence a clear and pressing need
for new tools that enable rapid, robust and low-cost validation of circuit
layouts. Optical backside imaging offers an attractive platform, but its
limited resolution and throughput cannot cope with the nanoscale sizes of
modern circuitry and the need to image over a large area. We propose and
demonstrate a multi-spectral imaging approach to overcome these obstacles by
identifying key circuit elements on the basis of their spectral response. This
obviates the need to directly image the nanoscale components that define them,
thereby relaxing resolution and spatial sampling requirements by 1 and 2 - 4
orders of magnitude respectively. Our results directly address critical
security needs in the integrated circuit supply chain and highlight the
potential of spectroscopic techniques to address fundamental resolution
obstacles caused by the need to image ever shrinking feature sizes in
semiconductor integrated circuits
Background-suppressed high-throughput mid-infrared photothermal microscopy via pupil engineering
First author draf