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Article ; Online: Improving the Sensitivity of Fluorescence-Based Immunoassays by Photobleaching the Autofluorescence of Magnetic Beads.

Roth, Shira / Hadass, Orr / Cohen, Meir / Verbarg, Jasenka / Wilsey, Jennifer / Danielli, Amos

Small (Weinheim an der Bergstrasse, Germany)

2018 Volume 15, Issue 3, Page(s) e1803751

Abstract: In fluorescence-based assays, usually a target molecule is captured using a probe conjugated to a capture surface, and then detected using a second fluorescently labeled probe. One of the most common capture surfaces is a magnetic bead. However, magnetic ...

Abstract	In fluorescence-based assays, usually a target molecule is captured using a probe conjugated to a capture surface, and then detected using a second fluorescently labeled probe. One of the most common capture surfaces is a magnetic bead. However, magnetic beads exhibit strong autofluorescence, which often overlaps with the emission of the reporter fluorescent dyes and limits the analytical performance of the assay. Here, several widely used magnetic beads are photobleached and their autofluorescence is reduced to 1% of the initial value. Their autofluorescence properties, including their photobleaching decay rates and autofluorescence spectra pre- and post-photobleaching, and the stability of the photobleaching over a period of two months are analyzed. The photobleached beads are stable over time and their surface functionality is retained. In a high-sensitivity LX-200 system using photobleached magnetic beads, human interleukin-8 is detected with a threefold improvement in detection limit and signal-to-noise ratio over results achievable with nonbleached beads. Since many contemporary immunoassays rely on magnetic beads as capture surfaces, prebleaching the beads may significantly improve the analytical performance of these assays. Moreover, nonmagnetic beads with low autofluorescence are also successfully photobleached, suggesting that photobleaching can be applied to various capture surfaces used in fluorescence-based assays.
MeSH term(s)	Biosensing Techniques/instrumentation ; Biosensing Techniques/methods ; Fluorescence ; Fluorescent Antibody Technique/instrumentation ; Fluorescent Antibody Technique/methods ; Fluorescent Antibody Technique/standards ; Fluorescent Dyes/chemistry ; Humans ; Immunoassay/instrumentation ; Immunoassay/methods ; Immunomagnetic Separation/instrumentation ; Immunomagnetic Separation/methods ; Interleukin-8/analysis ; Interleukin-8/isolation & purification ; Limit of Detection ; Magnetic Fields ; Magnetics/instrumentation ; Magnetite Nanoparticles/chemistry ; Microfluidic Analytical Techniques/instrumentation ; Microfluidic Analytical Techniques/methods ; Photobleaching ; Sensitivity and Specificity ; Signal-To-Noise Ratio
Chemical Substances	CXCL8 protein, human ; Fluorescent Dyes ; Interleukin-8 ; Magnetite Nanoparticles
Language	English
Publishing date	2018-11-08
Publishing country	Germany
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	1613-6829
ISSN (online)	1613-6829
DOI	10.1002/smll.201803751
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Square wave voltammetry of TNT at gold electrodes modified with self-assembled monolayers containing aromatic structures.

Trammell, Scott A / Zabetakis, Dan / Moore, Martin / Verbarg, Jasenka / Stenger, David A

PloS one

2014 Volume 9, Issue 12, Page(s) e115966

Abstract: Square wave voltammetry for the reduction of 2,4,6-trinitrotoluene (TNT) was measured in 100 mM potassium phosphate buffer (pH 8) at gold electrodes modified with self-assembled monolayers (SAMs) containing either an alkane thiol or aromatic ring thiol ... ...

Abstract	Square wave voltammetry for the reduction of 2,4,6-trinitrotoluene (TNT) was measured in 100 mM potassium phosphate buffer (pH 8) at gold electrodes modified with self-assembled monolayers (SAMs) containing either an alkane thiol or aromatic ring thiol structures. At 15 Hz, the electrochemical sensitivity (µA/ppm) was similar for all SAMs tested. However, at 60 Hz, the SAMs containing aromatic structures had a greater sensitivity than the alkane thiol SAM. In fact, the alkane thiol SAM had a decrease in sensitivity at the higher frequency. When comparing the electrochemical response between simulations and experimental data, a general trend was observed in which most of the SAMs had similar heterogeneous rate constants within experimental error for the reduction of TNT. This most likely describes a rate limiting step for the reduction of TNT. However, in the case of the alkane SAM at higher frequency, the decrease in sensitivity suggests that the rate limiting step in this case may be electron tunneling through the SAM. Our results show that SAMs containing aromatic rings increased the sensitivity for the reduction of TNT when higher frequencies were employed and at the same time suppressed the electrochemical reduction of dissolved oxygen.
MeSH term(s)	Electrochemical Techniques ; Electrodes ; Gold/chemistry ; Surface Properties ; Trinitrotoluene/chemistry
Chemical Substances	Trinitrotoluene (118-96-7) ; Gold (7440-57-5)
Language	English
Publishing date	2014
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	1932-6203
ISSN (online)	1932-6203
DOI	10.1371/journal.pone.0115966
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Reconfigurable acquisition system with integrated optics for a portable flow cytometer.

Kirleis, Matthew A / Mathews, Scott A / Verbarg, Jasenka / Erickson, Jeffrey S / Piqué, Alberto

The Review of scientific instruments

2013 Volume 84, Issue 11, Page(s) 115109

Abstract: Portable and inexpensive scientific instruments that are capable of performing point of care diagnostics are needed for applications such as disease detection and diagnosis in resource-poor settings, for water quality and food supply monitoring, and for ... ...

Abstract	Portable and inexpensive scientific instruments that are capable of performing point of care diagnostics are needed for applications such as disease detection and diagnosis in resource-poor settings, for water quality and food supply monitoring, and for biosurveillance activities in autonomous vehicles. In this paper, we describe the development of a compact flow cytometer built from three separate, customizable, and interchangeable modules. The instrument as configured in this work is being developed specifically for the detection of selected Centers for Disease Control (CDC) category B biothreat agents through a bead-based assay: E. coli O157:H7, Salmonella, Listeria, and Shigella. It has two-color excitation, three-color fluorescence and light scattering detection, embedded electronics, and capillary based flow. However, these attributes can be easily modified for other applications such as cluster of differentiation 4 (CD4) counting. Proof of concept is demonstrated through a 6-plex bead assay with the results compared to a commercially available benchtop-sized instrument.
MeSH term(s)	Animals ; Bacteria/cytology ; Electrical Equipment and Supplies ; Flow Cytometry/instrumentation ; Optical Devices ; Software ; Systems Integration
Language	English
Publishing date	2013-11
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	209865-9
ISSN	1089-7623 ; 0034-6748
ISSN (online)	1089-7623
ISSN	0034-6748
DOI	10.1063/1.4831835
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Article ; Online: Square wave voltammetry of TNT at gold electrodes modified with self-assembled monolayers containing aromatic structures.

Scott A Trammell / Dan Zabetakis / Martin Moore / Jasenka Verbarg / David A Stenger

PLoS ONE, Vol 9, Iss 12, p e

2014 Volume 115966

Abstract	Square wave voltammetry for the reduction of 2,4,6-trinitrotoluene (TNT) was measured in 100 mM potassium phosphate buffer (pH 8) at gold electrodes modified with self-assembled monolayers (SAMs) containing either an alkane thiol or aromatic ring thiol structures. At 15 Hz, the electrochemical sensitivity (µA/ppm) was similar for all SAMs tested. However, at 60 Hz, the SAMs containing aromatic structures had a greater sensitivity than the alkane thiol SAM. In fact, the alkane thiol SAM had a decrease in sensitivity at the higher frequency. When comparing the electrochemical response between simulations and experimental data, a general trend was observed in which most of the SAMs had similar heterogeneous rate constants within experimental error for the reduction of TNT. This most likely describes a rate limiting step for the reduction of TNT. However, in the case of the alkane SAM at higher frequency, the decrease in sensitivity suggests that the rate limiting step in this case may be electron tunneling through the SAM. Our results show that SAMs containing aromatic rings increased the sensitivity for the reduction of TNT when higher frequencies were employed and at the same time suppressed the electrochemical reduction of dissolved oxygen.
Keywords	Medicine ; R ; Science ; Q
Subject code	600
Language	English
Publishing date	2014-01-01T00:00:00Z
Publisher	Public Library of Science (PLoS)
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Prospective, multicenter study of P4HB (Phasix™) mesh for hernia repair in cohort at risk for complications: 3-Year follow-up.

Annals of medicine and surgery (2012)

2020 Volume 61, Page(s) 1–7

Abstract: Background: This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in ... ...

Abstract	Background: This study represents a prospective, multicenter, open-label study to assess the safety, performance, and outcomes of poly-4-hydroxybutyrate (P4HB, Phasix™) mesh for primary ventral, primary incisional, or multiply-recurrent hernia in subjects at risk for complications. This study reports 3-year clinical outcomes. Materials and methods: P4HB mesh was implanted in 121 patients via retrorectus or onlay technique. Physical exam and/or quality of life surveys were completed at 1, 3, 6,12, 18, 24, and 36 months, with 5-year (60-month) follow-up ongoing. Results: A total of n = 121 patients were implanted with P4HB mesh (n = 75 (62%) female) with a mean age of 54.7 ± 12.0 years and mean BMI of 32.2 ± 4.5 kg/m Conclusions: Long-term outcomes following ventral hernia repair with P4HB mesh demonstrate low recurrence rates at 3-year (36-month) postoperative time frame with no patients developing late mesh complications or requiring mesh removal. 5-year (60-month) follow-up is ongoing.
Language	English
Publishing date	2020-12-15
Publishing country	England
Document type	Journal Article
ZDB-ID	2745440-X
ISSN	2049-0801
ISSN	2049-0801
DOI	10.1016/j.amsu.2020.12.002
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Spinning magnetic trap for automated microfluidic assay systems.

Verbarg, Jasenka / Kamgar-Parsi, Kian / Shields, Adam R / Howell, Peter B / Ligler, Frances S

Lab on a chip

2012 Volume 12, Issue 10, Page(s) 1793–1799

Abstract: While sophisticated analyses have been performed using lab-on-chip devices, in most cases the sample preparation is still performed off chip. The global need for easy-to-use, disposable testing devices necessitates that sample processing is automated and ...

Abstract	While sophisticated analyses have been performed using lab-on-chip devices, in most cases the sample preparation is still performed off chip. The global need for easy-to-use, disposable testing devices necessitates that sample processing is automated and that transport complexity between the processing and analytical components is minimal. We describe a complete sample manipulation unit for performing automated target capture, efficient mixing with reagents, and controlled target release in a microfluidic channel, using an array of spinning magnets. The "MagTrap" device consists of 6 pairs of magnets in a rotating wheel, situated immediately beneath the microchannel. Rotation of the wheel in the direction opposite to the continuous flow entraps and concentrates the bead-target complexes and separates them from the original sample matrix. As the wheel rotates and the active pair of magnets moves away from the microchannel, the beads are released and briefly flow downstream before being trapped and pulled upstream by the next pair of magnets. This dynamic and continuous movement of the beads ensures that the full surface area of each bead is exposed to reagents and prevents aggregation. The release of the target-bead complexes for further analysis is facilitated by reversing the rotational direction of the wheel to sweep the beads downstream. Sample processing with the MagTrap was demonstrated for the detection of E. coli in a range of concentrations (1 × 10(3), 1 × 10(4) and 1 × 10(6) cells ml(-1)). Results show that sample processing with the MagTrap outperformed the standard manual protocols, improving the detection capability while simultaneously reducing the processing time.
MeSH term(s)	Equipment Design ; Escherichia coli/isolation & purification ; Fluorescent Dyes/chemistry ; Immunoassay/methods ; Immunoglobulin G/chemistry ; Immunomagnetic Separation/methods ; Magnets ; Microfluidic Analytical Techniques/instrumentation ; Microfluidic Analytical Techniques/methods ; Microspheres ; Models, Theoretical
Chemical Substances	Fluorescent Dyes ; Immunoglobulin G
Language	English
Publishing date	2012-02-17
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2056646-3
ISSN	1473-0189 ; 1473-0197
ISSN (online)	1473-0189
ISSN	1473-0197
DOI	10.1039/c2lc21189k
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Article ; Online: Catch and release: integrated system for multiplexed detection of bacteria.

Verbarg, Jasenka / Plath, William D / Shriver-Lake, Lisa C / Howell, Peter B / Erickson, Jeffrey S / Golden, Joel P / Ligler, Frances S

Analytical chemistry

2013 Volume 85, Issue 10, Page(s) 4944–4950

Abstract: An integrated system with automated immunomagnetic separation and processing of fluidic samples was demonstrated for multiplexed optical detection of bacterial targets. Mixtures of target-specific magnetic bead sets were processed in the NRL MagTrap with ...

Abstract	An integrated system with automated immunomagnetic separation and processing of fluidic samples was demonstrated for multiplexed optical detection of bacterial targets. Mixtures of target-specific magnetic bead sets were processed in the NRL MagTrap with the aid of rotating magnet arrays that entrapped and moved the beads within the channel during reagent processing. Processing was performed in buffer and human serum matrixes with 10-fold dilutions in the range of 10(2)-10(6) cells/mL of target bacteria. Reversal of magnets' rotation post-processing released the beads back into the flow and moved them into the microflow cytometer for optical interrogation. Identification of the beads and the detection of PE fluorescence were performed simultaneously for multiplexed detection. Multiplexing was performed with specifically targeted bead sets to detect E. coli 0157.H7, Salmonella Common Structural Antigen, Listeria sp., and Shigella sp., dose-response curves were obtained, and limits of detection were calculated for each target in the buffer and clinical matrix. Additional tests demonstrated the potential for using the MagTrap to concentrate target from larger volumes of sample prior to the addition of assay reagents.
MeSH term(s)	Bacteria/cytology ; Bacteria/isolation & purification ; Flow Cytometry/instrumentation ; Humans ; Immunomagnetic Separation/instrumentation ; Microarray Analysis/instrumentation ; Systems Integration
Language	English
Publishing date	2013-04-30
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	1508-8
ISSN	1520-6882 ; 0003-2700
ISSN (online)	1520-6882
ISSN	0003-2700
DOI	10.1021/ac303801v
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Article: Catch and Release: Integrated System for Multiplexed Detection of Bacteria

Verbarg, Jasenka / Erickson Jeffrey S / Golden Joel P / Howell Peter B / Ligler Frances S / Plath William D / Shriver-Lake Lisa C

Analytical chemistry. 2013 May 21, v. 85, no. 10

2013

Abstract	An integrated system with automated immunomagnetic separation and processing of fluidic samples was demonstrated for multiplexed optical detection of bacterial targets. Mixtures of target-specific magnetic bead sets were processed in the NRL MagTrap with the aid of rotating magnet arrays that entrapped and moved the beads within the channel during reagent processing. Processing was performed in buffer and human serum matrixes with 10-fold dilutions in the range of 10Â²â10â¶ cells/mL of target bacteria. Reversal of magnetsâ rotation post-processing released the beads back into the flow and moved them into the microflow cytometer for optical interrogation. Identification of the beads and the detection of PE fluorescence were performed simultaneously for multiplexed detection. Multiplexing was performed with specifically targeted bead sets to detect E. coli 0157.H7, Salmonella Common Structural Antigen, Listeria sp., and Shigella sp., doseâresponse curves were obtained, and limits of detection were calculated for each target in the buffer and clinical matrix. Additional tests demonstrated the potential for using the MagTrap to concentrate target from larger volumes of sample prior to the addition of assay reagents.
Keywords	antigens ; bacteria ; blood serum ; detection limit ; dose response ; Escherichia coli ; flow cytometry ; fluorescence ; humans ; immunomagnetic separation ; Listeria ; magnetic materials ; microbial detection ; Salmonella ; Shigella
Language	English
Dates of publication	2013-0521
Size	p. 4944-4950.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	1508-8
ISSN	1520-6882 ; 0003-2700
ISSN (online)	1520-6882
ISSN	0003-2700
DOI	10.1021%2Fac303801v
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Platinum-paper micromotors: an urchin-like nanohybrid catalyst for green monopropellant bubble-thrusters.

Claussen, Jonathan C / Daniele, Michael A / Geder, Jason / Pruessner, Marius / Mäkinen, Antti J / Melde, Brian J / Twigg, Mark / Verbarg, Jasenka M / Medintz, Igor L

ACS applied materials & interfaces

2014 Volume 6, Issue 20, Page(s) 17837–17847

Abstract: Platinum nanourchins supported on microfibrilated cellulose films (MFC) were fabricated and evaluated as hydrogen peroxide catalysts for small-scale, autonomous underwater vehicle (AUV) propulsion systems. The catalytic substrate was synthesized through ... ...

Abstract	Platinum nanourchins supported on microfibrilated cellulose films (MFC) were fabricated and evaluated as hydrogen peroxide catalysts for small-scale, autonomous underwater vehicle (AUV) propulsion systems. The catalytic substrate was synthesized through the reduction of chloroplatinic acid to create a thick film of Pt coral-like microstructures coated with Pt urchin-like nanowires that are arrayed in three dimensions on a two-dimensional MFC film. This organic/inorganic nanohybrid displays high catalytic ability (reduced activation energy of 50-63% over conventional materials and 13-19% for similar Pt nanoparticle-based structures) during hydrogen peroxide (H2O2) decomposition as well as sufficient propulsive thrust (>0.5 N) from reagent grade H2O2 (30% w/w) fuel within a small underwater reaction vessel. The results demonstrate that these layered nanohybrid sheets are robust and catalytically effective for green, H2O2-based micro-AUV propulsion where the storage and handling of highly explosive, toxic fuels are prohibitive due to size-requirements, cost limitations, and close person-to-machine contact.
Language	English
Publishing date	2014-10-22
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	1944-8252
ISSN (online)	1944-8252
DOI	10.1021/am504525e
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Facile Fabrication of Color Tunable Film and Fiber Nanocomposites via Thiol Click Chemistry

Boyd, Darryl A / Fontana Jake / Ligler Frances S / Naciri Jawad / Pacardo DennisB / Shields Adam R / Spillmann Christopher M / Verbarg Jasenka

Macromolecules. 2014 Jan. 28, v. 47, no. 2

2014

Abstract: A simple method for the fabrication of nanocomposite materials using thiol click chemistry is reported. The thiol click nanocomposite materials produced each displayed distinctive colors which were found to be dependent on both the ligand used to ... ...

Abstract	A simple method for the fabrication of nanocomposite materials using thiol click chemistry is reported. The thiol click nanocomposite materials produced each displayed distinctive colors which were found to be dependent on both the ligand used to functionalize the nanoparticles and the concentration of nanoparticles in the materials. Functionalized metallic nanospheres were combined with thiol click solutions forming viscous prepolymer solutions which were then polymerized upon UV light exposure. Films were fabricated in a custom-built film mold, and microfibers were fabricated using hydrodynamic focusing in a microfluidic channel. For this study, three unique thiolated ligandsincluding a newly synthesized ligandwere used to functionalize the nanospheres, thus assisting in the facile incorporation and stability of the nanospheres within the polymers. In comparison to a previously reported method in which thiol–ene nanocomposite films were fabricated, the method reported herein reduces the fabrication time from weeks to minutes. Furthermore, the method in this report is expanded to also include fabrication of thiol–yne nanocomposites. Young’s moduli and glass transition temperatures were determined for the materials, while UV–vis spectroscopy, transmission electron microscopy, and optical analyses were also performed in order to characterize the nanocomposites.
Keywords	chemistry ; color ; glass transition temperature ; hydrodynamics ; ligands ; modulus of elasticity ; nanocomposites ; nanoparticles ; nanospheres ; polymers ; thiols ; transmission electron microscopy ; ultraviolet radiation ; ultraviolet-visible spectroscopy
Language	English
Dates of publication	2014-0128
Size	p. 695-704.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	1491942-4
ISSN	1520-5835 ; 0024-9297
ISSN (online)	1520-5835
ISSN	0024-9297
DOI	10.1021%2Fma401636e
Database	NAL-Catalogue (AGRICOLA)

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