SRU Biosystems

Gill, MA, United States

SRU Biosystems

Gill, MA, United States
SEARCH FILTERS
Time filter
Source Type

Ge C.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Jian X.,University of Illinois at Urbana - Champaign | Tan Y.,University of Illinois at Urbana - Champaign | Cunningham B.T.,University of Illinois at Urbana - Champaign
Optics Express | Year: 2010

The fabrication of visible wavelength vertically emitting distributed feedback (DFB) lasers with a subwavelength grating fabricated by a replica molding process and an active polymer layer printed by a horizontal dipping process is reported. The combined techniques enable the organic DFB laser to be uniformly fabricated over large surface areas upon a flexible plastic substrate, with an approach that is compatible with rollbased manufacturing. Using a fixed grating period and depth, DFB laser output wavelength is controlled over a 35 nm range through manipulation of the waveguide layer thickness, which is controlled by the speed of the horizontal dipping process. We also demonstrate that the active area of the structure may be photolithographically patterned to create dense arrays of discrete DFB lasers. © 2010 Optical Society of America.


Pokhriyal A.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Schulz S.,SRU Biosystems | Huang C.S.,University of Illinois at Urbana - Champaign | Cunningham B.T.,University of Illinois at Urbana - Champaign
Proceedings of IEEE Sensors | Year: 2010

A photonic crystal substrate exhibiting resonant enhancement of multiple fluorophores has been demonstrated. The device, fabricated uniformly from plastic materials over a ∼3×5 in2 surface area by nanoreplica molding, utilizes two distinct resonant modes to enhance electric field stimulation of a dye excited by a λ = 632.8 nm laser (cyanine-5) and a dye excited by a λ = 532 nm laser (cyanine-3). Resonant coupling of the laser excitation to the photonic crystal surface is obtained for each wavelength at a distinct incident angle. Compared to detection of a dye-labeled protein on an ordinary glass surface, the photonic crystal surface exhibited a 32x increase in fluorescent signal intensity for cyanine-5 conjugated strepavidin labeling, while a 25x increase was obtained for cyanine-3 conjugated streptavidin labeling. The photonic crystal is capable of amplifying the output of any fluorescent dye with an excitation wavelength in the 532 nm < λ < 633 nm range by selection of an appropriate incident angle. The device is designed for biological assays that utilize multiple fluorescent dyes within a single imaged area, such as gene expression microarrays. ©2010 IEEE.


Chaudhery V.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Huang C.S.,University of Illinois at Urbana - Champaign | George S.,University of Illinois at Urbana - Champaign | Cunningham B.T.,University of Illinois at Urbana - Champaign
Journal of Fluorescence | Year: 2011

The effect of resonant fluorescent enhancement from a photonic crystal surface upon the fluorescent photobleaching rate of Cyanine-5 labeled protein has been investigated. We show that the enhanced excitation mechanism for photonic crystal enhanced fluorescence, in which the device surface resonantly couples light from an excitation laser, accelerates photobleaching in proportion to the coupling efficiency of the laser to the photonic crystal. We also show that the enhanced extraction mechanism, in which the photonic crystal directs emitted photons approximately normal to the surface, does not play a role in the rate of photobleaching. We show that the photobleaching rate of dye molecules on the photonic crystal surface is accelerated by 30x compared to an ordinary glass surface, but substantial signal gain is still evident, even after extended periods of continuous illumination at the resonant condition. © 2010 Springer Science+Business Media, LLC.


Ge C.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Tan Y.,University of Illinois at Urbana - Champaign | Cunningham B.T.,University of Illinois at Urbana - Champaign
Optics Express | Year: 2011

A 22× reduction in laser pump threshold and a 23× enhancement in energy conversion have been demonstrated on a second order distributed feedback (DFB) laser using a resonant optical pumping (ROP) technique. The ROP scheme couples the excitation light into a distinct resonant mode of the laser cavity through the illuminating at a specific resonant incident angle. Coupling excitation light into the resonant mode results in an enhanced near-field, which significantly increases pump absorption by the active medium. Consequently, high power conversion efficiency between pumping light and lasing emission is achieved and laser pump threshold power is reduced. © 2011 Optical Society of America.


Tan Y.,University of Illinois at Urbana - Champaign | Ge C.,University of Illinois at Urbana - Champaign | Chu A.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | And 5 more authors.
IEEE Sensors Journal | Year: 2012

A process that combines polymer nanoreplica molding with horizontal dipping was used to fabricate large area (∼ 3 × 5 inch 2) distributed feedback laser biosensors (DFBLB) on flexible plastic substrates, which were subsequently incorporated into standard format 96-well microplates. A room temperature nanoreplica molding process was used to create subwavelength periodic grating structures, while a horizontal dipping process was used to apply a ∼ 300 nm, dye-doped polymer film. In this work, the DFBLB emission wavelength, used to characterize the device uniformity, demonstrated a coefficient of variation (CV) of 0.41% over the fabricated device area, representing a thickness standard deviation of only ∼ 35 nm for the horizontal dipping process. The fabricated sensors were further characterized for sensitivity uniformity by measuring the bulk refractive index of the media exposed to the sensor surface and by measuring adsorption of biomolecular layers. An assay for detection of the cytokine Tumor Necrosis Factor-alpha (TNF-α) was used to demonstrate the operation of the sensor in the context of label-free detection of a disease biomarker. The demonstrated capability represents an important step towards roll-to-roll manufacturability for this biosensor that simultaneously incorporates high sensitivity with excellent wavelength shift resolution, and adaptability to the microplate format that is ubiquitous in pharmaceutical research. © 2011 IEEE.


Chaudhery V.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Pokhriyal A.,University of Illinois at Urbana - Champaign | Schulz S.C.,SRU Biosystems | Cunningham B.T.,University of Illinois at Urbana - Champaign
IEEE Sensors Journal | Year: 2012

Photonic crystal enhanced fluorescence (PCEF) has been demonstrated as an effective means for amplifying the excitation provided to surface-bound fluorescent molecules while simultaneously enhancing fluorescence emission collection efficiency. Optimal coupling of a fluorophore-exciting light source to the PC occurs with the use of collimated plane waves, as utilized in a special-purpose fluorescence microscope specifically designed for coupling with PCEF surfaces. However, PCEF surfaces are also capable of coupling light from focused sources, such as those used in commercially available confocal laser scanners, but with a reduction in the obtainable enhancement factor. Using computer simulations and experimental measurements, we describe the interaction between the resonant bandwidth of a PCEF device surface and the optical design of the detection instrumentation that is used to provide fluorescence excitation. We show that highly collimated illumination is required for achieving the greatest PCEF enhancement factors, but at the expense of poor tolerance to nonuniformities in resonant wavelength across the PCEF surface. To overcome this limitation, we demonstrate a fixed wavelength/multiple incident angle scanning detection system that is capable of measuring every pixel in a PCEF fluorescence image under conditions that optimize resonant excitation efficiency. © 2011 IEEE.


Pokhriyal A.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Huang C.S.,University of Illinois at Urbana - Champaign | Schulz S.,SRU Biosystems | Cunningham B.T.,University of Illinois at Urbana - Champaign
Applied Physics Letters | Year: 2010

A photonic crystal substrate exhibiting resonant enhancement of multiple fluorophores has been demonstrated. The device, fabricated uniformly from plastic materials over a ∼3×5 in.2 surface area by nanoreplica molding, utilizes two distinct resonant modes to enhance electric field stimulation of a dye excited by a λ=632.8 nm laser (cyanine-5) and a dye excited by a λ=532 nm laser (cyanine-3). Resonant coupling of the laser excitation to the photonic crystal surface is obtained for each wavelength at a distinct incident angle. Compared to detection of a dye-labeled protein on an ordinary glass surface, the photonic crystal surface exhibited a 32× increase in fluorescent signal intensity for cyanine-5 conjugated streptavidin labeling, while a 25× increase was obtained for cyanine-3 conjugated streptavidin labeling. The photonic crystal is capable of amplifying the output of any fluorescent dye with an excitation wavelength in the 532 nm<λ<633 nm range by selection of an appropriate incident angle. The device is designed for biological assays that utilize multiple fluorescent dyes within a single imaged area, such as gene expression microarrays. © 2010 American Institute of Physics.


Chaudhery V.,University of Illinois at Urbana - Champaign | Lu M.,SRU Biosystems | Pokhriyal A.,University of Illinois at Urbana - Champaign | Schulz S.C.,SRU Biosystems | Cunningham B.T.,University of Illinois at Urbana - Champaign
Proceedings of the IEEE Conference on Nanotechnology | Year: 2011

Photonic crystal enhanced fluorescence (PCEF) has been demonstrated as an effective technique for amplifying the electromagnetic excitation and emission extraction from surface-bound fluorescent molecules. Although optimal coupling of a fluorophore-exciting light source to the PC occurs with the use of collimated plane waves, PCEF surfaces are also capable of coupling light from focused sources but with a reduction in the obtainable enhancement factor. Using computer simulations and experimental measurements, we describe the interaction between the resonant bandwidth of a PCEF device surface and the optical design of the detection instrumentation that is used to provide fluorescence excitation. We show that highly collimated illumination is required for achieving the greatest PCEF enhancement factors, but at the expense of poor tolerance to non-uniformities in resonant wavelength across the PCEF surface. To overcome this limitation, we demonstrate a fixed wavelength/multiple incident angle scanning detection system that is capable of measuring every pixel in a PCEF fluorescence image under conditions that optimize resonant excitation efficiency. © 2011 IEEE.


Bova M.P.,Elan Pharmaceuticals Inc. | Nguyen L.,Elan Pharmaceuticals Inc. | Wallace W.,Elan Pharmaceuticals Inc. | Garrido C.,Elan Pharmaceuticals Inc. | And 5 more authors.
Journal of Biomolecular Screening | Year: 2011

Traditionally, cell adhesion assays are performed in a manual workstation format using fluorescence-based readouts. Herein, the authors describe a label-free homogeneous assay to identify inhibitors of α4β7 integrin-mediated cell adhesion to its ligand, the mucosal addressin cell adhesion molecule (MadCAM), using the SRU BIND platform. The biosensor is optically based and comprises a subwavelength polymer grating. The assay was validated using standard compounds and an α4 blocking antibody and correlated very closely with the manual assay format when running a battery of test compounds of varying potencies. Cell adhesion was strictly dependent on the presence of divalent cations where Mg2+ was greater than Ca2+ at promoting cell adhesion. This homogeneous and label-free format exhibited low variability with a calculated Z′ of 0.6. In addition to measuring α4β7-mediated 8866 cell adhesion to MadCAM, the authors also demonstrate that this platform can measure adhesion of Jurkat cells expressing α4β1 to the vascular cell adhesion molecule. Thus, the SRU BIND platform is widely applicable to measuring cell adhesion events mediated by other integrins binding to their receptors in an assay format that is amenable to high-throughput screening. © 2011 Society for Laboratory Automation and Screening.


Zheng J.,Urbana University | Ge C.,Urbana University | Wagner C.J.,Urbana University | Lu M.,SRU Biosystems | And 3 more authors.
Optics Express | Year: 2012

Continuous tuning over a 1.6 THz region in the near-infrared (842.5-848.6 nm) has been achieved with a hybrid ring/external cavity laser having a single, optically-driven grating reflector and gain provided by an injection-seeded semiconductor amplifier. Driven at 532 nm and incorporating a photonic crystal with an azobenzene overlayer, the reflector has a peak reflectivity of ̃80% and tunes at the rate of 0.024 nm per mW of incident green power. In a departure from conventional ring or external cavity lasers, the frequency selectivity for this system is provided by the passband of the tunable photonic crystal reflector and line narrowing in a high gain amplifier. Sub - 0.1 nm linewidths and amplifier extraction efficiencies above 97% are observed with the reflector tuned to 842.5 nm. © 2012 Optical Society of America.

Loading SRU Biosystems collaborators
Loading SRU Biosystems collaborators