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Ning B, Chandra S, Rosen J, Multala E, Argrave M, Pierson L, Trinh I, Simone B, Escarra MD, Drury S, Zwezdaryk KJ, Norton E, Lyon CJ, Hu T. Evaluation of SARS-CoV-2-Specific T-Cell Activation with a Rapid On-Chip IGRA. ACS NANO 2023; 17:1206-1216. [PMID: 36595218 PMCID: PMC9878992 DOI: 10.1021/acsnano.2c09018] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
Interferon-gamma release assays (IGRAs) that measure pathogen-specific T-cell response rates can provide a more reliable estimate of protection than specific antibody levels but have limited potential for widespread use due to their workflow, personnel, and instrumentation demands. The major vaccines for SARS-CoV-2 have demonstrated substantial efficacy against all of its current variants, but approaches are needed to determine how these vaccines will perform against future variants, as they arise, to inform vaccine and public health policies. Here we describe a rapid, sensitive, nanolayer polylysine-integrated microfluidic chip IGRA read by a fluorescent microscope that has a 5 h sample-to-answer time and uses ∼25 μL of a fingerstick whole blood sample. Results from this assay correlated with those of a comparable clinical IGRA when used to evaluate the T-cell response to SARS-CoV-2 peptides in a population of vaccinated and/or infected individuals. Notably, this streamlined and inexpensive assay is suitable for high-throughput analyses in resource-limited settings for other infectious diseases.
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Affiliation(s)
- Bo Ning
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Sutapa Chandra
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Juniper Rosen
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Evan Multala
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Melvin Argrave
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Lane Pierson
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Ivy Trinh
- Department
of Microbiology & Immunology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Brittany Simone
- Department
of Physics and Engineering Physics, Tulane
University, New Orleans, Louisiana 70118, United States
| | - Matthew David Escarra
- Department
of Physics and Engineering Physics, Tulane
University, New Orleans, Louisiana 70118, United States
| | - Stacy Drury
- Department
of Psychiatry, Tulane University, New Orleans, Louisiana 70112, United States
- Tulane
Brain
Institute, Tulane University, New Orleans, Louisiana 70112, United States
| | - Kevin J. Zwezdaryk
- Department
of Microbiology & Immunology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Elizabeth Norton
- Department
of Microbiology & Immunology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Christopher J. Lyon
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
| | - Tony Hu
- Center
for Cellular and Molecular Diagnostics, Tulane University School of Medicine, New Orleans, Louisiana 70112, United States
- Department
of Biochemistry and Molecular Biology, Tulane
University School of Medicine, New Orleans, Louisiana 70112, United States
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2
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Boriskina SV, Tsurimaki Y. Sensitive singular-phase optical detection without phase measurements with Tamm plasmons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:224003. [PMID: 29667599 DOI: 10.1088/1361-648x/aabefb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Spectrally-tailored interactions of light with material interfaces offer many exciting applications in sensing, photo-detection, and optical energy conversion. In particular, complete suppression of light reflectance at select frequencies accompanied by sharp phase variations in the reflected signal forms the basis for the development of ultra-sensitive singular-phase optical detection schemes such as Brewster and surface plasmon interferometry. However, both the Brewster effect and surface-plasmon-mediated absorption on planar interfaces are limited to one polarization of the incident light and oblique excitation angles, and may have limited bandwidth dictated by the material dielectric index and plasma frequency. To alleviate these limitations, we design narrow-band super-absorbers composed of plasmonic materials embedded into dielectric photonic nanostructures with topologically-protected interfacial Tamm plasmon states. These structures have planar geometry and do not require nanopatterning to achieve perfect absorption of both polarizations of the incident light in a wide range of incident angles, including the normal incidence. Their absorption lines are tunable across a very broad spectral range via engineering of the photon bandstructure of the dielectric photonic nanostructures to achieve reversal of the geometrical phase across the interface with the plasmonic absorber. We outline the design strategy to achieve perfect absorptance in Tamm structures with dissipative losses via conjugate impedance matching. We further demonstrate via modeling how these structures can be engineered to support sharp asymmetric amplitude resonances, which can be used to improve the sensitivity of optical sensors in the amplitude-only detection scheme that does not require use of bulky and expensive ellipsometry equipment.
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Affiliation(s)
- Svetlana V Boriskina
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
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3
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Wilson KA, Finch CA, Anderson P, Vollmer F, Hickman JJ. Combining an optical resonance biosensor with enzyme activity kinetics to understand protein adsorption and denaturation. Biomaterials 2014; 38:86-96. [PMID: 25453976 DOI: 10.1016/j.biomaterials.2014.10.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/02/2014] [Indexed: 11/30/2022]
Abstract
Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was used to study a catalytic enzyme's adsorption processes on different silane modified glass substrates (plain glass control, DETA, 13 F, and SiPEG). The WGM sensor was able to obtain high resolution kinetic data of glucose oxidase (GO) adsorption with sensitivity of adsorption better than that possible with SPR. The kinetic data, in combination with a functional assay of the enzyme activity, was used to test hypotheses on adsorption mechanisms. By fitting numerical models to the WGM sensograms for protein adsorption, and by confirming numerical predictions of enzyme activity in a separate assay, we were able to identify mechanisms for GO adsorption on different alkylsilanes and infer information about the adsorption of protein on nanostructured surfaces.
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Affiliation(s)
- Kerry A Wilson
- Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, FL 32826, USA
| | - Craig A Finch
- Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, FL 32826, USA
| | - Phillip Anderson
- Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, FL 32826, USA
| | - Frank Vollmer
- The Wyss & Rowland Institutes, Harvard University, 100 Edwin H. Land Blvd, Cambridge, MA 02142, USA
| | - James J Hickman
- Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Orlando, FL 32826, USA.
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Baaske MD, Foreman MR, Vollmer F. Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform. NATURE NANOTECHNOLOGY 2014; 9:933-9. [PMID: 25173831 DOI: 10.1038/nnano.2014.180] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/29/2014] [Indexed: 05/23/2023]
Abstract
Biosensing relies on the detection of molecules and their specific interactions. It is therefore highly desirable to develop transducers exhibiting ultimate detection limits. Microcavities are an exemplary candidate technology for demonstrating such a capability in the optical domain and in a label-free fashion. Additional sensitivity gains, achievable by exploiting plasmon resonances, promise biosensing down to the single-molecule level. Here, we introduce a biosensing platform using optical microcavity-based sensors that exhibits single-molecule sensitivity and is selective to specific single binding events. Whispering gallery modes in glass microspheres are used to leverage plasmonic enhancements in gold nanorods for the specific detection of nucleic acid hybridization, down to single 8-mer oligonucleotides. Detection of single intercalating small molecules confirms the observation of single-molecule hybridization. Matched and mismatched strands are discriminated by their interaction kinetics. Our platform allows us to monitor specific molecular interactions transiently, hence mitigating the need for high binding affinity and avoiding permanent binding of target molecules to the receptors. Sensor lifetime is therefore increased, allowing interaction kinetics to be statistically analysed.
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Affiliation(s)
- Martin D Baaske
- Max Planck Institute for the Science of Light, Laboratory of Nanophotonics and Biosensing, Günther-Scharowsky-Straße 1, 91058 Erlangen, Germany
| | - Matthew R Foreman
- Max Planck Institute for the Science of Light, Laboratory of Nanophotonics and Biosensing, Günther-Scharowsky-Straße 1, 91058 Erlangen, Germany
| | - Frank Vollmer
- Max Planck Institute for the Science of Light, Laboratory of Nanophotonics and Biosensing, Günther-Scharowsky-Straße 1, 91058 Erlangen, Germany
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5
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Foreman MR, Jin WL, Vollmer F. Optimizing detection limits in whispering gallery mode biosensing. OPTICS EXPRESS 2014; 22:5491-5511. [PMID: 24663890 DOI: 10.1364/oe.22.005491] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A theoretical analysis of detection limits in swept-frequency whispering gallery mode biosensing modalities is presented based on application of the Cramér-Rao lower bound. Measurement acuity factors are derived assuming the presence of uncoloured and 1/ f Gaussian technical noise. Frequency fluctuations, for example arising from laser jitter or thermorefractive noise, are also considered. Determination of acuity factors for arbitrary coloured noise by means of the asymptotic Fisher information matrix is highlighted. Quantification and comparison of detection sensitivity for both resonance shift and broadening sensing modalities are subsequently given. Optimal cavity and coupling geometries are furthermore identified, whereby it is found that slightly under-coupled cavities outperform critically and over coupled ones.
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Baaske M, Vollmer F. Optical Resonator Biosensors: Molecular Diagnostic and Nanoparticle Detection on an Integrated Platform. Chemphyschem 2011; 13:427-36. [DOI: 10.1002/cphc.201100757] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/28/2011] [Indexed: 11/08/2022]
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Boriskina SV, Dal Negro L. Self-referenced photonic molecule bio(chemical)sensor. OPTICS LETTERS 2010; 35:2496-2498. [PMID: 20634875 DOI: 10.1364/ol.35.002496] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report a new type of optical biosensor capable of differentiating between bulk and surface perturbations of the ambient refractive index as well as between specific and nonspecific binding of molecules on the sensor surface. The proposed detection scheme is based on tracking the shifts of hybridized bonding and antibonding optical modes in coupled optical microcavities (photonic molecules). We demonstrate that by using two measurements of spectral shifts it is possible to discriminate between surface and volume index perturbation, to detect specific target molecules in a complex environment and to estimate the thickness of thin layers of adsorbed molecules.
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Affiliation(s)
- Svetlana V Boriskina
- Department of Electrical and Computer Engineering & Photonics Center, Boston University, Boston, Massachusetts 02215, USA.
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8
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Loock HP, Barnes JA, Gagliardi G, Li R, Oleschuk RD, Wächter H. Absorption detection using optical waveguide cavities. CAN J CHEM 2010. [DOI: 10.1139/v10-006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cavity ring-down spectroscopy is a spectroscopic method that uses a high quality optical cavity to amplify the optical loss due to the light absorption by a sample. In this presentation we highlight two applications of phase-shift cavity ring-down spectroscopy that are suited for absorption measurements in the condensed phase and make use of waveguide cavities. In the first application, a fiber loop is used as an optical cavity and the sample is introduced in a gap in the loop to allow absorption measurements of nanoliters of solution at the micromolar level. A second application involves silica microspheres as high finesse cavities. Information on the refractive index and absorption of a thin film of ethylene diamine on the surface of the microresonator is obtained simultaneously by the measurements of the wavelength shift of the cavity mode spectrum and the change in optical decay time, respectively.
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Affiliation(s)
- Hans-Peter Loock
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
| | - Jack A. Barnes
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
| | - Gianluca Gagliardi
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
| | - Runkai Li
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
| | - Richard D. Oleschuk
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
| | - Helen Wächter
- Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
- Consiglio Nazionale Delle Ricerche-Istituto Nazionale Di Ottica (INO), Via Campi Flegrei 34, Pozzuoli, Naples 80078, Italy
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9
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Zhu H, Suter JD, Fan X. Label-Free Optical Ring Resonator Bio/Chemical Sensors. SPRINGER SERIES ON CHEMICAL SENSORS AND BIOSENSORS 2010. [DOI: 10.1007/978-3-642-02827-4_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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11
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Fan X, White IM, Shopova SI, Zhu H, Suter JD, Sun Y. Sensitive optical biosensors for unlabeled targets: A review. Anal Chim Acta 2008; 620:8-26. [PMID: 18558119 PMCID: PMC10069299 DOI: 10.1016/j.aca.2008.05.022] [Citation(s) in RCA: 794] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Revised: 05/10/2008] [Accepted: 05/12/2008] [Indexed: 02/07/2023]
Abstract
This article reviews the recent progress in optical biosensors that use the label-free detection protocol, in which biomolecules are unlabeled or unmodified, and are detected in their natural forms. In particular, it will focus on the optical biosensors that utilize the refractive index change as the sensing transduction signal. Various optical label-free biosensing platforms will be introduced, including, but not limited to, surface plasmon resonance, interferometers, waveguides, fiber gratings, ring resonators, and photonic crystals. Emphasis will be given to the description of optical structures and their respective sensing mechanisms. Examples of detecting various types of biomolecules will be presented. Wherever possible, the sensing performance of each optical structure will be evaluated and compared in terms of sensitivity and detection limit.
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12
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Tang D, Yuan R, Chai Y. Quartz crystal microbalance immunoassay for carcinoma antigen 125 based on gold nanowire-functionalized biomimetic interface. Analyst 2008; 133:933-8. [DOI: 10.1039/b719389k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Noto M, Keng D, Teraoka I, Arnold S. Detection of protein orientation on the silica microsphere surface using transverse electric/transverse magnetic whispering gallery modes. Biophys J 2007; 92:4466-72. [PMID: 17400701 PMCID: PMC1877779 DOI: 10.1529/biophysj.106.103200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Accepted: 02/15/2007] [Indexed: 11/18/2022] Open
Abstract
The state of adsorbed protein molecules can be examined by comparing the shifts in a narrow line resonance wavelength of transverse electric (TE) and transverse magnetic (TM) whispering gallery modes (WGM) when the molecules adsorb onto a transparent microsphere that houses WGM. In adsorption of bovine serum albumin (BSA) onto an aminopropyl-modified silica microsphere, the TM/TE shift ratio indicated highly anisotropic polarizability of BSA in the direction normal to the surface, most likely ascribed to anchoring the heart-shaped protein molecule by one of its tips. The polarization-dependent resonance shift was confirmed when the surrounding refractive index was uniformly changed by adding salt, which would simulate adsorption of large objects.
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Affiliation(s)
- Mayumi Noto
- Microparticle Photophysics Laboratory, Polytechnic University, Brooklyn, New York 11201, USA
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White IM, Suter JD, Oveys H, Fan X, Smith TL, Zhang J, Koch BJ, Haase MA. Universal coupling between metal-clad waveguides and optical ring resonators. OPTICS EXPRESS 2007; 15:646-651. [PMID: 19532287 DOI: 10.1364/oe.15.000646] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate excitation of whispering gallery modes in optical ring resonators using a gold-clad pedestal planar waveguide structure. The gold-clad structure provides a strong evanescent field for light-coupling into the resonator while enabling low transmission loss throughout much of the visible and near-infrared region. This is advantageous compared to the previously demonstrated anti-resonant reflecting optical waveguide (ARROW) structure, which can only transmit a narrow wavelength band. We show that the height of the pedestal waveguide can be designed to optimize the coupling conditions for the ring resonator. This technology enhances the practicality of optical ring resonators for sensing devices, laser systems, and many other important applications.
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Topolancik J, Vollmer F. Photoinduced transformations in bacteriorhodopsin membrane monitored with optical microcavities. Biophys J 2007; 92:2223-9. [PMID: 17208972 PMCID: PMC1861786 DOI: 10.1529/biophysj.106.098806] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photoinduced molecular transformations in a self-assembled bacteriorhodopsin (bR) monolayer are monitored by observing shifts in the near-infrared resonant wavelengths of linearly polarized modes circulating in a microsphere cavity. We quantify the molecular polarizability change upon all-trans to 13-cis isomerization and deprotonation of the chromophore retinal ( approximately -57 A(3)) and determine its orientation relative to the bR membrane ( approximately 61 degrees ). Our observations establish optical microcavities as a sensitive off-resonant spectroscopic tool for probing conformations and orientations of molecular self-assemblies and for measuring changes of molecular polarizability at optical frequencies. We provide a general estimate of the sensitivity of the technique and discuss possible applications.
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Affiliation(s)
- Juraj Topolancik
- Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts 02142, USA
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Johnson WR, Wilson DW, Fink W, Humayun M, Bearman G. Snapshot hyperspectral imaging in ophthalmology. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:014036. [PMID: 17343511 DOI: 10.1117/1.2434950] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Retinal imaging spectroscopy can provide functional maps using chromophore spectra. For example, oxygen saturation maps show ischemic areas from diabetes and venous occlusions. Obtaining retinal spatial-spectral data has been difficult due to saccades and long data acquisition times (>5 s). We present a snapshot imaging spectrometer with far-reaching applicability that acquires a complete spatial-spectral image cube in approximately 3 ms from 450 to 700 nm with 50 bands, eliminating motion artifacts and pixel misregistration. Current retinal spectral imaging approaches are incapable of true snapshot operation over a wide spectral range with a large number of spectral bands. Coupled to a fundus camera, the instrument returns true color retinal images for comparison to standard fundus images and for image validation while the patient is still dilated. Oxygen saturation maps were obtained with a three-wavelength algorithm: for healthy subjects arteries were approximately 95% and veins 30 to 35% less. The instrument is now undergoing clinical trials.
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Affiliation(s)
- William R Johnson
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Road, Pasadena, California 91109, USA
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Sandeep P, Bisht PB. Effect of adsorbed concentration on the radiative rate enhancement of photoexcited molecules embedded in single microspheres. J Chem Phys 2005; 123:204713. [PMID: 16351299 DOI: 10.1063/1.2126665] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The variation of the molecular density in a single microcavity and its influence on the radiative rate enhancement (RRE) are reported here. The quality factors of the observed morphology-dependent resonances (MDRs) of the microcavity remain unchanged in the absence of any absorbing effects. In contrast, the MDRs tend to disappear in the presence of strong absorption even due to the self-absorption by the molecule. Time-resolved fluorescence studies reveal the fact that the value of RRE decreases with an increase in the adsorbed concentration of the molecules. The results have been explained in terms of a detuning parameter, which is a function of the refractive index of the microcavity. The increased dispersing capability of the microsphere upon increasing its molecular density has been found to be responsible for the observed decrease in RRE.
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Affiliation(s)
- P Sandeep
- Department of Physics, Indian Institute of Technology-Madras, Chennai 600 036, India
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