scholarly journals Mapping Membrane Topology Label Free and Corrected for Changes in the Refractive Index of the Membrane on a Nanometer Scale

2014 ◽  
Keyword(s):  
Refractive Index ◽  
Membrane Topology ◽  
Nanometer Scale ◽  
Label Free

scholarly journals Critical angle reflection imaging for quantification of molecular interactions on glass surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guangzhong Ma ◽  
Runli Liang ◽  
Zijian Wan ◽  
Shaopeng Wang
Keyword(s):  
Refractive Index ◽  
Small Molecule ◽  
Molecular Interactions ◽  
Glass Surface ◽  
Critical Angle ◽  
Dynamic Range ◽  
Refractive Index Change ◽  
Label Free ◽  
Index Change ◽  
Sensing Range

AbstractQuantification of molecular interactions on a surface is typically achieved via label-free techniques such as surface plasmon resonance (SPR). The sensitivity of SPR originates from the characteristic that the SPR angle is sensitive to the surface refractive index change. Analogously, in another interfacial optical phenomenon, total internal reflection, the critical angle is also refractive index dependent. Therefore, surface refractive index change can also be quantified by measuring the reflectivity near the critical angle. Based on this concept, we develop a method called critical angle reflection (CAR) imaging to quantify molecular interactions on glass surface. CAR imaging can be performed on SPR imaging setups. Through a side-by-side comparison, we show that CAR is capable of most molecular interaction measurements that SPR performs, including proteins, nucleic acids and cell-based detections. In addition, we show that CAR can detect small molecule bindings and intracellular signals beyond SPR sensing range. CAR exhibits several distinct characteristics, including tunable sensitivity and dynamic range, deeper vertical sensing range, fluorescence compatibility, broader wavelength and polarization of light selection, and glass surface chemistry. We anticipate CAR can expand SPR′s capability in small molecule detection, whole cell-based detection, simultaneous fluorescence imaging, and broader conjugation chemistry.

scholarly journals Perfect Absorption and Refractive-Index Sensing by Metasurfaces Composed of Cross-Shaped Hole Arrays in Metal Substrate

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Zhendong Yan ◽  
Chaojun Tang ◽  
Guohua Wu ◽  
Yumei Tang ◽  
Ping Gu ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Performance ◽  
Narrow Band ◽  
Label Free ◽  
Hybrid Mode ◽  
Perfect Absorption ◽  
Refractive Index Sensing ◽  
Sensing Applications ◽  
Silver Substrate ◽  
Hole Arrays

Achieving perfect electromagnetic wave absorption with a sub-nanometer bandwidth is challenging, which, however, is desired for high-performance refractive-index sensing. In this work, we theoretically study metasurfaces for sensing applications based on an ultra-narrow band perfect absorption in the infrared region, whose full width at half maximum (FWHM) is only 1.74 nm. The studied metasurfaces are composed of a periodic array of cross-shaped holes in a silver substrate. The ultra-narrow band perfect absorption is related to a hybrid mode, whose physical mechanism is revealed by using a coupling model of two oscillators. The hybrid mode results from the strong coupling between the magnetic resonances in individual cross-shaped holes and the surface plasmon polaritons on the top surface of the silver substrate. Two conventional parameters, sensitivity (S) and figure of merit (FOM), are used to estimate the sensing performance, which are 1317 nm/RIU and 756, respectively. Such high-performance parameters suggest great potential for the application of label-free biosensing.

scholarly journals Label-Free Digital Holo-tomographic Microscopy Reveals Virus-Induced Cytopathic Effects in Live Cells

mSphere ◽  
2018 ◽  
Vol 3 (6) ◽  
Author(s):  
Artur Yakimovich ◽  
Robert Witte ◽  
Vardan Andriasyan ◽  
Fanny Georgi ◽  
Urs F. Greber
Keyword(s):  
Refractive Index ◽  
Vaccinia Virus ◽  
Virus Type ◽  
Live Cells ◽  
Refractive Index Gradient ◽  
Label Free ◽  
Virus Infections ◽  
Cytopathic Effects ◽  
Infected Cells ◽  
Index Gradient

ABSTRACTCytopathic effects (CPEs) are a hallmark of infections. CPEs are difficult to observe due to phototoxicity from classical light microscopy. We report distinct patterns of virus infections in live cells using digital holo-tomographic microscopy (DHTM). DHTM is label-free and records the phase shift of low-energy light passing through the specimen on a transparent surface with minimal perturbation. DHTM measures the refractive index (RI) and computes the refractive index gradient (RIG), unveiling optical heterogeneity in cells. We find that vaccinia virus (VACV), herpes simplex virus (HSV), and rhinovirus (RV) infections progressively and distinctly increased RIG. VACV infection, but not HSV and RV infections, induced oscillations of cell volume, while all three viruses altered cytoplasmic membrane dynamics and induced apoptotic features akin to those caused by the chemical compound staurosporine. In sum, we introduce DHTM for quantitative label-free microscopy in infection research and uncover virus type-specific changes and CPE in living cells with minimal interference.IMPORTANCEThis study introduces label-free digital holo-tomographic microscopy (DHTM) and refractive index gradient (RIG) measurements of live, virus-infected cells. We use DHTM to describe virus type-specific cytopathic effects, including cyclic volume changes of vaccinia virus infections, and cytoplasmic condensations in herpesvirus and rhinovirus infections, distinct from apoptotic cells. This work shows for the first time that DHTM is suitable to observe virus-infected cells and distinguishes virus type-specific signatures under noninvasive conditions. It provides a basis for future studies, where correlative fluorescence microscopy of cell and virus structures annotate distinct RIG values derived from DHTM.

scholarly journals Image-based analysis of living mammalian cells using label-free 3D refractive index maps reveals new organelle dynamics and dry mass flux

PLoS Biology ◽  
2019 ◽  
Vol 17 (12) ◽  
pp. e3000553 ◽  
Author(s):  
Patrick A. Sandoz ◽  
Christopher Tremblay ◽  
F. Gisou van der Goot ◽  
Mathieu Frechin
Keyword(s):  
Refractive Index ◽  
Mass Flux ◽  
Mammalian Cells ◽  
Dry Mass ◽  
Label Free ◽  
Index Maps

scholarly journals Label‐free bioanalysis of Leishmania infantum using refractive index tomography with partially coherent illumination

2019 ◽  
Vol 12 (9) ◽  
Author(s):  
Juan M. Soto ◽  
Alicia Mas ◽  
José A. Rodrigo ◽  
Tatiana Alieva ◽  
Gustavo Domínguez‐Bernal
Keyword(s):  
Refractive Index ◽  
Leishmania Infantum ◽  
Label Free ◽  
Partially Coherent ◽  
Coherent Illumination

scholarly journals Compact Inner-Wall Grating Slot Microring Resonator for Label-Free Sensing

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 5038 ◽  
Author(s):  
Hongjun Gu ◽  
He Gong ◽  
Chunxue Wang ◽  
Xiaoqiang Sun ◽  
Xibin Wang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Sodium Chloride ◽  
High Sensitivity ◽  
Microring Resonator ◽  
Silicon On Insulator ◽  
Label Free ◽  
Detection Range ◽  
Sodium Chloride Solutions ◽  
Sensing Application ◽  
Index Unit

In this paper, we present and analyze a compact inner-wall grating slot microring resonator (IG-SMRR) with the footprint of less than 13 μm × 13 μm on the silicon-on-insulator (SOI) platform for label-free sensing, which comprises a slot microring resonator (SMRR) and inner-wall grating (IG). Its detection range is significantly enhanced without the limitation of the free spectral region (FSR) owing to the combination of SMRR and IG. The IG-SMRR has an ultra-large quasi-FSR of 84.5 nm as the detection range, and enlarged factor is up to over 3 compared with the conventional SMRR. The concentration sensitivities of sodium chloride solutions and D-glucose solutions are 996.91 pm/% and 968.05 pm/%, respectively, and the corresponding refractive index (RI) sensitivities are 559.5 nm/RIU (refractive index unit) and 558.3 nm/RIU, respectively. The investigation on the combination of SMRR and IG is a valuable exploration of label-free sensing application for ultra-large detection range and ultra-high sensitivity in future.

Label-free biochemical refractive-index tomography of single cells with mid-infrared photothermal effect

2020 ◽  
Author(s):  
Miu Tamamitsu ◽  
Keiichiro Toda ◽  
Hiroyuki Shimada ◽  
Yu Nagashima ◽  
Ryoichi Horisaki ◽  
...  
Keyword(s):  
Refractive Index ◽  
Single Cells ◽  
Photothermal Effect ◽  
Label Free ◽  
Mid Infrared

Label free detection of DNA hybridization by refractive index tapered fiber biosensor

2010 ◽  
Author(s):  
M. I. Zibaii ◽  
H. Latifi ◽  
E. Ghanati ◽  
M. Gholami ◽  
S. M. Hosseini
Keyword(s):  
Refractive Index ◽  
Dna Hybridization ◽  
Label Free ◽  
Tapered Fiber ◽  
Label Free Detection

scholarly journals A Review of Refractometric Sensors Based on Long Period Fibre Gratings

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
G. Rego
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Transition Region ◽  
Food Quality ◽  
Scientific Community ◽  
Surrounding Medium ◽  
Quality And Safety ◽  
Label Free ◽  
Long Period ◽  
Food Quality And Safety

In the last decade refractometric sensors have attracted an increasing interest by the scientific community due to their ability to perform ambient monitoring, to assess food quality and safety, and also to the fact that they enable the development of label free sensors in the biomedical area. These advances result, namely, from the use of long period fibre gratings in the turning points and/or with thin films in the transition region that allows resolutions of 10−6to changes in the refractive index of the surrounding medium. Resolutions exceeding 10−8can also be achieved when long period fibre gratings are combined with evanescent field based devices. This paper reviews the recent path towards the development of ultrahigh sensitive optical fibre refractometric sensors.

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