scholarly journals Determination of nonlinear absorption and scattering in a single plasmonic nanostructure using X-scan technique

2019 ◽  
Author(s):  
Tushar C Jagadale ◽  
Dhanya Murali ◽  
Shi-Wei Chu
Keyword(s):  
Laser Scanning ◽  
Detection System ◽  
Optical Nonlinearity ◽  
Excitation Intensity ◽  
Laser Scanning Microscopy ◽  
Thin Sample ◽  
Channel Detection ◽  
Laser Focus ◽  
Novel Method ◽  
High Level

Nonlinear nano-plasmonics opens up many exciting opportunities, such as nano-laser, nano-antenna, nano-modulator, etc. A highly desirable tool in the field of nonlinear nano-plasmonics is to characterize nonlinearity of optical absorption and scattering in single nanostructures. Currently, the most widely used method to quantify optical nonlinearity is z-scan, which can derive real and imaginary parts of permittivity through translating a thin sample across a laser focus. However, z-scan typically works with thin films, and thus acquires nonlinear responses from ensemble of nanostructures, not a single one. In this work, we present an X-scan technique, which is based on laser scanning microscopy equipped with forward and backward detectors. The two-channel detection allows simultaneous quantification of nonlinear behaviours of scattering, absorption, as well as total attenuation, from a single nanostructure. At low excitation intensity, both scattering and absorption responses are linear, thus confirming the linearity of detection system. At high excitation intensity, we found that the nonlinear response can be derived directly from the point spread function of X-scan images. Surprisingly high level of nonlinearities in both scattering and absorption are unravelled simultaneously for the first time. Our study not only provides a novel method for characterizing single-nanostructure nonlinearity, but also reports exceptionally large plasmonic nonlinearities.

scholarly journals Nonlinear absorption and scattering of a single plasmonic nanostructure characterized by x-scan technique

2019 ◽  
Vol 10 ◽  
pp. 2182-2191 ◽  
Author(s):  
Tushar C Jagadale ◽  
Dhanya S Murali ◽  
Shi-Wei Chu
Keyword(s):  
Laser Scanning ◽  
Detection System ◽  
Nonlinear Behavior ◽  
Optical Nonlinearity ◽  
Research Area ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Thin Sample ◽  
Channel Detection ◽  
Novel Method

Nonlinear nanoplasmonics is a largely unexplored research area that paves the way for many exciting applications, such as nanolasers, nanoantennas, and nanomodulators. In the field of nonlinear nanoplasmonics, it is highly desirable to characterize the nonlinearity of the optical absorption and scattering of single nanostructures. Currently, the common method to quantify optical nonlinearity is the z-scan technique, which yields real and imaginary parts of the permittivity by moving a thin sample with a laser beam. However, z-scan typically works with thin films, and thus acquires nonlinear responses from ensembles of nanostructures, not from single ones. In this work, we present an x-scan technique that is based on a confocal laser scanning microscope equipped with forward and backward detectors. The two-channel detection offers the simultaneous quantification for the nonlinear behavior of scattering, absorption and total attenuation by a single nanostructure. At low excitation intensities, both scattering and absorption responses are linear, thus confirming the linearity of the detection system. At high excitation intensities, we found that the nonlinear response can be derived directly from the point spread function of the x-scan images. Exceptionally large nonlinearities of both scattering and absorption are unraveled simultaneously for the first time. The present study not only provides a novel method for characterizing nonlinearity of a single nanostructure, but also reports surprisingly large plasmonic nonlinearities.

LTCC Based Multi-Electrode Arrays for In-Vitro Cell Culture

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000269-000274
Author(s):  
Heike Bartsch ◽  
Dirk Stöpel ◽  
Marcel Himmerlich ◽  
Martin Baca ◽  
Philipp Stadie ◽  
...  
Keyword(s):  
Cell Culture ◽  
Laser Scanning ◽  
Neuronal Cell ◽  
Laser Scanning Microscopy ◽  
Gold Electrodes ◽  
Neural Cells ◽  
Electrode Arrays ◽  
Green Tape ◽  
High Level

Neurobiological concepts based on state-of-the art technology have so far lacked the complexity of actual high-level neurobiological systems. Two key advances are needed to improve our understanding of such systems: in vitro 3D-neuronal cell culture and 3D MEA systems for measuring such 3D-cultures. These requirements call for smart multilayer and packaging technology. The material Green Tape TM from DuPont Nemours is chosen for the presented works, because its compatibility and those of available metallisation with cell cultures is already proven. An LTCC multilayer circuit with gold electrodes is the base of the 3D MEA. The layout of the 3D MEA is designed to fit the MEA2100-System for in vitro recording from Multi Channel Systems and enable thus a comparable data processing to established 2D MEAs Slots. The surface topography of the thick film electrodes and the surface state is investigated with laser scanning microscopy, SEM, XPS and measurements of the wetting angle of contact. The impedance of the screen printed electrodes is discussed taking these data into account. Their impedance amounts to 24 kΩ and are falls thus below the impedance of commercially available electroplated gold electrodes of 30 kΩ. First promising results have been achieved using 3D MEAs for 2D culture of human pluripotent stem cell derived neural cells.

CaBP1, a calcium binding protein of the thioredoxin family, is a resident KDEL protein of the ER and not of the intermediate compartment

1994 ◽  
Vol 107 (10) ◽  
pp. 2719-2727 ◽  
Author(s):  
J. Fullekrug ◽  
B. Sonnichsen ◽  
U. Wunsch ◽  
K. Arseven ◽  
P. Nguyen Van ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Laser Scanning ◽  
Vero Cells ◽  
Subcellular Fractionation ◽  
Laser Scanning Microscopy ◽  
Cos Cells ◽  
Marker Proteins ◽  
Intermediate Compartment ◽  
High Level ◽  
High Degree

A cDNA encoding rat CaBP1 has been isolated and sequenced. The deduced polypeptide chain consists of 440 amino acids including two internal thioredoxin-like domains and a C-terminal KDEL retention/retrieval signal. Regarding the high degree of identity to the hamster protein P5, CaBP1 is considered to be the homologous rat protein. Previous work has suggested that CaBP1 is a resident luminal protein of the intermediate compartment (Schweizer, A., Peter, F., Nguyen Van, P., Soling, H.D. and Hauri, H.P. (1993) Eur. J. Cell Biol. 60, 366–370). Our conclusion that CaBP1 is a resident protein of the endoplasmic reticulum and not of the intermediate compartment is based on three different approaches: subcellular fractionation, indirect immunofluorescence and overexpression of CaBP1. Subcellular fractionation of Vero cells in a velocity controlled step gradient led to copurification of CaBP1-containing vesicles and several marker proteins for the ER including calreticulin and alpha-SSRP. The intermediate compartment, as defined by a monoclonal antibody against the marker protein p53 (ERGIC-53), could be separated from these ER markers. Double immunofluorescence analysed by laser scanning microscopy showed no significant colocalization between CaBP1 and p53, but between CaBP1 and calreticulin. In addition experiments, Vero cells were infected with VSV tsO45. At 15 degrees C the VSV-G protein accumulated in punctuate structures representing the intermediate compartment, while CaBP1 maintained its original reticular localization. Even after high-level overexpression in COS cells, CaBP1 was not detected in the intermediate compartment, but was efficiently retained in the ER as judged by light microscopy.

scholarly journals Acidic stress induces protective autophagy in SGC7901 cells

2018 ◽  
Vol 46 (8) ◽  
pp. 3285-3295 ◽  
Author(s):  
Jie Sheng ◽  
Li-Bin Sun ◽  
Shu-Fen Zhao ◽  
Wei-Wei Qi ◽  
Jing Lv ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cell Proliferation ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Acidic Environment ◽  
Bafilomycin A1 ◽  
Autophagosome Formation ◽  
Acidic Conditions ◽  
High Level

Objective To investigate the effect of acidity on gastric cancer SGC7901 cells in terms of autophagy and provide a new strategy for therapeutically targeting gastric cancer autophagy in an acidic environment. Methods Transmission electron microscopy (TEM) and confocal laser scanning microscopy were used to examine the effect of an acidic environment on autophagosome formation. Light chain 3 (LC3) and p62 levels in SGC7901 cells exposed to acidic conditions were measured using Western blot analysis. To explore changes in autophagy flux, the cells were treated with an inhibitor of autophagy bafilomycin A1. The CCK-8 assay was performed to determine if inhibiting acid-induced autophagy affected cell proliferation. Results Increased autophagosome formation was observed by TEM. Punctate LC3 structures were observed in cells cultured under acidic conditions, whereas untreated cells exhibited diffuse and weak staining for punctate LC3 structures. Cytoplasmic LC3-I translocated to the autophagic membrane (LC3-II) levels increased under acidic conditions, whereas p62 levels decreased. The bafilomycin A1-induced inhibition of autophagy caused by the acidic environment inhibited cell proliferation. Conclusion The acidic environment upregulates autophagy in SGC7901 cells. In long-term culture, a stable and high level of autophagy is maintained in an acidic environment, which has a protective effect on cells.

3-D imaging of cells using a confocal laser scanning microscope and digital image processing

1988 ◽  
Vol 46 ◽  
pp. 96-97
Author(s):  
Thomas M. Jovin ◽  
Michel Robert-Nicoud ◽  
Donna J. Arndt-Jovin ◽  
Thorsten Schormann
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Scanning Microscope ◽  
Laser Scanning Microscope ◽  
Biochemical Processes ◽  
Adjacent Structures

Light microscopic techniques for visualizing biomolecules and biochemical processes in situ have become indispensable in studies concerning the structural organization of supramolecular assemblies in cells and of processes during the cell cycle, transformation, differentiation, and development. Confocal laser scanning microscopy offers a number of advantages for the in situ localization and quantitation of fluorescence labeled targets and probes: (i) rejection of interfering signals emanating from out-of-focus and adjacent structures, allowing the “optical sectioning” of the specimen and 3-D reconstruction without time consuming deconvolution; (ii) increased spatial resolution; (iii) electronic control of contrast and magnification; (iv) simultanous imaging of the specimen by optical phenomena based on incident, scattered, emitted, and transmitted light; and (v) simultanous use of different fluorescent probes and types of detectors.We currently use a confocal laser scanning microscope CLSM (Zeiss, Oberkochen) equipped with 3-laser excitation (u.v - visible) and confocal optics in the fluorescence mode, as well as a computer-controlled X-Y-Z scanning stage with 0.1 μ resolution.

Vacuoles Induced in Mammalian Cells by Helicobacter Cytotoxin are Acidic Organelles

1990 ◽  
Vol 48 (3) ◽  
pp. 168-169
Author(s):  
M. H. Chestnut ◽  
C. E. Catrenich
Keyword(s):  
Acridine Orange ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Ulcer Disease ◽  
Gastroduodenal Disease ◽  
H Pylori

Helicobacter pylori is a non-invasive, Gram-negative spiral bacterium first identified in 1983, and subsequently implicated in the pathogenesis of gastroduodenal disease including gastritis and peptic ulcer disease. Cytotoxic activity, manifested by intracytoplasmic vacuolation of mammalian cells in vitro, was identified in 55% of H. pylori strains examined. The vacuoles increase in number and size during extended incubation, resulting in vacuolar and cellular degeneration after 24 h to 48 h. Vacuolation of gastric epithelial cells is also observed in vivo during infection by H. pylori. A high molecular weight, heat labile protein is believed to be responsible for vacuolation and to significantly contribute to the development of gastroduodenal disease in humans. The mechanism by which the cytotoxin exerts its effect is unknown, as is the intracellular origin of the vacuolar membrane and contents. Acridine orange is a membrane-permeant weak base that initially accumulates in low-pH compartments. We have used acridine orange accumulation in conjunction with confocal laser scanning microscopy of toxin-treated cells to begin probing the nature and origin of these vacuoles.

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