scholarly journals Bacteria Single-Cell and Photosensitizer Interaction Revealed by Quantitative Phase Imaging

2021 ◽  
Vol 22 (10) ◽  
pp. 5068
Author(s):  
Igor Buzalewicz ◽  
Agnieszka Ulatowska-Jarża ◽  
Aleksandra Kaczorowska ◽  
Marlena Gąsior-Głogowska ◽  
Halina Podbielska ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Single Cells ◽  
Three Dimensional ◽  
Bacterial Biofilm ◽  
Phase Imaging ◽  
Label Free ◽  
Biophysical Processes ◽  
Contemporary Medicine

Quantifying changes in bacteria cells in the presence of antibacterial treatment is one of the main challenges facing contemporary medicine; it is a challenge that is relevant for tackling issues pertaining to bacterial biofilm formation that substantially decreases susceptibility to biocidal agents. Three-dimensional label-free imaging and quantitative analysis of bacteria–photosensitizer interactions, crucial for antimicrobial photodynamic therapy, is still limited due to the use of conventional imaging techniques. We present a new method for investigating the alterations in living cells and quantitatively analyzing the process of bacteria photodynamic inactivation. Digital holographic tomography (DHT) was used for in situ examination of the response of Escherichia coli and Staphylococcus aureus to the accumulation of the photosensitizers immobilized in the copolymer revealed by the changes in the 3D refractive index distributions of single cells. Obtained results were confirmed by confocal microscopy and statistical analysis. We demonstrated that DHT enables real-time characterization of the subcellular structures, the biophysical processes, and the induced local changes of the intracellular density in a label-free manner and at sub-micrometer spatial resolution.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

scholarly journals Label-Free and Quantitative Dry Mass Monitoring for Single Cells during In Situ Culture

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1635
Author(s):  
Ya Su ◽  
Rongxin Fu ◽  
Wenli Du ◽  
Han Yang ◽  
Li Ma ◽  
...  
Keyword(s):  
Cell Growth ◽  
Single Cell ◽  
Hela Cells ◽  
Quantitative Measurement ◽  
Single Cells ◽  
Dry Mass ◽  
Quantitative Detection ◽  
Label Free ◽  
Mass Sensitivity

Quantitative measurement of single cells can provide in-depth information about cell morphology and metabolism. However, current live-cell imaging techniques have a lack of quantitative detection ability. Herein, we proposed a label-free and quantitative multichannel wide-field interferometric imaging (MWII) technique with femtogram dry mass sensitivity to monitor single-cell metabolism long-term in situ culture. We demonstrated that MWII could reveal the intrinsic status of cells despite fluctuating culture conditions with 3.48 nm optical path difference sensitivity, 0.97 fg dry mass sensitivity and 2.4% average maximum relative change (maximum change/average) in dry mass. Utilizing the MWII system, different intrinsic cell growth characteristics of dry mass between HeLa cells and Human Cervical Epithelial Cells (HCerEpiC) were studied. The dry mass of HeLa cells consistently increased before the M phase, whereas that of HCerEpiC increased and then decreased. The maximum growth rate of HeLa cells was 11.7% higher than that of HCerEpiC. Furthermore, HeLa cells were treated with Gemcitabine to reveal the relationship between single-cell heterogeneity and chemotherapeutic efficacy. The results show that cells with higher nuclear dry mass and nuclear density standard deviations were more likely to survive the chemotherapy. In conclusion, MWII was presented as a technique for single-cell dry mass quantitative measurement, which had significant potential applications for cell growth dynamics research, cell subtype analysis, cell health characterization, medication guidance and adjuvant drug development.

The label-free separation and culture of tumor cells in a microfluidic biochip

The Analyst ◽  
2020 ◽  
Vol 145 (5) ◽  
pp. 1706-1715 ◽  
Author(s):  
Jian Zhou ◽  
Chunlong Tu ◽  
Yitao Liang ◽  
Bobo Huang ◽  
Yifeng Fang ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Label Free

An integrated microfluidic biochip was designed for the streamlined separation, capture, in situ culture and/or immunofluorescence characterization of tumor cells.

scholarly journals Microstructural characterization of a Canadian oil sand

2012 ◽  
Vol 49 (10) ◽  
pp. 1212-1220 ◽  
Author(s):  
Dinh Hong Doan ◽  
Pierre Delage ◽  
Jean François Nauroy ◽  
Anh Minh Tang ◽  
Souhail Youssef
Keyword(s):  
Three Dimensional ◽  
Microstructural Characterization ◽  
Water Layer ◽  
3D Image ◽  
Oil Sand ◽  
X Ray ◽  
Mcmurray Formation ◽  
Gas Expansion

The microstructure of oil sand samples extracted at a depth of 75 m from the estuarine Middle McMurray Formation (Alberta, Canada) has been investigated using high resolution three-dimensional (3D) X-ray microtomography (µCT) and cryo scanning electron microscopy (CryoSEM). µCT images evidenced some dense areas composed of highly angular grains surrounded by fluids, which are separated by larger pores full of gas. In dense areas, 3D image analysis provided porosity values comparable with in situ log data and macroscopic laboratory determinations, showing that they are representative of intact states. µCT hence provided some information on the morphology of the cracks and disturbance created by gas expansion. The CryoSEM technique, in which the sample is freeze fractured within the SEM chamber prior to observation, provided pictures in which the (frozen) bitumen clearly appears between the sand grains. No evidence of the existence of a thin connate water layer between grains and the bitumen, frequently mentioned in the literature, has been obtained. Bitumen appears to strongly adhere to the grains, with some grains being completely coated. The curved shape of some bitumen menisci suggests a bitumen wet behaviour.

scholarly journals Functional Tomographic Fluorescence Imaging of pH Microenvironments in Microbial Biofilms by Use of Silica Nanoparticle Sensors

2009 ◽  
Vol 75 (23) ◽  
pp. 7426-7435 ◽  
Author(s):  
Gabriela Hidalgo ◽  
Andrew Burns ◽  
Erik Herz ◽  
Anthony G. Hay ◽  
Paul L. Houston ◽  
...  
Keyword(s):  
Fluorescence Imaging ◽  
Tricarboxylic Acid Cycle ◽  
Three Dimensional ◽  
Silica Nanoparticle ◽  
In Situ Characterization ◽  
Local Conditions ◽  
Glucose Addition ◽  
Microbial Biofilms

ABSTRACT Attached bacterial communities can generate three-dimensional (3D) physicochemical gradients that create microenvironments where local conditions are substantially different from those in the surrounding solution. Given their ubiquity in nature and their impacts on issues ranging from water quality to human health, better tools for understanding biofilms and the gradients they create are needed. Here we demonstrate the use of functional tomographic imaging via confocal fluorescence microscopy of ratiometric core-shell silica nanoparticle sensors (C dot sensors) to study the morphology and temporal evolution of pH microenvironments in axenic Escherichia coli PHL628 and mixed-culture wastewater biofilms. Testing of 70-, 30-, and 10-nm-diameter sensor particles reveals a critical size for homogeneous biofilm staining, with only the 10-nm-diameter particles capable of successfully generating high-resolution maps of biofilm pH and distinct local heterogeneities. Our measurements revealed pH values that ranged from 5 to >7, confirming the heterogeneity of the pH profiles within these biofilms. pH was also analyzed following glucose addition to both suspended and attached cultures. In both cases, the pH became more acidic, likely due to glucose metabolism causing the release of tricarboxylic acid cycle acids and CO2. These studies demonstrate that the combination of 3D functional fluorescence imaging with well-designed nanoparticle sensors provides a powerful tool for in situ characterization of chemical microenvironments in complex biofilms.

scholarly journals Three‐dimensional in situ sequencing of single cells in intact tissue

2019 ◽  
Vol 33 (S1) ◽  
Author(s):  
Xiao Wang ◽  
William E. Allen ◽  
Karl Deisseroth
Keyword(s):  
Single Cells ◽  
Three Dimensional ◽  
Intact Tissue

scholarly journals Three-dimensional label-free observation of individual bacteria upon antibiotic treatment using optical diffraction tomography

2019 ◽  
Author(s):  
Jeonghun Oh ◽  
Jea Sung Ryu ◽  
Moosung Lee ◽  
Jaehwang Jung ◽  
Seung yun Han ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Time Lapse ◽  
Optical Diffraction ◽  
Response Analysis ◽  
Diffraction Tomography ◽  
Label Free ◽  
Optical Diffraction Tomography ◽  
Quantitative Manner ◽  
Basic Studies

AbstractMeasuring alterations in bacteria upon antibiotic application is important for basic studies in microbiology, drug discovery, and clinical diagnosis, and disease treatment. However, imaging and 3D time-lapse response analysis of individual bacteria upon antibiotic application remain largely unexplored mainly due to limitations in imaging techniques. Here, we present a method to systematically investigate the alterations in individual bacteria in 3D and quantitatively analyze the effects of antibiotics. Using optical diffraction tomography, in-situ responses of Escherichia coli and Bacillus subtilis to various concentrations of ampicillin were investigated in a label-free and quantitative manner. The presented method reconstructs the dynamic changes in the 3D refractive-index distributions of living bacteria in response to antibiotics at sub-micrometer spatial resolution.

scholarly journals Strain Analysis on Electrochemical Failures of Nanoscale Silicon Electrode Based on Three-Dimensional In Situ Measurement

2020 ◽  
Vol 10 (2) ◽  
pp. 468 ◽  
Author(s):  
Zhifeng Qi ◽  
Zhongqiang Shan ◽  
Weihao Ma ◽  
Linan Li ◽  
Shibin Wang ◽  
...  
Keyword(s):  
Silicon Film ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Image Correlation ◽  
Mechanical Parameters ◽  
Stress Strain ◽  
Full Field ◽  
Battery Capacity

Nanoscale silicon film electrodes in Li-ion battery undergo great deformations leading to electrochemical and mechanical failures during repeated charging-discharging cycles. In-situ experimental characterization of the stress/strain in those electrodes still faces big challenges due to remarkable complexity of stress/strain evolution while it is still hard to predict the association between the electrode cycle life and the measurable mechanical parameters. To quantificationally investigate the evolution of the mechanical parameters, we develop a new full field 3D measurement method combining digital image correlation with laser confocal profilometry and propose a strain criterion of the failure based on semi-quantitative analysis via mean strain gradient (MSG). The experimental protocol and results illustrate that the revolution of MSG correlates positively with battery capacity decay, which may inspire future studies in the field of film electrodes.

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