Search results for " microscopy"

Two-photon excitation microscopy of tryptophan-containing proteins.

2002

We have examined the feasibility of observing single protein molecules by means of their intrinsic tryptophan emission after two-photon excitation. A respiratory protein from spiders, the 24-meric hemocyanin, containing 148 tryptophans, was studied in its native state under almost in vivo conditions. In this specific case, the intensity of the tryptophan emission signals the oxygen load, allowing one to investigate molecular cooperativity. As a system with even higher tryptophan content, we also investigated latex spheres covered with the protein avidin, resulting in 340 tryptophans per sphere. The ratio of the fluorescence quantum efficiency to the bleaching efficiency was found to vary b…

Algorithms and software for biological multiscale image analysis

2013

Phosphotungstic acid (PTA) in the synthesis of 3D CdS superstructures by diffusion assisted hydrothermal method

2015

Abstract In this study, the synthesis of cadmium sulfide (CdS) microstructures by gas diffusion assisted hydrothermal method using phosphotungstic acid (PTA) is reported. The as-synthesized products were characterized by Fourier transform infrared (FTIR), powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of PTA dose, thioacetamide amount, time and temperature on the morphology of obtained particles have been studied. In this process, PTA ion host stabilizes the CdS particles against aggregation and thioacetamide plays two roles, being at the same time a sulfur source and a capping ligand. Based on the performed analyses it seems that the thioacetamide is mor…

Correlative Raman-Electron-Light (CREL) Microscopy Analysis of Lipid Droplets in Melanoma Cancer Stem Cells.

2022

Among all neoplasms, melanoma is characterized by a very high percentage of cancer stem cells (CSCs). Several markers have been proposed for their identification, and lipid droplets (LDs) are among them. Different techniques are used for their characterization such as mass spectrometry, imaging techniques, and vibrational spectroscopies. Some emerging experimental approaches for the study of LDs are represented by correlative light–electron microscopy and by correlative Raman imaging–scanning electron microscopy (SEM). Based on these scientific approaches, we developed a novel methodology (CREL) by combining Raman micro-spectroscopy, confocal fluorescence microscopy, and SEM coupled with an…

Exosome investigation: the approach of electron microscopy

2018

A mixture of cell-derived extracellular vesicles (EVs) are contained in the extracellular environment, in particular body fluids. The EVs originate from the lipid membranes of a variety of cells and are engaged in the intercellular communication in a broad range of physiological processes and pathological conditions. The smallest type of EVs, exosomes, with sizes ranging from 40 nm up to approximately 100 nm in diameter, originate from the endosome. Exosomes are natural nanoshuttles that are capable of delivering their cargo of RNA, lipids, and proteins to cells in close proximity and to distant cellular destinations. There is a rapidly growing interest in utilizing exosomes present in pati…

Nanodevices by DNA based gold nanostructures

2017

In this thesis DNA based structures were utilized to create gold nanostructures for nanosensing and nanoelectronic applications. In the past, both of these fields have been dominated by the conventional lithography methods, e.g., electron beam lithography and UV-lithography, but more recently scaling down the components by these techniques has become increasingly more complex and costly. Especially in the micro- and nanoelectronics, the increase in the component density and thus computational power would require fabrication of sub-10-nm components, which is challenging for the top-down approaches. Aforementioned developments have led researchers to seek alternative methods to fabricate these…

Experimental study of electron transport in mesoscopic carbon based nanostructures

2012

In this thesis we have studied experimentally electronic transport in mesoscopic hybrid polypyrrole-gold devices and single multiwalled carbon nanotube devices. A novel fabrication technique for mesoscopic conducting hybrid polymer-gold films has been developed. The hybrid polymer-gold films have been fabricated by electrochemical deposition of polypyrrole on a gold nanoisland layer. Temperature dependence of conductance show that the dominant transport mechanism in the polypyrrole-gold films is variable range hopping in the temperature range from 20 K to 300 K. At very low temperature strong nonlinearities in the field dependent conductance are observed. The field dependence follows a phen…

Control of Morphology and Corona Composition in Aggregates of Mixtures of PS-b-PAA and PS-b-P4VP Diblock Copolymers: Effects of Solvent, Water Conten…

2014

The morphologies and corona compositions in aggregates of mixtures of PS-b-PAA and PS-b-P4VP diblock copolymers are influenced by controllable assembly parameters such as water content, block copolymer molar ratios, and solvent effects as well as the hydrophilic block lengths and block length ratios. All these factors can affect the morphology of the aggregates as well as their corona composition, the latter especially in vesicles, where two interfaces are involved. The morphologies and corona compositions of the aggregates were investigated by transmission electron microscopy and electrophoretic mobility, respectively. They depend, to a large extent, on the solubility of P4VP and PAA in th…

Control of Corona Composition and Morphology in Aggregates of Mixtures of PS-b-PAA and PS-b-P4VP Diblock Copolymers: Effects of pH and Block Length

2014

The corona compositions and morphologies in aggregates of mixtures of amphiphilic polystyrene-block-poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers are influenced by controllable assembly parameters such as the hydrophilic block length and solution pH. The morphologies and corona compositions of the aggregates were investigated by transmission electron microscopy and electrophoretic mobility, respectively. When mineral acids or bases are present during aggregate formation, they can exert a strong influence on the corona composition. Morphology changes were also seen with changing pH, as well as changes in corona composition, specifica…

The Use of Electron Microscopy and Stereology in the Study of the Mammalian Pineal Gland

1983

Now that transmission electron microscopy (TEM) has been used for many years to study the pineal gland it is timely to evaluate what progress has been achieved by using this technique and to speculate which aspects of pineal research may benefit most by its application in the future.