scholarly journals Dynamic single-molecule counting for the quantification and optimization of nanoparticle functionalization protocols

Nanoscale ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 4128-4136 ◽  
Author(s):  
Matěj Horáček ◽  
Dion J. Engels ◽  
Peter Zijlstra
Keyword(s):  
Single Molecule ◽  
Super Resolution ◽  
Medical Applications ◽  
Single Molecule Level ◽  
Microscopy Method ◽  
Super Resolution Microscopy ◽  
Direct Quantification

We provide a super-resolution microscopy method to characterize the chemical interface of nanoparticles at the single-molecule level. This provides a direct quantification and optimization of functionalization protocols for bio-medical applications.

scholarly journals Bioorthogonal labeling with tetrazine-dyes for super-resolution microscopy

2018 ◽  
Author(s):  
Gerti Beliu ◽  
Andreas Kurz ◽  
Alexander Kuhlemann ◽  
Lisa Behringer-Pliess ◽  
Natalia Wolf ◽  
...  
Keyword(s):  
Single Molecule ◽  
Signal To Noise Ratio ◽  
Super Resolution ◽  
Alder Reaction ◽  
Cell Permeability ◽  
High Signal ◽  
Noncanonical Amino Acids ◽  
Single Molecule Level ◽  
Genetic Code Expansion ◽  
Super Resolution Microscopy

Genetic code expansion (GCE) technology allows the specific incorporation of functionalized noncanonical amino acids (ncAAs) into proteins. Here, we investigated the Diels-Alder reaction between trans-cyclooct-2-ene (TCO)-modified ncAAs, and 22 known and novel 1,2,4,5-tetrazine-dye conjugates spanning the entire visible wavelength range. A hallmark of this reaction is its fluorogenicity - the tetrazine moiety can elicit substantial quenching of the dye. We discovered that photoinduced electron transfer (PET) from the excited dye to tetrazine as the main quenching mechanism in red-absorbing oxazine and rhodamine derivatives. Upon reaction with dienophiles quenching interactions are reduced resulting in a considerable increase in fluorescence intensity. Efficient and specific labeling of all tetrazine-dyes investigated permits super-resolution microscopy with high signal-to-noise ratio even at the single-molecule level. The different cell permeability of tetrazine-dyes can be used advantageously for specific intra- and extracellular labeling of proteins and highly sensitive fluorescence imaging experiments in fixed and living cells.

Protein clustering and spatial organization in T-cells

2015 ◽  
Vol 43 (3) ◽  
pp. 315-321 ◽  
Author(s):  
Michael J. Shannon ◽  
Garth Burn ◽  
Andrew Cope ◽  
Georgina Cornish ◽  
Dylan M. Owen
Keyword(s):  
T Cell ◽  
Single Molecule ◽  
Spatial Organization ◽  
Super Resolution ◽  
Cell Protein ◽  
Single Molecule Level ◽  
Composition And Structure ◽  
Resolution Analysis ◽  
And Function ◽  
Super Resolution Microscopy

T-cell protein microclusters have until recently been investigable only as microscale entities with their composition and structure being discerned by biochemistry or diffraction-limited light microscopy. With the advent of super resolution microscopy comes the ability to interrogate the structure and function of these clusters at the single molecule level by producing highly accurate pointillist maps of single molecule locations at ~20nm resolution. Analysis tools have also been developed to provide rich descriptors of the pointillist data, allowing us to pose questions about the nanoscale organization which governs the local and cell wide responses required of a migratory T-cell.

scholarly journals Direct Observation of Anisotropy-Driven Formation of Amyloid Protein Core-Shell Structures in Real-time by Super-resolution Microscopy

2021 ◽  
Author(s):  
Min Zhang ◽  
Henrik Dahl Pinholt ◽  
Xin Zhou ◽  
Soeren S-R Bohr ◽  
Luca Banneta ◽  
...  
Keyword(s):  
Real Time ◽  
Single Molecule ◽  
Growth Rates ◽  
Super Resolution ◽  
Average Growth ◽  
Single Molecule Level ◽  
Aggregation Processes ◽  
Morphological Transitions ◽  
Super Resolution Microscopy ◽  
Kinetics Of

Proteins misfolding and aggregation in the form of fibrils or amyloid containing spherulite-like structures, are involved in a spectrum of degenerative diseases. Current understanding of protein aggregation mechanism primarily relies on conventional spectrometric methods reporting the average growth rates and microscopy readouts of final structures, consequently masking the morphological and growth heterogeneity of the aggregates. Here we developed REal-time kinetics via binding and Photobleaching LOcalization Microscopy (REPLOM) super resolution method to observe directly and quantify the existence and abundance of diverse aggregation morphologies as well as the heterogeneous growth kinetics of each of them. Our results surprisingly revealed insulin aggregation is not exclusively isotropic, but it may also occur anisotropically. Combined with Machine learning we associated growth rates to specific morphological transitions and provided energy barriers and the energy landscape for each aggregation morphology. Our unifying framework of detection and analysis of spherulite growth can be extended to other protein systems and reveal their aggregation processes at single molecule level.

scholarly journals Cellular dynamics of the SecA ATPase at the single molecule level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anne-Bart Seinen ◽  
Dian Spakman ◽  
Antoine M. van Oijen ◽  
Arnold J. M. Driessen
Keyword(s):  
Protein Secretion ◽  
Single Molecule ◽  
Membrane Surface ◽  
Super Resolution ◽  
Single Molecule Level ◽  
Cellular Environment ◽  
A Minor ◽  
Super Resolution Microscopy ◽  
Dynamic Interplay ◽  
Gain Access

AbstractIn bacteria, the SecA ATPase provides the driving force for protein secretion via the SecYEG translocon. While the dynamic interplay between SecA and SecYEG in translocation is widely appreciated, it is not clear how SecA associates with the translocon in the crowded cellular environment. We use super-resolution microscopy to directly visualize the dynamics of SecA in Escherichia coli at the single-molecule level. We find that SecA is predominantly associated with and evenly distributed along the cytoplasmic membrane as a homodimer, with only a minor cytosolic fraction. SecA moves along the cell membrane as three distinct but interconvertible diffusional populations: (1) A state loosely associated with the membrane, (2) an integral membrane form, and (3) a temporarily immobile form. Disruption of the proton-motive-force, which is essential for protein secretion, re-localizes a significant portion of SecA to the cytoplasm and results in the transient location of SecA at specific locations at the membrane. The data support a model in which SecA diffuses along the membrane surface to gain access to the SecYEG translocon.

scholarly journals Simultaneous spatiotemporal super-resolution and multi-parametric fluorescence microscopy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jagadish Sankaran ◽  
Harikrushnan Balasubramanian ◽  
Wai Hoh Tang ◽  
Xue Wen Ng ◽  
Adrian Röllin ◽  
...  
Keyword(s):  
Single Molecule ◽  
Temporal Dynamics ◽  
Growth Factor Receptor ◽  
Super Resolution ◽  
Actin Binding ◽  
Biological Knowledge ◽  
Data Set ◽  
Epidermal Growth ◽  
Molecular Brightness ◽  
Super Resolution Microscopy

AbstractSuper-resolution microscopy and single molecule fluorescence spectroscopy require mutually exclusive experimental strategies optimizing either temporal or spatial resolution. To achieve both, we implement a GPU-supported, camera-based measurement strategy that highly resolves spatial structures (~100 nm), temporal dynamics (~2 ms), and molecular brightness from the exact same data set. Simultaneous super-resolution of spatial and temporal details leads to an improved precision in estimating the diffusion coefficient of the actin binding polypeptide Lifeact and corrects structural artefacts. Multi-parametric analysis of epidermal growth factor receptor (EGFR) and Lifeact suggests that the domain partitioning of EGFR is primarily determined by EGFR-membrane interactions, possibly sub-resolution clustering and inter-EGFR interactions but is largely independent of EGFR-actin interactions. These results demonstrate that pixel-wise cross-correlation of parameters obtained from different techniques on the same data set enables robust physicochemical parameter estimation and provides biological knowledge that cannot be obtained from sequential measurements.

scholarly journals Comparing Super-Resolution Microscopy Techniques to Analyze Chromosomes

2021 ◽  
Vol 22 (4) ◽  
pp. 1903
Author(s):  
Ivona Kubalová ◽  
Alžběta Němečková ◽  
Klaus Weisshart ◽  
Eva Hřibová ◽  
Veit Schubert
Keyword(s):  
Single Molecule ◽  
Imaging Techniques ◽  
Chromatin Condensation ◽  
Super Resolution ◽  
Stimulated Emission ◽  
Wide Field ◽  
Structured Illumination Microscopy ◽  
Metaphase Chromosomes ◽  
Localization Microscopy ◽  
Super Resolution Microscopy

The importance of fluorescence light microscopy for understanding cellular and sub-cellular structures and functions is undeniable. However, the resolution is limited by light diffraction (~200–250 nm laterally, ~500–700 nm axially). Meanwhile, super-resolution microscopy, such as structured illumination microscopy (SIM), is being applied more and more to overcome this restriction. Instead, super-resolution by stimulated emission depletion (STED) microscopy achieving a resolution of ~50 nm laterally and ~130 nm axially has not yet frequently been applied in plant cell research due to the required specific sample preparation and stable dye staining. Single-molecule localization microscopy (SMLM) including photoactivated localization microscopy (PALM) has not yet been widely used, although this nanoscopic technique allows even the detection of single molecules. In this study, we compared protein imaging within metaphase chromosomes of barley via conventional wide-field and confocal microscopy, and the sub-diffraction methods SIM, STED, and SMLM. The chromosomes were labeled by DAPI (4′,6-diamidino-2-phenylindol), a DNA-specific dye, and with antibodies against topoisomerase IIα (Topo II), a protein important for correct chromatin condensation. Compared to the diffraction-limited methods, the combination of the three different super-resolution imaging techniques delivered tremendous additional insights into the plant chromosome architecture through the achieved increased resolution.

scholarly journals Graphene Energy Transfer for Single‐Molecule Biophysics, Biosensing, and Super‐Resolution Microscopy

2021 ◽  
pp. 2101099
Author(s):  
Izabela Kamińska ◽  
Johann Bohlen ◽  
Renukka Yaadav ◽  
Patrick Schüler ◽  
Mario Raab ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Single Molecule ◽  
Super Resolution ◽  
Single Molecule Biophysics ◽  
Super Resolution Microscopy

Sodium sulfite as a switching agent for single molecule based super-resolution optical microscopy

2021 ◽  
Author(s):  
Anders K Engdahl ◽  
Oleg Grauberger ◽  
Mark Schüttpelz ◽  
Thomas Huser
Keyword(s):  
Single Molecule ◽  
Fluorescent Dyes ◽  
Sodium Sulfite ◽  
Super Resolution ◽  
Oxygen Scavenger ◽  
Dark State ◽  
Alexa Fluor ◽  
High Illumination ◽  
Human Osteosarcoma Cells ◽  
Super Resolution Microscopy

Photoinduced off-switching of organic fluorophores is routinely used in super-resolution microscopy to separate and localize single fluorescent molecules, but the method typically relies on the use of complex imaging buffers. The most common buffers use primary thiols to reversibly reduce excited fluorophores to a non-fluorescent dark state, but these thiols have a limited shelf life and additionally require high illumination intensities in order to efficiently switch the emission of fluorophores. Recently a high-index, thiol-containing imaging buffer emerged which used sodium sulfite as an oxygen scavenger, but the switching properties of sulfite was not reported on. Here, we show that sodium sulfite in common buffer solutions reacts with fluorescent dyes, such as Alexa Fluor 647 and Alexa Fluor 488 under low to medium intensity illumination to form a semi-stable dark state. The duration of this dark state can be tuned by adding glycerol to the buffer. This simplifies the realization of different super-resolution microscopy modalities such as direct Stochastic Reconstruction Microscopy (dSTORM) and Super-resolution Optical Fluctuation Microscopy (SOFI). We characterize sulfite as a switching agent and compare it to the two most common switching agents by imaging cytoskeleton structures such as microtubules and the actin cytoskeleton in human osteosarcoma cells.

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