Search results for "Correlation spectroscopy"
showing 10 items of 39 documents
Properties of baculovirus particles displaying GFP analyzed by fluorescence correlation spectroscopy.
2003
Abstract Recombinant baculovirus particles displaying green fluorescent protein (GFP) fused to the major envelope glycoprotein gp64 of the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) were characterized by fluorescence correlation spectroscopy (FCS). FCS detected Brownian motion of single, intact recombinant baculovirus display particles with a diffusion coefficient (D) of (2.89±0.74)10 8 cm2s 1 and an apparent hydrodynamic radius of 83.35±21.22 nm. In the presence of sodium dodecyl sulfate (SDS), Triton X-100, and octylglucoside, the diffusion time was reduced to the 0.2 ms range (D = 7.5710 7 cm2s 1), showing that the fusion proteins were anchored in the viral envelope…
Diffusion of single molecular and macromolecular probes during the free radical bulk polymerization of MMA : towards a better understanding of the Tr…
2016
Free radical bulk polymerizations exhibit complex kinetics due to the viscosity increase during the polymerization process. Especially the termination rate constant can be strongly influenced by the mobility of polymer chains in the polymerization mixture. As a consequence an autoacceleration period, the so-called Trommsdorff effect, can be observed often. In order to investigate this behaviour on a nanoscopic scale, we directly visualized the mobility of molecules and macromolecules in polymerizing MMA solutions using a combination of highly sensitive fluorescence correlation spectroscopy and widefield fluorescence microscopy. For this purpose, rather monodisperse PMMA chains were synthesi…
HPMA-Based Nanoparticles for Fast, Bioorthogonal iEDDA Ligation
2019
Contains fulltext : 216143.pdf (Publisher’s version ) (Open Access) Fast and bioorthogonally reacting nanoparticles are attractive tools for biomedical applications such as tumor pretargeting. In this study, we designed an amphiphilic block copolymer system based on HPMA using different strategies to introduce the highly reactive click units 1,2,4,5-tetrazines (Tz) either at the chain end (Tz-CTA) or statistical into the hydrophobic block. This reactive group undergoes a rapid, bioorthogonal inverse electron-demand Diels-Alder reaction (iEDDA) with trans-cyclooctenes (TCO). Subsequently, this polymer platform was used for the preparation of different Tz-covered nanoparticles, such as micell…
Aggregation behavior of amphiphilic p(HPMA)-co-p(LMA) copolymers studied by FCS and EPR spectroscopy.
2012
A combined study of fluorescence correlation spectroscopy and electron paramagnetic resonance spectroscopy gave a unique picture of p(HPMA)-co-p(LMA) copolymers in aqueous solutions, ranging from the size of micelles and aggregates to the composition of the interior of these self-assembled systems. P(HPMA)-co-p(LMA) copolymers have shown high potential as brain drug delivery systems, and a detailed study of their physicochemical properties can help to elucidate their mechanism of action. Applying two complementary techniques, we found that the self-assembly behavior as well as the strength of hydrophobic attraction of the amphiphilic copolymers can be tuned by the hydrophobic LMA content or…
High-throughput drug screening by Printing Biology
2015
Printing biology is our way to define a novel field employing material printing techniques generally used in plastic electronics to solve important issues of biology by miniaturized and high-throughput platforms. In this field, we already showed the possibility to use Dip Pen Lithography to fabricate single-cell biochips [1]. Also,we employed non-contact patterning methods such as inkjet printing methods to fabricate microarrays for drug screening at solid-liquid interfaces [2] or in picoliter-scale liquid droplets [3] so enabling high-throughput screening of chemical libraries onto disease-based targets. In this regard, printing methods would greatly reduce times and costs of standard drug…
Toward oxygen binding curves of single respiratory proteins
2004
Oxygen binding curves of single molecules promise to discriminate between different models describing cooperativity because load distributions are accessible. Individual tarantula hemocyanins could be detected by fluorescence correlation spectroscopy using intrinsic tryptophan fluorescence as sensor of bound oxygen. However, imaging of immobilized proteins was not possible due to fast photo-bleaching. It is shown that tetra-methyl-carboxy-rhodamine (TAMRA), commonly used as a fluorescence label in single-molecule spectroscopy, can also be applied to monitor bound oxygen. The dye's fluorescence is quenched due to Förster energy transfer to the oxygenated active sites of hemocyanin.
Expanding the chemical scope of RNA:methyltransferases to site-specific alkynylation of RNA for click labeling.
2010
This work identifies the combination of enzymatic transfer and click labeling as an efficient method for the site-specific tagging of RNA molecules for biophysical studies. A double-activated analog of the ubiquitous co-substrate S-adenosyl-l-methionine was employed to enzymatically transfer a five carbon chain containing a terminal alkynyl moiety onto RNA. The tRNA:methyltransferase Trm1 transferred the extended alkynyl moiety to its natural target, the N2 of guanosine 26 in tRNA(Phe). LC/MS and LC/MS/MS techniques were used to detect and characterize the modified nucleoside as well as its cycloaddition product with a fluorescent azide. The latter resulted from a labeling reaction via Cu(I…
The oxidation state of a protein observed molecole-by-molecule.
2005
We report the observation of the redox state of the blue copper protein azurin on the single-molecule level. The fluorescence of a small fluorophore attached to the protein is modulated by the change in absorption of the copper center via fluorescence resonance energy transfer (FRET). In our model system, the fluorescence label Cy5 was coupled to azurin from Pseudomonas aeruginosa via cysteine K27C. The Cy5 fluorescence was partially quenched by the absorption of the copper center of azurin in its oxidized state. In the reduced state, absorption is negligible, and thus no quenching occurs. We report on single-molecule measurements, both in solution by using fluorescence correlation spectros…
Towards bioarrays of cellular-like compartments for monitoring few molecular binding events
2016
The aim of this work is to artificially reproduce scalable cellular-like compartments on a chip, thus realizing specialized small volume systems to study the behaviour of interacting biomolecules by few binding events. In particular, we show an unprecedented solution-based protein-binding assay based on arrays of oil-confined water droplets containing protein targets, labelled ligands and other compounds.
Measurement of haemodynamics of exercising and non-exercising vastus lateralis muscle with hybrid diffuse optics
2016
We present simultaneous diffuse correlation spectroscopy (DCS) and time resolved spectroscopy (TR NIRS) measurements on exercising and non-exercising vastus lateralis muscle. We discuss the results at two different exercise levels.