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Covalent labeling

Johann Thurn, Johannes Maier, Martti Pärs, Katja Gräf, Mukundan Thelakkat, Jürgen Köhler
Photochromic molecules that are covalently linked to a strong fluorophore combine the requirements of external control and strong fluorescence, which will become increasingly important for super-resolution microscopy techniques based on single molecules. However, given the bulky structure of such constructs, steric hindrance might affect their photoconversion efficiencies upon immobilising them for imaging purposes. In this study the efficiencies of the photochromic conversion processes of molecular triads that are embedded in a polymer have been studied as a function of temperature...
September 19, 2017: Physical Chemistry Chemical Physics: PCCP
Ewald T J van den Bremer, Aran F Labrijn, Ramon van den Boogaard, Patrick Priem, Kai Scheffler, Joost P M Melis, Janine Schuurman, Paul Parren, Rob N de Jong
Bispecific antibodies (bsAbs) are one of the most versatile and promising pharmaceutical innovations for countering heterogeneous and refractory disease by virtue of their ability to bind two distinct antigens. One critical quality attribute of bsAb formation requiring investigation is the potential randomization of cognate heavy chain (H)/light (L) chain pairing, which could occur to a varying extent dependent on bsAb format and the production platform. To assess the content of such HL chain-swapped reaction products with high sensitivity, we developed cysteine-SILAC, a method that facilitates the detailed characterization of disulfide-bridged peptides by mass-spectrometry...
September 18, 2017: Analytical Chemistry
Renyong Liu, Jun Zhao, Guangmei Han, Tingting Zhao, Ruilong Zhang, Bianhua Liu, Zhengjie Liu, Cheng Zhang, Linlin Yang, Zhongping Zhang
Precise identification and detection of cancer cells using nanoparticle probes are critically important for early cancer diagnosis and the subsequent therapy. We herein develop a novel folate receptor (FR)-targeted surface-enhanced Raman scattering (SERS) nanoprobes for cancer cell imaging based on click coupling strategy. A Raman-active derivative (DNBA-N3) is designed with a disulfide bond for covalently anchoring to the surface of hollow gold nanoparticles (HAuNPs) and a terminal azide group for facilitating highly efficient conjugation with bioligand...
September 18, 2017: ACS Applied Materials & Interfaces
Qijun Ding, Jinsong Zeng, Bin Wang, Wenhua Gao, Kefu Chen, Zhe Yuan, Jun Xu
Cellulose nanocrystals (CNCs) have excellent properties, such as reproducibility, low biodegradability and a large amount of reactive hydroxyl groups on the surface. This study focused on the labeling efficiency and fluorescent properties of the fluorescent labeling of CNCs by means of electrostatic adsorption and covalent bonding. The CNCs in the sample were approximately 94.76% successfully labeled with dyes, and the number of dye molecules adsorbed by per CNC was approximately 208 by electrostatic adsorption...
November 1, 2017: Carbohydrate Polymers
Marta García-Cortés, María Teresa Fernández-Argüelles, José M Costa-Fernández, Alfredo Sanz-Medel
Herein, high-quality Mn-doped ZnS quantum dots (QDs) have been synthesized using a facile approach directly in aqueous media. The surface of the obtained QDs was further modified by cap-exchange of the native cysteine shell with dihydrolipoic acid (DHLA) ligands resulting in nanocrystals with high water-stability having an intense phosphorescent signal. Covalent bioconjugation of the DHLA-coated nanoparticles with an anti-IgG antibody was then carried out. Interestingly the QD immunoprobe (QD-labelled antibodies) maintained an intense phosphorescence emission, without any significant spectral-shift (as compared to the free QDs)...
September 22, 2017: Analytica Chimica Acta
Valeriy Metelev, Surong Zhang, Shaokuan Zheng, Anand T N Kumar, Alexei Bogdanov
Short oligonucleotide sequences are now being widely investigated for their potential therapeutic properties. The modification of oligonucleotide termini with short fluorinated residues is capable of drastically altering their behavior in complex in vitro and in vivo systems, and thus may serve to greatly enhance their therapeutic potential. The main goals of our work were to explore: 1) how modification of STAT3 transcription factor-binding oligodeoxynucleotide (ODN) duplexes (ODND) with one or two short fluorocarbon (FC)-based residues would change their properties in vitro and in vivo, and if so, how this would affect their intracellular uptake by cancer cells, and 2) the ability of such modified ODND to form non-covalent complexes with FC-modified carrier macromolecule...
2017: Theranostics
Lanyi Chang, Yi-Ju Chen, Chan-Yo Fan, Chin-Ju Tang, Yi-Hsiu Chen, Penk-Yeir Low, Albert Ventura, Chun-Cheng Lin, Yu-Ju Chen, Takashi Angata
Siglecs are a family of receptor-type glycan recognition proteins (lectins) involved in self-nonself discrimination by the immune system. Identification of Siglec ligands is necessary to understand how Siglec-ligand interaction translates into biological outcomes. However, this is challenging because the interaction is weak. To facilitate identification of Siglec ligands, we adopted a proximity labeling method based on the tyramide radicalization principle. Cells that express Siglec ligands were labeled with Siglec-peroxidase complexes and incubated with biotin tyramide and hydrogen peroxide, to generate short-lived tyramide radicals that covalently label the proteins near the Siglec-peroxidase complex...
September 13, 2017: Journal of Proteome Research
Richard Janissen, Prasana K Sahoo, Clelton A Santos, Aldeliane M da Silva, Antonio A G von Zuben, Denio E P Souto, Alexandre D T Costa, Paola Celedon, Nilson I T Zanchin, Diogo B Almeida, Douglas S Oliveira, Lauro T Kubota, Carlos Lenz Cesar, Anete Pereira de Souza, Monica Alonso Cotta
Electrically active field-effect transistors (FET) based biosensors are of paramount importance in life science applications, as they offer direct, fast, and highly sensitive label-free detection capabilities of several biomolecules of specific interest. In this work, we report a detailed investigation on surface functionalization and covalent immobilization of biomarkers using biocompatible ethanolamine and poly(ethylene glycol) derivate coatings - as compared to the conventional approaches using silica monoliths - in order to substantially increase both the sensitivity and molecular selectivity of nanowire-based FET biosensor platforms...
September 12, 2017: Nano Letters
Jill A Dembowski, Neal A Deluca
The goal of this protocol is to isolate herpes simplex virus type 1 (HSV-1) DNA from infected cells for the identification of associated viral and cellular proteins by mass spectrometry. Although proteins that interact with viral genomes play major roles in determining the outcome of infection, a comprehensive analysis of viral genome associated proteins was not previously feasible. Here we demonstrate a method that enables the direct purification of HSV-1 genomes from infected cells. Replicating viral DNA is selectively labeled with modified nucleotides that contain an alkyne functional group...
August 31, 2017: Journal of Visualized Experiments: JoVE
Beata Miksa, Malgorzata Sierant, Ewa Skorupska, Adam Michalski, Slawomir Kazmierski, Urszula Steinke, Artur Rozanski, Pawel Uznanski
Here we report the first of the phenosafranin-chlorambucil conjugate as a new type of a chemotherapeutic agent suitable for dual detection methods (spectrophotometric and fluorescence) in imaging systems and cancer treatment. The synthetic cationic dye (3,7-diamino-5-phenylphenazinium chloride) is used as a fluorescent light-triggered scaffold that acts as a carrier for an anti-cancer drug. The chlorambucil was attached covalently via amide bonds to the bifunctional fluorophore, which facilitates tracking with visible light...
September 1, 2017: Colloids and Surfaces. B, Biointerfaces
Rui Sun, Ling Yin, Shaohua Zhang, Lei He, Xiaju Cheng, Anna Wang, Huawei Xia, Haibin Shi
A simple and mild light-triggered fluorescent labeling approach, based on the photolysis and reactive carbene insertion of diazirine, to rapidly generate fluorescent nanoparticles is reported. Proof of concept studies demonstrated that the non-fluorescent SiNPs could be covalently labeled by diazirine-conjugated fluorescein (dFITC) upon photo irradiation (λ=365 nm) to afford fluorescent SiNPs with good fluorescent stability and low cytotoxicity. In vitro cellular imaging results indicated that the internalization of SiNPs into living cells could be readily visualized based on fluorescein-labeled SiNPs (F-SiNPs) in real time...
September 8, 2017: Chemistry: a European Journal
Peng Zhao, Justin George, Bin Li, Nooshin Amini, Janet Paluh, Jun Wang
We report a novel strategy for fabrication of multifunctional dumbbell particles (DPs) through click chemistry for monitoring single-cell cytokine releasing. Two different types of DPs were prepared on a large scale through covalent bioorthogonal reaction between methyltetrazine and trans-cyclooctene on a microchip under a magnetic field. After collection of the DPs, the two sides of each particle were further functionalized with different antibodies for cell capturing and cytokine detection, respectively. These DPs labeled with different fluorescent dyes have been used for multiplex detection and analysis of cytokines secreted by single live cells...
September 18, 2017: ACS Applied Materials & Interfaces
Mark P Hendricks, Kohei Sato, Liam C Palmer, Samuel I Stupp
Peptide amphiphiles (PAs) are small molecules that contain hydrophobic components covalently conjugated to peptides. In this Account, we describe recent advances involving PAs that consist of a short peptide sequence linked to an aliphatic tail. The peptide sequence can be designed to form β-sheets among the amino acids near the alkyl tail, while the residues farthest from the tail are charged to promote solubility and in some cases contain a bioactive sequence. In water, β-sheet formation and hydrophobic collapse of the aliphatic tails induce assembly of the molecules into supramolecular one-dimensional nanostructures, commonly high-aspect-ratio cylindrical or ribbonlike nanofibers...
September 6, 2017: Accounts of Chemical Research
Hussein Kanso, Nicolas Inguimbert, Georges Istamboulie, Lise Barthelmebs, Carole Calas-Blanchard, Thierry Noguer
New chemiluminescence-based immunoassays for sensitive detection of 17-β estradiol (E2) and ethinylestradiol (EE2) are described on the basis of the use of biotinylated estrogen derivatives. Estrogen derivatives bearing a carboxylic group (E2-COOH and EE2-COOH) on C-3 position were synthesized, covalently bound to aminated biotin and subsequently immobilized on avidin-coated microtiter plates. The assay principle was based on competition between free and immobilized estrogens for their binding to primary antibodies, with subsequent revelation using horseradish peroxidase (HRP)-labeled secondary antibodies...
September 7, 2017: Analytical Biochemistry
Ian Samuel Diner, Jeromy Dooyema, Marla Gearing, Lary Walker, Nicholas T Seyfried
The benzothiazole-aniline derivative Pittsburgh Compound B (PiB) is the prototypical amyloid affinity probe developed for the in vivo positron emission tomography (PET) detection of amyloid beta (Aβ) deposits in Alzheimer's disease (AD). Specific high-affinity binding sites for PiB have been found to vary among AD cases with comparable Aβ load, and they are virtually absent on human-sequence Aβ deposits in animal models, none of which develop the full phenotype of AD. PiB thus could be an informative probe for studying the pathobiology of Aβ, but little is known about the localization of PiB binding at the molecular or structural level...
September 1, 2017: Bioconjugate Chemistry
Yanyan Li, Manru Zhao, Haiyan Wang
We report a label-free peptide aptamer based biosensor for highly sensitive detection of TNT which was designed with a ternary assembly layer consisting of anti-TNT peptide aptamer (peptamer), dithiothreitol (DTT), and 6-mercaptohexanol (MCH), forming Au/peptamer-DTT/MCH. A linear relationship between the change in electron transfer resistance and the logarithm of the TNT concentration from 0.44 to 18.92 pM, with a detection limit of 0.15 pM, was obtained. In comparison, the detection limit of the aptasensor with a common binary assembly layer (Au/peptamer/MCH) was 0...
August 29, 2017: Analytical and Bioanalytical Chemistry
Bei Liu, Chunxia Li, Guanying Chen, Bin Liu, Xiaoran Deng, Yi Wei, Jun Xia, Bengang Xing, Ping'an Ma, Jun Lin
Elaborately designed biocompatible nanoplatforms simultaneously achieving multimodal bioimaging and therapeutic functions are highly desirable for modern biomedical applications. Herein, uniform MoS2 nanoflowers with a broad size range of 80-180 nm have been synthesized through a facile, controllable, and scalable hydrothermal method. The strong absorbance of MoS2 nanoflowers at 808 nm imparts them with high efficiency and stability of photothermal conversion. Then a novel multifunctional composite of MoS2@Fe3O4-ICG/Pt(IV) (labeled as Mo@Fe-ICG/Pt) is designed by covalently grafting Fe3O4 nanoparticles with polyethylenimine (PEI) functionalized MoS2, and then loading indocyanine green molecules (ICG, photosensitizers) and platinum (IV) prodrugs (labeled as Pt(IV) prodrugs) on the surface of MoS2@Fe3O4...
August 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Tao Wen, Ronghui Wang, America Sotero, Yanbin Li
SalmonellaTyphimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM), a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding...
August 28, 2017: Sensors
Matías Regiart, Martin Rinaldi-Tosi, Pedro R Aranda, Franco A Bertolino, Jhonny Villarroel-Rocha, Karim Sapag, Germán A Messina, Julio Raba, Martín A Fernández-Baldo
We report a microfluidic electrochemical immunosensor for Xanthomonas arboricola (XA) determination, based on the covalently immobilization of monoclonal anti-XA antibody (anti-XA) on a previously amino functionalized SBA-15 in situ synthesized in the central channel of a glass-poly(dimethylsiloxane) microfluidic immunosensor. The synthetized amino-SBA-15 was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy and infrared spectroscopy. XA was detected by a direct sandwich immunoassay through an alkaline phosphatase (AP) enzyme-labeled anti-XA conjugate...
December 1, 2017: Talanta
Kaikai Chen, Matyas Juhasz, Felix Gularek, Elmar Weinhold, Yu Tian, Ulrich F Keyser, Nicholas A W Bell
Nanopore sensors show great potential for rapid, single-molecule determination of DNA sequence information. Here, we develop an ionic current-based method for determining the positions of short sequence motifs in double-stranded DNA molecules with solid-state nanopores. Using the DNA-methyltransferase M.TaqI and a biotinylated S-adenosyl-l-methionine cofactor analogue we create covalently attached biotin labels at 5'-TCGA-3' sequence motifs. Monovalent streptavidin is then added to bind to the biotinylated sites giving rise to additional current blockade signals when the DNA passes through a conical quartz nanopore...
September 13, 2017: Nano Letters
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