Search results for: Fluorescence
#34562938 2021/09/20 To Up
Electrically Controlled Neurochemical Delivery from Microelectrodes for Focal and Transient Modulation of Cellular Behavior.Electrically controlled drug delivery of neurochemicals and biomolecules from conducting polymer microelectrode coatings hold great potentials in dissecting neural circuit or treating neurological disorders with high spatial and temporal resolution. The direct doping of a drug into a conducting polymer often results in low loading capacity, and the type of molecule that can be released is limited. Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with sulfonated silica nanoparticles (SNP) has been developed as a more versatile platform for drug delivery. In this work, we demonstrate that neurochemicals with different surface charge, e.g., glutamate (GLU), gamma-Aminobutyric acid (GABA), dopamine (DA), 6,7-Dinitroquinoxaline- 2,3-dione (DNQX) and bicuculline, can be, respectively, incorporated into the SNP and electrically triggered to release repeatedly. The drug loaded SNPs were incorporated in PEDOT via electrochemical deposition on platinum microelectrodes. After PEDOT/SNP(drug) coating, the charge storage capacity (CSC) increased 10-fold to 55 Â± 3 mC/cm, and the impedance at 1 kHz was also reduced approximately 6-fold. With the aid of a porous SNP, the loading capacity and number of releases of GLU was increased >4-fold and 66-fold, respectively, in comparison to the direct doping of PEDOT with GLU (PEDOT/GLU). The focal release of GLU and GABA from a PEDOT/SNP (drug) coated microelectrode were tested in cultured neurons using Ca imaging. The change in fluo-4 fluorescence intensity after electrically triggered GLU (+6.7 Â± 2.9%) or GABA (-6.8 Â± 1.6%) release indicated the successful modulation of neural activities by neurotransmitter release. In addition to activating neural activities, glutamate can also act on endothelial cells to stimulate nitric oxide (NO) release. A dual functional device with two adjacent sensing and releasing electrodes was constructed and we tested this mechanism in endothelial cell cultures. In endothelial cells, approximately 7.6 Â± 0.6 nM NO was detected in the vicinity of the NO sensor within 6.2 Â± 0.5 s of GLU release. The rise time of NO signal, T, was 14.5 Â± 2.2 s. In summary, our work has demonstrated (1) a platform that is capable of loading and releasing drugs with different charges; (2) proof of concept demonstrations of how focal release of drugs can be used as a pharmacological manipulation to study neural circuitry or NO's effect on endothelial cells.
Chao Tan, Neetu Kushwah, Xinyan Tracy Cui
1037 related Products with: Electrically Controlled Neurochemical Delivery from Microelectrodes for Focal and Transient Modulation of Cellular Behavior.96T50 ml50 mL100ug 1 G 2x5L100 mg 100 G 50 UG0.25 mg
#34562931 2021/09/16 To Up
Genetically Encoded Sensor Cells for the Screening of Glucocorticoid Receptor (GR) Effectors in Herbal Extracts.A
Chungwon Kang, Soyoun Kim, Euiyeon Lee, Jeahee Ryu, Minhyeong Lee, Youngeun Kwon
1017 related Products with: Genetically Encoded Sensor Cells for the Screening of Glucocorticoid Receptor (GR) Effectors in Herbal Extracts.100 μg100 assays2 Pieces/Box-100ug Lyophilized100 assays100ug100ug100ug Lyophilized96T
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#34562930 2021/09/15 To Up
FLIM-Based Intracellular and Extracellular pH Measurements Using Genetically Encoded pH Sensor.The determination of pH in live cells and tissues is of high importance in physiology and cell biology. In this report, we outline the process of the creation of SypHerExtra, a genetically encoded fluorescent sensor that is capable of measuring extracellular media pH in a mildly alkaline range. SypHerExtra is a protein created by fusing the previously described pH sensor SypHer3s with the neurexin transmembrane domain that targets its expression to the cytoplasmic membrane. We showed that with excitation at 445 nm, the fluorescence lifetime of both SypHer3s and SypHerExtra strongly depend on pH. Using FLIM microscopy in live eukaryotic cells, we demonstrated that SypHerExtra can be successfully used to determine extracellular pH, while SypHer3s can be applied to measure intracellular pH. Thus, these two sensors are suitable for quantitative measurements using the FLIM method, to determine intracellular and extracellular pH in a range from pH 7.5 to 9.5 in different biological systems.
Alexander S Goryashchenko, Alexey A Pakhomov, Anastasia V Ryabova, Igor D Romanishkin, Eugene G Maksimov, Alexander N Orsa, Oxana V Serova, Andrey A Mozhaev, Margarita A Maksimova, Vladimir I Martynov, Alexander G Petrenko, Igor E Deyev
1632 related Products with: FLIM-Based Intracellular and Extracellular pH Measurements Using Genetically Encoded pH Sensor.Two 96-Well Microplate KiOne 96-Well Microplate Ki100ugOne 96-Well Microplate Ki50 ug One 96-Well Microplate KiOne 96-Well Microplate KiTwo 96-Well Microplate Ki50 ug One 96-Well Microplate Ki500 testsOne 96-Well Microplate Ki
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#34562905 2021/09/04 To Up
Electrochemical Biosensors for Tracing Cyanotoxins in Food and Environmental Matrices.The adoption of electrochemical principles to realize on-field analytical tools for detecting pollutants represents a great possibility for food safety and environmental applications. With respect to the existing transduction mechanisms, i.e., colorimetric, fluorescence, piezoelectric etc., electrochemical mechanisms offer the tremendous advantage of being easily miniaturized, connected with low cost (commercially available) readers and unaffected by the color/turbidity of real matrices. In particular, their versatility represents a powerful approach for detecting traces of emerging pollutants such as cyanotoxins. The combination of electrochemical platforms with nanomaterials, synthetic receptors and microfabrication makes electroanalysis a strong starting point towards decentralized monitoring of toxins in diverse matrices. This review gives an overview of the electrochemical biosensors that have been developed to detect four common cyanotoxins, namely microcystin-LR, anatoxin-a, saxitoxin and cylindrospermopsin. The manuscript provides the readers a quick guide to understand the main electrochemical platforms that have been realized so far, and the presence of a comprehensive table provides a perspective at a glance.
Antonella Miglione, Maria Napoletano, Stefano Cinti
1850 related Products with: Electrochemical Biosensors for Tracing Cyanotoxins in Food and Environmental Matrices.96 wells 5 G500 MG 100 G250 mg 1 G 1 G1 Set
#34562903 2021/09/03 To Up
Cocaine Detection by a Laser-Induced Immunofluorometric Biosensor.The trafficking of illegal drugs by criminal networks at borders, harbors, or airports is an increasing issue for public health as these routes ensure the main supply of illegal drugs. The prevention of drug smuggling, including the installation of scanners and other analytical devices to detect small traces of drugs within a reasonable time frame, remains a challenge. The presented immunosensor is based on a monolithic affinity column with a large excess of immobilized hapten, which traps fluorescently labeled antibodies as long as the analyte cocaine is absent. In the presence of the drug, some binding sites of the antibody will be blocked, which leads to an immediate breakthrough of the labeled protein, detectable by highly sensitive laser-induced fluorescence with the help of a Peltier-cooled complementary metal-oxide-semiconductor (CMOS) camera. Liquid handling is performed with high-precision syringe pumps and microfluidic chip-based mixing devices and flow cells. The biosensor achieved limits of detection of 7 ppt (23 pM) of cocaine with a response time of 90 s and a total assay time below 3 min. With surface wipe sampling, the biosensor was able to detect 300 pg of cocaine. This immunosensor belongs to the most sensitive and fastest detectors for cocaine and offers near-continuous analyte measurement.
Martin Paul, Robert Tannenberg, Georg Tscheuschner, Marco Ponader, Michael G Weller100tests 100ul100 assays100tests100 ul96 tests400 assays1 Kit100tests
#34562902 2021/09/03 To Up
Real-Time Detection of Tumor Cells during Capture on a Filter Element Significantly Enhancing Detection Rate.Circulating tumor cells (CTCs) that enter the bloodstream play an important role in the formation of metastases. The prognostic significance of CTCs as biomarkers obtained from liquid biopsies is intensively investigated and requires accurate methods for quantification. The purpose of this study was the capture of CTCs on an optically accessible surface for real-time quantification. A filtration device was fabricated from a transparent material so that capturing of cells could be observed microscopically. Blood samples were spiked with stained tumor cells and the sample was filtrated using a porous structure with pore sizes of 7.4 Âµm. The possible removal of lysed erythrocytes and the retention of CTCs were assessed. The filtration process was observed in real-time using fluorescence microscopy, whereby arriving cells were counted in order to determine the number of CTCs present in the blood. Through optimization of the microfluidic channel design, the cell retention rate could be increased by 13% (from 76% Â± 7% to 89% Â± 5%). Providing the possibility for real-time detection significantly improved quantification efficiency even for the smallest cells evaluated. While end-point evaluation resulted in a detection rate of 63% Â± 3% of the spiked cells, real-time evaluation led to an increase of 21% to 84% Â± 4%. The established protocol provides an advantageous and efficient method for integration of fully automated sample preparation and CTC quantification into a lab-on-a-chip system.
Astrid Lux, Hannah Bott, Nisar Peter Malek, Roland Zengerle, Tanja Maucher, Jochen Hoffmann
1072 related Products with: Real-Time Detection of Tumor Cells during Capture on a Filter Element Significantly Enhancing Detection Rate.96 tests25100tests25 assays251 kit100tests
#34562863 2021/09/09 To Up
Turn-on, photostable, nontoxic and specific, iron(II) sensor.The pressing need to develop a specific analytical sensor that can identify and quantify Fe(II) without a cytotoxic response was the major motivation drive in this work. The turn-on fluorescent sensor here described can successfully detect Fe(II) and discriminate this ion from other analytes that commonly act as interferents in biological media. Moreover, this reduced fluoresceinamine-based sensor has a high photostability and high dissociation constant, which is an indication that the complex obtained between reduced fluoresceinamine (RFL) and Fe(II) is highly stable. This fluorescence-based sensor has a binding mechanism of 1:1 and a positive cooperativity was found between analyte and sensor. The detection, quantification and sensitivity parameters of the sensor were determined: 21.6Â Â±Â 0.1Â Î¼M; 65.6Â Â±Â 0.1Â Î¼M and 48Â Â±Â 3 (Ã10) Î¼M, respectively. To evaluate a possible cytotoxicity effect an erythrocyte assay was performed and the obtained data were evaluated considering CdTe Quantum Dots (QDs) passivated with mercaptoacetic acid has experimental control. According to the resulting data RFL is not cytotoxic even when used in high concentrations, 660Â mM. On the other hand QDs are quite different. Indeed it was proven that these heavy metal-based nanoparticles are responsible for 40% erytrocytes hemolysis in concentrations of 600Â mM.
Helena M R GonÃ§alves, Isabel S Tavares, Susana A F Neves, Rui Fontes, Abel J Duarte5mg0.1 mg100ug Lyophilized4 Arrays/Slide1000 tests2 Pieces/Box100ug 6 ml Ready-to-use 96 Tests/kit4 Membranes/Box2 Pieces/Box50ug
#34562860 2021/09/16 To Up
Phenanthridine based rapid "turn-on" fluorescent sensor for selective detection of Th ion and its real-time application.A new and highly sensitive and selective phenanthridine based sensor, 9-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)benzo[h]quinolin-10-ol (PHBQ), was developed for the fluorescent ''turn-on'' detection of Th ion in acetonitrile: water (8:2) medium. The fluorescence intensity of PHBQ diminished in the region of pH 1 to 3 and could be recovered by adjusting the pH to above 4. The sensor PHBQ showed distinct spectral changes in response to Th ion over other competitive metal ions. The fluorescence displayed good linearity with the Th concentration in the equivalence of 0-0.5 equivalents. The detection limit was calculated to be as low as 99Â nM, which was less than that of previously reported sensors. The recognizing mechanism of PHBQ towards Th was investigated in detail using HR-MS, NMR, and IR spectroscopy. The economically viable Whatman filter paper was fabricated with PHBQ to develop a paper-based fluorescence kit to detect the Th in an aqueous medium efficiently. Furthermore, the application of sensor ligand in fluorescence imaging was studied in E-coli cells due to its minimal cytotoxicity and good optical properties. The obtained data suggest that the ligand PHBQ can be used as a fluorescent sensor for tracking Th in multiple applications.
Sathish Sawminathan, Sathiyanarayanan Kulathu Iyer
2471 related Products with: Phenanthridine based rapid "turn-on" fluorescent sensor for selective detection of Th ion and its real-time application.1x96 well plate2596 tests/kit50ul2525 100ul1x96 well plate2525
#34562859 2021/09/16 To Up
Novel lysosome-targeted fluorescent molecular rotors based on a cyanine-like modular system and their application in living cells.Two novel fluorescence molecular rotors DpIn and NaIn were designed and synthesized involving of indolium units linked with meta-diphenol or ortha-naphthalenediol moiety, respectively. They underwent intramolecular charge transfer to form a cyanine-like modular system at a physiological pH. In glycerol aqueous solutions, the probe DpIn exhibited NIR strong emission (3-fold) at ca. 700Â nm, while the probe NaIn displayed a turn-on emission (8-fold) with a larger Stokes shift (â¿Î» â 97Â nm). The HeLa cell imaging experiments indicated probe DpIn and NaIn both exhibited excellent selectivity for staining intracellular lysosomes instead of mitochondria. H NMR spectra revealed that more electrons were accumulated around benzene ring of indolium groups, which could be the evidence for its basic character leading to the lysosomes targeted staining. Furthermore, the probe NaIn proved to be an ideal lysosome-targeting tracer for monitor the changes of viscosity caused by stimuli in living cells.
Yiping Cai, Chang Liu, Zhaoxia Lei, Zhiming Wang, Yaye Bian, Song He, Xianshun Zeng
2022 related Products with: Novel lysosome-targeted fluorescent molecular rotors based on a cyanine-like modular system and their application in living cells.0.1ml (1mg/ml) 100ul96 tests100ug Lyophilized100ug Lyophilized 100ul100 µg1mg0.1ml
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