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https://www.readbyqxmd.com/read/28436517/real-time-measurement-of-the-intracellular-ph-of-yeast-cells-during-glucose-metabolism-using-ratiometric-fluorescent-nanosensors
#1
Mohamed M Elsutohy, Veeren M Chauhan, Robert Markus, Mohammed Aref Kyyaly, Saul J B Tendler, Jonathan W Aylott
Intracellular pH is a key parameter that influences many biochemical and metabolic pathways that can also be used as an indirect marker to monitor metabolic and intracellular processes. Herein, we utilise ratiometric fluorescent pH-sensitive nanosensors with an extended dynamic pH range to measure the intracellular pH of yeast (Saccharomyces cerevisiae) during glucose metabolism in real-time. Ratiometric fluorescent pH-sensitive nanosensors consisting of a polyacrylamide nanoparticle matrix covalently linked to two pH-sensitive fluorophores, Oregon green (OG) and 5(6)carboxyfluorescein (FAM), and a reference pH-insensitive fluorophore, 5(6)carboxytetramethylrhodamine (TAMRA), were synthesised...
April 24, 2017: Nanoscale
https://www.readbyqxmd.com/read/28426068/amplification-of-the-molecular-chiroptical-effect-by-low-loss-dielectric-nanoantennas
#2
Weixuan Zhang, Tong Wu, Rongyao Wang, Xiangdong Zhang
We report here the chiroptical amplification effect occurring in the hybrid systems consisting of chiral molecules and Si nanostructures. Under resonant excitation of circularly polarized light, the hybrid systems show strong CD induction signals at the optical frequency, which arise from both the electric and magnetic responses of the Si nanostructures. More interestingly, the induced CD signals from Si-based dielectric nanoantennas are always larger than that from Au-based plasmonic counterparts. The related physical origin was disclosed...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28415440/template-electrodeposition-of-high-performance-copper-oxide-nanosensors-for-electrochemical-analysis-of-hydrogen-peroxide
#3
Gajjala Rajendra Kumar Reddy, P Suresh Kumar
We report on the facile electrodeposition of copper nanostructures on graphite lead substrate using anionic, cationic and non-ionic surfactant templates. Physical and electrochemical characterisation confirmed the influence of templates on the morphology and electrochemical catalytic activities of the copper electrodeposits. These electrodes were shown to be excellent electrocatalyst for the fast detection of hydrogen peroxide. A maximum sensitivity of 951.45μA/mM/cm(2), LOD of 0.43μM, response time of <1s and a linearity in wide range of concentration from 1μM to 5mM were observed when sodium dodecyl sulfate was used as the template...
June 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28399445/sensitive-detection-of-alkaline-phosphatase-by-switching-on-gold-nanoclusters-fluorescence-quenched-by-pyridoxal-phosphate
#4
Mohamed Ibrahim Halawa, Wenyue Gao, Muhammad Saqib, Shimeles Addisu Kitte, Fengxia Wu, Guobao Xu
In this work, we designed highly sensitive and selective luminescent detection method for alkaline phosphatase using bovine serum albumin functionalized gold nanoclusters (BSA-AuNCs) as the nanosensor probe and pyridoxal phosphate as the substrate of alkaline phosphatase. We found that pyridoxal phosphate can quench the fluorescence of BSA-AuNCs and pyridoxal has little effect on the fluorescence of BSA-AuNCs. The proposed mechanism of fluorescence quenching by PLP was explored on the basis of data obtained from high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), UV-vis spectrophotometry, fluorescence spectroscopy, fluorescence decay time measurements and circular dichroism (CD) spectroscopy...
April 6, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28397497/semipermeable-functional-dna-encapsulated-nanocapsules-as-protective-bioreactors-for-biosensing-in-living-cells
#5
Cheng-Yi Hong, Shu-Xian Wu, Shi-Hua Li, Hong Liang, Shan Chen, Juan Li, Huang-Hao Yang, Weihong Tan
The development of functional DNA-based nanosensors in living cells has experienced some design challenges, including, for example, poor cellular uptake, rapid nuclease degradation, and high false positives. Herein, we designed selectively permeable poly(methacrylic acid) (PMA) nanocapsules to encapsulate functional DNAs for metal ions and small-molecules sensing in living cells. Since functional DNAs are concentrated in the nanocapsules, an increasing reaction rate is obtained in vitro. During endocytosis, polymeric capsules simultaneously improve cellular uptake of functional DNAs and preserve their structural integrity inside the confined capsule space...
April 25, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28394490/synthesis-and-validation-of-functional-nanogels-as-ph-sensors-in-the-hair-follicle
#6
Mathias Dimde, Fitsum Feleke Sahle, Virginia Wycisk, Dirk Steinhilber, Luis Cuellar Camacho, Kai Licha, Jürgen Lademann, Rainer Haag
In the present study, a pH responsive dendritic polyglycerol nanogel (dPG-NG) is developed to measure the pH values inside the hair follicle (HF) using an ex vivo porcine ear model. The macromolecular precursors are labeled with a pH sensitive indodicarbocyanine dye (pH-IDCC) and a control dye (indocarbocyanine dye: ICC) and crosslinked via a mild and surfactant-free Thiol-Michael reaction using an inverse nanoprecipitation method. With this method, it is possible to prepare tailor-made particles in the range of 100 nm to 1 µm with a narrow polydispersity...
April 10, 2017: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28390322/simple-and-highly-selective-detection-of-arsenite-based-on-the-assembly-induced-fluorescence-enhancement-of-dna-quantum-dots
#7
Li Zhang, Xiu-Zhi Cheng, Lan Kuang, Ai-Zhen Xu, Ru-Ping Liang, Jian-Ding Qiu
Novel fluorescent DNA quantum dots (QDs) were synthesized by hydrothermal treatment of G-/T-rich ssDNA at relatively low reaction temperature. The obtained DNA QDs demonstrate unique optical properties, maintain the basic structure and biological activities of ssDNA precursors, which makes the DNA QDs able to specifically bind with arsenite, driving the (GT)29 region suffer conformation evolution and form well-ordered assembly rather than random aggregations. We speculate that the strong inter-molecule interaction and efficient stacking of base pairs stiffen the assembly structure, block the nonradiative relaxation channels, populate the radiative decay, and thus making the assembly be highly emissive as a new fluorescence center...
March 30, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28382350/highly-sensitive-biosensors-based-on-all-dielectric-nanoresonators
#8
Nicolò Bontempi, Katie E Chong, Henry W Orton, Isabelle Staude, Duk-Yong Choi, Ivano Alessandri, Yuri S Kivshar, Dragomir N Neshev
Biosensing based on nanophotonic structures has shown a great potential for cost-efficient, high-speed and compact personal medical diagnostics. While plasmonic nanosensors offer high sensitivity, their intrinsically restricted resonance quality factors and strong heating due to metal absorption impose severe limitations on real life applications. Here, we demonstrate an all-dielectric sensing platform based on silicon nanodisks with strong optically-induced magnetic resonances, which are able to detect a concentration of streptavidin of as low as 10(-10) M (mol L(-1)) or 5 ng mL(-1), thus pushing the current detection limit by at least two orders of magnitudes...
April 6, 2017: Nanoscale
https://www.readbyqxmd.com/read/28379693/influence-of-linker-flexibility-on-the-binding-affinity-of-bidentate-binders
#9
Miguel A Soler, Sara Fortuna
The design of responsive nanosensors typically relies on the availability of probes capable of capturing their target with high affinity and specificity. This can be achieved by coupling two or more binding units through a linker. In this work, we study the dependence on the binder architecture of the binding affinity between a target molecule and a semi-rigid bidentate binder. Using two different binder architectures, central-rigid and extreme-rigid, and modifying the length and the flexibility degree of the linker we generated 153 different architectures...
April 5, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28379687/kinetic-requirements-for-spatiotemporal-chemical-imaging-with-fluorescent-nanosensors
#10
Daniel Meyer, Annika Hagemann, Sebastian Kruss
Fluorescent nanosensors are powerful tools for basic research and bioanalytical applications. Individual nanosensors are able to detect single molecules, while ensembles of nanosensors can be used to measure the bulk concentration of an analyte. Collective imaging of multiple nanosensors could provide both spatial and temporal chemical information from the nano- to the microscale. This type of chemical imaging with nanosensors would be very attractive to study processes such as chemical signaling between cells (e...
April 25, 2017: ACS Nano
https://www.readbyqxmd.com/read/28372728/determination-of-cdna-encoding-bcr-abl-fusion-gene-in-patients-with-chronic-myelogenous-leukemia-using-a-novel-fret-based-quantum-dots-dna-nanosensor
#11
Mojtaba Shamsipur, Vahid Nasirian, Ali Barati, Kamran Mansouri, Asad Vaisi-Raygani, Soheila Kashanian
In the present study, we developed a sensitive method based on fluorescence resonance energy transfer (FRET) for the determination of the BCR/ABL fusion gene, which is used as a biomarker to confirm the clinical diagnosis of both chronic myelogenous leukemia (CML) and acute lymphocytic leukemia (ALL). For this purpose, CdTe quantum dots (QDs) were conjugated to amino-modified 18-mer oligonucleotide ((N)DNA) to form the QDs-(N)DNA nanosensor. In the presence of methylene blue (MB) as an intercalator, the hybridization of QDs-(N)DNA with the target BCR/ABL fusion gene (complementary DNA), brings the MB (acceptor) at close proximity of the QDs (donor), leading to FRET upon photoexcitation of the QDs...
May 8, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28368062/graphene-quantum-dot-based-switch-on-nanosensors-for-intracellular-cytokine-monitoring
#12
Guozhen Liu, Kai Zhang, Ke Ma, Andrew Care, Mark R Hutchinson, Ewa M Goldys
The detection of cytokines in body fluids, cells, tissues and organisms continues to attract considerable attention due to the importance of these key cell signalling molecules in biology and medicine. We report a graphene quantum dot (GQD) based aptasensor able to specifically detect ultra-small amounts of cytokine molecules intracellularly. Graphene quantum dots modified with cytokine aptamers (Ap-GQDs) and epitope modified GQDs (Ep-GQDs) were prepared; both are normally fluorescent at sufficient dilution...
April 3, 2017: Nanoscale
https://www.readbyqxmd.com/read/28359155/visualization-and-inhibition-of-mitochondria-nuclear-translocation-of-apoptosis-inducing-factor-by-a-graphene-oxide-dna-nanosensor
#13
Yuhui Sun, Wen Gao, Yujie Zhao, Wenhua Cao, Zhenhua Liu, Guanwei Cui, Lili Tong, Fengcai Lei, Bo Tang
High concentrations of oxidized low density lipoprotein (oxLDL) induce aberrant apoptosis of vascular smooth muscle cells (VSMCs) in atherosclerotic plaques. This apoptosis cannot be blocked completely by the inhibition of caspase, and it eventually potentiates plaque disruption and risk for cardiovascular disease. Given the important role of apoptosis inducing factor (AIF) in caspase-independent apoptosis, here we develop an AIF-targeting nanosensor by the assembly of graphene oxide (GO) nanosheets and dye-labeled DNA hybrid structures...
April 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28355161/sensitive-detection-of-pdt-induced-cell-damages-with-luminescent-oxygen-nanosensors
#14
Hong-Ru Ma, Hong-Shang Peng, Fang-Tian You, Jian-Tao Ping, Chao Zhou, Lan-Ying Guo
In this work luminescent nanosensors specifically created for intracellular oxygen (ic-O2) were utilized to assess photodynamic therapy (PDT) -induced cell damages. Firstly, ic-O2 was demonstrated to be consumed much faster than extracellular O2 with respective O2 nanosensors. Using the ic-O2 nanosensors, PDT-treated cells with different degree of impairment were then resolved according to the oxygen consumption rate (OCR). The evolving trend of cytotoxicity derived from OCRs was in agreement with cell viability obtained from 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay...
July 28, 2016: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28352000/crosslinked-polymer-nanoparticles-containing-single-conjugated-polymer-chains
#15
Rodrigo A Ponzio, Yésica L Marcato, María L Gómez, Carolina V Waiman, Carlos A Chesta, Rodrigo E Palacios
Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension...
March 29, 2017: Methods and Applications in Fluorescence
https://www.readbyqxmd.com/read/28342376/label-free-silicon-nanodots-featured-ratiometric-fluorescent-aptasensor-for-lysosomal-imaging-and-ph-measurement
#16
Yanan Zhang, Shan Guo, Shibo Cheng, Xinghu Ji, Zhike He
The homeostasis of lysosomal pH is crucial in cell physiology. Developing small fluorescent nanosensors for lysosome imaging and ratiometric measurement of pH is highly demanded yet challenging. Herein, a pH-sensitive fluorescein tagged aptamer AS1411 has been utilized to covalently modify the label-free fluorescent silicon nanodots via a crosslinker for construction of a ratiometric pH biosensor. The established aptasensor exhibits the advantages of ultrasmall size, hypotoxicity, excellent pH reversibility and good photostability, which favors its application in an intracellular environment...
March 22, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28341740/nanomolar-nitric-oxide-concentrations-quickly-and-reversibly-modulate-astrocytic-energy-metabolism
#17
Alejandro San Martín, Robinson Arce-Molina, Alex Galaz, Gustavo Pérez-Guerra, L Felipe Barros
Nitric oxide (NO) is an intercellular messenger involved in multiple bodily functions. Prolonged NO exposure irreversibly inhibits respiration by covalent modification of mitochondrial cytochrome oxidase, a phenomenon of pathological relevance. However, the speed and potency of NO's metabolic effects at physiological concentrations are incompletely characterized. To this end, we set out to investigate the metabolic effects of NO in cultured astrocytes from mice by taking advantage of the high spatiotemporal resolution afforded by genetically-encoded Foerster resonance energy transfer (FRET) nanosensors...
March 24, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28341438/engineering-a-novel-porin-ompgf-via-strand-replacement-from-computational-analysis-of-sequence-motif
#18
Meishan Lin, Ge Zhang, Monifa Fahie, Leslie K Morgan, Min Chen, Timothy A Keiderling, Linda J Kenney, Jie Liang
β-Barrelmembrane proteins (βMPs) form barrel-shaped pores in the outer membrane of Gram-negative bacteria, mitochondria, and chloroplasts. Because of the robustness of their barrel structures, βMPs have great potential as nanosensors for single-molecule detection. However, natural βMPs currently employed have inflexible biophysical properties and are limited in their pore geometry, hindering their applications in sensing molecules of different sizes and properties. Computational engineering has the promise to generate βMPs with desired properties...
March 21, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28340708/phosphoserine-imprinted-nanosensor-for-detection-of-cancer-antigen-125
#19
Sibel Büyüktiryaki, Rıdvan Say, Adil Denizli, Arzu Ersöz
Cancer antigen 125 (CA 125) is widely used as diagnostic biomarker for ovarian cancer. Change in the concentration level of CA 125 is associated with disease progression or regression. CA 125 posseses a phosphorylation site and protein backbone is phosphorylated on serine, before secretion. In this study, we have developed an imprinting method for CA 125 recognition and determination. In this method, methacryloyl antipyrine europium (III) [(MAAP)2-Eu(III)] and methacryloyl antipyrine terbium (III) [(MAAP)2-Tb(III)] have been used as new metal-chelating monomers via metal coordination-chelation interactions...
May 15, 2017: Talanta
https://www.readbyqxmd.com/read/28339185/red-emission-b-n-s-co-doped-carbon-dots-for-colorimetric-and-fluorescent-dual-mode-detection-of-fe-3-ions-in-complex-biological-fluids-and-living-cells
#20
Yinghua Liu, Wenxiu Duan, Wei Song, Juanjuan Liu, Cuiling Ren, Jiang Wu, Dan Liu, Hongli Chen
Colorimetric and fluorescent dual mode detection methods have gained much attention in recent years; however, it is still desirable to develop new colorimetric and fluorescent dual mode nanosensors with more simple preparation procedures, low cost, and excellent biocompatibility. Herein, a colorimetric and fluorescent nanosensor based on B, N, S-co-doped carbon dots (BNS-CDs) was synthesized by one-step hydrothermal treatment of 2,5-diaminobenzenesulfonic acid and 4-aminophenylboronic acid hydrochloride. Using this nanosensor, a highly sensitive assay of Fe(3+) in the range of 0...
April 3, 2017: ACS Applied Materials & Interfaces
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