共查询到20条相似文献,搜索用时 15 毫秒
1.
Rational design of ratiometric near-infrared fluorescent pH probes with various pKa values, based on aminocyanine 总被引:1,自引:0,他引:1
Myochin T Kiyose K Hanaoka K Kojima H Terai T Nagano T 《Journal of the American Chemical Society》2011,133(10):3401-3409
Novel ratiometric, near-infrared fluorescent pH probes with various pK(a) values have been designed and synthesized on the basis of aminocyanine bearing a diamine moiety, and their photochemical properties were evaluated. Under acidic conditions, these pH probes showed a 46- to 83-nm red shift of the absorption maximum. This change is sufficiently large to permit their use as ratiometric pH probes, and is reversible, whereas monoamine-substituted aminocyanines showed irreversible changes because of their instability under acidic conditions. Furthermore, the pK(a) values of these probes can be predicted from the calculated pK(a) values of the diamine moieties, obtained from the SciFinder database. This design strategy is very simple and flexible, and should be applicable to develop NIR pH probes for various applications. 相似文献
2.
This paper describes a novel ratiometric fluorescence sensor for pH measurement. Two pH-sensitive fluorophores, N-allyl-4-(4'-methyl-piperazinyl)-1,8-naphthalimide (AMPN) and meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP), which served as referencing indicators for each other, were co-polymerized with acrylamide, hydroxyethyl methacrylate and triethylene glycol dimethacrylate on the silanized glass surface. The proposed sensor is based on the pH-dependent fluorescence intensities of the two fluorophores in different pH ranges. The sensor covers a broad dynamic range of pH 1.5-9.0. It exhibits satisfactory analytical performance in terms of selectivity, reproducibility and stability. The successful fabrication of the proposed sensor provides an alternative concept to utilizing two or more fluorophores for the development of ratiometric sensors covering a broad range of pH. 相似文献
3.
Biomolecular recognition has long been an important theme in artificial sensing technologies. A current limitation of protein- and nucleic acid-based recognition, however, is that the useful dynamic range of single-site binding typically spans an 81-fold change in target concentration, an effect that limits the utility of biosensors in applications calling for either great sensitivity (a steeper relationship between target concentration and output signal) or the quantification of more wide-ranging concentrations. In response, we have adapted strategies employed by nature to modulate the input-output response of its biorecognition systems to rationally edit the useful dynamic range of an artificial biosensor. By engineering a structure-switching mechanism to tune the affinity of a receptor molecule, we first generated a set of receptor variants displaying similar specificities but different target affinities. Using combinations of these receptor variants (signaling and nonsignaling), we then rationally extended (to 900000-fold), narrowed (to 5-fold), and edited (three-state) the normally 81-fold dynamic range of a representative biosensor. We believe that these strategies may be widely applicable to technologies reliant on biorecognition. 相似文献
4.
Polysulphone dosimeters using a simple to use filter have been developed and tested to provide an extended dynamic measurement range of personal solar UV exposures over an extended period (3 to 6 days). At a Southern Hemisphere subtropical site (27.6 degrees S, 151.9 degrees E), the dynamic range of the filtered polysulphone allowed measurements of erythemal exposures to approximately 100 minimum erythemal dose (MED) for a change in optical absorbance at 330 nm (deltaA330) of 0.35. In comparison, unfiltered polysulphone dosimeters were exposed to approximately 8 MED for the same deltaA330. The error associated with the use of the filtered polysulphone dosimeters is of the order of +/-15%, compared with +/-10% of the unfiltered variety. The developed filtered polysulphone dosimeter system allowed the measurement of erythemal UV exposures over 3 to 6 days at a subtropical site without the need to replace the dosimeters because of saturation. The results show that longer-term measurement programs of personal solar UV have been made more feasible with the use of these polysulphone dosimeters with an extended dynamic range compared with unfiltered polysulphone dosimeters. 相似文献
5.
DG Smith BK McMahon R Pal D Parker 《Chemical communications (Cambridge, England)》2012,48(68):8520-8522
Europium and terbium complexes of two structurally related ligands have been evaluated as optical probes to monitor changes in lysosomal pH; calibration using ionophores and fluorescent probes allows monitoring of the time dependence of lysosomal pH change, examining the green/red intensity ratio from internalised Tb-Eu complexes. 相似文献
6.
Conventional optical nanoparticle pH sensors that are designed for ratiometric measurements in cells have been based on utilizing one sensor fluorophore and one reference fluorophore in each nanoparticle, which results in a relatively narrow dynamic measurement range. This results in substantial challenges when conducting live cell measurements, which often leads to misleading results. In the present work we provide a simple solution to this problem. 相似文献
7.
Palacios MA Wang Z Montes VA Zyryanov GV Hausch BJ Jursíková K Anzenbacher P 《Chemical communications (Cambridge, England)》2007,(36):3708-3710
8-Hydroxyquinoline-based ligands with extended conjugated fluorophores were designed to provide turn-on and ratiometric signal output optimized for use in fluorescence-based sensor arrays, where the changes in blue and green channels of the RGB signal are used to distinguish between cationic analytes. 相似文献
8.
I. Sánchez-Barragán A. Sanz-Medel Francisco J. Ferrero Juan Carlos Campo 《Analytica chimica acta》2006,562(2):197-203
A new fiber-optic prototype of luminometer has been designed in order to perform ratiometric-based measurements for optical sensing purposes. The coupling of a pH-selective sensing phase to the fiber-optic prototype has been evaluated for robust pH optosensing in drinking water. The pH-sensitive material has been synthesized by entrapping a pH-sensitive luminescent indicator (mercurochrome) in a sol-gel inorganic matrix. The pH optosensing is based on the detection of pH-induced reversible changes in the mercurochrome fluorescent emission and in the light reflected by the sensing phase.The instrument has been constructed using low-cost and simple optoelectronic components. The active phase was excited by means of a visible 470 nm high intensity light emitting diode (LED). The radiant power of the LED was modulated using a sinusoidal function so that scattered light due to light sources of different frequency than the modulating signal (e.g. sunlight) can be easily removed by adequate electronic filtering of the emission signal. Both the fluorescence emission from the dye and the sensing phase reflected light were collected in a bifurcated fiber-optic to allow the ratiometric measurement.Two different ratiometric approaches have been evaluated. The analytical performance of the pH optrode using both measurement methods have been compared, between them and with simple fluorescence intensity measurements, in terms of sensitivity, measurement range, response time, repeatability and insensitivity to changes in excitation light intensity.The applicability of the developed pH optrode and methods has been tested for pH analysis in tap and bottled still mineral water samples. The results obtained showed good agreement with the corresponding pH values provided by a commercial glass electrode.In this work, pH was selected as a model analyte to evaluate the performance of the proposed methodology, although other optical sensors for different applications/analytes could benefit of this approach. 相似文献
9.
Samar Alheety Domenic Valenti Nirvani Mujumdar Nakita Ellis Andres D. Campiglia James K. Harper Emily C. Heider 《Photochemistry and photobiology》2020,96(6):1176-1181
Utilizing organisms as sources of fluorophores relieves the demand for petroleum feedstock in organic synthesis of fluorescent products, and endophytic fungi provide a promising vein for natural fluorescent products. We report the characterization of a pH-responsive fluorophore from an endophytic fungus isolated from sand pine. The endogenous fluorescence of the live organism was measured using fluorescence microscopy. Computational interpretation of the spectra was accomplished with time-dependent density functional theory methods. The combined use of experimental and theoretically predicted spectra revealed the pH equilibria and photoexcited tautomerization of the natural product, 5-methylmellein. This product shows promise both as a stand-alone pH-indicating fluorophore, with alkaline pKa, and as "green" feedstock for synthesis of custom fluorophores. 相似文献
10.
An optical pH sensor was developed based on the fluorophor, fluoresceinamine isomer II (FA), covalently immobilized in a sol–gel matrix. This sol–gel matrix was created by the copolymerization of two precursors, methyltriethoxysilane (MTES) and 3-glycidoxypropyltrimethoxysilane (GPTMS), in an ethanolic solution. Fluoresceinamine was covalently bound to the glycidoxypropyl chain group of GPTMS, thereby preventing it from leaching. Moreover, the immobilization of the fluoresceinamine also extended its linear detection range. The sensor showed good repeatability, a short response time of less than 8 s, high long-term stability and no temperature effect in the biologically relevant range. In the pH range of 4–10, the sensor was very sensitive and its linear range was found to be between pH 6 and 9 (R2 = 0.995). 相似文献
11.
Following excitation in the range 370-405 nm, the emission spectrum of a cell permeable macrocyclic Eu(III) complex incorporating an N-methylsulfonamide moiety changes form with pH, allowing ratiometric pH measurements in the range 6 to 8. 相似文献
12.
《中国化学快报》2021,32(10):3057-3060
Intracellular pH is a key parameter related to various biological and pathological processes. In this study, a ratiometric pH fluorescent sensor ABTT was developed harnessing the amino-type excited-state intramolecular proton transfer (ESIPT) process. Relying on whether the ESIPT proceeds normally or not, ABTT exhibited the yellow fluorescence in acidic media, or cyan fluorescence in basic condition. According to the variation, ABTT behaved as a promising sensor which possessed fast and reversible response to pH change without interference from the biological substances, and exported a steady ratiometric signal (I478/I546). Moreover, due to the ESIPT effect, large Stokes shift and high quantum yield were also exhibited in ABTT. Furthermore, ABTT was applied for monitoring the pH changes in living cells and visualizing the pH fluctuations under oxidative stress successfully. These results elucidated great potential of ABTT in understanding pH-dependent physiological and pathological processes. 相似文献
13.
Niu CG Gui XQ Zeng GM Guan AL Gao PF Qin PZ 《Analytical and bioanalytical chemistry》2005,383(2):349-357
A fluorescence ratiometric sensor for pH determination is described in this paper. The sensor incorporated the pH-sensitive
dye meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP) as an indicator and a pH-insensitive dye N-(2-methacryloxyethyl)benzo[k,l]thioxanthene-3,4-dicarboximide (MBTD), a benzothioxanthene derivative, as a reference for fluorescence ratiometric measurement.
To prevent leakage of the dyes, both were photocopolymerized with acrylamide, hydroxyethyl methacrylate, and triethylene glycol
dimethacrylate on the silanized glass surface. The reproducibility and response time of the prepared sensor were sufficient.
Most common coexisting inorganic ions and organic compounds did not interfere with pH sensing. In the acidic pH range from
1.5 to 5.0 the fluorescence intensity ratio of the two dyes varied linearly as a function of pH. The sensing membrane was
found to have a lifetime of at least one month. The sensor was applied to the analysis of waste water and artificial samples. 相似文献
14.
A self-assembled acid-functionalised monolayer on a gold surface has an interfacial pH 2.93 more acidic than the bulk and surface pK(a) very similar to that of the free acid. 相似文献
15.
Two pH-sensitive neutral carrier/PVC electrodes are used simultaneously for the measurement of pH by flow injection. One of these is based on the neutral carrier tridodecylamine and the other on octadecyl isonicotinate, and together they allow the pH range 1–13 to be covered. These electrodes have been used in a very low dispersion miniature potentiometric flow cell designed specifically for use in flow injection in conjunction with a multi-channel data acquisition system. The effects of the solution ionic strength and buffer capacity on the pH measurement are discussed. A flow-injection manifold is proposed which can be used for high-accuracy pH measurements without ionic strength adjustment of the sample and for simultaneous pH and ion concentration measurements with ionic strength adjustment. This has been tested on some synthetic samples for the simultaneous determination of potassium and calcium and the measurement of pH. 相似文献
16.
Yuan L Lin W Cao Z Wang J Chen B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(4):1247-1255
Dual-excitation ratiometric fluorescent probes allow the measurement of fluorescence intensities at two excitation wavelengths, which should provide a built-in correction for environmental effects. However, most of the small-molecule dual-excitation ratiometric probes that have been reported thus far have shown rather limited separation between the excitation wavelengths (20-70 nm) and/or a very small molar absorption coefficient at one of the excitation wavelengths. These shortcomings can lead to cross-excitation and thus to errors in the measurement of fluorescence intensities and ratios. Herein, we report a FRET-based molecular strategy for the construction of small-molecule dual-excitation ratiometric probes in which the donor and acceptor excitation bands exhibit large separations between the excitation wavelengths and comparable excitation intensities, which is highly desirable for determining the fluorescence intensities and signal ratios with high accuracy. Based on this strategy, we created a coumarin-rhodamine FRET platform that was then employed to develop the first class of FRET-based dual-excitation ratiometric pH probes that have two well-resolved excitation bands (excitation separations>160 nm) and comparable excitation intensities. In addition, these pH probes may be considered as in a kind of "secured ratioing mode". As a further application of these pH probes, the dual-excitation ratiometric pH probes were transformed into the first examples of photocaged dual-excitation ratiometric pH probes to improve the spatiotemporal resolution. It is expected that the modular nature of our FRET-based molecular strategy should render it applicable to other small-molecule dual-dye energy-transfer systems based on diverse fluorescent dyes for the development of a wide range of dual-excitation ratiometric probes with outstanding spectral features, including large separations between the excitation wavelengths and comparable excitation intensities. 相似文献
17.
Geiser L Henchoz Y Galland A Carrupt PA Veuthey JL 《Journal of separation science》2005,28(17):2374-2380
CZE allows to measure the acidic dissociation constant (pKa) of many drug substances. However, determining the EOF intensity may be time-consuming, especially at a low pH. In order to overcome this drawback, a dynamic coating procedure of the capillary was carried out to increase microEOF, and thus to reduce the analysis time. In addition, this coating procedure enhanced migration time stability. The effective mobilities of 15 compounds were measured at different pH, producing pK'a values dependent on BGE ionic strength. The latter values were corrected with the activity coefficient to obtain a "true" pKa value. The 15 investigated compounds were (i) five acids: namely, salicylic acid, benzoic acid, ketoprofen, phenobarbital, and phenol, (ii) four bases: lidocaine, propafenone, propranolol, and quinine, (iii), five ampholytes: sulfanilamide, sulfabenzamide, sulfadimethoxine, sulfadoxine, and sulfisoxazole, and (iv) one zwitterion: cetirizine. The range of determined pKa values was between 1.2 and 11.2, and close to the pKa values available from the literature. 相似文献
18.
N.J. Miller-Ihli T.C. O''Haver J.M. Harnly 《Spectrochimica Acta Part B: Atomic Spectroscopy》1984,39(12):1603-1614
Several curve fitting methods, including linear, quadratic, and rational least squares fits and linear, cubic spline, and Stineman interpolations, are evaluated for their ability to fit highly nonlinear atomic absorption analytical calibration curves. In addition, the number of standards required to effectively calibrate a dynamic range covering 3 orders of magnitude of concentration is determined. Finally, the concentration ranges providing minimum relative concentration precision (RCP) are identified and the slopes of the calibration curves in these ranges are noted. Concentration ranges of minimum RCP also provide minimum curve fitting errors and generally have log-log slopes of approximately 0.5 indicating that linearity alone is not a sufficient criterion for choosing suitable calibration and curve fitting concentration ranges. 相似文献
19.
《Letters in Heat and Mass Transfer》1979,6(6):469-477
An analysis is made of a heat pipe operating close to saturation and some specific features of operation with superheating of vapor are noted. Experimental investigation was carried out in a heat pipe with ethanol as a working fluid at the vapor temperatures exceeding 520 K. 相似文献
20.
Qian Pengcheng Qin Yingnan Lyu Yanlong Li Yunfei Wang Lei Wang Shuo Liu Yaqing 《Analytical and bioanalytical chemistry》2019,411(8):1517-1524
Analytical and Bioanalytical Chemistry - Highly sensitive detection of H2O2 and glucose is critical for fundamental research and disease diagnosis. A ratiometric sensor can simultaneously afford... 相似文献