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  • 1
    Publication Date: 2011-02-09
    Description: Luminescence imaging of biological parameters is an emerging field in biomedical sciences. Tools to study 2D pH distribution are needed to gain new insights into complex disease processes, such as wound healing and tumor metabolism. In recent years, luminescence-based methods for pH measurement have been developed. However, for in vivo applications, especially for studies on humans, biocompatibility and reliability under varying conditions have to be ensured. Here, we present a referenced luminescent sensor for 2D high-resolution imaging of pH in vivo. The ratiometric sensing scheme is based on time-domain luminescence imaging of FITC and ruthenium(II)tris-(4,7-diphenyl-1,10-phenanthroline). To create a biocompatible 2D sensor, these dyes were bound to or incorporated into microparticles (aminocellulose and polyacrylonitrile), and particles were immobilized in polyurethane hydrogel on transparent foils. We show sensor precision and validity by conducting in vitro and in vivo experiments, and we show the versatility in imaging pH during physiological and chronic cutaneous wound healing in humans. Implementation of this technique may open vistas in wound healing, tumor biology, and other biomedical fields.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 105 (1974), S. 1283-1291 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 1.3-Cyclohexanediones easily react with aromatic amines and triethyl orthoformate yielding enaminoketones. With malononitrile and KOH hexahydroquinolinediones can be obtained, in the presence of piperidine cyclisation to hexahydroisoquinolinones occurs. The way of cyclisation depends upon the amine part of the used enaminoketones.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 109 (1978), S. 1021-1021 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 106 (1975), S. 1207-1212 
    ISSN: 1434-4475
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reaction of 2-indanone with malonitrile and ethyl cyanoacetate provides a simple way of preparing substituted indeno[1,2-a]fluorenes. Tetracyanoethylene does not yield the desired 1-dicyano-methylene-2-indanone but gives a bisproduct (5), which with phenylhydrazine, yields 2,3-dihydro-5H-indeno-[2,1-c]pyridazine (6). In the presence of aromatic amines, 2-indanone reacts with triethyl orthoformate to give 1-anilinomethylene-2-indanones.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The applicability of various potential-sensitive dyes (PSD) for optical sensing of anions is reported. Specifically, nitrate-responsive polymer membranes have been developed which are composed of a plasticized polymer, an anion exchange catalyst, and a fluorescent dye. On exposure to nitrate, the fluorescence intensity of such membranes increases, while the wavelengths of the excitation and emission maxima remain virtually unchanged. The membranes typically are 2–4 μm thick and exhibit highest sensitivity to nitrate in the 2 to 200 mgl–1 range. Signal changes on exposure to 100 mmol/l nitrate can be as high as +300%. The detection limit is 0.2 mgl–1. The cationic PSD octadecyl acridine organe was tested in combination with a tin-organic and an indium-organic anion carrier rather than with tridodecylmethylammonium chloride, but both carriers were found to display no improved selectivity.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 359 (1997), S. 150-154 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A pH-optode is described based on 1, 3, 5, 7-tetramethyl-8-(4-dimethylamino)-4-difluorobora-3a, 4a-diaza-(s)-indacene (1) immobilized in a hydrogel matrix. Its uncharged form is non-fluorescent, whereas the protonated form displays strong emission. The quenching of the emission can be mechanistically explained by a PET (photoinduced electron transfer) from the dimethylamino group to the fluorophore. The perpendicular configuration at the C(8)-aryl bond contributes to the efficiency of the on/off-switching behavior. Incorporation of the dye into a hydrogel matrix results in a transparent sensor membrane which can be used to measure the pH in the range of 1-3. The sensor shows high signal intensity, good reproducibility, and the response characteristic is stable over hours of operation even at low pH-values.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 366 (2000), S. 481-487 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A fast responding fiber-optic microsensor for sensing pCO2 in marine sediments with high spatial resolution is presented. The tip diameter varies typically between 20 and 50 μm. In order to make the pH-indicator ¶8-hydroxypyrene-1,3,6-trisulfonate soluble in the ethyl cellulose matrix, it was lipophilized with tetraoctylammonium as the counterion [HPTS-(TOA)4]. The microsensor was tuned to sense very low levels of dissolved carbon dioxide which are typically present in marine systems. The detection limit is 0.04 hPa pCO2 which corresponds to 60 ppb CO2 of dissolved carbon dioxide. A soluble Teflon derivative with an extraordinarily high gas permeability was chosen as a protective coating to eliminate interferences by ionic species like chloride or pH. Response times of less than 1 min were observed. The performance of the new microsensor is described with respect to reproducibility of the calibration curves, dynamic range, temperature behavior, long term stability and storage stability. The effect of hydrogen sulfide as an interferent, which is frequently present in anaerobic sediment layers, was studied in detail.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A technique for coating the wells of microtiterplates with polyaniline layers and with polyaniline/enzyme layers is presented. The resulting wells are shown to be useful for assaying enzyme substrates (as exemplified for glucose via pH) and hydrogen peroxide (via the redox properties of the film). Analyte detection is based on monitoring the absorption spectra of the polyaniline, which turn purple as a result of redox processes, or green on formation of acids by enzymatic reactions. Hydrogen peroxide (a species produced by all oxidases) and glucose (which yields protons on enzymatic oxidation) have been determined in the millimolar to micromolar concentration range. High sensitivity, film stability and good reproducibility of the measurements make the system an attractive alternative to existing biosensing schemes.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 367 (2000), S. 426-428 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The first potassium optode based on a protic chromoionophore immobilized in a hydrogel matrix is presented. The highly selective protic chromoionophore consists of a cryptohemispherand moiety and a trinitroanilino chromophore part. The acidifying power of potassium ions over sodium ions is 0.6 pH units. This correlates with the findings in solution. In contrast to several crown and aza-crown based chromophores the highly pre-organized moiety allows ion detection even in aqueous environment. The detection limit for potassium ions at ¶pH 7.7 is 5 μM.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The displacement of non-specific dyes from molecularly imprinted polymer (MIP) chromatographic stationary phases has been used for the detection and quantification of ligand-polymer binding events. A blank polymer and an L-phenylalaninamide-imprinted polymer were prepared using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as a crosslinker. The MIP is first loaded with dye, and a solution of the dye in the eluent is passed through the MIP. If analyte is injected into the dye solution in the eluent, part of the dye is competitively replaced by the analyte from the MIP. Specifically, the competitive displacement of rhodamine B by amino acids and phenylalaninamide (Phe-NH2), respectively, has been studied under polar and hydrophobic elution conditions. Enantioselective binding of Phe and Phe-NH2 to the imprinted polymer was shown to occur in the micromolar concentration range. It is proposed that the displacement of non-specific dyes from MIPs be used for the development of multisensors based upon these highly specific and stable materials, which provide promising alternatives to the use of biological macromolecules in sensor technology.
    Type of Medium: Electronic Resource
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