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  • 1
    Electronic Resource
    Electronic Resource
    Fiber-Optic DNA Sensor for Fluorometric Nucleic Acid Determination (1995)
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 2635-2643 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00111a022
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  • 2
    Electronic Resource
    Electronic Resource
    Depth Profiling of Functionalized Silane Films on Quartz and Silicon Substrates and of Urease Immobilized on Such Films by Angle-Resolved X-ray Photoelectron Spectroscopy (1995)
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 2625-2634 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00111a021
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray photoelectron spectroscopy of silica surfaces treated with polyfunctional silanes (1988)
    s.l. : American Chemical Society
    Analytical chemistry 60 (1988), S. 169-172 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00153a014
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  • 4
    Electronic Resource
    Electronic Resource
    Self-quenching of nitrobenzoxadiazole labeled phospholipids in lipid membranes (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 6019-6027 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The emission intensity, wavelength, and lifetime of the fluorophore nitrobenzoxadiazole dipalmitoylphosphatidylethanolamine (NBD-PE) are sensitive to the local environmental structure when this species is present as a component of an amphiphilic membrane. Alterations of the physical and electrostatic structure of a membrane can result in changes in the fluorescence signal owing to changes in the extent of self-quenching of the probe. To investigate self-quenching, NBD-PE was incorporated into monolayers and vesicles composed of Egg phosphatidylcholine at concentrations of 0.1 to 50 mol %. Monolayer samples were dipcast onto glass slides at a pressure of 35 mN m−1. Both the integrated intensity per fluorophore (quantum yield) from vesicles and dipcast monolayers, and the mean fluorescence lifetime from vesicles decreased as the concentration of fluorophore in the membranes was increased. At all concentrations studied the decay of NBD-PE fluorescence was fitted to two discrete exponentials, and both lifetime components were observed to change with concentration. The complexity of the fluorescence decay did not permit the use of standard theoretical models such as the Klafter–Blumen or Stern–Volmer equations which are normally employed to describe changes in fluorescence lifetime with changes in quencher concentration. Instead, a phenomenological approach was used to develop an empirical model of fluorescence self-quenching which could describe the observed alterations in the fluorescence lifetime and intensity. The model was based on a combination of Perrin quenching and Förster energy transfer. The fluorescence data was fit by a model wherein NBD-PE formed nonemissive trap sites with a critical radius of Rc=1.0±0.1 nm (Perrin quenching), with Förster energy transfer occurring to the trap sites with an R0 value of 2.55±0.10 nm as determined from spectral overlap integrals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467112
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of phospholipids suitable for covalent binding to surfaces (1987)
    s.l. : American Chemical Society
    The @journal of organic chemistry 52 (1987), S. 5478-5480 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00233a037
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on the keto-enol equilibria of methyl 2-oxocycloalkanoates with 5-8 carbons in the ring by IR, carbon-13 NMR, and mass spectrometry (1988)
    s.l. : American Chemical Society
    The @journal of organic chemistry 53 (1988), S. 1320-1322 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00241a040
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  • 7
    Electronic Resource
    Electronic Resource
    Stabilized bilayer lipid membranes for flow-through experiments (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 531-536 
    Details
    ISSN: 1040-0397
    Keywords: Biosensors ; Bilayer lipid membranes ; Stabilization ; Flow-through injection ; Differential scanning calorimetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work reports a technique for the stabilization of solventless bilayer lipid membranes (BLMs), and the use of stabilized BLMS as flow detectors. Microporous filters composed of glass fibers, polytetrafluoroethylene (PTFE) and polycarbonate (nominal pore sizes from 1 to 5 μM) can serve as interfaces that separate two solution compartments. The micropores in the filter media can act as supports for formation and stabilization of BLMs. One of the solution compartments is used to cast lipid films on the filters, while a carrier electrolyte solution concurrently flows through the opposing compartment. Optimization of the flow cell design, and the chemical composition and methods for preparation of stabilized BLMs, are described. Lipid membranes composed of mixtures of phosphatidyl choline and phosphatidic acid could respond rapidly to pH alterations of the carrier electrolyte solution. Signals would reproducibly appear within a few seconds following the injection of an electrolyte of different pH than the carrier. Signals took the form of a single ion current transient with magnitude of tens of picoamperes (pA) and a duration of seconds. The mechanism of signal generation is explored by differential scanning calorimetry. The results show that a phase transition within a lipid membrane can be triggered by pH alterations of the electrolyte solution. Stabilized BLMs which provide artificial ion gating events hold prospects for chemical sensing of process streams.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140070605
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  • 8
    Electronic Resource
    Electronic Resource
    Bilayer lipid membranes as electrochemical detectors for flow injection immunoanalysis (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 1082-1089 
    Details
    ISSN: 1040-0397
    Keywords: Immunological reaction ; Bilayer lipid membranes ; Flow injection ; Differential scanning calorimetry ; Antibody regeneration ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This work describes the use of filter-supported stabilized bilayer lipid membranes (BLMs) for the rapid electrochemical monitoring of an immunological reaction in flowing solution streams. BLMs were prepared from egg phosphatidylcholine (egg PC) and dipalmitoyl phosphatidic acid (DPPA) and the ultrafiltration membranes used were composed of glass microfibers. Thyroxin (T4)/anti-rabbit T4 was used as a representative immunological reaction for these studies. Antibody was incorporated into a floating lipid matrix at an air-electrolyte interface, and then a casting procedure was used to deliver the lipid onto the filter supports for BLM formation. Injections of antigen were made into flowing streams of a carrier electrolyte solution. Experiments were done in a stopped-flow mode using lipid mixtures containing 15% (w/w) DPPA to provide only a single transient current signal with a magnitude related to the antigen concentration. Differential scanning calorimetric experiments provided evidence that the antibody-lipid interactions at the BLMs occurred through electrostatic interactions. BLMs containing 35% DPPA were used to examine regeneration of the active sites of antibody after complex formation by washing with the carrier electrolyte solution. Repetitive cycles of injection of antigen followed by regeneration of antibody binding activity have shown that the maximum number of cycles is about 5, followed by a degradation of signal for a larger number of injections. However, the sensor can also be easily regenerated by recasting of the existing lipid/antibody film at the air-electrolyte interface to form fresh BLMs.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140071116
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  • 9
    Electronic Resource
    Electronic Resource
    Mass spectra of aliphatic dicarboxylic acids and their dimethyl esters: Cyclic structures for the [M - H2O]+· ions from the diacids and [M - MeOH]+· ions from the dimethyl esters (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 723-728 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 2-oxocycIoalkane carboxylate structures are proposed lor the [M - MeOH]+· ions from dimethyl adipate, pimelate, suberate and azelate. This proposal is based on a comparison of the metastable ion mass spectra and the kinetic energy releases for the major fragmentation reaction of these species with the same data for the molecular ions of authentic cyclic β-keto esters. The mass spectra of α,α,α′,α′-d4-pimelic acid and its dimethyl ester indicate that the α-hydrogens are involved only to a minor extent in the formation of [M - ROH]+· and [M - 2ROH]+· ions, while these α-hydrogens are involved almost exclusively in the loss of ROH from the [M - RO·]+ ions (R = H or CH3). The molecules XCO(CH2)7COOMe (X = OH, Cl) form abundant ions in their mass spectra with the same structure as the [M - 2MeOH]+· ions from dimethyl azelate.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210231009
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  • 10
    Electronic Resource
    Electronic Resource
    Fast atom bombardment mass spectrometry of some alkoxv- and chloro-silanes (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 26 (1991), S. 81-84 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The positive and negative FAB mass spectra of a series of alkoxy- and chloro-silanes Xm(CH3)3-mSi(CH2)nR [m = 1 or 3, n = 3, 10 or 17, X = Cl or OMe or OEt, R = Me, NH2, glycidoxy, COOMe, NHCO(CH2)7COOMe or NHCO(CH2)10CH2OAc] were recorded in NBA and NPOE matrices. The chlorosilanes underwent rapid hydrolysis into silanols which condense to form siloxanes, the process being complete in NBA and partial in NPOE, yielding siloxane-based fragment ions in the positive spectra and silyloxyanions in the negative spectra. The alkoxysilanes were more resistant to hydrolysis, affording abundant [MH - HX]+ ions (X = OMe or OEt) in their positive FAB spectra and moderate to high intensity [M - H]- ions in the negative mode, the latter undergoing characteristic sequential loss of C2H4, EtOH and C2H4. Significant variations were observed in the positive spectra of all the silanes with change of matrix.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210260206
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