bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral tuning of electroluminescence in conjugated copolymers by application of an external electric field
Authors: Faraggi Erez Z. , Davidov Dan , Cohen Gil , Neumann Ronny , Avny Yair
Published: May 2005

Color or spectral tuning of light emitted by LEDs based on conjugated polymers is important if such LEDs are to find applications in multicolor display devices. A copolymer system is described in which the wavelength of the electroluminescence can be controlled by the external voltage applied. Following an account of the monomer synthesis and copolymerization route, features of the photoluminescence, absorption, and electroluminescence spectra are reported and preliminary ideas presented about how to explain the results.
Electroluminescent diodes from a single component emitting layer of dendritic macromolecules
Authors: Wang Pei‐Wei , Liu Yu‐Ju , Devadoss Chelladurai , Bharathi P. , Moore Jeffrey S.
Published: May 2005

Organic LEDs based on dendrimer materials are reported (see the figure for an example; a dot represents phenylene). Single‐organic‐layer devices have been produced using structurally welldefined dendritic modules. Although the efficiency of the devices is still low, this work provides a basis for a systematic strategy for tuning the properties of the active layers of organic LEDs.

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Two‐ and three‐dimensional crystallization of polymeric microspheres by micromolding in capillaries
Authors: Kim Enoch , Xia Younan , Whitesides George M.
Published: May 2005

Micromolding in capillaries (MIMIC) is a novel, simple and convenient procedure for crystallizing microspheres from latex suspensions onto a support, and for delivering microspheres to and assembling them in geometrically confined regions on the surface of substrate (see figure). The principle of the method is outlined, examples are given, and possibilities for applications—e.g., in optical devices and microelectronics—are sketched.

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Materials science in Italy: The role of the universities
Authors: Gatteschi Dante
Published: May 2005

This special issue on Materials Science in Italy kicks off with an account of the relatively short tradition of materials science in Italian universities. Professor D. Gatteschi, who coordinated this special issue, describes special projects in materials science launched by the CNR (the major funding agency for Italian research) and the organization of two consortia of university departments with the aim of competing successfully for funding.
Biodegradable Polymeric Materials
Authors: Chiellini Emo , Solaro Roberto
Published: May 2005

What can stop the mountain of discarded plastic packaging from growing? One solution to be considered is the development and use of biodegradable polymers. The advantages and drawbacks of various biodegradable plastics, water‐soluble polymers, and natural and semisynthetic polymers are outlined in tis review. The Figure shows a fork made of ECO‐PLA, which is based on poly(lactic acid), after 33 days of degradation.

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Angle‐Scanned Photoelectron Diffraction: Probing crystalline ultrathin films
Authors: Granozzi Gaetano , Sambi Mauro
Published: May 2005

Electrons emitted from the core levels of a photon‐irradiated crystalline sample undergo scattering by atoms in the vicinity of the emitting species. Subsequent interference phenomena between the electron wave portions propagating to the detector produce intensity modulations as a function of the direction of detection. This process constitutes the physical basis of the angle‐scanned X‐ray photoelectron diffraction (XPD) technique. The resulting modulations, properly interpreted, are rich in structural information concerning the near‐surface atomic layers. In this review, after an introduction to the principles of XPD, some selected results in the field of ultrathin epitaxial films will be reported in order to outline the merits of the technique. Qualitative structural information (e. g., growth modes and lattice distortions) is directly obtained from the experimental raw data without the need for theoretical simulation. On the other hand, quantitative structural parameters, as well as the presence of stacking faults and other structural defects, may be deduced by using a trial‐and‐error fitting procedure based on simple scattering models.
Functionalization of sexithiophene with electron‐donating methylsulphanyl groups
Authors: Barbarella Giovanna , Zambianchi Massimo , Di Toro Rossanna , Colonna Martino , Antolini Luciano , Bongini Alessandro
Published: May 2005

Novel soluble sexithiophenes (6Ts) β‐functionalized with electron‐donating methylsulphanyl groups are reported. The resulting processable sexithiophenes, two examples of which are shown in the Figure, have optical gaps that can be finely tuned around the value for unsubstituted α‐6T. The observed liquid‐crystal behavior described here indicates a high degree of molecular organization in the solid in at least one case.

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A novel method for the preparation of nanosized tio2 thin films
Authors: Sberveglieri Giorgio , Depero Laura E. , Nelli Paolo , Perego Cesare , Sangaletti Luigi , Ferroni Matteo , Guidi Vincenzo , Martinelli Giuliano
Published: May 2005

Nanostructured titanium dioxide has many important applications, including several in chemical sensors, for example in “electronic noses”. A new method of preparing nanosized TiO2 thin films based on rf magnetron sputtering is reported and the characterization of the resulting films described. Results are presented for the temperature variation of the electrical response of the films to NO2, in particular the response and recovery times of the resistance of the layer.
Fluoride crystals for tunable lasers in the near infrared
Authors: Tonelli Mauro , Di Lieto Alberto , Minguzzi Paolo , Toncelli Alessandra , Jenssen Hans P.
Published: May 2005

Laser emission in the near infrared has been studied for a long tme with the aim of developing efficient solid‐state sources. As part of the development of such a source, an investigation of the fluorescence of the active medium (LiYF4 doped with either Er or Er ad Tm) in the laser cavity has provided deeper insights into the mode of operation of the laser. Since the near infrared is an “eye‐safe” region, applications can be foreseen wherever atmospheric propagation is required.
NLO responses of organic materials: The vibrational approach
Authors: Zerbi Giuseppe , Del Zoppo Mirella , Castiglioni Chiara , Zuliani Paola
Published: May 2005

How the hyperpolarizabilities of organic polyconjugated materials can be obtained using vibrational spectroscopy is described. This recent work by a group in Milan opens up a completely new field of vibrational spectroscopy relevant o photonics. Results for the molecule shown in the Figure (among others) are presented as an illustration of the reliability of this method.

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Cascading of Second‐Order Nonlinearities in Polar Materials
Authors: Bosshard Christian
Published: May 2005

The combination of two second‐order nonlinear optical (NLO) processes, termed cascading, can induce third‐order nonlinearities, which are of major interest for all‐optical signal processing. The concept of cascading and the basic ideas behind it are explained and some of the molecules of greatest potential in this area (e.g., DANPH, see Figure) introduced. Methods for determining cascaded nonlinearities, effects based on cascaded processes, and materials considerations are also reviewed.

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Patterning of poly(3‐octylthiophene) conducting polymer films by electron beam exposure
Authors: Persson S. H. Magnus , Dyreklev Peter , Inganäs Olle
Published: May 2005

Accurate patterning of a conducting polymer using electron beam lithography has been demonstrated for poly(3‐octylthiophene) for line widths down to 50 nm. It also proved possible to attach very closely spaced gold electrodes, with separations down to tens of nanometers, enabling the measurement of the electron transport properties of small strips consisting of a limited number of conducting polymer chains. Information gained from these experiments will be useful in molecular electronics and possibly for single electron devices.
A mesogen‐functionized carbosilane dendrimer: A dendritic liquid crystalline polymer
Authors: Lorenz Klaus , Hölter Dirk , Stühn Bernd , Mülhaupt Rolf , Frey Holger
Published: May 2005

The first dendritic liquid crystalline polymer (DLCP), consisting of a flexible, second‐generation dendritic carbosilane scaffold substituted with 36 rid cyanobiphenyl groups (see Figure), has been prepared. The synthesis and characterization of the mesophase are reported as an initial approach to determining how the formation of liquid crystal phases is related to the mesogen density and the spacer length in DLCPs.

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Vapor‐phase synthesis and processing of nanoparticle materials (NANO)
Authors: Fissan Heinz J. , Schoonman Joop
Published: May 2005

The NANO initiative, sponsored by the European Science Federation (ESF), is a five‐year program concerned with the vapor‐phase synthesis and processing of nanoparticle materials. Arising from an ESF Exploratory Workshop held in 1993, the program, which began in 1995, aims to build bridges between the aerosol community and the materials science community. The activities included in the program, e.g., conferences and various forms of support, are outlined and the themes of the various working groups are detailed.
Crystalline superlattices with designed structure from elementally modulated reactants
Authors: Noh Myungkeun , Thiel James , Johnson David C.
Published: May 2005

The synthesis of new „designed”︁ layer structures from superlattice reactants is outlined. Annealing of interwoven layers of elements within a superlattice–i.e., at greater than nanometer spacing–kinetically traps the final desired nanostructured product (see also the cover of this issue). A series of crystalline superlattices containing a niobium diselenide and titanium diselenide superstructure are used to explore the effect of the superstructure on the superconducting properties of the niobium diselenide.
Nanoparticular intermetallics and alloys via inorganic grignard reagents
Authors: Aleandri Lorraine E. , Bogdanović Borislav , Dürr Christine , Jones Deborah J. , Rozière Jacques , Wilczok Ursula
Published: May 2005

Novel inorganic Grinard complexes (e.g., that in the Figure) used as reagents enable nanoparticulate bimetallic systems, i.e., intermetallics or alloys, to be prepared in a controlled two‐stage process. The preparation and characterization of inorganic Grignard reagents and, in particular, the synthesis of nanoparticulate intermetallics and alloys via such reagents are briefly reviewed.

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Novel PPV derivatives emitting light over a broad wavelength range
Authors: Jin Jung ‐H , Chung Sung‐Jae , Kim Kong‐Kyum
Published: May 2005

Organic films for display applications have usually been developed with the aim of individual emission of red, blue, and green light. Another approach, presented here, is to design organic light‐emitting devices that emit over a broad spectral range, i.e., essentially white light. The preparation of two new polymer (see Figure) films is described, together with the results of absorption, photoluminescence, and electroluminescence measurements.

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A ferrocene crown ether–functionalized polypyrrole film electrode for the electrochemical recognition of barium and calcium cations
Authors: Ion Alina , Ion Ion , Popescu Angela , Ungureanu Mihaela , Moutet Jean‐Claude , Saint‐Aman Eric
Published: May 2005

Transfer of the recognition activity of a ferrocene ionophore to an electrode surface from the homogeneous phase has been successfully accomplished for the first time. The synthesis and electrochemical characterization of a new pyrrole‐substituted ferrocene crown ether are described, followed by the formation of the corresponding polymer film modified electrode. It is shown that the electrode exhibits amperometric recognition in an organic solvent of Ca2⊕ and Ba2⊕ among the alkaline and alkaline earth metal cations.
Novel κ‐type organic metal based on a bis‐fused tetrathiafulvalene derivative
Authors: Misaki Yohji , Miura Takeshi , Taniguchi Masateru , Fujiwara Hideki , Yamabe Tokio , Mori Takehiko , Mori Hatsumi , Tanaka Shoji
Published: May 2005

A novel k‐type organic metal based on 4,5,‐cyclohexeno‐TTP (where TTP is bis‐fused tetrathiafulvalene, TTF), see Figure, is reported. The synthesis, structure, and electrical properties are described. It is suggested that, following this demonstration of a TTF‐based organic metal without a chalcogeno‐based substituent, further CH‐TTP salts should be investigated for conductivity and superconductivity.

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Synthesis and photoconducting properties of poly(p‐phenylenevinylene)containing a bis(terpyridine)ruthenium(II) complex
Authors: Ng Wai Yue , Chan Wai Kin
Published: May 2005

Can a photosensitizer enhance the photoconductivity of PPV (poly(p‐phenylenevinylene))? The use of a palladium‐catalyzed coupling reaction is described for the production of a series of PPV derivatives that contain different amounts of a bis(terpyridine) ruthenium(II) metal complex, a well‐known photosensitizer when covalently linked to electron donating and accepting groups. Results of optical and electrical investigations are presented that indicate that the opening question can be answered in the affirmative.
Stepwise assembly in three dimensions: Preparation and characterization of layered gold nanoparticles in porous silica matrices
Authors: Fan Hongyou , Zhou Yuqing , Lopez Gabriel P.
Published: May 2005

Arrays of metal nanoparticles with well‐defined two‐ or three‐dimensional ordered structures in a solid matrix have many potential applications, e.g., novel optical gratings, data‐storage systems, and microelectronics. A synthetic method is described for preparing multilayer composite thin films with metal nanoparticles in porous ceramic matrices through colloidal adsorption and sol‐gel processing. Techniques for the control of the interparticulate distance, the number of particles in each layer, the interlayer distance, and the pore structure are outlined.
Rapid microbiology: Applications of bioluminescence in the food industry a review
Authors: Stannard C. J. , Gibbs P. A.
Published: May 2005

The bioluminescent assay of ATP is rapid and simple and may be used as an estimate of microbial numbers. It therefore shows great potential as a technique to provied information on the microbiological quality of a food within a few minutes, in comparison with conventional techniques, which provide results retrospectively. Howver, despite the advantages of speed and senstitivity, no food microbiologists are using the technique for routine quality control and hygiene monitoring. This review seeks to highlight the reasons for this, and to offer some ideas for future research to increase the acceptance of ATP assays within the food industry.
Systematic distribution of bioluminescence in living organisms
Authors: Herring Peter J.
Published: May 2005

A list of the genera of living organisms known or believed to contain luminous species is provided in the Appendix, in a systematic context. The constraints on the accuracy of such a list and some aspects of the apparent distribution of bioluminescence are discussed.
Analysis of luminol‐dependent chemiluminescence from granule depleted neutrophil cytoplasts reveals two different light‐emitting mechanisms
Authors: Dahlgren Claes
Published: May 2005

When neutrophil cytoplasts (granule‐free vesicles of cytoplasm enclosed by plasmalemma) were exposed to the chemotactic peptide formylmethionyl‐leucyl‐phenylalanine, no luminol‐dependent chemiluminescence was detected, despite a pronounced production of superoxide anions and hydrogen peroxide. Addition of purified myeloperoxidase (MPO) or human serum albumin (HSA) to the cytoplasts before the stimulus resulted in a chemiluminescence response. In contrast to the bimodal response obtained from normal PMNL, only a single peak of chemiluminescence was obtained from the cytoplasts responding to the peptide. The time‐course of the response obtained in the presence of albumin was more prolonged than the response obtained in the presence of MPO. Furthermore, the involvement of different oxidative metabolites in the MPO and the HSA systems, respectively, was demonstrated by the accumulated chemiluminescence effect obtained when MPO, but not HSA, was introduced in the measuring system after FMLP addition.

From these results it can be concluded that there are at least two different light‐generating mechanisms in FMLP‐induced luminol‐dependent chemiluminescence of neutrophil cytoplasts. One of these is dependent on myeloperoxidase and possibly related to the myeloperoxidase‐hydrogen peroxide reaction, whereas the other one is hydrogen peroxide independent.
Stability of firefly luciferase in Tricine buffer and in a commercial enzyme stabilizer
Authors: Hall Marliese S. , Leach Franklin R.
Published: May 2005

A solution of firefly luciferase in AuthentiZyme Enzyme Stabilizer® retains full activity when stored in an ice bath (0.5°C) during one day. These solutions have the advantage that no additional protein (other than the luciferase) is present, which is desirable for proteolytic digestion and protein dervatization experiments. For longer‐term experiments, firefly luciferase solutions in 0.05 mol/l Tricine buffer at pH 7.8, 10 mmol/l MgSO4, 1 mmol/l EDTA, and 1 mmol/I DTT which contain 100μg/ml of bovine serum albumin are stable for 6 weeks if frozen and thawed only once.
The transcription of bacterial luminescence is regulated by sigma 32
Authors: Ulitzur S. , Kuhn J.
Published: May 2005

Luminescence in the marine bacterium, Vibrio fischeri, is regulated by a small molecule, the autoinducer. The transcription of the V. fischeri lux genes also requires a regulatory protein, (luxR), cAMP and CRP. We show that, apart from these components, the transcription of the PR lux operon is also controlled by the activity of σ32 (htpR protein). In luminescent Escherichia coli (E. coli/pChv1), as well as in different marine luminous bacteria and their naturally occurring dark (K) variants, the luminescence system can be induced by starvation under microaerophilic conditions. Heat shock also induces luminescence in htpR+ but not in htpR− strains of E. coli/pChv1.

An htpR− mutant of E. coli containing pChv1 is very dim and its luminescence is not induced by starvation or heat shock. The addition of a plasmid bearing the gene for htpR+ into such cells restores their response to starvation and heat shock. Cells of wild type E. coli/pChv1 that have been starved or heat shocked respond to lower concentrations of V. fischeri inducer than untreated cells. These cultures also produce more extracellular inducer than untreated cells. Starvation, heat shock and the presence of σ32 do not induce luminescence in luxl deleted E. coli/pChv1 cells.

SOS‐inducing agents advance the onset of luminescence in both htpR+ and htpR− strains but not in luxl deleted E. coli/pChvi cells.

DNA sequencing of the luxR‐luxl region reveals the presence of a promoter region of the kind typical for σ32 at the beginning of the luxl gene. In addition we find a LexA protein‐DNA binding site in the non‐consensus sequence for the −35 region of the PR operon. It is proposed that the regulatory protein‐inducer complex displaces the LexA protein and allows the transcription of the right operon. SOS‐inducing agents result in proteolysis of LexA protein and advance the onset of luminescence. σ32 enhances the transcription from the PR operon and thus initiates a positive control circuit. It seems that σ32 is the major controlling element in determining the onset of luminescence both in vivo and in vitro.
Detection of genotoxicity of metallic compounds by the bacterial bioluminescence test
Authors: Ulitzur S. , Barak M.
Published: May 2005

Twenty metallic compounds were assayed for their genotoxic mutagenic activity by the bioluminescence test restoration of the luminescence of dark mutant of the luminous bacterium Photobacterium fischeri). The activity of the metals was tested in a liquid medium as well as on a solid medium. K2Cr2O7, MnCl2, BeCl2, KH2AsO4, ZnCl2 and Na2WO4 showed strong activity in liquid medium while AgNO3, Cd(OOCCH3)2, CoCl2, CuCl2, HgCl2, Na2SeO3 and Pb(NO3)2 were more active in the solid medium test. BaCl2, Na2MoO4, NaAsO2, NiSO4, Na2SeO4, RbCl, and SnCl2 were not active in the bioluminescence test. The correlation between the genotoxic activity of the tested metallic compounds in the bioluminescence test and other bacterial tests for genotoxic agents as well as the correlation between these results and the carcinogenicity of these compounds is discussed.
Measurement of urinary somatomedin C by a chemiluminescent method
Authors: Orlando Claudio , Tode Bettina , Pinzani Pamela , Bassi Francesca , Messeri Gianni
Published: May 2005

We present a method for the measurement of the total Somatomedin C (SmC) content in human early morning urine samples after dialysis, extraction, and concentration. We modified a chemiluminescence immunoassay, previously developed for SmC determination in serum, for analysis of SmC in urine. Appropriate sensitivity was obtained by the preparation of a new chemiluminescent tracer (AEEI‐COOH‐SmC) and the optimization of a competitive non‐equilibrium immunoassay system which had a detection limit of 0.24 fmol SmC per tube.
Effects of granulocytes on human neuroblastoma cells measured by chemiluminescence and chromium‐51 release assay
Authors: Bruchelt Gernot , Handgretinger Rupert , Kimmig Astrid , Goeke Barbara , Siedner Ruben , Reisfeld Ralph A. , Niethammer Dietrich , Treuner Jörn
Published: May 2005

We investigated whether polymorphonuclear leukocytes (PMN) are able to kill human neuroblastoma cells either directly or if coated with antibody MAb 14.18 that recognizes ganglioside GD2 present on the cell surface of most neuroblastoma cells. Neuroblastoma cells could not be destroyed directly, whereas in the antibody‐dependent reaction (ADCC‐reaction) they were easily eliminated. In order to answer the question whether reactive oxygen intermediates are involved in this process, chemiluminescence measurements were performed. Compared to the signals that could be measured using opsonized zymosan as stimulus, only weak CL‐signals could be registered during the ADCC reaction. Pretreatment of PMN with granulocyte‐macrophage colony stimulating factor (GM‐CSF) enhanced the CL‐signals, catalase and SOD reduced it; however, cell killing was only slightly influenced in the presence of catalase and superoxide dismutase. These data suggested that reactive oxygen compounds do not play a prominent role in the killing process. Definitive evidence for this suggestion could be obtained using PMN from a patient with chronic granulomatous disease (CGD): MAb 14.18 coated neuroblastoma cells could be killed effectively, but no CL‐signal could be registered, either in the ADCC‐reaction or using opsonized zymosan as stimulus.
Free fatty acid determination by peroxidase catalysed luminol chemiluminescence
Authors: Näslund Birgitta M. A. , Bernström Kerstin , Lundin Arne , Arner Peter
Published: May 2005

A sensitive, specific, and partly automatic method for the analysis of free fatty acids is described. The assay involves activation of free fatty acids by acyl‐CoA synthetase (EC 6.2.1.3) followed by oxidation of the thioesters by acyl‐CoA oxidase. The H2O2 formed is determined in a reaction catalysed by horseradish peroxidase (EC 1.11.1.7) using luminol as electron donor. The assay has a linear range of 0.05 to 5 nmol of different free fatty acids (C10‐C18) in the original sample. The efficiency of the method toward capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, and linoleic acid measured as recovery of light emission compared to that of H2O2 standards, was over 90%. AffiGel 501 was used to covalently bind the free thiol group in CoASH eliminating interference of this substance in the peroxidase‐luminol reaction.
Determination of absolute chemiluminescence quantum yields for reactions of bis‐(pentachlorophenyl) oxalate, hydrogen peroxide and fluorescent compounds
Authors: Catherall Colin L. R. , Palmer T. Frank , Cundall Robert B.
Published: May 2005

Absolute chemiluminescence quantum yields (ϕCL) for reactions of bis‐(pentachlorophenyl) oxalate (PCPO), hydrogen peroxide (H2O2) and 9:10 diphenyl anthracene (DPA) have been determined. A fully corrected chemiluminescence monitoring spectrometer was calibrated for spectral sensitivity using the chemiluminescence of the bis‐(pentachlorophenyl) oxalate system as a liquid light source, the total photon output of which had previously been determined by chemical actinometry. At high (PCPO)/(H2O2) ratios ϕCL was found to be independent of PCPO and H2O2 concentrations.
The ATP‐bioluminescence method for a rapid evaluation of the microbial activity in the stone materials of monuments
Authors: Tiano Piero , Tomaselli Luisa , Orlando Claudio
Published: May 2005

The examination of the state of conservation of works of art in stone includes the assessment of the presence of microbiological agents on the surface of the decayed monuments. These microorganisms can accelerate, via their metabolic activity, the decay process of the stone surface. At present this assessment is made with the traditional techniques for the microbiological examination of the soil, provides results only after a delay of 30 days. A bioluminescent ATP assay should provide rapid quantitation of actively growing organisms on the surface of a stone monument, and the applicability of this technique was verified on some samples of sandstone (Pietraforte) collected from a historic building (the Strozzi Palace) in Florence. These samples were evaluated for the amount of the ATP and the total number of microorganisms.

The results obtained suggest that the bioluminescent assay could be suitable for detecting and quantitating the presence of microorganisms in a sample of stone.
Preliminary evaluation of urinary estrone‐3‐glucuronide (E1‐3G)LIA measurement for monitoring induction of ovulation in an in vitro fertilization programme (FIVET)
Authors: Rapi S. , Pellegrini S. , Massi G. B.
Published: May 2005

This study compares urinary E1‐3G and serum E2 measurements in monitoring ovulation induction in an in vitro fertilization programme (FIVET).

We used an RIA kit, ESTR.CTK2 (Sorin, Italy), for the daily determination of serum E2, and an LA kit, Fertilux (Bouty, Milan), for the determination of E1‐3G in early morning urine samples using a timed and measured volume urine collection procedure.

A significant correlation was found between serum E2 as measured by RIA and urinary E1‐3G as measured by LIA.

Considering the RIA disadvantages (the short half‐life of the reagents, the hazards of handling radioactive materials, the inconvenience of frequent venepuncture for the patients) the LIA measurement seems to be a useful method in a FIVET programme.
Site‐directed mutagenesis of bacterial luciferase: Analysis of the ‘essential’ thiol
Authors: Baldwin T. O. , Chen L. H. , Chlumsky L. J. , Devine J. H. , Ziegler M. M.
Published: May 2005

It has been appreciated for many years that the luciferase from the luminous marine bacterium Vibrio harveyi has a highly reactive cysteinyl residue which is protected from alkylation by binding of flavin. Alkylation of the reactive thiol, which resides in a hydrophobic pocket, leads to inactivation of the enzyme. To determine conclusively whether the reactive thiol is required for the catalytic mechanism, we have constructed a mutant by oligonucleotide directed site‐specific mutagenesis in which the reactive cysteinyl residue, which resides at position 106 of the α subunit, has been replaced with a seryl residue. The resulting α106Ser luciferase retains full activity in the bioluminescence reaction, although the mutant enzyme has a ca 100‐fold increase in the FMNH2 dissociation constant. The α106Ser luciferase is still inactivated by N‐ethylmaleimide, albeit at about 1/10 the rate of the wild‐type (α106Cys) enzyme, demonstrating the existence of a second, less reactive, cysteinyl residue that was obscured in the wild‐type enzyme by the highly reactive cysteinyl residue at position α106. An α106Ala variant luciferase was also active, but the α106Val mutant enzyme was about 50‐fold less active than the wild type. All three variants (Ser, Ala and Val) appeared to have somewhat reduced affinities for the aldehyde substrate, the valine mutant being the most affected.

It is interesting to note that the α106 mutant luciferases are much less subject to aldehyde substrate inhibition than is the wild‐type V. harveyi luciferase, suggesting that the molecular mechanism of aldehyde substrate inhibition involves the Cys at α106.
Chemiluminescent assay of various enzyme activites and its application to enzyme immunoassays
Authors: Maeda Masako , Arakawa Hidetoshi , Tsuji Akio
Published: May 2005

A highly sensitive chemiluminescent assay for NAD(P)H have been developed. The principle of the method is as follows; NAD(P)H reduces molecular oxygen to superoxide anion (O) and hydrogen peroxide (H2O2) in the presence of 1‐methoxy‐5‐methylphenazinium methyl sulphate (1‐MPMS) as electron mediator. The produced O and H2O2 can be measured by chemiluminescent reaction using isoluminol (IL) and microperoxidase (m‐POD). A linear relationship between chemiluminescence intensity and NAD(P)H concentration (log/log) was obtained ranged from 10−9 mol/I to 10−5 mol/I. This chemiluminescent reaction has been coupled to the assay of glucose‐6‐phosphate dehydrogenase (G6PDH), β‐D‐galactosidase (β‐Gal) and alkaline phosphatase (ALP). The detection limits of G6PDH, β‐Gal and ALP were 10−18 mol, 10−20 mol and 10−18 mol per assay, respectively. The chemiluminescent assay of these enzymes applied to chemiluminescent enzyme immunoassay for 17α‐hydroxy‐progesterone and DNA hybridization assay using these enzymes as label.
Enhanced chemiluminescence ELISA for the detection of antibody to hepatitis B virus surface antigen
Authors: Ireland Deborah , Samuel Dhanraj
Published: May 2005

A chemiluminescent enzyme linked immunosorbent assay (ELISA) for the detection of antibody to hepatitis B virus surface antigen (anti‐HBs) in human serum has been developed. Polystyrene microtitre plates were coated with recombinant, yeast‐derived hepatitis B surface antigen (rec‐HBsAg). Patient serum samples and appropriate controls were added to the rec‐HBsAg‐coated wells and incubated to bind anti‐HBs. The wells were then washed and a fluorescein isothiocyanate (FITC) conjugate of a human plasma‐derived hepatitis B surface antigen (HBsAg) was added. Following incubation and further washing the bound FITC‐labelled HBsAg was detected after addition of a horseradish peroxidase (HRP) conjugate of a monoclonal anti‐FITC antibody and assaying for the enzyme. The activity of the HRP was measured using luminol and hydrogen peroxide as substrates and iodophenol as a chemiluminescence enhancer. The luminescence was recorded using a camera luminometer.

Preliminary tests have shown the assay to be suitable for the detection of antibody in sera from both vaccinees and also from individuals with a past hepatitis B virus infection. The use of the FITC‐anti‐FITC system together with the measurement of a chemiluminescence signal makes possible the completion of this assay in a few hours. The assay has been shown to be both specific and sensitive and provides a permanent photographic record.
Opsonophagocytosis of bacteria studied by chemiluminescence in microtitre plates
Authors: Hastings J. G. M. , Jewes L. A. , Oxley K. M.
Published: May 2005

A protocol for polymorphonuclear leukocyte chemiluminescence (PMN CL) assays of opsonophagocytosis was developed for a microtitre‐plate luminometer. The complete procedure was performed in a single microtitre plate and was simpler and more efficient than previous protocols. The kinetics of the PMN CL response were best when microtitre plates were incubated on a shaking incubator between readings. The new protocol was used in a study of the pathogenicity of Corynebacterium jeikeium, an organism found in association with infection in the immunocompromised. No differences were found when PMN CL induction by 15 strains of C. jeikeium were compared with 15 isolates of other corynebacteria. Both groups of organisms required complement for efficient opsonophagocytosis; C. jeikeium strains showed no requirement for specific antibody. Resistance to opsonophagocytosis does not appear to be an explanation for the increased pathogenicity of C. jeikeium. Microtitre‐plate luminometers are particularly well suited to bacterial opsonization studies where large numbers of strains often need to be assessed.
Phagocytosis induction of chemiluminescence and chemoattractant increased superoxide anion release from activated human alveolar macrophages in asthma
Authors: Damon M. , Cluzel M. , Chanez P. , Godard Ph.
Published: May 2005

Human alveolar macrophages (AM) were demonstrated to generate reactive toxic derivatives of oxygen in many pulmonary disorders. These cells are involved in local inflammation which characterizes bronchial asthma. In the present work, we studied the ability of stimulated macrophages from healthy volunteers, and asthmatic patients to generate oxygen species in vitro. AM obtained by bronchoalveolar lavage were purified by adherence. The production of oxygen species was measured by luminol‐enhanced chemiluminescence (CL) after challenge with opsonized zymosan. The maximal values were significantly (p < 0.03 and p < 0.01) higher in AM from asthmatics than in AM from healthy subjects. A significant correlation (p < 0.01) was observed between maximal value of CL and the severity of asthma as assessed by the clinical score. But, no difference was observed between AM from asthmatics in a stable state and healthy subjects. On the other hand, assays for superoxide anion generation emphasized the activation state of these macrophages stimulated by formyl‐peptides.
Construction of a fused luxAB gene by site‐directed mutagenesis
Authors: Boylan M. O. , Pelletier J. , Dhepagnon S. , Trudel S. , Sonenberg N. , Meighen E. A.
Published: May 2005

Bacterial luciferases are heteropolymetric enzymes consisting of two non‐identical subunits (alpha and beta). The two polypeptides are produced by transcription in the same direction of two genes, luxA and luxB, located immediately adjacent to each other and separated by only 29 base pairs in the Vibrio harveyi genome. Using site‐directed mutagenesis, stop codons after luxA were eliminated and the luxB gene was placed in‐frame with luxA, resulting in a fused luxAB gene. Transcription of two luxAB mutant genes from the bacteriophage T7 promoter and translation in Escherichia coli resulted in the synthesis of fused polypeptides containing the alpha and the beta subunits of luciferase linked by either a single amino acid residue or a decapeptide. E. coli synthesizing the latter fusion protein with the decapeptide linker expressed a level of luminescence comparable to E. coli containing the wild type genes while E. coli synthesizing the polypeptide with a single amino acid as a linker expressed about 2000‐fold lower light. These results provide the basis for generating a bacterial luciferase system that can be expressed under the control of a single promoter in both eukaryotic and prokaryotic systems.
Luminescence in the study of lipid metabolism
Authors: Wieland E. , Niedmann D. , Diedrich F. , Seidel D. , Kather H.
Published: May 2005

Using bioluminescence assays for glycerol, free fatty acids, β‐hydroxybutyrate and lactate, we were able to perform complex studies of human energy and lipid metabolism both in serum samples in vivo and in isolated fat cells in vitro. These studies would have been impossible without reliable, specific and highly sensitive luminescence methods. Oxidatively modified low density lipoprotein (LDL) has been implicated in the pathogenesis of atherosclerosis. Adaptation of a chemiluminescence assay for lipid hydroperoxides to LDL isolated by specific precipitation from serum makes it possible to measure LDL oxidation in vivo. Cell dependent chemiluminescence was used to investigate whether receptor mediated endocytosis of LDL by macrophages leads to oxygen radical production in these cells. No activation of the membrane NAD(P)H oxidase was observed.
Principles and applications of luminescence spectrometry coupled to liquid chromatographic techniques
Authors: Baeyens Willy R. G. , Ling Betty Lin , Brinkman Udo A. Th. , Schulman Stephen G.
Published: May 2005

An overview is presented of the physicochemical basis of luminescence, and its application to the detection of chemicals (drugs, biomedically important compounds, environmentally active substances) in liquid chromatographic systems.
Luminescence biosensors
Authors: Aizawa M. , Tanaka M. , Ikariyama Y. , Shinohara H.
Published: May 2005

A novel optical biosensor for homogeneous immunoassay has been developed on the basis of the finding that electrochemical luminescence of pyrene‐labelled antigen is extremely inhibited by immunochemical complexation. Electrochemical luminescence homogeneous immunoassay for human serum albumin (HSA), as a model analyte, was performed with a platinum plate electrode which was located in the vicinity of an optical fibre tip. HSA was determined in the concentration range of 3–25 × 10−6 mol/I.

To improve electrochemical luminescence measurement an optical fibre electrode has been developed by fabricating a transparent platinum film on the top of an optical fibre. The minimum detectable limit of luminol was 10−11 mol/l with the optical fibre electrode. Luminol was applied as a label for homogeneous immunoassay.
A chemiluminescent method for the measurement of pregnanetriol‐3α‐glucuronide in human diluted urine
Authors: Pinzani P. , Magini A. , Franceschetti F. , Messeri G. , Pazzagli M.
Published: May 2005

Pregnanetriol‐3α‐glucuronide (PTG) is the majority urinary metabolite of 17‐hydroxyprogesterone (17OHP) and it typically increases in the commonest form of congenital adrenal hyperplasia (CAH), due to 21 hydroxylase deficiency.

We developed a simple chemiluminescent immunoassay for the direct measurement of PTG in diluted urine in order to avoid the preliminary hydrolysis and extraction steps that are usually employed in gas–liquid chromatographic methods. The immunogenic complex PTG‐bovine‐serum‐albumin was used to induce the formation of specific antibodies in New Zealand rabbits. In addition, PTG was conjugated to aminoethylethylisoluminol and the resulting tracer was characterized by mass spectrometry and used to monitor the immunological reaction. The characteristics of the antibody were determined with regard to specificity and sensitivity. The precision of the assay method was also established.

PTG excretion was studied before and after the ACTH stimulation test (1 mg synthetic ACTH i.m.) in 11 normal women and in one subject affected by CAH due to 21‐hydroxylase deficiency. PTG levels well correlated with 17OHP plasma concentrations both under basal and stimulated conditions, in normal women as well as in the patient affected by CAH.
Automation and computerization of chemiluminescence: A new methodological approach in the study of human phagocytes
Authors: Parente R. , Melotti C.
Published: May 2005

Peripheral blood phagocytic cells (PMNLs) are activated by contact with opsonized particles. Metabolic activation of PMNLs is associated with a remarkable increase in the respiratory burst and generates high energy oxygen compounds which are responsible for the bactericidal activity of PMNLs and for their ability to produce luminol‐dependent chemiluminescence (CL). The CL phenomenon is measured by an automated and computerized photoluminometer (Berthold LB950) in whole blood stimulated with opsonized zymosan.

This whole blood method of CL measurement has been applied to the study of the phagocytic process and to the investigation of cellular and humoral abnormalities in several pathologies, indicating this assay as a simple, rapid and reliable test.
Comparison of serum free thyroxine measurements by chemiluminescence and equilibrium dialysis
Authors: Bigos S. Thomas , MacLean J. , Butler B.
Published: May 2005

A study of 239 patients compared free thyroxine (FT4) measurements made by equilibrium dialysis (ED) with measurements made using the Magic Lite FT4 chemiluminescence (Cl) immunoassay (Ciba Corning Immunodiagnostics). Patient groups: 41 normals; 27 hyperthyroid; 29 hypothyroid; 37 sick euthyroid; 10 chronic renal failure (CRF) and 25 pregnant patients; 13 oestrogen; 10 heparin; 12 salicylate; and 9 dilantin‐treated patients; 3 lipaemic; 5 haemolysed; 6 hyperbilirubinaemic patients; 6 low thyroid binding protein (TBP) and 6 high TBP level patients. The two assays gave comparable results in most groups. Both assays tended to give elevated values in heparinized patients but FT4–ED results were more obviously affected. Pregnant patients and women on oral oestrogen had higher mean values with FT4–ED. In both assays the sick euthyroid and CRF patients had mean FT4 values similar to healthy euthyroid patients; the range of values in sick euthyroid and CRF patients was similar in both assays but wider than in healthy euthyroid patients. A supplemental study of 81 unselected acutely ill patients using FT4–Cl alone confirmed the wider range of values to be anticipated in sick euthyroid patients.
The chromophore of pholasin: A highly luminescent protein
Authors: Müller T. , Campbell A. K.
Published: May 2005

Pholasin is the photoprotein extracted from the marine bivalve Pholas dactylus. It undergoes an oxidative chemiluminescent reaction to oxypholasin with superoxide anion, hypochlorite, peroxidases and other oxidants. Since the observed absorbance and chemiluminescent emission spectra of pholasin solutions cannot be brought about solely by the amino acids composing the protein, there has to be a chemiluminescent chromophore. However, little is known about the chemical nature of this molecule. This work seeks to identify the chemical structure of the luminescent prosthetic group of pholasin.

Pholasin could not be reactivated using chromophores from the hydroid Obelia geniculata (coelenterazine) and from the ostracod shrimp Vargula (formerly Cypridina) hilgendorfi. Furthermore, the reaction product of the Vargula chromophore could not be detected in solutions containing oxypholasin. Fluorescence analysis of such a solution revealed a compound with an emission spectrum (γmax 480 nm; excitation at 320 nm), resembling the emission spectrum of the chemiluminescent reaction. This fluorescent substance was separated by gel filtration. It exhibited an apparent molecular mass of < 2000. Fluorescence masurements of extracts of partially purified pholasin suggested that a flavin moiety may be involved in pholasin luminescence.
Chemiluminescence of bronchoalveolar lavage cells as an indicator of leukocyte activation in rats with a hyperreactive bronchus
Authors: Linssen M. , Wilhelms O.‐H.
Published: May 2005

Activation and generation of inflammatory mediators by different leukocytes may be important in the pathogenesis of airway hyperreactivity. We studied the effect of active sensitization with ovalbumin as antigen and i.v. treatment with Sephadex particles on bronchial reactivity (BR) in rats and its possible relation to leukocyte infiltration (LI) and activation (LA) in bronchoalveolar lavage (BAL).

A marked BR to aerosols of serotonin (5‐HT) and ovalbumin was found in Sephadex treated animals but not in control animals. In parallel to this a marked increase in BAL cell count from Sephadex‐treated animals compared to controls was seen. This increase in BAL cell count corresponded with a clear augmentation of spontaneous, buffer‐induced and C3Z‐induced, luminol‐amplified CL.

We deduce that detection of CL of BAL cells from rats might be used for studying inflammatory mechanisms which lead to a hyperreactive bronchus.
Control of the lux regulon of Vibrio fischeri
Authors: Shadel G. S. , Devine J. H. , Baldvvin T. O.
Published: May 2005

Regulation of expression of bioluminescence from the Vibrio fischeri lux regulon in Escherichia coli is a consequence of a unique form of positive feedback superimposed on a poorly defined cis‐acting repression mechanism. The lux regulon consists of two divergently transcribed operons. The leftward operon contains only a single gene, luxR, which encodes a transcriptional activator protein. The rightward operon contains luxl, which together with luxR and the 218 base pairs separating the two operons comprises the primary regulatory circuit, and the five structural genes, luxC, luxD, luxA, luxB and luxE, which are required for the bioluminescence activity. Transcription of luxR from PL is stimulated by binding of the E. coli crp gene product to the sequence TGTGACAAAAATCCAA upstream of the presumed promoter. Binding of pure E. coli CAP protein in a cAMP‐ dependent reaction to the V. fischeri lux regulatory region has been demonstrated by in vitro footprinting. The luxl gene product is an enzyme which catalyses a condensation reaction of cytoplasmic substrates to yield the autoinducer, N‐(3‐oxo‐hexanoyl) homoserine lactone. Accumulation of autoinducer, which is freely diffusible, results in formation of a complex with LuxR. The complex binds to the sequence ACCTGTAGGATCGTACAGGT upstream of PR to stimulate transcription of the rightward operon. Increased transcription from PR should yield increased levels of Luxl and higher levels of autoinducer which would further activate LuxR. The LuxR binding site is also a LexA binding site, as demonstrated by in vitro footprinting. Basal transcription from both PL and PR is repressed by sequences within the luxR coding region. Hence there appear to be at least two effects resulting from the interaction between LuxR: autoinducer and the control region DNA. One effect is to relieve the repression afforded by the sequences within luxR and the second is to stimulate transcription from PR. Recent analysis of the rightward promotor by site‐directed mutagenesis has suggested a different location for PR than that which was implicated in earlier studies. Our results suggest that the −35 sequence is located at a position which overlaps the 3′ edge of the LuxR binding site by one base pair.
Luc genes: Introduction of colour into bioluminescence assays
Authors: Wood Keith V.
Published: May 2005

Luminescence assays are generally based on measurements of light intensity alone. Inclusion of colour as an additional parameter of the assay could increase the information content. Colour variation in luminescence is particularly prevalent among beetle luciferases. To study the relationship between enzyme structure and colour, luciferases from a Jamalcan click beetle were examined as a model system. These luciferases emit light ranging from green to orange, though their amino acid sequences differ by less than 5%. Through mutation of their respective cDNA clones, the amino acids responsible for the colour variation were identified. These specific amino acids are few, and they act upon colour independently with respect to the enzyme structure. Analysis of their effects indicates that the potential for colour variation among beetle luciferases is greater than is evident among the click beetle luciferase. Because of the subtle changes of enzyme structure that effect colour, luciferases that emit different colours may be useful as paired genetic reporters. They should interact equivalently with the intracellular environment of a host, but could be distinguished by colour in their assay. Such paired reporters could be used to observed simultaneous events, or to provide internal control for luminescence measurements.