bluuebunny/crossref_metadata_2025 huggingface dataset:
Antifungal Activity Evaluation of the Constituents of Haliclona baeri and Haliclona cymaeformis, Collected from the Gulf of Thailand
Authors: Wattanadilok Rawiwan , Sawangwong Pichan , Rodrigues Cátia , Cidade Honorina , Pinto Madalena , Pinto Eugenia , Silva Artur , Kijjoa Anake
Published: October 2008

A new compound maleimide-5-oxime was isolated, together with 3,4- dihydroxybenzoic acid, tetillapyrone, from the ethyl acetate extract of the marine sponge Haliclona baeri while tetillapyrone, nortetillapyrone, p-hydroxybenzaldehyde and phenylacetic acid were isolated from the ethyl acetate extract of Haliclona cymaeformis, collected from the Gulf of Thailand. The structures of tetillapyrone and nortetillapyrone were re-examined using HMBC correlations. Maleimide-5-oxime, tetillapyrone and nortetillapyrone were found to be inactive against three human tumor cell lines (the estrogen-dependent ER(+) MCF-7, the estrogen-independent ER(-) MDA-MB-231 and NCI-H460. Maleimide-5-oxime, p-hydroxybenzaldehyde, phenylacetic acid, tetillapyrone and nortetillapyrone were evaluated for their growth inhibitory effect against seven yeasts and eight filamentous fungi. Only nortetillapyrone showed antifungal activity, with a preponderance on the dermatophytic filamentous fungi.
Cytotoxicity of the Ascidian Cystodytes dellechiajei Against Tumor Cells and Study of the Involvement of Associated Microbiota in the Production of Cytotoxic Compounds
Authors: Martínez-García Manuel , Díaz-Valdés Marta , Ramos-Esplá Alfonso , Salvador Nélida , Lopez Patricia , Larriba Eduardo , Antón Josefa
Published: October 2008

Many cytotoxic compounds of therapeutic interest have been isolated from marine invertebrates, and some of them have been reported to be of microbial origin. Pyridoacridine alkaloids are the main compounds extracted from the ascidian Cystodytes dellechiajei. Here we describe the in vitro antiproliferative activity against different tumor cell lines of the ascidian extracts and provide some insights on the role of the microbial community associated with the tunicate in the production of these compounds. C. dellechiajei extracts showed remarkably high antiproliferative activity (IC50 ≤5 μg/mL) in human lung carcinoma A-549, colon adenocarcinoma H-116, pancreatic adenocarcinoma PSN-1 and breast carcinoma SKBR3 cell lines. Moreover, we found that the maximum activity was located in the tunic tissue of the colony, which harbours a microbial community. In order to ascertain the involvement of this community in the synthesis of the bioactive compounds different approachs that included culture and culture independent methods were carried out. We undertook a screening for antiproliferative activities of the bacterial isolates from the ascidian, as well as a comprative analysis of the cytotoxic activities and the microbial communities from two color morphs of the ascidian, green and blue. In addition, the changes of the antiproliferative activities and the composition of the microbial communities were studied from ascidians kept in aquaria and treated with antibiotics for one month. Our data obtained from the different experiments did not point out to bacteria as the source of the cytotoxic compounds, suggesting thus an ascidian origin.
Cytoskyrins and Cytosporones Produced by Cytospora sp. CR200: Taxonomy, Fermentation and Biological Activities
Authors: Singh Maya P. , Janso Jeffrey E. , Brady Sean F.
Published: October 2008

In screening endophytic fungi from Costa Rica for bioactivity, fungal culture CR200, isolated from a buttonwood tree, was found to contain compounds that initiate DNA damage in a test strain of E. coli (Biochemical Induction Assay, BIA) and inhibit growth of Gram-positive bacteria, including antibiotic-resistant strains. Two new bisanthraquinones (cytoskyrins A and B) and five new related octaketides (cytosporones A-E) were isolated from fermentation broths of this fungus. Cytoskyrin A exhibited potent in-vitro antibacterial (MICs against Gram-positive bacteria, 0.03 - 0.25 μg/mL) and DNA-damaging activities (10 ng/spot), whereas cytoskyrin B was inactive in these assays. Among the cytosporones, only D and E exhibited Gram-positive activity, but they were inactive in the BIA. Mechanistically, cytoskyrin A specifically inhibited DNA synthesis in E. coli imp at its MIC; however, it also moderately inhibited protein synthesis at 2x its MIC. Cytoskyrin A exhibited poor cytotoxicity against tumor cell lines (IC50 > 5 μg/mL) compared to known antitumor agents. The nuclear ribosomal internal transcribed spacer region of CR200 was found to share highest similarity (94-96%) with Cytospora spp. Micro- and macroscopic morphological observations of the conidia and conidiomata, respectively, also suggested this fungus to be a Cytospora sp.
Molecular Structure of Endotoxins from Gram-negative Marine Bacteria: An Update
Authors: Leone Serena , Silipo Alba , Nazarenko Evgeny L. , Lanzetta Rosa , Parrilli Michelangelo , Molinaro Antonio
Published: October 2008

Marine bacteria are microrganisms that have adapted, through millions of years, to survival in environments often characterized by one or more extreme physical or chemical parameters, namely pressure, temperature and salinity. The main interest in the research on marine bacteria is due to their ability to produce several biologically active molecules, such as antibiotics, toxins and antitoxins, antitumor and antimicrobial agents. Nonetheless, lipopolysaccharides (LPSs), or their portions, from Gram-negative marine bacteria, have often shown low virulence, and represent potential candidates in the development of drugs to prevent septic shock. Besides, the molecular architecture of such molecules is related to the possibility of thriving in marine habitats, shielding the cell from the disrupting action of natural stress factors. Over the last few years, the depiction of a variety of structures of lipids A, core oligosaccharides and O-specific polysaccharides from LPSs of marine microrganisms has been given. In particular, here we will examine the most recently encountered structures for bacteria belonging to the genera Shewanella, Pseudoalteromonas and Alteromonas, of the γ-Proteobacteria phylum, and to the genera Flavobacterium, Cellulophaga, Arenibacter and Chryseobacterium, of the Cytophaga- Flavobacterium-Bacteroides phylum. Particular attention will be paid to the chemical features expressed by these structures (characteristic monosaccharides, non-glycidic appendages, phosphate groups), to the typifying traits of LPSs from marine bacteria and to the possible correlation existing between such features and the adaptation, over years, of bacteria to marine environments.
Differential Effects of Domoic Acid and E. coli Lipopolysaccharide on Tumor Necrosis Factor-α, Transforming Growth Factor-β1 and Matrix Metalloproteinase-9 Release by Rat Neonatal Microglia: Evaluation of the Direct Activation Hypothesis
Authors: Mayer Alejandro M. S. , Guzman Marcio , Peksa Renee , Hall Mary , Fay Michael J. , Jacobson Peer B. , Romanic Anne M. , Gunasekera Sarath P.
Published: October 2008

The excitatory amino acid domoic acid is the causative agent of amnesic shellfish poisoning in humans. The in vitro effects of domoic acid on rat neonatal brain microglia were compared with E. coli lipopolysaccharide (LPS), a known activator of microglia mediator release over a 4 to 24 hour observation period. LPS [3 ng/mL] but not domoic acid [1mM] stimulated a statistically significant increase in TNF-α mRNA and protein generation. Furthermore, both LPS and domoic acid did not significantly affect TGF- β1 gene expression and protein release. Finally, an in vitro exposure of microglia to LPS resulted in statistically significant MMP-9 expression and release, thus extending and confirming our previous observations. However, in contrast, no statistically significant increase in MMP-9 expression and release was observed after domoic acid treatment. Taken together our observations do not support the hypothesis that a short term (4 to 24 hours) in vitro exposure to domoic acid, at a concentration toxic to neuronal cells, activates rat neonatal microglia and the concomitant release of the pro-inflammatory mediators tumor necrosis factor-α (TNF-α) and matrix metalloproteinases-9 (MMP-9), as well as the anti- inflammatory cytokine transforming growth factor β1 (TGF-β1).
Characterization of Aerosols Containing Microcystin
Authors: Cheng Yung Sung , Yue Zhou , Irvin C. Mitch , Kirkpatrick Barbara , Backer Lorraine C.
Published: October 2008

Toxic blooms of cyanobacteria are ubiquitous in both freshwater and brackishwater sources throughout the world. One class of cyanobacterial toxins, calledmicrocystins, is cyclic peptides. In addition to ingestion and dermal, inhalation is a likelyroute of human exposure. A significant increase in reporting of minor symptoms,particularly respiratory symptoms was associated with exposure to higher levels ofcyanobacteria during recreational activities. Algae cells, bacteria, and waterborne toxinscan be aerosolized by a bubble-bursting process with a wind-driven white-capped wavemechanism. The purposes of this study were to: evaluate sampling and analysis techniquesfor microcystin aerosol, produce aerosol droplets containing microcystin in the laboratory,and deploy the sampling instruments in field studies. A high-volume impactor and an IOMfilter sampler were tried first in the laboratory to collect droplets containing microcystins.Samples were extracted and analyzed for microcystin using an ELISA method. Thelaboratory study showed that cyanotoxins in water could be transferred to air via a bubble-bursting process. The droplets containing microcystins showed a bimodal size distributionwith the mass median aerodynamic diameter (MMAD) of 1.4 and 27.8 μm. The samplingand analysis methods were successfully used in a pilot field study to measure microcystinaerosol in situ.
A Sesquiterpene Quinone, 5-Epi-smenospongine, Promotes TNF-α Production in LPS-stimulated RAW 264.7 Cells
Authors: Oda Taiko , Wang Weifang , Ukai Kazuyo , Nakazawa Takahiro , Mochizuki Masataka
Published: October 2008

Eight sesquiterpene quinones: ilimaquinone (1), smenospongidine (3),smenospongiarine (5), smenospongine (7), and their corresponding 5-epimers 2, 4, 6, and 8,isolated from the Palauan marine sponge Hippospongia sp., were examined regarding theireffects on TNF-α production in LPS-stimulated RAW 264.7 cells. 5-Epi-smenospongine(8) promoted the production of TNF-α to a level three times greater than the control at10 μM, but compounds 1-7 did not show apparent activity. The results suggest that thecis-decaline ring and a primary amine in the benzoquinone ring are necessary for activity.This is the first study to report the modulation of TNF-α production by a sesquiterpenequinone.
Mechanisms of Toxicity of 3-Alkylpyridinium Polymers from Marine Sponge Reniera sarai
Authors: Turk Tom , Frangež Robert , Sepčić Kristina
Published: October 2008

Polymeric 3-alkylpyridinium salts (poly-APS) present in the marine spongeReniera sarai show a broad spectrum of biological activities. They are lytic to erythrocytesand various other mammalian cells, enabling the transfection of the latter with alien DNA.Furthermore, they show inhibitory effects to marine bacteria and can inhibit fouling ofmicro- and macroorganisms to submerged surfaces. Finally, poly-APS act as potentcholinesterase inhibitors. The kinetics of acetylcholinesterase inhibition by poly-APS invitro is complex and comprises several successive phases ending in irreversible inhibitionof the enzyme. The latter is accounted for by aggregation and precipitation of the enzyme-inhibitor complexes. Poly-APS are lethal to rats in concentrations above 2.7 mg/kg.Monitoring of the basic vital functions and histopathological analysis showed that theeffects directly ascribable to acetylcholinesterase inhibition are only observed afterapplication of lower concentrations of poly-APS. At higher concentrations, such effectswere masked by other, more pronounced and faster developing lethal effects of the toxin,such as haemolysis and platelet aggregation.
Report on the First Detection of Pectenotoxin-2, Spirolide-A and Their Derivatives in French Shellfish
Authors: Amzil Zouher , Sibat Manoella , Royer Florence , Masson Nadine , Abadie Eric
Published: October 2008

In the context of the French Phytoplankton and Phycotoxins MonitoringNetwork (REPHY) programme, shellfish samples were harvested from different locationswhere harmful algae blooms were known to have occurred. For all shellfish samples foundpositive by the mouse bioassay for diarrhetic shellfish poisoning (DSP) toxins, liquidchromatography (LC) coupled with mass spectrometry (MS) was used to search for thefollowing lipophilic toxins: okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins(PTXs), azaspiracids (AZAs), yessotoxins (YTXs), spirolides (SPXs) and gymnodimines(GYMs). In order to investigate the presence of acyl-OAs and/or acyl-DTX-1,-2 (DTX-3),alkaline hydrolysis was performed on all samples, and LC/MS analyses were carried out onthe samples before and after hydrolysis. The results revealed different lipophilic toxinprofiles as a function of the shellfish sampling location. The primary finding was that all ofthe samples contained OA and acyl-OA. In addition, other lipophilic toxins were found inshellfish samples: DTX-2, acyl-DTX-2 and SPXs (SPX-A, SPX-desMeC) on the Atlanticcoast (Southern Brittany, Arcachon), and pectenotoxins (PTX-2, PTX-2-seco-acid and 7-epi-PTX-2-seco-acid) on the Mediterranean coast (Thau lagoon, the island of Corsica).This paper reports on the first detection of PTX-2, SPX-A and their derivatives in Frenchshellfish.
Production of the Neurotoxin BMAA by a Marine Cyanobacterium
Authors: Banack Sandra Anne , Johnson Holly E. , Cheng Ran , Cox Paul Alan
Published: October 2008

Diverse species of cyanobacteria have recently been discovered to produce theneurotoxic non-protein amino acid β-methylamino-L-alanine (BMAA). In Guam, BMAAhas been studied as a possible environmental toxin in the diets of indigenous Chamorropeople known to have high levels of Amyotrophic Lateral Sclerosis/ ParkinsonismDementia Complex (ALS/PDC). BMAA has been found to accumulate in brain tissues ofpatients with progressive neurodegenerative illness in North America. In Guam, BMAAwas found to be produced by endosymbiotic cyanobacteria of the genus Nostoc which livein specialized cycad roots. We here report detection of BMAA in laboratory cultures of afree-living marine species of Nostoc. We successfully detected BMAA in this marinespecies of Nostoc with five different methods: HPLC-FD, UPLC-UV, Amino AcidAnalyzer, LC/MS, and Triple Quadrupole LC/MS/MS. This consensus of five differentanalytical methods unequivocally demonstrates the presence of BMAA in this marinecyanobacterium. Since protein-associated BMAA can accumulate in increasing levelswithin food chains, it is possible that biomagnification of BMAA could occur in marineecosystems similar to the biomagnification of BMAA in terrestrial ecosystems. Productionof BMAA by marine cyanobacteria may represent another route of human exposure toBMAA. Since BMAA at low concentrations causes the death of motor neurons, low levelsof BMAA exposure may trigger motor neuron disease in genetically vulnerableindividuals.
Chemopreventive Effects of Sarcotriol on Ultraviolet B-induced Skin Tumor Development in SKH-1 Hairless Mice
Authors: Kundoor Vipra , Zhang Xiaoying , Bommareddy Ajay , Khalifa Sherief , Fahmy Hesham , Dwivedi Chandradhar
Published: October 2008

Sarcotriol (ST) has been shown to be chemopreventive on 7,12-dimethylbenz( a)anthracene (DMBA) initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)- promoted skin tumor development in CD-1 mice in recent studies from our laboratory. The objective of this study was to determine the chemopreventive effects of ST on ultraviolet B (UVB)-induced skin tumor development in female SKH-1 hairless mice, an experimental model relevant to human skin cancer development, and its possible mechanisms of action. Female SKH-1 mice were divided into two groups: Control and ST treated. Control was topically treated with 100 μL acetone and ST treated group administered with 30 μg ST in 100 μL acetone one hour before UVB exposure. For UVB-induced tumorigenesis, carcinogenesis was initiated and promoted by UVB (180 mJ/cm2). Group weights and tumor counts were taken once every week. After 30 weeks, mice were sacrificed and dorsal skin samples were collected. The proteins from the skin sample were further used for SDSPAGE and Western blotting using specific antibodies against caspase-3, caspase-8, caspase-9 and p53. Tumor multiplicity was found 19.6, 5.2 in the control and ST treated groups respectively. Caspase-3, -8, -9 and p53 were significantly (P < 0.05) upregulated in ST treated group compared to Control group. Together, this study for the first time identifies the chemopreventive effects of ST in UVB-induced carcinogenesis possibly by inducing apoptosis and upregulating p53.
Evaluation of Harmful Algal Bloom Outreach Activities
Authors: Fleming Lora E. , Jerez Eva , Stephan Wendy Blair Blair , Cassedy Amy , Bean Judy A. , Reich Andrew , Kirkpatrick Barbara , Backer Lorraine , Nierenberg Kate , Watkins Sharon , Hollenbeck Julie , Weisman Richard
Published: October 2008

With an apparent increase of harmful algal blooms (HABs) worldwide,healthcare providers, public health personnel and coastal managers are struggling toprovide scientifically-based appropriately-targeted HAB outreach and education. Since1998, the Florida Poison Information Center-Miami, with its 24 hour/365 day/year freeAquatic Toxins Hotline (1-888-232-8635) available in several languages, has received over 25,000 HAB-related calls. As part of HAB surveillance, all possible cases of HAB-relatedillness among callers are reported to the Florida Health Department. This pilot studyevaluated an automated call processing menu system that allows callers to access bilingualHAB information, and to speak directly with a trained Poison Information Specialist. Themajority (68%) of callers reported satisfaction with the information, and many provided specific suggestions for improvement. This pilot study, the first known evaluation of use and satisfaction with HAB educational outreach materials, demonstrated that the automated system provided useful HAB-related information for the majority of callers, and decreased the routine informational call workload for the Poison Information Specialists, allowing them to focus on callers needing immediate assistance and their healthcare providers. These results will lead to improvement of this valuable HAB outreach, education and surveillance tool. Formal evaluation is recommended for future HAB outreach and educational materials.
Bioactive Compound Synthetic Capacity and Ecological Significance of Marine Bacterial Genus Pseudoalteromonas
Authors: Bowman John P.
Published: October 2008

The genus Pseudoalteromonas is a marine group of bacteria belonging to theclass Gammaproteobacteria that has come to attention in the natural product andmicrobial ecology science fields in the last decade. Pigmented species of the genus havebeen shown to produce an array of low and high molecular weight compounds withantimicrobial, anti-fouling, algicidal and various pharmaceutically-relevant activities.Compounds formed include toxic proteins, polyanionic exopolymers, substitutedphenolic and pyrolle-containing alkaloids, cyclic peptides and a range of bromine-substituted compounds. Ecologically, Pseudoalteromonas appears significant and to datehas been shown to influence biofilm formation in various marine econiches; involved inpredator-like interactions within the microbial loop; influence settlement, germinationand metamorphosis of various invertebrate and algal species; and may also be adopted bymarine flora and fauna as defensive agents. Studies have been so far limited to arelatively small subset of strains compared to the known diversity of the genussuggesting that many more discoveries of novel natural products as well as ecologicalconnections these may have in the marine ecosystem remain to be made.
The New Theory of Ion-Selective Electrodes
Authors: Pungor Ernõ
Published: October 2008

The paper discusses the anomalies of the former interpretation of the working mechanism of the ion-selective electrodes. It was thorougly discussed why the Donnan experiment could not be applied as the theoretical background of glass electrodes. It was assumed according to the Donnan interpretation that the measurable potential is produced by the transfer of the primary ion through the membrane. Since the 1960s, the author and coworkers have been investigating the problem of what can be the reason for the potential response of the electrodes. Practical measurements in connection with the response time, surface hindered reactions etc. were interpreted. Furthermore, the energy problems according to the Gibbs theory using two electrode components were investigated. It was established that the electrodes on which chemical reactions may occur with the primary ion have a surface reaction as the chemical basis of the response. For electrodes that work on the principle of the lyotropic series, surface reactions are also involved, but their response is not always Nernstian. The energy demand is covered by the charge separation at the electrodesolution interface.
Affinity sensors in non-equilibrium conditions: highly selective chemosensing by means of low selective chemosensors
Authors: Mirsky Vladimir  M.
Published: October 2008

The selectivity of measurements by means of affinity sensors in (quasi)equilibrium conditions and in non-equilibrium conditions was compared. The results show that the measurements in non-equilibrium conditions can reduce or even eliminate a relative contribution of interferents to a sensor signal.
Electrochemical Characterisation and Application of Multi Microelectrode Array Devices to Biological Electrochemistry
Authors: Kudera Michael , Hill H.  Allen O. , Dobson Peter  J. , Leigh Peter  A. , McIntire William   S.
Published: October 2008

A new design for microelectrode array (MEA) devices fabricated by semiconductor-processing techniques is presented. The microelectrode surfaces consist of gold and are surrounded by an insulating silicon nitride layer. Each chip of these so-called Multi MEAs contains regular arrays with circular-shaped electrodes of eight different sizes: 1, 3, 5, 10, 50, 100, 500 and 1000μm. The Multi MEAs were electrochemically characterised by use of ferrocenecarboxylic acid. Well-defined cyclic voltammograms of the two small redox proteins, horse heart cytochrome c and amicyanin from Thiobacillus versutus, were obtained at variously surface-modified Multi MEAs. Furthermore, a very simple method to manufacture Multi MEAs with carbon surfaces is introduced.
Errors in Chemical Sensor Measurements
Authors: Dybko Artur
Published: October 2008

Various types of errors during the measurements of ion-selective electrodes, ionsensitive field effect transistors, and fibre optic chemical sensors are described. The errors were divided according to their nature and place of origin into chemical, instrumental and non-chemical. The influence of interfering ions, leakage of the membrane components, liquid junction potential as well as sensor wiring, ambient light and temperature is presented.
Improving the Responses of Several Accelerometers Used in a Car Under Performance Tests by Using Kalman Filtering
Authors: Hernández Wilmar
Published: October 2008

In this paper a Kalman filter is used to cancel noise and interference contained in two accelerometers embedded in a car under performance tests. Here, the frequency bands of the signals of interest and their noise (deterministic as well as stochastic) are not strongly mixed with each other but it is very difficult to diminish the noise by using the classical approach to filtering. This reason, among others, justifies the necessity of the application of optimal filtering; and the Kalman filtering application allowed us to obtain optimal results (in the minimum mean-square sense) and signal-to-noise ratio improvements higher than 30 dB were achieved. The experimental results demonstrate the importance of using both analog signal conditioning and digital signal processing when dealing with signals corrupted by noise.
Assembly method fabricating linkers for covalently bonding DNA on glass surface
Authors: Li Jiong , Wang Hong , Zhao Yujie , Cheng Lu , He Nongyue , Lu Zuhong
Published: October 2008

A fabrication method of linkers to covalently anchor nucleic acid probes (such as, oligonucleotides, PCR-products or peptide nucleic acid oligomers) on glass was developed by alternatively covalently assembling the different molecular components. The linkers with controllable length, flexibility and hydrophilicity could be prepared simply by dipping subtracts alternatively in different chemical solutions. A dialkoxy aminosilane (N-(2-aminoethyl)-3-aminopropylmethyl dimethoxylsilane, AEAPS) was chosen to substitute common used trialkoxy aminosilane to modify glass surface. The end groups of the linkers were formed as aldehyde or amino group, which were successfully used for attaching prefabricated DNA or in situ synthesis of oligonucleotides, respectively. The both experiments showed that the linker produce good reproducibility and uniformity of fluorescent hybridizing images, which can distinguish an internal single base mismatch in 20mer oligonucleotides.
New Trends in Biosensors for Organophosphorus Pesticides
Authors: Jaffrezic-Renault Nicole
Published: October 2008

Biosensors are sensitive and can be used as disposable sensors for environmental control. These biosensors are based either on inhibition of acyl cholinesterases acetylcholinesterase or butyrylcholinesterase) by organophosphorus compounds or on inhibition of enzymes phosphatases (acid or alkaline) or on direct detection of organophosphorus compounds by organophosphorus hydrolase. The state-of-the-art of the three types of biosensors will be presented in this paper and a particular development will be done on our work on ENFET (Enzymatic Field Effect Transistor) biosensors.
Electrochemical Metal Ion Sensors. Exploiting Amino Acids and Peptides as Recognition Elements
Authors: Gooding J.  Justin , Hibbert D.  Brynn , Yang Wenrong
Published: October 2008

Amino acids and peptides are known to bind metal ions, in some cases very strongly. There are only a few examples of exploiting this binding in sensors. The review covers the current literature on the interaction of peptides and metals and the electrochemistry of bound metal ions. Peptides may be covalently attached to surfaces. Of particular interest is the attachment to gold via sulfur linkages. Sulfur-containing peptides (eg cysteine) may be adsorbed directly, while any amino group can be covalently attached to a carboxylic acid-terminated thiol. Once at a surface, the possibility for using the attached peptide as a sensor for metal ions becomes realised. Results from the authors’ laboratory and elsewhere have shown the potential for selective monitoring of metal ions at ppt levels. Examples of the use of poly-aspartic acid and the copper binding peptide Gly-Gly-His for detecting copper ions are given.
An Optical Biosensor for Monitoring Antigen Recognition Based on Surface Plasmon Resonance Using Avidin-Biotin System
Authors: Mu Ying , Zhang Hanqi , Zhao Xiaojun , Song Daqian , Wang Zhen , Sun Jing , Li Minjing , Jin Qinhan
Published: October 2008

A novel optical biosensor based on simultaneous multiwave length detection surface plasmon resonance (SPR) has been developed for immunosensing. The sensor is designed on the basis of fixing angle of incidence and measuring the reflected intensities of light in the wavelength range of 400–800 nm. The SPR spectra are shown in terms of reflected light intensity verus wavelength of incident light. The intensity of the reflected light is the minimum at the resonant wavelength. The biorecognition surface, formed on a chemically modified gold layer, consists of avidin that is specifically bound with biotin. These sensing membranes were self-assembled on gold layer. The processes of sensing monolayer formation were studied in real time through observing the change of resonant wavelength. The modified surface was used as a model immunosensor and to detect successfully the human factor B (Bf). The Bf was determined in the concentration range of 0.5~100 μg/mL. Under optimum experimental conditions, the sensor has a good repeatability, reversibility and selectivity.
Nafion Coated Electrodes as Voltammetric Sensors for Iron Analysis in Sediments and Pore Waters: an Example from the Lagoon of Venice
Authors: Ugo Paolo , Cavalieri Francesca , Rudello Danilo , Moretto Ligia M. , Argese Emanuele
Published: October 2008

Glassy carbon electrodes coated with Nafion are used for the ion-exchange voltammetric (IEV) determination of Fe(II) in the pore-waters and acidic extracts of sediments of the lagoon of Venice (Italy). The coated electrodes give reversible voltammetric signals, well resolved from background currents, which can be used for quantitative determinations. The yield of iron extracted by HCl from the sediment depends on the experimental conditions, in particular on the concentration of hydrochloric acid. By combining IEV on the acid extract with trapping and analysis of gaseous H2S evolved it is possible to obtain quantitative information both on the total content of iron dissolved by the acid attack and on the fraction of iron present in the form of acid volatile sulphides (AVS). As far as pore-waters are concerned, in this kind of samples the IEV determination of iron can be performed simply after dilution with HCl. The pore-waters here examined were sampled without alteration of their equilibrium conditions by using a suitable “in situ” sampler. IEV data obtained in samples from the lagoon of Venice (Italy) show satisfactory correlation with previous results obtained using different analytical techniques.
A Fiber-Optic Electrochemilunescence Sensor Placed into Sample Solution
Authors: Zhao Changzhi , Xu Songyun , Ding Zhaohong , Zhao Guoliang , Egashira Naoyoshi
Published: October 2008

A novel fiber-optic electrochemiluninescence sensor has been developed. It can be conveniently applied by placing into the sample solution in a manner similar to a conventional ion selective electrode, without requiring liquid luminous reagent and a flowing system. The sensor is consisted of an independent probe and a case for exclusion the ambient light, allowing the sample solution to pass through. Within the body of the probe, an optical fiber is utilized to collect and transmit light signal. In the three electrode configuration of the probe, a Pt electrode coated with Ru(bpy)32+- modified chitosan/silica gel membrane is used to give the electrolytic potential and provide a selective luminous membrane. The linear responses of the sensor to oxalic acid and amino acid were obtained in the concentration range of 2.0 × 10-4 to 1.0 × 10 –2 mol/dm3 with the relative standard deviations of 3.5% and 5.7%, respectively. The response of the sensor was not less than 80% of the initial value after the service time was over one month.
A Siren Detection System based on Mechanical Resonant Filters
Authors: Fragoulis Dimitris  K. , Avaritsiotis John  N.
Published: October 2008

A system based on mechanical resonant filters is proposed that can be used for the detection of acoustical signals the frequency components of which vary according to specific periodic patterns. Usually, signals of this category produced by the siren of an emergency vehicle. The device essentially implements a mechanical narrow filter bank that covers the frequency range of a typical siren sound. Signal detection is obtained by measuring the time delay between successive activation of the filters of the bank. The whole analysis reveals how a set of simple, low-cost mechanical resonant filters can replace an electronic analog or digital system for the implementation of a filter bank. Moreover, a scaling down procedure is proposed so that a microsystem may be developed.
Magnetism-Based Remote Query Glucose Sensors
Authors: Ong K.  G. , Paulose M. , Jain M.  K. , Gong D. , Varghese O.  K. , Mungle C. , Grimes C. A.
Published: October 2008

Two wireless, passive remote query magnetism-based glucose sensors, which operate in combination with a mass and volume changing glucose responsive polymer, are presented. One sensor design is based upon the magnetostatic coupling of magnetically soft thin-film elements; as the polymer volume changes in response to glucose concentration so does the magnetostatic coupling between elements. In response to a time varying magnetic field, upon reversal of the magnetization vector of the elements the magnetostatic coupling determines the time rate of change of magnetic flux, and hence the amplitude of the voltage spike generated in a pick-up coil. The other sensor consists of a free-standing magnetoelastic thick-film, coated with a thin layer of the glucose responsive polymer. In response to a time varying magnetic field the sensor mechanically vibrates at a characteristic resonant frequency; the characteristic resonant frequency of the sensor linearly tracks the change in mass of the glucose responsive polymer.
Evaluation of Protein Adsorption on Chitosan Surfaces with Reflectometry Interference Spectroscopy
Authors: Lü Xiao  Ying , Huang Yan , Ma Chao  Qun
Published: October 2008

Using a biomedical sensor setup RIfS we have investigated the kinetic behavior of human albumin (Alb), human fibrinogen (Fib), and human immunoglobulin G (IgG) adsorbed onto surfaces of chitosan. Polystyrene (PS) was used as the control material in this study. The optical thickness of three kinds of proteins measured by RIfS was related to their molecular dimensions and potential orientations on a film surface. According to the operation principle of RIfS and the molecular dimensions of three kinds of proteins, the adsorbed layers of proteins onto the surface of chitosan and PS was calculated by using a newly introduced equation. The microstructure of the chitosan and polystyrene film and the surfaces with adsorbed proteins were imaged by atomic force microscopy (AFM). With AFM analyses the lateral distribution of the protein molecules on surfaces have been recognized. The results show that the number of adsorbed layers of the three proteins on the surface of chitosan are 0.635 for Alb, 0.158 for Fib and 0.0967 for IgG, and of polystyrene are: 0.577 for IgG, 0.399 for Fib, 0.336 for Alb. This study confirmed that RIfS is a useful tool for the analysis of plasma proteins adsorbed on a surface of biomaterials. Results show that at first on the surface of chitosan film much more Alb than Fib was adsorbed which demonstrated that chitosan has a antithrombus function. Secondly, on the surface of chitosan film more Alb and less Fib were adsorbed than on the surface of PS film, which demonstrated that chitosan has a better blood compatibility than polystyrene. Thirdly, the calculated layer number of the three proteins indicated that on both chitosan and PS substrates monolayer coatings form.
Sensors and Asymptotic w-observer for Distributed Diffusion Systems
Authors: Al-Saphory R. , Jai A.  El
Published: October 2008

The aim of this paper is to study the regional observer concept through the consideration of sensors. For a class of distributed diffusion systems, we propose an approach derived from the Luenberger observer type as introduced by Gressang and Lamont [1]. Furthermore, we show that the structures of sensors allow the existence of regional observer and we give a sufficient condition for each regional observer. We also show that, there exists a dynamical system for diffusion systems is not observer in the usual sense, but it may be regional observer.
A „Hybrid“ Thin-Film pH Sensor with Integrated Thick-Film Reference
Authors: Simonis Anette , Krings Thomas , Lüth Hans , Wang Joseph , Schöning Michael  J.
Published: October 2008

A reference electrode fabricated by means of thick-film technique is deposited onto a silicon substrate and combined with a thin-film pH sensor to a “hybrid” chip system. To evaluate the suitability of this combination, first investigations were carried out. The characteristics of the thin-film pH sensor were studied towards the thick-film Ag/AgCl reference electrode. Measurements were performed in the capacitance/voltage (C/V) and constant capacitance (Concap) mode for different pH values keeping the concentration of chloride ions constant. No difference of the sensor behaviour could be found when comparing the results to measurements, obtained versus a conventional macroscopic Ag/AgCl reference electrode.
A Carbon Nanotube-based Sensor for CO2 Monitoring
Authors: Ong Keat  G. , Grimes Craig  A.
Published: October 2008

A carbon dioxide (CO2) sensor is fabricated by depositing a thin layer of a multiwall carbon nanotube (MWNT) – silicon dioxide (SiO2) composite upon a planar inductorcapacitor resonant circuit. By tracking the resonant frequency of the sensor the complex permittivity of the coating material can be determined. It is shown that the permittivity of MWNTs changes linearly in response to CO2 concentration, enabling monitoring of ambient CO2 levels. The passive sensor is remotely monitored with a loop antenna, enabling measurements from within opaque, sealed containers. Experimental results show the response of the sensor is linear, reversible with no hysteresis between increasing and decreasing CO2 concentrations, and with a response time of approximately 45 s. An array of three such sensors, comprised of an uncoated, SiO2 coated, and a MWNT-SiO2 coated sensors is used to self-calibrate the measurement for operation in a variable humidity and temperature environment. Using the sensor array CO2 levels can be measured in a variable humidity and temperature environment to a ± 3% accuracy.
Sulfonated Polyaniline Coated Mercury Film Electrodes for Voltammetric Analysis of Metals in Water
Authors: Fungaro Denise  Alves
Published: October 2008

The electrochemical polymerization of 2-aminobenzenesulfonic acid with and without aniline has been carried by cyclic potencial sweep in sulfuric acid solution at the glassy carbon electrode. The polymer and copolymer formed have been characterized voltammetrically. The sulfonated polyaniline coated mercury thin-film electrodes have been evaluated for use with anodic stripping voltammetry. The electrodes were tested and compared with a conventional thin-film mercury electrode. Calibration plots showed linearity up to 10-7 mol L-1. Detection limits for zinc, lead and cadmium test species are very similar at around 12 nmol L-1. Applications to analysis of waters samples are demonstrated.
Mediated Electron Transfer at Redox Active Monolayers
Authors: Lyons Michael  E.G.
Published: October 2008

A theoretical model describing the transport and kinetic processes involved in heterogeneous redox catalysis of solution phase reactants at electrode surfaces coated with redox active monolayers is presented. Although the analysis presented has quite general applicability, a specific focus of the paper is concerned with the idea that redox active monolayers can be used to model an ensemble of individual molecular nanoelectrodes. Three possible rate determining steps are considered: heterogeneous electron transfer between immobilized mediator and support electrode ; bimolecular chemical reaction between redox mediator and reactant species in the solution phase, and diffusional mass transport of reactant in solution. A general expression for the steady state reaction flux is derived which is valid for any degree of reversibility of both the heterogeneous electron transfer reaction involving immobilized mediator species and of the bimolecular cross exchange reaction between immobilized mediator and solution phase reactant. The influence of reactant transport in solution is also specifically considered. Simplified analytical expressions for the net reaction flux are derived for experimentally reasonable situations and a kinetic case diagram is constructed outlining the relationships between the various approximate solutions. The theory enables simple diagnostic plots to be constructed which can be used to analyse experimental data.
Determination of Active Components in Rhubarb by Cyclodextrin-modified Capillary Zone Electrophoresis
Authors: Xiaoyu Shang , Zhuobin Yuan
Published: October 2008

A cyclodextrin-modified capillary zone electrophoresis was developed for the determination of four bioactive components in Rhubarb. Effects of pH, b-CD concentration and organic modifier content on the migration and separation of the components were studied. The four components were separated in the running buffer of 50 mmol/L NaOHH3BO3 (pH 10.7) containing 10 mmol/L b-CD and 12.5% v/v ethanol. The analytical performance of the method was tested with respect to linearity response, precision and recovery. The determination of two commercial Rhubarb samples under the optimized conditions showed a satisfactory result.
Detection of Antioxidative Activity of Plant Extracts at the DNA-Modified Screen-Printed Electrode
Authors: Labuda J. , Bučková M. , Heilerová L. , Čaniová-Žiaková A. , Brandšteterová E. , Mattusch J. , Wennrich R.
Published: October 2008

A simple procedure for the voltammetric detection of antioxidative activity of plant extracts based on the protection from DNA damage at the electrode surface is reported. A disposable electrochemical DNA biosensor fabricated as a carbon-based screen-printed electrode modified by a surface layer of the calf thymus double stranded (ds) DNA was used as a working electrode in combination with a silver/silver chloride reference electrode and a separate platinum auxiliary electrode. The [Co(phen)3]3+ ion served as the dsDNA redox marker and the [Fe(EDTA)]- complex with hydrogen peroxide under the electrochemical reduction of the iron atom were used as the DNA cleavage mixture. A remarkable antioxidative activity of phenolic antioxidants such as rosmarinic and caffeic acids as standards and the extracts of lemon balm, oregano, thyme and agrimony was found which is quite in agreement with an antiradical activity determined spectrophotometrically using 2,2’-diphenyl-1-picrylhydrazyl (DPPH) radical.
A (Bio-)Chemical Field-Effect Sensor with Macroporous Si as Substrate Material and a SiO2 / LPCVD-Si3N4 Double Layer as pH Transducer
Authors: Schöning Michael , Simonis Anette , Ruge Christian , Ecken Holger , Müller-Veggian Mattea , Lüth Hans
Published: October 2008

Macroporous silicon has been etched from n-type Si, using a vertical etching cell where no rear side contact on the silicon wafer is necessary. The resulting macropores have been characterised by means of Scanning Electron Microscopy (SEM). After etching, SiO2 was thermally grown on the top of the porous silicon as an insulating layer and Si3N4 was deposited by means of Low Pressure Chemical Vapour Deposition (LPCVD) as transducer material to fabricate a capacitive pH sensor. In order to prepare porous biosensors, the enzyme penicillinase has been additionally immobilised inside the porous structure. Electrochemical measurements of the pH sensor and the biosensor with an Electrolyte/Insulator/Semiconductor (EIS) structure have been performed in the Capacitance/Voltage (C/V) and Constant capacitance (ConCap) mode.
In-Situ Chemiresistor Sensor Package for Real-Time Detection of Volatile Organic Compounds in Soil and Groundwater
Authors: Ho Clifford  K. , Hughes Robert  C.
Published: October 2008

This paper presents the development of a real-time microsensor-based monitoring system that can be used to detect and characterize volatile organic compounds in soil and groundwater. The system employs an array of polymer-based microsensors (chemiresistors) packaged in a waterproof housing that is designed to protect the sensor from harsh subsurface environments, including completely water-saturated conditions. The sensors and packaging have been tested in field and laboratory environments, and characterization methods are being developed that utilize contaminant-transport models and time-dependent, in-situ sensor data to identify the location of the contaminant source.
Surface Plasmon Resonance Studies on Molecular Imprinting
Authors: Li Ping , Huang Yan , Hu Junze , Yuan Chunwei , Lin Baoping
Published: October 2008

The molecular imprinted polymer (MIP) members were fabricated with the print molecule L-phenylalanine ethyl ester. The elution and adsorption procedures were investigated by surface plasmon resonance in situ. The changes of refractive angle during elution procedure suggest that the MIP is prepared on the base of the non-covalent interactions. This MIP member sensor can achieve enantioselective recognition.
Studies on the Electrochemical Behaviour of Hydroquinone at L-cysteine Self-Assembled Monolayers Modified Gold Electrode
Authors: Wang Shengfu , Du Dan
Published: October 2008

L-Cysteine is combined onto gold electrode to form a self-assembled monolayers modified electrode (L-Cys/Au SAMs) by taking advantage of strong sulfur-gold interaction. ATR-FTIR, SEM, cyclic voltammetry (CV) and impedance were used for the characterization of the film. It shows excellent stability upon voltametric scanning and a good voltametric response towards hydroquinone with the potential ranged from 0.8 to –0.2 V (vs.SCE) in 0.5M HAc-NaAc buffer solution (pH 4.8). The oxidation potential of hydroquinone on the modified electrode shifted negatively about 330 mV as compared with the bare gold electrode. The plot of catalytic current vs.its concentration has a good linear relation in the range of 2.0×10-6~2.0×10-4M with the correlation coefficient of 0.9986 and the detection limit of 4.0×10-7M by different pulse voltammetry (DPV). Mechanism for the electrocatalytical process has been studied.
A Ceramic Thick Film Humidity Sensor Based on MnZn Ferrite
Authors: Arshaka K. , Twomey K. , Egan D.
Published: October 2008

A ceramic thick film humidity sensor, produced from MnZn ferrite, is presented. The proposed sensing mechanism is a combination of proton hopping, hydronium diffusion, and vacancy donor traps releasing electrons into the conduction band. The sensor structure comprises a two-layer device; the first layer is an interdigitated conductor and the second layer is a 30μm thick sensing layer. The effects of sintering the sensing pastes in air and vacuum have been reported. The air-fired sample exhibits the highest humidity sensitivity (1.54%/RH%) and the lowest temperature sensitivity (0.37%/oC). The vacuum-fired sample has the lowest humidity sensitivity (0.043%/RH) and the highest temperature sensitivity (0.77%/oC). The sensitivity results indicate that the air-fired sample has the best potential for use in humidity sensing applications.
Bimetallic Layers Increase Sensitivity of Affinity Sensors Based on Surface Plasmon Resonance
Authors: Zynio Stepan  A. , Samoylov Anton  V. , Surovtseva Elena  R. , Mirsky Vladimir  M. , Shirshov Yuri  M.
Published: October 2008

Two metals are used in resonant layers for chemical sensors based on surface plasmon resonance (SPR) - gold and silver. Gold displays higher shift of the resonance angle to changes of ambient refraction index and is chemically stable. Silver posses narrower resonance curve thus providing a higher signal/noise ratio of SPR chemical sensors, but has a poor chemical stability. A new structure of resonant metallic film based on bimetallic silver/gold layers (gold as an outer layer) is suggested. It combines advantages of both gold and silver resonant layers. Bimetallic resonant films display so high shift of resonance angle on changes of ambient refraction index as gold films, but show narrower resonance curve, thus providing a higher signal / noise ratio. Additionally, the outer gold layer protects silver against oxidation.