Suchergebnisse

11 pages, 3 figures, 7 tables.-- Available online Nov 16, 2002. ; A field-test kit (SensioScreen® TR500) for the determination of triazine herbicides in water samples has been evaluated. The test is based on an ELISA method performed on a membrane that allows the visual estimation of the presence of triazine herbicides in <10 min. The kit contains all necessary reagents and equipment, and operates on a very simple protocol. The detection level of this semiquantitative kit has been set at 0.5 μg/l (for the sum of all triazines), although concentration levels of 0.1 μg/l for atrazine can be detected. This is the first time that a commercial field-test kit to control water contamination by herbicides performs in compliance with the EU and USA legislations regarding the limit of detection reached. Evaluation and validation studies have been performed using spiked, certified (AquaCheck) and real environmental samples comparing the results with chromatographic methods. In spite of the semiquantitative–qualitative character of the kit, the results demonstrate that the test SensioScreen® TR500 provides a very good estimation of the atrazine concentration in the sample. This test format could be adapted to the detection of other contaminants of environmental relevance. ; This work has been supported by CICYT (BIO2000-0351-P4-05) and by INIA (VIN0053-C3). ; Peer reviewed

Environmental pollutants vigilance is one of the main problems that the aquaculture industry has to face with the objective to ensure the quality of their products and prevent entrance in the food chain that finally may arrive to the consumer. Contaminants such as hormones, antibiotics or biocides are especially relevant due to their toxicity, pharmacological effect or hormonal activity that can be considered harmful for the final consumer. The contaminants can be detected in the environment where the food is growing, and their concentration can be found (i.e., seawater) in the range of µg·L−1, ng·L−1 or even in lower concentrations. Thus, sensitive and selective methods for their monitoring are required to avoid their arrival in the food chain. Here, the development of a multiplexed amperometric biosensor is described, based on the use of specific antibodies to reach the necessary detectability to measure the targeted contaminants directly in seawater. The multiplexed immunosensor allows the detection of four relevant pollutants, such as el Irgarol 1051, sulfapyridine, chloramphenicol and estradiol, reaching an IC50 of 5.04 ± 0.29, 3.45 ± 0.29, 4.17 ± 0.44 and 5.94 ± 0.28 µg·L−1, directly measured in seawater. ; The ICTS "NANOBIOSIS", and particularly the Custom Antibody Service (CAbS, IQAC-CSIC, CIBER-BBN), is acknowledged for the assistance and support related to the immunoreagents used in this work. A.M. and K.K. also thank the support of the Eramus+ program of the European Union. The Nb4D group (formerly Applied Molecular Receptors group, AMRg) is a consolidated research group (Grup de Recerca) of the Generalitat de Catalunya and has support from the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (expedient: 2017 SGR 1441). CIBER-BBN is an initiative funded by the Spanish National Plan for Scientific and Technical Research and Innovation 2013–2016, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. ; Peer reviewed

30 pages, 2 figures, 2 tables.-- Presented at the Southern and Eastern Africa Network of Analytical Chemists (SEANAC), Gaborone, Botswana, July 7-10, 2003. ; Biosensors can be excellent analytical tools for monitoring programs working to implement legislation. In this article, biosensors for environmental analysis and monitoring are extensively reviewed. Examples of biosensors for the most important families of environmental pollutants, including some commercial devices, are presented. Finally, future trends in biosensor development are discussed. In this context, bioelectronics, nanotechnology, miniaturization, and especially biotechnology seem to be growing areas that will have a marked influence on the development of new biosensing strategies in the next future. ; This work has been supported by AWACSS (EVK1-CT-2000-00045) and by RADAR (QLRT-2000- 01670). Sara Rodriguez acknowledges Ministerio de Ciencia y Tecnología (Project PPQ 2000-3006-CE) and I3P Program (Itinerario integrado de inserción professional; co-financed by CSIC and European Social Funds). María J. López de Alda acknowledges a Ramon y Cajal contract from the Spanish Ministry of Science and Technology. ; Peer reviewed

The development of a highly sensitive, specific, and reliable immunochemical assay to detect pyocyanin (PYO), one of the most important virulence factors (VFs) of Pseudomonas aeruginosa, is here reported. The assay uses a high-affinity monoclonal antibody (mAb; C.9.1.9.1.1.2.2.) raised against 1-hydroxyphenazine (1-OHphz) hapten derivatives (PC1; a 1:1 mixture of 9-hydroxy- and 6-hydroxy-phenazine-2-carobxylic acids). Selective screening using PYO and 1-OHphz on several cloning cycles allowed the selection of a clone able to detect PYO at low concentration levels. The microplate-based ELISA developed is able to achieve a limit of detection (LoD) of 0.07 nM, which is much lower than the concentrations reported to be found in clinical samples (130 μM in sputa and 2.8 μM in ear secretions). The ELISA has allowed the investigation of the release kinetics of PYO and 1-OHphz (the main metabolite of PYO) of clinical isolates obtained from P. aeruginosa-infected patients and cultured in Mueller-Hinton medium. Significant differences have been found between clinical isolates obtained from patients with an acute or a chronic infection (~6,000 nM vs. ~8 nM of PYO content, respectively) corroborated by the analysis of PYO/1-OHphz levels released by 37 clinical isolates obtained from infected patients at different stages. In all cases, the levels of 1-OHphz were much lower than those of PYO (at the highest levels 6,000 nM vs. 300 nM for PYO vs. 1-OHphz, respectively). The results found point to a real potential of PYO as a biomarker of P. aeruginosa infection and the possibility to use such VF also as a biomarker for patient stratification[2] and for an effective management of these kinds of infections. ; This work has been funded by the Spanish Government to M-PM through the Ministry of Science and Innovation (SAF2015-67476-R, RTI2018-096278-B-C21, PI, M-PM) and by Fundació Marató de TV3 (201825-30-31, PI, M-PM). The Nb4D group is a consolidated research group (Grup de Recerca) of the Generalitat de Catalunya and has support from the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (expedient: 2017 SGR 1441). CIBER Actions are financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund (ERDF). Moreover, BR-U has an FI fellowship from the AGAUR (Agència de Gestió d'Ajuts Universitaris I de Recerca) of the Government of Catalonia (Generalitat de Catalunya) (2019FI_B00289). El Fons social Europeu Inverteix en el teu futur. ; Peer reviewed

Lab‐on‐a‐chip devices incorporating valves and pumps can perform complex assays involving multiple reagents. However, the instruments used to drive these chips are complex and bulky. In this article, a new wax valve design that uses light from a light emitting diode (LED) for both opening and closing is reported. The valves and a pumping chamber are integrated in lab‐ona‐foil chips that can be fabricated at low cost using rapid prototyping techniques. A chip for the implementation of enzyme‐linked immunosorbent assays (ELISA) is designed. A porous nitrocellulose material is used for the immobilization of capture antibodies in the microchannel. A compact generic instrument with an array of 64 LEDs, a linear actuator to drive the pumping chamber, and absorbance detection for a colorimetric readout of the assay is also presented. Characterization of all the components and functionalities of the platform and the designed chip demonstrate their potential for assay automation. ; This research was funded by the H2020 PANBioRA (EU760921) project of the European Union. ; Peer reviewed

The excellent self-assembling properties of DNA and the excellent specificity of the antibodies to detect analytes of small molecular weight under competitive conditions have been combined in this study. Three oligonucleotide sequences (N1up, N2up, and N3up) have been covalently attached to three steroidal haptens (8, hG, and 13) of three anabolic-androgenic steroids (AAS), stanozolol (ST), tetrahydrogestrinone (THG), and boldenone (B), respectively. The synthesis of steroid-oligonucleotide conjugates has been performed by the reaction of oligonucleotides carrying amino groups with carboxyl acid derivatives of steroidal haptens. Due to the chemical nature of the steroid derivatives, two methods for coupling the haptens and the ssDNA have been studied: a solid-phase coupling strategy and a solution-phase coupling strategy. Specific antibodies against ST, THG, and B have been used in this study to asses the possibility of using the self-assembling properties of the DNA to prepare biofunctional SPR gold chips based on the immobilization of haptens, by hybridization with the complementary oligonucleotide strands possessing SH groups previously immobilized. The capture of the steroid-oligonucleotide conjugates and subsequent binding of the specific antibodies can be monitored on the sensogram due to variations produced on the refractive index on top of the gold chip. The resulting steroid-oligonucleotide conjugates retain the hybridization and specific binding properties of oligonucleotides and haptens as demonstrated by thermal denaturation experiments and surface plasmon resonance (SPR). ; This work was supported by grants from the Ministry of Science and Innovation, MICINN (MAT2011-29335-C03-01 and CTQ2010-20541-C03-01), CCEE (FUNMOL, FP7-NMP-213382-2), Generalitat de Catalunya (2009/SGR/1343, 2009/SGR/208), and CIBER-BBN. CIBER-BBN is an initiative funded by the VI National R&D&i Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. Núria Tort has a FI_B fellowship from the AGAUR (Agència de Gestió d'Ajuts Universitaris i de Recerca) of the (Generalitat de Catalunya) Government of Catalonia. ; Peer reviewed

The detection of living organisms at very low concentrations is necessary for the early diagnosis of bacterial infections, but it is still challenging as there is a need for signal amplification. Cell culture, nucleic acid amplification, or nanostructure-based signal enhancement are the most common amplification methods, relying on long, tedious, complex, or expensive procedures. Here, we present a cyanotype-based photochemical amplification reaction enabling the detection of low bacterial concentrations up to a single-cell level. Photocatalysis is induced with visible light and requires bacterial metabolism of iron-based compounds to produce Prussian Blue. Bacterial activity is thus detected through the formation of an observable blue precipitate within 3 h of the reaction, which corresponds to the concentration of living organisms. The short time-to-result and simplicity of the reaction are expected to strongly impact the clinical diagnosis of infectious diseases. ; This project has received funding from the European Union Horizon 2020 Research and Innovation Programme under the Marie Skłodow-ska-Curie grant agreement no. 675412 as a part of the consortium New Diagnostics for Infectious Diseases (ND4ID). G.G. thanks the Ministerio de Ciencia e Innovación of Spain for financial support through the project PID2019-106171RB-I00. Patent (P42106384SE00) based on part of this work was granted. M.-P.M. and L.V. would like to thank the Ministry of Science and Innovation (SAF2015-67476-R and RTI2018-096278-B-C21) and Fundación Marató de TV3 (TV32018-201825-30-31). ; Peer reviewed

Gold nanostars (GNST), gold nanospheres (GNP) and carbon black (CB) are chosen as alternative nanomaterials to modify carbon screen-printed electrodes (c-SPEs). The resulting three kinds of modified c-SPEs (GNP-SPE, CB-SPE and GNSP-SPE) were electrochemically and microscopically characterized and compared with standardized c-SPEs after pretreatment with phosphate buffer by pre-anodization (pre-SPE). The results show outstanding electrochemical performance of the carbon black-modified SPEs which show low transient current, low capacitance and good porosity. A competitive chronoamperometric immunoassay for the shellfish toxin domoic acid (DA) is described. The performances of the CB-SPE, GNP-SPE and pre-SPE were compared. Hapten-functionalized magnetic beads were used to avoid individual c-SPE functionalization with antibody while enhancing the signal by creating optimum surface proximity for electron transfer reactions. This comparison shows that the CB-SPE biosensor operated best at a potential near − 50 mV (vs. Ag/AgCl) and enables DA to be determined with a detection limit that is tenfold lower compared to pre-SPE (4 vs. 0.4 ng mL−1). These results show very good agreement with HPLC data when analysing contaminated scallops, and the LOD is 0.7 mg DA kg−1 of shellfish. ; This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 720325. ; Peer reviewed

In this work, we report the development of a highly sensitive biosensor for sulfapyridine detection based on an integrated bio micro-electromechanical system (Bio-MEMS) containing four gold working electrodes (WEs), a platinum counter electrode (CE), and a reference electrode (RE). Firstly, the cleaned WEs were modified with 4-aminophenylacetic acid (CMA). Then, (5-[4-(amino)phenylsulfonamide]-5-oxopentanoic acid (SA2BSA) was immobilized onto the transducers surface by carbodiimide chemistry. The analyte was quantified by competitive detection with SA2BSA immobilized on the WE toward a mixture of Ab155 antibody (with fixed concentration) and sulfapyridine. In order to obtain a highly sensitive biosensor, Ab155 was immobilized onto magnetic latex nanoparticles surface to create a 3D architecture (Ab-MLNp). Using electrochemical impedance spectroscopy (EIS), we investigated the influence of the Ab-MLNp on the sensitivity of our approach. The optimized system was analyzed, as competitive assay, with different concentrations of sulfapyridine (40 µM, 4 µM, and 2 nM) and with phosphate buffer solution. From data fitting calculations and graphs, it was observed that the EIS showed more linearity when Ab-MLNp was used. This result indicates that the magnetic latex nanoparticles increased the sensitivity of the biosensor. ; The authors acknowledge the financial support from the projects European Communities Seventh Framework Program: SEA-on-a-CHIP (FP7-OCEAN-2013) under the grant agreement N° 614168, and funding from the European Union's Horizon 2020 research and innovation program entitled KardiaTool under grant agreement N° 643694, and the fellowship from Science Without Borders program—Conselho Nacional de Desenvolvimento Ciêntífico Tenológico (CNPq)–Brazil grant N° 249056/2013-5. ; Peer reviewed

Standard methods for chemical food safety testing in official laboratories rely largely on liquid or gas chromatography coupled with mass spectrometry. Although these methods are considered the gold standard for quantitative confirmatory analysis, they require sampling, transferring the samples to a central laboratory to be tested by highly trained personnel, and the use of expensive equipment. Therefore, there is an increasing demand for portable and handheld devices to provide rapid, efficient, and on-site screening of food contaminants. Recent technological advancements in the field include smartphone-based, microfluidic chip-based, and paper-based devices integrated with electrochemical and optical biosensing platforms. Furthermore, the potential application of portable mass spectrometers in food testing might bring the confirmatory analysis from the laboratory to the field in the future. Although such systems open new promising possibilities for portable food testing, few of these devices are commercially available. To understand why barriers remain, portable food analyzers reported in the literature over the last ten years were reviewed. To this end, the analytical performance of these devices and the extent they match the World Health Organization benchmark for diagnostic tests, i.e., the Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end-users (ASSURED) criteria, was evaluated critically. A five-star scoring system was used to assess their potential to be implemented as food safety testing systems. The main findings highlight the need for concentrated efforts towards combining the best features of different technologies, to bridge technological gaps and meet commercialization requirements. ; This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 720325, FoodSmartphone. ; Peer reviewed

Food contaminants monitoring is conducted in an intensive manner yet, there are still food safety scandals related to various chemical compounds. This fact highlights the need to review the requirements posed by the current legal framework on analytical methods performance and evaluate its application in published studies. Herein, we present an inventory including more than 470 publications on screening and confirmatory methods, which were used to control hazardous compounds such as pesticides, antibiotics, mycotoxins, aquatic toxins and allergens. Analytical performance characteristics, trends and state of the art, both merits and shortcomings, are critically discussed and summarized in excel tabulations. This repository highlights the ever-increasing use of screening methods and the necessity to confirm their performance by applying confirmatory methods. In conclusion, more effort is needed on validation and benchmarking, especially of newly developed technology such as smartphone-based methods, to avoid false-negative results and ensure that methods fit for purpose. © 2019 The Authors ; This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 720325 , FoodSmartphone. Appendix A ; Peer reviewed

Kynurenic acid (KYNA) is a product of the tryptophan (TRP) metabolism via the kynurenine pathway (KP). This pathway is activated in neurodegenerative disorders, such as Alzheimer´s disease (AD). KYNA is primarily produced by astrocytes and is considered neuroprotective. Thus, altered KYNA levels may suggest an inflammatory response. Very recently, significant increases in KYNA levels were reported in cerebrospinal fluid (CSF) from AD patients compared with normal controls. In this study, we assessed the accuracy of KYNA in CSF for the classification of patients with AD, cognitively healthy controls, and patients with a variety of other neurodegenerative diseases, including frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS), and progressive supranuclear palsy (PSP). Averaged KYNA concentration in CSF was higher in patients with AD when compared with healthy subjects and with all the other differentially diagnosed groups. There were no significant differences in KYNA levels in CSF between any other neurodegenerative groups and controls. These results suggest a specific increase in KYNA concentration in CSF from AD patients not seen in other neurodegenerative diseases. ; This research was funded by Instituto de Salud Carlos III (PI18/00118), FEDER, CIBERNED, CIBER-BBN; the Ministry of Science and Innovation (TryKySeNS project, CTQ2011-29163-C03-01); and S2017/BMD-3700 (NEUROMETAB-CM) from Comunidad de Madrid co-financed with the Structural Funds of the European Union. The Nb4D group is a consolidated research group (Grup de Recerca) of the Generalitat de Catalunya and has support from the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (expedient: 2017 SGR 1441). ; Peer reviewed