ORCID Profile
0000-0001-8016-1565
Current Organisation
Universitat Rovira i Virgili - Campus Sescelades
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Colloid and Surface Chemistry | Analytical Chemistry | Macromolecular and Materials Chemistry | Synthesis of Materials | Sensor Technology (Chemical aspects) | Electroanalytical Chemistry | Immunological and Bioassay Methods | Physical Chemistry (Incl. Structural) | Electrochemistry | Environmental Biotechnology Diagnostics (incl. Biosensors)
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Chemical Sciences | Urban Water Evaluation (incl. Water Quality) | Food Safety | Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments |
Related Links
Publications
Biomolecule immobilization in biosensor development: Tailored strategies based on affinity interactions
Publisher: Bentham Science Publishers Ltd.
Date: 08-2008
DOI: 10.2174/092986608785203791
Abstract: The exponential development of biosensors as powerful analytical tools in the last four decades mainly relies on the high sensitivity and selectivity offered when detecting the target analyte. The transducer and the biological receptor are the bases of the biosensor development. Nevertheless, the bioreceptor immobilisation is also important, playing a key role in the retention of the biological activity, and thus affecting the sensitivity. Parameters such as shelf-life and surface regeneration also depend on the biomolecule immobilisation. Researchers are focusing their efforts towards random and oriented immobilisation procedures. Adsorption, entrapment, cross-linking and electrostatic interactions provide randomly immobilised biomolecules, sometimes partially hindering their biological activity. Covalent binding and affinity interactions may enable oriented biomolecule immobilisations, providing controlled, reproducible and highly active modified surfaces. This paper reviews the main immobilisation strategies used in the biosensors development, putting special emphasis on our contribution to mild and oriented immobilisation techniques.
Selection of an Aptamer against the Enzyme 1-deoxy-D-xylulose-5-phosphate Reductoisomerase from Plasmodium falciparum
Publisher: MDPI AG
Date: 19-11-2022
DOI: 10.3390/PHARMACEUTICS14112515
Abstract: The methyl erythritol phosphate (MEP) pathway of isoprenoid biosynthesis is essential for malaria parasites and also for several human pathogenic bacteria, thus representing an interesting target for future antimalarials and antibiotics and for diagnostic strategies. We have developed a DNA aptamer (D10) against Plasmodium falciparum 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), the second enzyme of this metabolic route. D10 binds in vitro to recombinant DXR from P. falciparum and Escherichia coli, showing at 10 µM a ca. 50% inhibition of the bacterial enzyme. In silico docking analysis indicates that D10 associates with DXR in solvent-exposed regions outside the active center pocket. According to fluorescence confocal microscopy data, this aptamer specifically targets in P. falciparum in vitro cultures the apicoplast organelle where the MEP pathway is localized and is, therefore, a highly specific marker of red blood cells parasitized by Plasmodium vs. naïve erythrocytes. D10 is also selective for the detection of MEP+ bacteria (e.g., E. coli and Pseudomonas aeruginosa) vs. those lacking DXR (e.g., Enterococcus faecalis). Based on these results, we discuss the potential of DNA aptamers in the development of ligands that can outcompete the performance of the well-established antibody technology for future therapeutic and diagnostic approaches.
Disperse-and-Collect Approach for the Type-Selective Detection of Matrix Metalloproteinases in Porous Silicon Resonant Microcavities
Publisher: American Chemical Society (ACS)
Date: 07-12-2017
Label-free electrochemical DNA sensor using “click”-functionalized PEDOT electrodes
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.BIOS.2015.07.037
Abstract: Here we describe a label-free electrochemical DNA sensor based on poly(3,4-ethylenedioxythiophene)-modified (PEDOT-modified) electrodes. An acetylene-terminated DNA probe, complementary to a specific "Hepatitis C" virus sequence, was immobilized onto azido-derivatized conducting PEDOT electrodes using "click" chemistry. DNA hybridization was then detected by differential pulse voltammetry, evaluating the changes in the electrochemical properties of the polymer produced by the recognition event. A limit of detection of 0.13 nM was achieved using this highly selective PEDOT-based genosensor, without the need for labeling techniques or microelectrode fabrication processes. These results are promising for the development of label-free and reagentless DNA hybridization sensors based on conducting polymeric substrates. Biosensors can be easily prepared using any DNA sequence containing an alkyne moiety. The data presented here reveal the potential of this DNA sensor for diagnostic applications in the screening of diseases, such as "Hepatitis C", and genetic mutations.
Highly sensitive detection of pathogen Escherichia coli O157:H7 by electrochemical impedance spectroscopy
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.BIOS.2013.01.009
Abstract: The presence of enterohemorrhagic Escherichia coli bacteria in food can cause serious foodborne disease outbreaks. Early detection and identification of these pathogens is extremely important for public health and safety. Here we present a highly sensitive label-free immunosensor for the detection of pathogenic E. coli O157:H7. Anti-E. coli antibodies were covalently immobilised onto gold electrodes via a self-assembled monolayer (SAM) of mercaptohexadecanoic acid and the pathogenic bacteria were detected by electrochemical impedance spectroscopy (EIS). Surface Plasmon Resonance (SPR) was used to monitor the antibody immobilisation protocol and antibody patterned surfaces were used to demonstrate the specificity of the antibody coated surfaces against the pathogenic bacteria. The immunosensor showed a very low limit of detection (2CFU/mL) and a large linear range (3 × 10-3 × 10(4)CFU/mL). Finally, the selectivity of the sensor was demonstrated and no significant adsorption of Salmonella typhimurium was observed.
Evaluation of different strategies for the development of amperometric biosensors for l-lactate
Publisher: Elsevier BV
Date: 15-05-2007
DOI: 10.1016/J.BIOS.2006.10.034
Abstract: Two strategies were investigated for the development of lactate biosensors based on sol-gel matrixes and polysulfone composite films, both containing L-lactate dehydrogenase (LDH). Firstly, reagentless disposable screen-printed electrodes (SPE's) with Meldola's Blue (MB) and the cofactor NAD(+) inside a sol-gel matrix were prepared. These showed relatively low sensitivities (260 microA/M). Secondly, mediator-modified-polysulfone-graphite composite films deposited over both cylindrical epoxy-graphite and SPE's. These electrodes showed enhanced performance characteristics: improved sensitivity (80 mA/M), detection limit (0.87 microM) and reproducibility (2%). Reagentless electrodes, incorporating NAD(+) in the polysulfone film, had a decreased sensitivity, although better than that achieved by the sol-gel electrodes. While sol-gel electrodes showed a linear range between 1.25 x 10(-4) and 2.48 x 10(-3)M, the epoxy-graphite composite electrodes based on polysulfone composite films allowed the detection of lactate at a linear range of lower concentrations from 1 x 10(-6) to 1.2 x 10(-5)M. Finally, the performance of the LDH-MB-polysulfone-composite film-based SPE's in a flow system was studied. Short response times were obtained (t<30s). Furthermore, repeatability and reproducibility values were notably improved, especially when working with electrodes covered with a polyamide layer prepared with N-(2-aminoethyl)-piperazine.
Biosensors for secondary metabolites, two case studies: Ochratoxin A and microcystin
Publisher: Springer US
Date: 2010
DOI: 10.1007/978-1-4419-7347-4_21
Abstract: Secondary metabolites are chemical compounds that are not directly involved in the normal growth, development or reproduction of organisms. Due to the toxicity shown by some of these compounds, their presence can represent a threat to human health. Reliable detection systems able to control their presence are required, as a tool to ensure public health. This chapter offers an overview of different techniques developed for the detection of toxic secondary metabolites, taking ochratoxin A and microcystins as two representative ex les. While ochratoxin A is a mycotoxin produced by several species of fungi, microcystins are cyanotoxins released by certain strains of cyanobacteria. Biosensor-based strategies are emphasized as powerful screening tools.
Aptamer-DNAzyme hairpins for biosensing of Ochratoxin A
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.BIOS.2011.12.011
Abstract: We report an aptasensor for biosensing of Ochratoxin A (OTA) using aptamer-DNAzyme hairpin as biorecognition element. The structure of this engineered nucleic acid includes the horseradish peroxidase (HRP)-mimicking DNAzyme and the OTA specific aptamer sequences. A blocking tail captures a part of these sequences in the stem region of the hairpin. In the presence of OTA, the hairpin is opened due to the formation of the aptamer-analyte complex. As a result, self-assembly of the active HRP-mimicking DNAzyme occurs. The activity of this DNAzyme is linearly correlated with OTA concentration up to 10 nM, showing a limit of detection of 2.5 nM.
High-sensitive flow-based kinetic exclusion assay for okadaic acid assessment in shellfish samples
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.BIOS.2009.10.039
Abstract: Episodes of shellfish contamination with okadaic acid (OA) are a human health threat that is causing increasing concern. As a way to overcome the shortcomings involved in the reference methods of analysis set by legislations, alternative procedures are envisaged. This paper describes the development of different immunosensors for the analysis of OA, focusing on the comparison of their sensitivity, precision, ease of use and s le matrix effects. Initially, a surface plasmon resonance (SPR)-based immunosensor was developed, which enabled the quantification of the toxin in mussel s les at concentrations in the range of the 160 microg kg(-1) European regulatory limit with good percentages of recovery. Nevertheless, calibration curves with spiked mussel s les showed that matrix effects could not be neglected. Alternatively, a flow-immunosensing system based on kinetic exclusion measurements was developed achieving the theoretical lowest limit of detection enabled by the affinity of the anti-OA antibody (IC(70)=0.03 microg L(-1) in the assay solution). This highly sensitive automated system allows rapid and reliable OA quantification, with no significant matrix effects for the analysis of spiked mussel and scallop s les. Performance features such as high sensitivity and precision, low limits of detection and simplicity of the analysis protocol, shows the biosensing-systems based on kinetic exclusion measurements for toxin detection in shellfish s les as highly performing tools for rapid and continuous screening.
Electrochemical biosensors as a tool for antioxidant capacity assessment
Publisher: Elsevier BV
Date: 2008
Hyaluronic Acid–Modified Porous Silicon Films for the Electrochemical Sensing of Bacterial Hyaluronidase
Publisher: Wiley
Date: 11-05-2018
Abstract: The development of enzyme-responsive hyaluronic acid methacrylate (HYAMA)-coated porous silicon (pSi) films and their application in electrochemical diagnostic devices for the in situ detection of the enzyme hyaluronidase (hyal), which is secreted by Staphylococcus aureus (S. aureus) bacteria, are reported. The approach relies on a HYAMA-pSi electrode made of thermally hydrocarbonized pSi (pSi-THC) that is impregnated with crosslinked HYAMA olyethylene glycol diacrylate (PEGDA) hydrogels. The enzymatic degradation of HYAMA by bacterial hyal is monitored by differential pulse voltammetry (DPV) utilizing pSi-THC as a working electrode and ferro/ferricyanide (FF) as external redox probe. The degradation of HYAMA results in reduced diffusion of the redox probe through the partially charged film, thereby enabling the detection of hyal by DPV. In addition to the determination of the concentration-dependent response in NaOAc buffer (pH 5.2), the detection of hyal as indicator for the presence of S. aureus bacteria above a threshold level in bacterial supernatants and artificial wound fluid is highlighted.
Designing Electrochemical Biosensing Platforms Using Layered Carbon-Stabilized Porous Silicon Nanostructures
Publisher: American Chemical Society (ACS)
Date: 14-03-2022
Determination of the antioxidants' ability to scavenge free radicals using biosensors
Publisher: Springer US
Date: 2010
DOI: 10.1007/978-1-4419-7347-4_16
Abstract: Free radicals are highly reactive molecules generated during cellular metabolism. However, their overproduction results in oxidative stress, a deleterious process that can damage cell structures, including lipids and membranes, proteins and DNA. Antioxidants respond to this problem, scavenging free radicals. This chapter critically reviews the electrochemical biosensors developed for the evaluation of the antioxidant capacity of specific compounds. Due to the ability of these devices to perform simple, fast and reliable analysis, they are promising biotools for the assessment ofantioxidant properties.
Microwave Heating of Poly(N-isopropylacrylamide)-Conjugated Gold Nanoparticles for Temperature-Controlled Display of Concanavalin A
Publisher: American Chemical Society (ACS)
Date: 14-12-2015
Label-Free Bacterial Toxin Detection in Water Supplies Using Porous Silicon Nanochannel Sensors
Publisher: American Chemical Society (ACS)
Date: 29-05-2019
Tailored carbon nanotube immunosensors for the detection of microbial contamination
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.BIOS.2014.09.089
Abstract: The use of carbon nanotubes (CNTs) as building blocks in the design of electrochemical biosensors has been attracting attention over the last few years, mainly due to their high electrical conductivity and large surface area. Here, we present two approaches based on tailored single-walled CNTs (SWCNTs) architectures to develop immunosensors for the bacteriophage MS2, a virus often detected in sewage-impacted water supplies. In the first approach, SWCNTs were used in the bottom-up design of sensors as antibody immobilization support. Carboxy-functionalised SWCNTs were covalently tethered onto gold electrodes via carbodiimide coupling to cysteamine-modified gold electrodes. These SWCNTs were hydrazide functionalized by electrochemical grafting of diazonium salts. Site-oriented immobilization of antibodies was then carried out through hydrazone bond formation. Results showed microarray electrode behavior, greatly improving the signal-to-noise ratio. Excellent sensitivity and limit of detection (9.3 pfu/mL and 9.8 pfu/mL in buffer and in river water, respectively) were achieved, due to the combination of the SWCNTs' ability to promote electron transfer reactions with electroactive species at low overpotentials and their high surface-to-volume ratio providing a favorable environment to immobilize biomolecules. In the second approach, SWCNTs were decorated with iron oxide nanoparticles. Diazonium salts were electrochemically grafted on iron-oxide-nanoparticle-decorated SWCNTs to functionalize them with hydrazide groups that facilitate site-directed immobilization of antibodies via hydrazone coupling. These magnetic immunocarriers facilitated MS2 separation and concentration on an electrode surface. This approach minimized non-specific adsorptions and matrix effects and allowed low limits of detection (12 pfu/mL and 39 pfu/mL in buffer and in river water, respectively) that could be further decreased by incubating the magnetic immunocarriers with larger volumes of s le. Significantly, both approaches permitted the detection of MS2 to levels regularly encountered in sewage-impacted environments.
Performance optimisation of porous silicon rugate filter biosensor for the detection of insulin
Publisher: Elsevier BV
Date: 11-2018
Sensitive detection of ochratoxin A in wine and cereals using fluorescence-based immunosensing
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.FOODCHEM.2012.05.060
Abstract: Ochratoxin A (OTA) is a mycotoxin found in a wide range of food and feedstuffs. Intake of OTA-contaminated food causes health concern due to the harmful effects reported on humans and animals. Much effort is currently devoted to set up and optimise highly sensitive and accurate methods of OTA analysis. This work describes the comparison of fluorescence-based immunosensing strategies for the analysis of OTA. First, an indirect competitive fluoroimmunoassay was designed and optimised. The assay enabled the quantification of the toxin at the levels set by the European legislation. Then, a flow-immunoassay based on kinetic exclusion measurements was developed. It showed the theoretical lowest limit of detection enabled by the affinity of the anti-OTA antibody (IC(80)=12ngL(-1) in the assay solution). Wine and cereal s les were analysed using the optimised flow system. No significant matrix effects were observed after simple pre-treatment of wine and OTA extraction from corn-flakes s les. This simple and highly sensitive automated biosensing-system allows OTA quantification in food and beverages. It is envisaged as a powerful tool for rapid and reliable toxin screening.
Carbon-stabilized porous silicon as novel voltammetric sensor platforms
Publisher: Elsevier BV
Date: 05-2021
Label-Free <inline-formula> <tex-math notation=TeX>$\hbox{Si}_{3}\hbox{N}_{4}$</tex-math></inline-formula> Photonic Crystal Based Immunosensors for Diagnostic Applications
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2014
New advances in electrochemical biosensors for the detection of toxins: Nanomaterials, magnetic beads and microfluidics systems. A review
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.ACA.2015.11.050
Abstract: The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised.
Latest trends in mycotoxin detection
Publisher: Portico
Date: 2008
DOI: 10.2212/SPR.2008.6.3
Malate biosensors for the monitoring of malolactic fermentation: Different approaches
Publisher: Informa UK Limited
Date: 07-2006
Electrochemical Biosensors Based on Convectively Assembled Colloidal Crystals
Publisher: MDPI AG
Date: 30-06-2022
DOI: 10.3390/BIOS12070480
Abstract: Rapid, sensitive, selective and portable virus detection is in high demand globally. However, differentiating non-infectious viral particles from intact/infectious viruses is still a rarely satisfied sensing requirement. Using the negative space within monolayers of polystyrene (PS) spheres deposited directly on gold electrodes, we fabricated tuneable nanochannels decorated with target-selective bioreceptors that facilitate the size-selective detection of intact viruses. Detection occurred through selective nanochannel blockage of diffusion of a redox probe, [Fe(CN)6]3/4−, allowing a quantifiable change in the oxidation current before and after analyte binding to the bioreceptor immobilised on the spheres. Our model system involved partial surface passivation of the mono-assembled PS spheres, by silica glancing angle deposition, to confine bioreceptor immobilisation specifically to the channels and improve particle detection sensitivity. Virus detection was first optimised and modelled with biotinylated gold nanoparticles, recognised by streptavidin immobilised on the PS layer, reaching a low limit of detection of 37 particles/mL. Intact, label-free virus detection was demonstrated using MS2 bacteriophage (~23–28 nm), a marker of microbiological contamination, showing an excellent limit of detection of ~1.0 pfu/mL. Tuneable nanochannel geometries constructed directly on sensing electrodes offer label-free, sensitive, and cost-efficient point-of-care biosensing platforms that could be applied for a wide range of viruses.
Development of L-lactate dehydrogenase biosensor based on porous silicon resonant microcavities as fluorescence enhancers
Publisher: Elsevier BV
Date: 12-2015
Novel highly-performing immunosensor-based strategy for ochratoxin A detection in wine samples
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.BIOS.2007.10.002
Abstract: The increasing concern about ochratoxin A (OTA) contamination of different food and feedstuffs demands high-performing detection techniques for quality assessment. Two indirect competitive enzyme-linked immunosorbent assay (ELISA) strategies were investigated for the development of OTA electrochemical immunosensors based on different OTA immobilisation procedures. Immunosensors based on avidin/biotin-OTA showed enhanced performance characteristics compared to those based on the adsorption of bovine serum albumin (BSA)-OTA conjugate. Performance of polyclonal (PAb) and monoclonal (MAb) antibodies against OTA was compared, showing at least one-order of magnitude lower IC(50) values when working with MAb. Alkaline phosphatase (ALP)- and horseradish peroxidase (HRP)-labelled secondary antibodies were evaluated. Both conjugates led to similar results when working with OTA standard solutions in buffer. However, whereas electroactive interferences present in spiked wine s les did not affect HRP-labelled immunosensors (4% slope deviation), they were likely oxidised at 0.225 V versus Ag/AgCl, the working potential for ALP-labelled immunosensors (25% slope deviation). Considering 80% of antibody binding as the limit of detection, values of 0.7 and 0.3 ng/mL for HRP- and ALP-labelled immunosensors respectively, validate these immunosensors as useful screening tools to assess OTA levels in wine.
Porous Silicon Nanostructures as Effective Faradaic Electrochemical Sensing Platforms
Publisher: Wiley
Date: 15-04-2019
Metal-Dispersed Xerogel-Based Composite Films for the Development of Interference Free Oxidase-Based Biosensors
Publisher: American Chemical Society (ACS)
Date: 27-02-2004
DOI: 10.1021/CM035110U
Rapid high-throughput analysis of ochratoxin A by the self-assembly of DNAzyme-aptamer conjugates in wine
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.TALANTA.2013.07.011
Abstract: We report a new label-free colorimetric aptasensor based on DNAzyme-aptamer conjugate for rapid and high-throughput detection of Ochratoxin A (OTA, a possible human carcinogen, group 2B) in wine. Two oligonucleotides were designed for this detection. One is N1 for biorecognition, which includes two adjacent sequences: the OTA-specific aptamer sequence and the horseradish peroxidase (HRP)-mimicking DNAzyme sequence. The other is a blocking DNA (B2), which is partially complementary to a part of the OTA aptamer and partially complementary to a part of the DNAzyme. The existence of OTA reduces the hybridization between N1 and B2. Thus, the activity of the non-hybridized DNAzyme is linearly correlated with the concentration of OTA up to 30 nM with a limit of detection of 4 nM (3σ). Meanwhile, a double liquid-liquid extraction (LLE) method is accordingly developed to purify OTA from wine. Compared with the existing HPLC-FD or immunoassay methods, the proposed strategy presents the most appropriate balance between accuracy and facility, resulting in a considerable improvement of real-time quality control, and thereby, preventing chronic poisoning caused by OTA contained red wine.
Recent Advances in Batteryless NFC Sensors for Chemical Sensing and Biosensing
Publisher: MDPI AG
Date: 31-07-2023
DOI: 10.3390/BIOS13080775
Abstract: This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed.
Comparative study of electron mediators used in the electrochemical oxidation of NADH
Publisher: Elsevier BV
Date: 05-2004
Towards the rapid detection of haze‐forming proteins
Publisher: Elsevier BV
Date: 02-2024
Magnetic nanoparticles enhance pore blockage-based electrochemical detection of a wound biomarker
Publisher: Frontiers Media SA
Date: 12-06-2019
Electrochemical immunosensor for breast cancer biomarker detection using high-density silicon microneedle array
Publisher: Elsevier BV
Date: 11-2021
Dense arrays of uniform submicron pores in silicon and their applications
Publisher: American Chemical Society (ACS)
Date: 09-01-2015
DOI: 10.1021/AM506891D
Enzyme-Linked Immunosorbent Assay (ELISA) based on superparamagnetic nanoparticles for aflatoxin M1 detection
Publisher: Elsevier BV
Date: 10-2008
DOI: 10.1016/J.TALANTA.2008.05.048
Abstract: Five different clones of antibodies developed against the aflatoxin M(1) were investigated by using the classical indirect and direct competitive Enzyme-Linked Immunosorbent Assay (ELISA) formats, and also the direct competitive ELISA based on the use of the superparamagnetic nanoparticles. The purpose of this study was to assess if not so friendly time classical ELISA procedures can be further improved, by reducing the coating, blocking and competition time. Here we showed that a complete dc-ELISA (coating, blocking and competition step) based on the use of superparamagnetic nanoparticles can be performed in basically 40 min, if coating step (20 min) should be taken into account. Moreover, the standard analytical characteristics of the proposed method fulfil the requirements for detecting AFM(1) in milk, in a wide linear working range (4-250 ng/L). The IC(50) value is 15 ng/L. The matrix effect and the recovery rate were assessed, using the European Reference Material (BD282, zero level of AFM(1)), showing an excellent percentage of recovery, close to 100%.
Parametric study on bond of GFRP bars in alkali-activated cement concrete
Publisher: Thomas Telford Ltd.
Date: 07-2020
Abstract: Bond behaviour plays an important role in the design and performance of reinforced-concrete structures. In this study, finite-element modelling is used to perform a parametric study. The bond between the glass fibre-reinforced polymer (GFRP) bar and alkali-activated cement concrete is modelled by surface-based cohesive behaviour. The accuracy of the model is validated by comparing model predictions with experimental results. The effect of concrete cover, bar diameter, compressive strength, lead length, embedment length and GFRP elastic modulus on bond behaviour is investigated. Each of these parameters are varied based on a range of applicable values to study their influence on bond behaviour. The parametric study showed that bond behaviour is mainly affected by concrete cover, bar diameter, embedment length and the compressive strength of the concrete. The effect of the elastic modulus of the GFRP bar is not as pronounced as that of the other parameters, while the influence of lead length can be avoided by providing enough unbonded length at the loaded end. The parametric study is further used to calibrate a well-known bond equation and develop a new regression equation for predicting the maximum bond stress. The predicted results from these equations showed a good agreement with the experimental results as well as those of the finite-element model.
Photonic crystal based immunosensor for clinical diagnosis
Publisher: IEEE
Date: 05-2014
Porous silicon membrane-modified electrodes for label-free voltammetric detection of MS2 bacteriophage
Publisher: Elsevier BV
Date: 06-2016
Differential functionalisation of the internal and external surfaces of carbon-stabilised nanoporous silicon
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9CC03755A
Abstract: A versatile strategy to differentiate the surface chemistry of the internal and external pore walls of highly-stable nanoporous silicon.
New redox mediator-modified polysulfone composite films for the development of dehydrogenase-based biosensors
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.BIOS.2005.12.014
Abstract: This work presents polysulfone membranes as new materials for the development of compact dehydrogenase-based biosensors. Composite films were prepared by mixing polysulfone with graphite and were deposited on epoxy-graphite composite electrodes. Redox mediators were successfully immobilized in the composite film leading to highly reproducible biosensors, without leakage of the immobilized species. This results in a more reliable analytical system as, at the same time, problems of electrode fouling related to the detection of the coenzyme nicotinamide adenine dinucleotide (NADH) on which is based the erometric detection of dehydrogenase-based biosensors are avoided. Scanning electron microscopy was used to study the morphological characteristics of the surface and the cross-section of the polysulfone-graphite composite films. Several procedures to immobilize enzymes in these membranes were demonstrated. Glutamate dehydrogenase (GlDH) was immobilized as an ex le of dehydrogenase enzyme, in this case for the development of an ammonium biosensor. High sensitivity, good selectivity, wide linear ranges and short response times were obtained for the optimized sensors and biosensors. Their good performance combined with the simplicity of the construction method, make the polysulfone-graphite composite films attractive matrices for the development of new enzyme-based biosensors, especially those based on dehydrogenase enzymes.
Novel peptidylated surfaces for interference-free electrochemical detection of cardiac troponin I
Publisher: Elsevier BV
Date: 2018
Array of peptide-modified electrodes for the simultaneous determination of Pb(II), Cd(II) and Zn(II)
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.TALANTA.2014.02.052
Abstract: This paper reports the development of three peptide modified sensors in which glutathione (GSH) and its fragments Cys-Gly and γ-Glu-Cys were immobilized respectively through aryl diazonium electrochemical grafting onto the surface of graphite-epoxy composite electrodes (GEC), and used for the simultaneous determination of Cd(II), Pb(II) and Zn(II). The concentration interval ranged from 0.1 to 1.5 μmol L(-1) for each metal, and the technique used was differential pulse adsorptive stripping voltammetry. This study aimed to the comparison of the information provided by one single modified electrode at both fixed and multiple pH values (pH 6.8, 7.5 and 8.2) for the simultaneous determination of the three metals, with those supplied by the three-sensor array at multiple pH values. For the processing of the voltammograms, the fast Fourier transform was selected as the preprocessing tool for data compression coupled with an artificial neural network for the modeling of the obtained responses.
Immunochemical tools for mycotoxin detection in food
Publisher: Springer Science and Business Media LLC
Date: 17-03-2009
Past, present and future of diatoms in biosensing
Publisher: Elsevier BV
Date: 05-2015
Transdermal Electrochemical Monitoring of Glucose via High‐Density Silicon Microneedle Array Patch
Publisher: Wiley
Date: 04-03-2021
Abstract: Current technology for blood glucose level monitoring is mainly based on the invasive finger‐prick extraction of a small drop of blood using a lancet and measured via a handheld glucometer, which is not conducive to continuous measurements. Interstitial fluid (ISF) is gaining attention as an alternative biofluid. Its biochemical composition is very similar to that of blood and it can be monitored in a continuous manner via minimally invasive methods that cause no pain and minimize any risk of infection. Herein, a microneedle array (MNA) based transdermal sensing system for the pain free monitoring of ISF glucose is presented. High‐density silicon microneedles ( ≈ 9500 microneedles cm −2 ) are used to prepare a three‐electrode patch for the electrochemical monitoring of glucose. The MNA glucose patch shows very good selectivity when tested in artificial ISF, with a sensitivity of 0.1622 µ A m m −1 cm −2 and a detection limit of 0.66 m m . In vivo application of the microneedle array in mice shows that the ISF glucose concentrations obtained with the MNA sensor gave very good correlation with the blood glucose levels determined with a commercial glucometer. This microneedle‐based sensing system hence provides an alternative transdermal diagnostic tool to the invasive existing techniques.
Emerging biotools for assessment of mycotoxins in the past decade
Publisher: Elsevier BV
Date: 07-2007
A portable point-of-use EIS device for in-vivo biomédical applications
Publisher: IEEE
Date: 11-2014
Label-free ITO-based immunosensor for the detection of very low concentrations of pathogenic bacteria
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.BIOELECHEM.2014.09.002
Abstract: Here we describe the fabrication of a highly sensitive and label-free ITO-based impedimetric immunosensor for the detection of pathogenic bacteria Escherichia coli O157:H7. Anti-E. coli antibodies were immobilized onto ITO electrodes using a simple, robust and direct methodology. First, the covalent attachment of epoxysilane on the ITO surface was demonstrated by Atomic Force Microscopy and cyclic voltammetry. The immobilization of antibody on the epoxysilane layer was quantified by Optical Waveguide Lightmode Spectroscopy, obtaining a mass variation of 12 ng cm(− 2) (0.08 pmol cm(− 2)). Microcontact printing and fluorescence microscopy were used to demonstrate the specific binding of E. coli O157:H7 to the antibody-patterned surface. We achieved a ratio of 1:500 Salmonella typhimurium/E. coli O157:H7, thus confirming the selectivity of the antibodies and efficiency of the functionalization procedure. Finally, the detection capacity of the ITO-based immunosensor was evaluated by Electrochemical Impedance Spectroscopy. A very low limit of detection was obtained (1 CFU mL(− 1)) over a large linear working range (10–10(6) CFU mL(− 1)). The specificity of the impedimetric immunosensor was also examined. Less than 20% of non-specific bacteria (S. typhimurium and E. coli K12) was observed. Our results reveal the applicability of ITO for the development of highly sensitive and selective impedimetric immunosensors.
signal off aptasensor based on enzyme inhibition induced by conformational switch
Publisher: American Chemical Society (ACS)
Date: 10-01-2014
DOI: 10.1021/AC402258X
Abstract: A novel sensing strategy for electrochemical aptamer-based sensors is presented. Nucleic acid aptamers are considered alternatives to antibodies. However, some of their intrinsic properties, such as that they can undergo conformational changes during the binding of the target, can be used to design novel sensing strategies. Unlike other electrochemical "signal off" aptamer-based sensors, we report a strategy based on enzymatic inhibition. Our approach shows the feasibility to detect small molecules based on the aptamer conformational change induced by the target that leads to the inhibition of the enzyme used as a label. Additionally, we prove the ability to regenerate the function of the aptasensor by simply applying a short potential pulse. As a proof-of-concept, the widely used aptamer for ochratoxin A (OTA) has been selected as a model. After self-assembling short oligonucleotides onto a gold electrode, complementary to the 3' end of the aptamer, hybridization of the aptamer takes place. To investigate the mechanism induced by the OTA-binding, surface plasmon resonance assays were performed, which confirmed the conformational switch of the aptamer rather than the aptamer displacement by dehybridization from the DNA-modified sensor surface. The electrochemical sensor can successfully detect OTA in wine at the limits stipulated by the European Commission. Given its sensitivity, rapid and easy detection, and regeneration, it can be envisaged as screening tool for OTA detection. Moreover, this sensing strategy has the potential to be applied to other aptamer-based biochemical assays for the detection of small molecules in the fields of food safety, environmental monitoring, and medical diagnostics.
Electrochemical fingerprints of brominated trihaloacetic acids (HAA3) mixtures in water
Publisher: Elsevier BV
Date: 08-2017
Bioelectronic tongues: New trends and applications in water and food analysis
Publisher: Elsevier BV
Date: 05-2016
DOI: 10.1016/J.BIOS.2015.12.075
Abstract: Over the last years, there has been an increasing demand for fast, highly sensitive and selective methods of analysis to meet new challenges in environmental monitoring, food safety and public health. In response to this demand, biosensors have arisen as a promising tool, which offers accurate chemical data in a timely and cost-effective manner. However, the difficulty to obtain sensors with appropriate selectivity and sensitivity for a given analyte, and to solve analytical problems which do not require the quantification of a certain analyte, but an overall effect on a biological system (e.g. toxicity, quality indices, provenance, freshness, etc.), led to the concept of electronic tongues as a new strategy to tackle these problems. In this direction, to improve the performance of electronic tongues, and thus to spawn new application fields, biosensors have recently been incorporated to electronic tongue arrays, leading to what is known as bioelectronic tongues. Bioelectronic tongues provide superior performance by combining the capabilities of electronic tongues to derive meaning from complex or imprecise data, and the high selectivity and specificity of biosensors. The result is postulated as a tool that exploits chemometrics to solve biosensors' interference problems, and biosensors to solve electronic tongues' selectivity problems. The review presented herein aims to illustrate the capabilities of bioelectronic tongues as analytical tools, especially suited for screening analysis, with particular emphasis in water analysis and the characterization of food and beverages. After briefly reviewing the key concepts related to the design and principles of electronic tongues, we provide an overview of significant contributions to the field of bioelectronic tongues and their future perspectives.
2D photonic crystal membranes for optical biosensors
Publisher: IEEE
Date: 05-2014
Electrochemical biosensors featuring oriented antibody immobilization via electrografted and self-assembled hydrazide chemistry
Publisher: American Chemical Society (ACS)
Date: 13-01-2014
DOI: 10.1021/AC401747J
Abstract: Appropriate site-directed chemistry is essential to maximize the performance of immunosensors. We present two new functionalization strategies that preserve proper folding and binding potential of antibodies by forcing their oriented immobilization. Both strategies are based on the formation of hydrazone bonds between aldehyde groups on the Fc moieties of periodate-oxidized antibodies and hydrazide groups on functionalized gold electrodes. Those hydrazide groups are introduced by electrografting of diazonium salts or by self assembly of mono- and dithiolated hydrazide linkers, resulting in films with tailored functional groups and, thus, antibody distribution and spacing. Their barrier properties and permeability toward electroactive species are evaluated. To demonstrate the potential of these new functionalization strategies, detection of bacteriophage MS2 is performed through either a direct assay using electrochemical impedance spectroscopy (EIS) or through a sandwich assay using differential pulse voltammetry (DPV). Diazonium and monothiolated self-assembled monolayer-modified electrodes enable the detection of less than 1 plaque forming unit (pfu)/mL in a direct EIS assay. However, nonspecific adsorption renders measurements in river water s les difficult. In contrast, sandwich-assays on electrodes with electrografted diazonium salts and monothiolated self-assembled monolayers do not show significant matrix effects using river water s les, but the limits of detection are 10(8) times higher than those of the direct assay. Best results are achieved for immunosensors based on mixed monolayers of hydrazide and hydroxyl diothiolated linkers (15 pfu/mL). These new functionalization techniques are facile to implement. They afford the possibility to tune the surface composition and tailor the electrochemical properties of electrochemical sensors. These advantages should translate into broad interest in this type of surface chemistry for biosensor development.
Evaluation of different mediator-modified screen-printed electrodes used in a flow system as amperometric sensors for NADH
Publisher: Elsevier BV
Date: 30-03-2007
DOI: 10.1016/J.TALANTA.2006.09.022
Abstract: This work presents a comparative study between two different methods for the preparation of mediator-modified screen-printed electrodes, to be used as detectors in a reliable flow injection system for the determination of the nicotinamide adenine dinucleotide (NADH) coenzyme. The best strategy was selected for the final development of compact biosensors based on dehydrogenase enzymes. For the first immobilisation strategy, different redox mediators were electropolymerised onto the SPE surface. The second immobilisation strategy was carried out using polysulfone-graphite composites, which were deposited by screen-printing technology onto the screen-printed electrode (SPE) surface. Both methods achieved an effective and reliable incorporation of redox mediators to the SPE configuration. Finally, a flow system for ammonium determination was developed using a glutamate dehydrogenase (GlDH)-Meldola's Blue (MB)-polysulfone-composite film-based biosensor. The stability of the redox mediators inside the composite films as well as the negligible fouling effect observed on the electrode surface improve the repeatability and reproducibility of the sensors, important features for continuous analysis in flow systems. Furthermore, the optimised bio/sensors, incorporated in a flow injection system, showed good sensitivities and short response times. Such a good analytical performance together with the simple and fast sensor construction are interesting characteristics to consider the polysulfone-composite films as attractive electrochemical transducer materials for the development of new dehydrogenase-based SPEs.
Electrochemical aptamer-based sensors
Publisher: Springer Science and Business Media LLC
Date: 18-05-2010
Enzyme-Linked Aptamer Assays (ELAAs), based on a competition format for a rapid and sensitive detection of Ochratoxin A in wine
Publisher: Elsevier BV
Date: 05-2011
Battery-Less NFC Potentiostat for Electrochemical Point-of-Care Sensors Based on COTS Components
Publisher: MDPI AG
Date: 23-09-2022
DOI: 10.3390/S22197213
Abstract: This work studies the feasibility of using a battery-less Near-Field Communication (NFC) potentiostat for the next generation of electrochemical point-of-care sensors. A design based on an NFC microchip, a microcontroller, and a custom potentiostat based on an operational lifier is presented. A proof-of-concept prototype has been designed and used to quantify glucose concentration using commercial glucose test strips from chrono erometry measurements. The device is harvested and the sensor is read using a mobile phone. The prototype uses an antenna loop covered with ferrite sheets to ensure stable operation of the electronics when the mobile phone is used as reader. The use of ferrite reduces the detuning caused by the proximity of the metal parts of the mobile phone. A comparison with a commercial glucometer device is provided. Results obtained using a commercial glucometer and those provided by the proposed potentiostat show an excellent agreement.
Toward multiplexing detection of wound healing biomarkers on porous silicon resonant microcavities
Publisher: Wiley
Date: 04-02-2015
Electrochemical detection of N‐nitrosodimethylamine using a molecular imprinted polymer
Publisher: Elsevier BV
Date: 12-2016
Identification of Inflammatory and Regulatory Cytokines IL-1α-, IL-4-, IL-6-, IL-12-, IL-13-, IL-17A-, TNF-α-, and IFN-γ-Producing Cells in the Milk of Dairy Cows with Subclinical and Clinical Mastiti
Publisher: MDPI AG
Date: 17-03-2022
DOI: 10.3390/PATHOGENS11030372
Abstract: In naturally occurring bovine mastitis, effects of infection depend on the host inflammatory response, including the effects of secreted cytokines. Knowledge about the inflammatory and regulatory cytokines in milk cells of free-stall barn dairy cows and in naturally occurring mastitis is lacking as most studies focus on induced mastitis. Hereby, the aim of the study was to determine inflammatory and regulatory cytokines in the milk of dairy cows with subclinical and clinical mastitis. The following examinations of milk s les were performed: differential counting of somatic cells (SCC), bacteriological examination, and immunocytochemical analysis. Mean SCC increased in subclinical and clinical mastitis cases. The number of pathogenic mastitis-causing bacteria on plates increased in subclinical mastitis cases but decreased in clinical mastitis. The inflammatory and regulatory markers in the milk cells of healthy cows showed the highest mean cell numbers (%). In mastitis cases, immunoreactivity was more pronounced for IL-4, IL-6, IL-12, IL-13, IL-17A, TNF-α, and IFN-γ. Data about subclinical and clinical mastitis demonstrate inflammatory responses to intramammary infection driven by IL-1α, IL-4, and IL-17A. Moreover, the host defense response in mastitis is characterized by continuation or resolution of initial inflammation. IL-12 and INF-γ immunoreactivity was recognized to differ mastitis cases from the relative health status.
Bond of spliced GFRP reinforcement bars in alkali activated cement concrete
Publisher: Elsevier BV
Date: 09-2017
Biosensors to detect marine toxins: Assessing seafood safety
Publisher: Elsevier BV
Date: 15-05-2007
DOI: 10.1016/J.TALANTA.2006.12.036
Abstract: This article describes the different types of marine toxins and their toxic effects, and reviews the bio/analytical techniques for their detection, putting special emphasis to biosensors. Important health concerns have recently appeared around shellfish (diarrheic, paralytic, amnesic, neurologic and azaspiracid) and fish (ciguatera and puffer) poisonings produced by different types of phycotoxins, making evident the urgent necessity of counting on appropriate detection technologies. With this purpose, several analysis methods (bioassays, chromatographic techniques, immunoassays and enzyme inhibition-based assays) have been developed. However, easy-to-use, fast and low-cost devices, able to deal with complicated matrices, are still required. Biosensors offer themselves as promising biotools, alternative and/or complementary to conventional analysis techniques, for fast, simple, cheap and reliable toxicity screening. Nevertheless, despite the wide range of seafood toxins and the already rooted biosensing systems, the literature on biosensors for phycotoxins is scarce. This article discusses the existing biosensor-based strategies and their advantages and limitations. Finally, the article gives a general overlook about the regulation toxin levels and monitoring programmes currently established around the world concerning seafood safety.
Towards a portable point-of-use blood analysis with EIS technique device
Publisher: IEEE
Date: 02-2014
A review of the use of genetically engineered enzymes in electrochemical biosensors
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.SEMCDB.2009.01.009
Abstract: This article gives an overview of the electrochemical biosensors that incorporate genetically modified enzymes. Firstly, the improvements on the sensitivity and selectivity of biosensors that integrate mutated enzymes are summarised. Next, new trends focused on the oriented immobilisation of mutated enzymes through specific functional groups located at their surface are reviewed. Finally, the effect of enzyme mutations on the electron transfer distance and kinetics of electrochemical biosensors is described.
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