Anna Spehar

Anna Spehar
Biomensio, Finland

PhD, analytical chemistry
Development of point-of-need tests for food safety and clinical monitoring

About

51
Publications
8,171
Reads
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608
Citations
Additional affiliations
January 2007 - February 2009
Dublin City University
Position
  • Researcher
Description
  • Characterised novel electrochemiluminescent nanomaterials and luminophores, developed bioanalytical applications.

Publications

Publications (51)
Article
Full-text available
Lactate electrochemical biosensors were fabricated using Pediococcus sp lactate oxidase (E.C. 1.1.3.2), an external polyurethane membrane laminate diffusion barrier and an internal ionomeric polymer barrier (sulphonated polyether ether sulphone polyether sulphone, SPEES PES). In a needle embodiment, a Pt wire working electrode was retained within s...
Article
Semi‐implantable needle oxygen electrodes were used for forearm subcutaneous monitoring in human subjects undertaking high intensity cycling and fist clenching exercise. pO2 variations in the range between 40 and100 mm Hg oxygen were seen. Superimposed on these were paradoxical rises in subcutaneous pO2, of up to 100 mm Hg which paralleled the scal...
Article
Mycotoxins produced by Fusarium species including trichothecenes, zearalenone and fumonisins, can co-contaminate food and feed throughout the supply chain, including cereal grains and animal feeds. There is an increasing demand to enhance global food security by improving the monitoring of mycotoxins throughout our food supply chain. For time and c...
Chapter
There are significant challenges in food analysis, problems with food contamination and authentication, and a worldwide need to ensure food safety. This book provides a description of antibody-based technologies used in food analysis. It focuses on key applications, outlining the approaches used, their advantages and limitations, and describes futu...
Article
There are an ample number of commercial testing kits available for mycotoxin analysis on the market today, including enzyme-linked immunosorbent assays, membrane-based immunoassays, fluorescence polarisation immunoassays and fluorometric assays. It can be observed from the literature that not only are developments and improvements ongoing for these...
Article
Full-text available
An electrochemiluminescence (ECL) immunosensor for the rapid detection of the Francisella tularensis pathogen using whole antibodies or antibody fragments as capture biomolecule is described. A sandwich immunoassay was used with either lipopolysaccharide (LPS) or the whole inactivated bacterial cell (LVS) as a target, while Ru(bpy)32+-encapsulated...
Article
Full-text available
Development of a fully automated electrochemiluminescence (ECL) DNA assay for multiplex detection of six biowarfare agents is described. Aminated-DNA capture probes were covalently immobilised on activated-carbon electrodes and subsequently hybridised to target strands. Detection was achieved via a sandwich-type assay after Ru(bpy)32+-labelled repo...
Article
Full-text available
A solid state electrochemiluminescence (ECL) sensor based on Ru(bpy)3 2+-encapsulated silica nanoparticles (RuNP) covalently immobilised on a screen printed carbon electrode has been developed and characterised. RuNPs were synthesised using water-in-oil microemulsion method, amino groups were introduced on their surface, and they were characterised...
Article
The properties of electropolymerised phenolic films at amperometric needle electrodes were investigated and their applicability as selective, internal barriers for potential in vivo oxidase enzyme based biosensors evaluated. Polyphenol, poly(phenol red) and dual layer poly(phenol red)/poly(4-aminophenol) films were formed by electropolymerisation a...
Chapter
Full-text available
There are many remaining challenges impeding future progress in field of Clinical Diagnostics. This book presents a technical assessment and vision of clinical leaders, scoping the clinical and other diagnostic needs and the bottle-necks in their cognate fields. Issues of real environmental biological measurements from the perspective of the end-us...
Conference Paper
Full-text available
To enable continuous monitoring of electrochemical sensors outside the laboratories, there is a significant demand on electrochemical measurement systems to be miniaturized. The paper presents a low-cost, portable miniature device for electrochemical measurements. The device consists of a 35mm × 20mm × 25mm wireless tag, which enables potentiometri...
Article
Full-text available
Lactate is one of the most important biomarkers of tissue oxygenation and thus of paramount importance for sports and health care applications. Lactate levels provide information on anaerobic threshold which is very important for tailoring training programs in endurance sports. In this contribution we present an implantable amperometric lactate sen...
Article
AbstractA recess disk electrode for amperometric monitoring of oxygen and glucose is reported. The basic design of sensor is a needle structure for easy implantation, embodying a gold filled silica capillary with a 80 µm inner diameter working electrode. Recess and inlaid disc electrodes, placed inside stainless steel tubes which served as a counte...
Article
Essential properties of biosensors for continuous monitoring in blood and tissue are selectivity, sensitivity and biocompatibility. A variety of membranes have been explored to achieve these properties. A good understanding of the diffusion properties of analytes and interferent species through these membranes is important for improvement of design...
Conference Paper
The aim of this work was to develop needle based sensors for oxygen sensing using different types of membranes. For oxygen sensors it is important to achieve fast response time, good linearity, low biofouling and high sensitivity. The effect of different types of polymeric barrier membranes and their various combinations were assessed and compared....
Article
Water-soluble 4-(dimethylamino) pyridine (DMAP) stabilized gold nanoparticles (DMAP-AuNP) were synthesized by ligand exchange and phase transfer (toluene/water). The DMAP-AuNPs are positively charged with the core diameter of 4 +/- 1 nm. Metallopolymer-gold nanocomposites were prepared by mixing gold nanoparticles and [Ru(bpy)(2)PVP(10)](ClO(4))(2)...
Article
Full-text available
A ruthenium polymer in which two complexes, [Ru(dp-phen)2]2+ (RuN6) and [Ru(dp-phen)2Cl]+ (RuN5Cl), were bound to PVP polymer backbone was synthesized and characterized; dp-phen is 4,7 - diphenyl- 1,10-phenanthroline and PVP is poly(4-vinylpyri-dine). Polymer solution in acetonitrile has two photoluminescence emission peaks, one centered at 620 nm...
Article
The oxidative electropolymerization of [Ru(aphen)3](PF6)2 from an ionic liquid, 1-butyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BDMITFSI), is reported; aphen is 5-amino-1,10-phenanthroline. The deposition rate in the ionic liquid is more than an order of magnitude faster than in conventional solvents such as anhydrous acetonitr...
Article
The electrochemical and photonic properties of a metallopolymer in which both [Ru(dpp)2Cl]+ (N5Cl) and [Ru(dpp)2]2+ (N6) moieties are coordinated to a poly(4-vinylpyridine) backbone are described, dpp is 4,7-diphenyl-1,10-phenanthroline. Cyclic voltammetry and luminescence studies indicate that approximately 2% of centres are bis-coordinated to the...
Article
This paper describes a heterogeneous DNA-hybridization assay based on electrochemiluminescence (ECL) detection on gold electrodes. Short, 15-mer oligonucleotides were conjugated with a synthesized electrochemiluminescent label, bis(2,2'-bipyridine)-5-isothiocyanato-1,10-phenanthroline ruthenium(II) at the amino-modified 5'-end. Gold electrodes were...
Article
Full-text available
The aim of this thesis was to investigate bioanalytical applications of electrochemiluminescence (ECL), which refers to the generation of light at the surface of an electrode. Two types of ECL detection were studied: anodic ECL and cathodic hot electron-induced ECL (HECL). In anodic ECL light is generated at traditional electrode materials, such as...
Article
This paper describes a heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence (HECL) of a rhodamine label. Thin oxide-film coated aluminum and silicon electrodes were modified with an aminosilane layer and derivatized with short, 15-mer oligonucleotides via diisothiocyanate coupling. Target oligonuc...
Article
Reactive Al/OH-�(aq) interface was studied and used as a source of chemical energy in the generation of chemiluminescence. The observed extrinsic lyoluminescence emission during dissolution of aluminum in an alkaline Tb(III) or Eu(III) chelate solution was clearly based either on 5D 4 - 7F J radiative transitions of Tb(III) or 5 D 0 - 7 F J transit...
Article
Rhodamine B (RhB) exhibits strong cathodic electrogenerated chemiluminescence (ECL) in aqueous solutions during high-amplitude pulse polarization at thin oxide film-coated aluminum electrodes. This method allows the detection of RhB below nanomolar concentration level and provides linear calibration plots spanning over several orders of magnitude o...
Article
Time-resolved electrogenerated chemiluminescence of multidentate phenolic Eu(III) chelates were studied in aqueous solution. 2,6-bis[N,N-bis(carboxymethyl)-aminomethyl]-4-benzoylphenol forms a photoluminescent and electrochemiluminescent Eu(III) chelate, whereas 2,6-bis[N,N-bis(carboxymethyl)-aminomethyl]-4-methyl phenol-chelated Eu(III) turned out...
Article
Hot electrons can be injected from conductor/insulator/electrolyte (C/I/E) junctions into an aqueous electrolyte solution by cathodic pulse-polarization of the electrode. Injected hot electrons induce electrogenerated chemiluminescence of various luminophores including coumarins in fully aqueous solutions. This is based on the tunnel emission of ho...
Article
Cathodic DC polarization of oxide-covered aluminum produces electrogenerated chemiluminescence from hydrated and chelated Tb(III) ions in aqueous electrolyte solutions. At the moment of cathodic voltage onset, a strong cathodic flash is observed, which is attributed to a tunnel emission of hot electrons into the aqueous electrolyte solution and the...
Article
Ruthenium(II) tris(2,2 -bipyridine) chelate shows chemiluminescence (CL) both during dissolution of metallic aluminium in alkaline conditions, and during dissolution of magnesium metal in acidic conditions. The presence of peroxodisulfate ions strongly enhances the CL. Magnesium system provides considerably better detectability of the present chela...
Article
Many genomic assays rely on a distance-dependent interaction between luminescent labels, such as luminescence quenching or resonance energy transfer. We studied the interaction between electrochemically excited Ru(bpy)(3) (2+) and Cy5 in a hybridization assay on a chip. The 3' end of an oligonucleotide was labelled with Ru(bpy)(3) (2+) and the 5' e...
Article
This paper characterizes the basic electrokinetic phenomena occurring within native poly(dimethylsiloxane) (PDMS) microchannels. Using simple buffers and current measurements, current density and electroosmosis data were determined in trapezoidal, reversibly sealed PDMS/PDMS and hybrid PDMS/glass channels with a cross-sectional area of 1035.5 micro...
Article
Heterogeneous and homogeneous immunoassays of human thyroid stimulating hormone (hTSH) were developed on immunometric basis using aromatic Tb(III) chelates as electrochemiluminescent labels and varied types of disposable oxide-covered aluminum electrodes as the solid phase of the immunoassays. The long luminescence lifetime of the present labels al...
Article
Electrogenerated chemiluminescence of 1-aminonaphthalene-4-sulphonate (ANS) provides a sensitive means for the detection of the ANS in aqueous solution when oxide-covered aluminium electrodes are used as tunnel emission electrodes and cathodic pulse polarisation is used for the excitation of the luminophore. During the pulse polarisation of insulat...
Article
Cathodic pulse polarisation of oxide-covered aluminium electrodes can generate electrochemiluminescence (ECL) from metalloporphyrins. This is based on the tunnel emission of hot electrons into aqueous electrolyte solution, which probably results in the generation of hydrated electrons as reducing mediators. These tunnel emitted electrons allow the...

Questions

Question (1)
Question
I am trying to measure electrochemically an amino acid type compound. The signal is good, but after a single measurement electrode becomes completely blocked and unresponsive and cannot be cleaned. Any suggestions how to modified surface to prevent adsorption? I have tried Nafion, PEDOT and PSS (polyelectrolyte) modifications of surface, but they don't help. Any other suggestions, a membrane materials or something to try?

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