CERES :: Browsing by Author "Davis, Frank"

Browsing by Author "Davis, Frank"

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Open Access
Biofuelcells-Recent advances and applications
(Elsevier, 2007-02-15) Davis, Frank; Higson, Seamus P. J.
In 2006, the journal Biosensors and Bioelectronics published a special issue devoted exclusively to biofuel cells, including several research papers and an extensive review of the field [Bullen, R.A., Arnot, T.C., Lakeman, J.B., Walsh, F.C., 2006. Biosens. Bioelectron.]. Within this review a brief description will firstly be given of the history of biofuel cells together with coverage of some of the major historical advances. The review is intended, however, to largely concentrate on and give an overview of the advances made in recent years in this area together with a discussion surrounding the practical application of biofuel cells. There are several classes of biofuel cells: we shall firstly discuss the recent advances in biofuel cells that convert chemical fuels to produce electrical power by use of catalytic enzymes. This will be followed by a section on similar cells where micro-organisms rather than enzymes are used to convert the fuel to energy. Thirdly we shall consider hybrid biofuel cells that combine the utilisation of photochemical chemistries and biological systems for the generation of electricity. Finally we will discuss some of the proposed uses of biofuel cells together with a short consideration of future research possibilities and applications of these systems.
Open Access
Carrier systems and biosensors for biomedical applications.
(2007-10-31T00:00:00Z) Davis, Frank; Higson, Seamus P. J.
This chapter addresses both carrier systems and biosensors which are often applied directly to tissues, either as skin patches, implanted or ingested by a variety of routes. It follows that there is a common theme between these applications and many of those discussed elsewhere within this book. Any device, scaffold or implant within the body must usually display extreme biocompatibility if it is not to cause harm to the patient. The techniques of tailoring surfaces to ensure no adverse reactions are a common theme running throughout this work on tissue engineering.
Open Access
Characterization of Langmuir-Blodgett films of a calix[8]arene and sensing properties towards volatile organic vapors
(Elsevier Science B.V., Amsterdam., 2010-07-15T00:00:00Z) Capan, R.; Ozbek, Z.; Goktas, H.; Sen, S.; Ince, F. G.; Ozel, M. E.; Stanciu, G. A.; Davis, Frank
Within this article, we report the characterization and organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of calix[8]arenes. Surface pressure-area isotherms show that very stable monolayers are formed at the air- water interface. The LB film could be deposited onto different substrates which allowed the films to be characterized by UV, quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and atomic force microscopy (AFM). The results indicate that good quality, uniform LB films can be prepared with transfer ratios of over 0.95. QCM results showed that the deposited mass of calix[8]arene monolayer onto a quartz crystal decreased from 693 to 204 ng as the number of layers is increased. AFM studies showed a smooth, and void free surface morphology with a rms value of 1.202 nm. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices are also studied. Responses of the LB films to various vapors are fast, large, and reversible. It was found that the obtained LB film is significantly more sensitive to chloroform than other vapors. It can be concluded that this molecule could have a potential application in the research area of room temperature vapor sensing devices. (C) 2010 Elsevier B.V. All rights reserved.
Open Access
A chemical sensor based on a photonic-crystal L3 nanocavity defined in a silicon-nitride membrane
(Royal Society of Chemistry, 2014-08-27) Deasy, Kieran; Sediq, Khalid N.; Brittle, Stuart; Wang, Tao; Davis, Frank; Richardson, Tim H.; Lidzey, David G.
The application of a silicon-nitride based L3 optical nanocavity as a chemical sensor is explored. It is shown that by adjusting the thickness of an ultra-thin Lumogen Red film deposited onto the nanocavity surface, the fundamental optical mode undergoes a progressive red-shift as the layer-thickness increases, with the cavity being able to detect the presence of a single molecular monolayer. The optical properties of a nanocavity whose surface is coated with a thin layer of a porphyrin-based polymer are also explored. On exposure of the cavity to an acidic-vapour, it is shown that changes in the optical properties of the porphyrin-film (thickness and refractive index) can be detected through a reversible shift in the cavity mode wavelength. Such effects are described using a finite difference time-domain model.
Open Access
Construction and interrogation of enzyme microarrays using scanning electrochemical microscopy - optimisation of adsorption and determination of enzymatic activity.
(Royal Society of Chemistry, 2011-12-21T00:00:00Z) Roberts, William St John; Davis, Frank; Collyer, Stuart D.; Higson, Seamus P. J.
Scanning electrochemical microscopy (SECM) has been used to image and study the catalytic activity of horseradish peroxidase (HRP) immobilised in a patterned fashion onto glass slides. Microarrays of HRP islands could be deposited on amino-modified glass slides using glutaraldehyde crosslinking combined with the SECM being used as a micro-deposition device. The enzymatic activity of the immobilised enzyme on the surface was in the presence of its substrate observed to give rise to substantial positive feedback between the slide and the SECM microelectrode tip. Conversely when either blank slides - or slides coated with HRP which had been subsequently thermally denatured were utilised, these showed negative feedback effects. Various conditions such as enzyme concentration, incubation time and substrate concentration were systematically varied to optimise sensitivity. Regular arrays of HRP could be assembled and when imaged, displayed lower limits of detection of 1.2 × 10(-12) mol ml(-1) of benzoquinone.
Open Access
Current trends in explosive detection techniques
(Elsevier Science B.V., Amsterdam., 2012-01-15T00:00:00Z) Caygill, J. S.; Davis, Frank; Higson, Seamus P. J.
The detection of explosives and explosive-related compounds has become a heightened priority in recent years for homeland security and counter-terrorism applications. There has been a huge increase in research within this area- through both the development of new, innovative detection approaches and the improvement of existing techniques. Developments for miniaturisation, portability, field-ruggedisation and improvements in stand-off distances, selectivity and sensitivity have been necessary to develop and improve techniques. This review provides a consolidation of information relating to recent advances in explosive detection techniques without being limited to one specific research area or explosive type. The focus of this review will be towards advances in the last 5 years, with the reader being referred to earlier reviews where appropriate.
Open Access
Detection of volatile organic compounds (VOCs) using an optical fibre long period grating with a calixarene anchored mesoporous thin film
(SPIE, 2013-05-06) Korposh, Sergiy; Davis, Frank; James, Stephen W.; Wang, T.; Lee, Seung-Woo; Higson, Seamus P. J.; Tatam, Ralph P.
A long period grating (LPG) modified with a mesoporous film infused with a functional compound, calix[4]arene, was employed for the detection of volatile organic compounds (VOCs). The mesoporous film consisted of an inorganic part, of SiO2 nanoparticles (NPs) along with an organic moiety of poly(allylamine hydrochloride) polycation PAH, which was finally infused with functional compound, p-sulphanatocalix[4]arene (CA[4]). The LPG sensor was designed to operate at the phase matching turning point to provide the highest sensitivity. The sensing mechanism is based on the measurement of the refractive index (RI) change induced by the complexion of the VOCs with calix[4]arene (CA). The LPG modified with 5 cycles of (SiO2 NPs/PAH)5PAA responded to exposure to chloroform and benzene vapours. The sensitivity to humidity as an interfering parameter was also investigated.
Open Access
Editorial, Seminars in Cell & Developmental Biology
(Elsevier Science B.V., Amsterdam, 2009-02-01T00:00:00Z) Davis, Frank; Higson, Seamus P. J.
It is a pleasure to introduce this special edition of Cell and Development Biology dedicated to the field and application of Biosensors. This edition comprises seven reviews covering the most active research areas where we believe some of the most prominent advances in the field are likely to emerge in the near to medium term. In line with scope of this journal, some emphasis is given towards techniques applicable to Cell Biology.
Open Access
Electrochemical detection of TNT at cobalt phthalocyanine mediated screen-printed electrodes and application to detection of airborne vapours
(Wiley-Blackwell, 2013-10-11) Caygill, J. S.; Collyer, Stuart D.; Holmes, Joanne L.; Davis, Frank; Higson, Seamus P. J.
We describe the use of cobalt phthalocyanine as a mediator to improve the sensitivity for the electrochemical detection of TNT. Commercial screen-printed electrodes containing cobalt phthalocyanine were employed for determination of TNT. Improved sensitivities compared to screen-printed carbon electrodes without phthalocyanine were observed, current response for cyclic voltammetric measurements at modified electrodes being at least double that of unmodified electrodes. A synergistic effect between oxygen and TNT reduction was also observed. Correlation between TNT concentrations and sensor output was observed between 0–200 µM TNT. Initial proof-of-concept experiments combining electrochemical determinations, with the use of an air-sampling cyclone, are also reported.
Open Access
The electrochemistry of the ferri/ferrocyanide couple at a calix [4]resorcinarenetetrathiol-modified gold electrode as a study of novel electrode modifying coatings for use within electro-analytical sensors
(Elsevier Science B.V., Amsterdam., 2003-06-05T00:00:00Z) Collyer, Stuart D.; Davis, Frank; Lucke, Andrew; Stirling, Charles J. M.; Higson, Seamus P. J.
The electrochemistry of the ferri/ferrocyanide redox couple has been studied at Au electrodes modified with calix[4]resorcinarenetetrathiol. Cyclic voltammetry in Fe(CN)63- solutions yields three separate pairs of faradaic peaks. Evidence is given for these redox couples corresponding to the reduction of Fe(CN)63- and the subsequent re-oxidation of Fe(CN)64- in three differing steric arrangements. One pair of peaks suggest that when the Fe(CN)63- ion resides within the calix [4]resorcinarene bowl, electron transport is facilitated by the calix [4]resorcinarene acting as a charge transfer mediator; in this arrangement the activation energy is found to be lowered by ~24kJmol-1. Another pair of peaks is thought to correspond to the reduction of Fe(CN)63- as it approaches the Au electrode by packing itself in-between adjacent calix[4]resorcinarene molecules. The third pair of redox peaks is attributed to the reduction and subsequent re- oxidation of Fe(CN)63-/Fe(CN)64- when the ion resides above a saturated calix [4]resorcinarene coating; in this case the activation energy was raised by ~45kJmol-1. FTIR spectroscopy of calix[4]resorcinarene-coated Au electrodes and calix[4]resorcinarene-coated Au electrodes exposed to Fe(CN)63- lends further support to this argument, by demonstrating that the Fe(CN)63- ion resides within at least two and possibly three differing environments. Calix[4]resorcinarene modified electrodes previously exposed to ferricyanide lose the calix [4]resorcinarene coating together with a surface layer of gold when subsequently scanned in a phosphate buffer. It therefore appears that the calix [4]resorcinarene/Fe(CN)63- association is stronger than the Au binding to the underlying glass material.
Open Access
Electrochromic effects from a simple commercial polymer membrane.
(Elsevier Science B.V., Amsterdam., 2007-08-01T00:00:00Z) Davis, Frank; Law, Karen A.; Bridge, Kerry; Higson, Seamus P. J.
A simple commercial polyester polymer membrane has been found to exhibit an intense electrochromic effect. Most polymers which undergo electrochromic effects contain either transition metals or extensive conjugated systems. We have found that a simple commercial polyester membrane when coated with gold and polarised to −4 V (versus Ag) in aprotic organic solvents displays an electrochromic colour change from a colourless to an intense red stat
Open Access
Flexible Ultrathin PolyDVB/EVB Composite Membranes for the Optimization of a Lactate Sensor.
(John Wiley & Sons, Ltd, 2007-01-01T00:00:00Z) Bridge, Kerry; Davis, Frank; Collyer, Stuart D.; Higson, Seamus P. J.
An ultrathin composite membrane has been developed as the outer covering barrier in a model amperometric lactate oxidase enzyme electrode. The membrane was formed by cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of a gold coated polyester support membrane. Permeability coefficients were determined for O2 and lactate across membranes with a range of polymer thicknesses. Anionic interferents (such as ascorbate) were screened from the working electrode by the composite membrane. The composite enzyme electrode showed an increased working concentration range and extended linearity of responses in comparison to an uncoated enzyme electrode.
Open Access
Flexible Ultrathin PolyDVB/EVB Composite Membranes for the Optimization of a Whole Blood Glucose Sensor.
(John Wiley & Sons, Ltd, 2007-01-01T00:00:00Z) Bridge, Kerry; Davis, Frank; Collyer, Stuart D.; Higson, Seamus P. J.
An ultrathin composite membrane has been developed as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The membrane was formed by cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of a gold coated polyester support membrane. Permeability coefficients were determined for O2 and glucose across membranes with a range of polymer thicknesses. Anionic interferents (such as ascorbate), were screened from the working electrode via a charge exclusion mechanism. The enzyme electrode showed an initial 10% signal drift when first exposed to whole human blood over a period of 2 hours, after which responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r2=0.99 compared to standard hospital analyses.
Open Access
Graphene modified electrodes for enhanced electrochemical detection
(Cranfield University, 2016-01) Walch, Nicholas John; Higson, Seamus P. J.; Davis, Frank
The ability to inexpensively and reliably detect organic compounds is important across a multitude of different areas of science. Benzene ring functional groups are found in a wide variety of biological molecules, (such as amino acids, DNA nucleotide bases and blood based components). The qualification and quantification of these compounds in a sample has been achieved by techniques such as high performance liquid chromatography (HPLC), gas chromatography (GC), mass spectrometry (MS) and nuclear magnetic resonance (NMR), amongst others. These techniques, however, often require cumbersome, expensive equipment along with exhaustive sample preparation techniques and are thus not necessarily suitable for portable in-situ analysis of these compounds. This thesis details the fabrication and characterisation of graphene modified electrodes that show an increased sensitivity towards biomolecular compounds such as dopamine, amino acids, and DNA. The graphene was synthesised using a novel semi-automated method which was performed using a bespoke apparatus designed to alleviate the labour involved in synthesising graphene by the sonochemical method. The method involved pumping an aqueous solution of the surfactant into a solution of graphite in water which was under constant sonication. When used in an electrochemical system employing cyclic voltammetry the graphene modified electrodes showed not only a lower limit of detection in all cases, but also a shift in peak position which allowed for simultaneous quantification of mixtures of compounds. This could not be achieved with screen printed carbon electrodes alone as different peaks often occur at similar potentials, making it difficult or impossible to quantify these compounds individually. Slower scan rates can often give rise to separate peaks, however this adds time to the experiment which is not necessary with graphene modification. The binding interactions of novel resorcinarene molecules were also predicted by molecular modelling techniques and then confirmed using NMR binding experiments. The resorcinarene was tested against a range of different analytes and showed a degree of specificity. The interaction between the two surfactant molecules and the graphene surface was also analysed to determine whether or not the resorcinarene molecules could be adsorbed onto graphene to produce a viable, molecularly specific electrode surface.
Open Access
Labeless AC impedimetric antibody-based sensors with pg ml-1 sensitivities for point-of-care biomedical applications.
(Elsevier Science B.V., Amsterdam., 2009-01-01T00:00:00Z) Barton, Andrew C.; Collyer, Stuart D.; Davis, Frank; Garifallou, Goulielmos-Zois; Tsekenis, Georgios; Tully, Elizabeth; O'Kennedy, Richard; Gibson, Tim; Millner, Paul A.; Higson, Seamus P. J.
This paper describes the development and characterisation of labeless immunosensors for (a) the cardiac drug digoxin and (b) bovine serum albumin (BSA). Commercial screen-printed carbon electrodes were used as the basis for the sensors. Two methods were used to immobilise antibodies at the electrode surface. Aniline was electropolymerised onto these electrodes to form a thin planar film of conductive polyaniline; the polyaniline film was then utilised as a substrate to immobilise biotinylated anti-digoxin using a classical avidin- biotin affinity approach. As an alternative approach, poly(1,2-diaminobenzene) was electrodeposited onto the carbon electrodes and this modified surface was then sonochemically ablated to form an array of micropores. A second electropolymerisation step was then used to co-deposit conductive polyaniline along with antibodies for BSA within these pores to produce a microarray of polyaniline protrusions with diameters of several μm, containing entrapped anti- BSA
Open Access
Labeless and reversible immunosensor assay based upon an electrochemical current-transient protocol
(Elsevier Science B.V., Amsterdam., 2003-10-24T00:00:00Z) Grant, Sarah; Davis, Frank; Pritchard, Jeanette A.; Law, Karen A.; Higson, Seamus P. J.; Gibson, Timothy D.
A novel labeless and reversible immunoassay based upon an electrochemical current-transient protocol is reported which offers many advantages in comparison to classical immuno-biochemical analyses in terms of simplicity, speed of response, reusability and possibility of multiple determinations. Conducting polypyrrole films containing antibodies against 1) Bovine Serum Albumin (BSA) and 2) Digoxin were deposited on the surface of platinum electrodes to produce conductive affinity matrices having clearly defined binding characteristics. The deposition process has been investigated using 125I labelled anti-digoxin to determine optimal fabrication protocols. Antibody integrity and activity, together with non-specific binding of antigen on the conducting matrix have also been investigated using tritiated digoxin to probe polypyrrole/anti-digoxin films. Amperometric responses to digoxin were recorded in flow conditions using these films, but the technique was limited in use mainly due to baseline instability. Anti-BSA - polypyrrole matrices were investigated in more detail in both flow and quiescent conditions. No observable response was found in flow conditions, however under quiescent conditions (in non-stirred batch cell), anti-BSA – polypyrrole films have been demonstrated to function as novel quantitative chronoamperometric immuno-biosensors when interrogated using a pulsed potential waveform. The behaviour of the electrodes showed that the antibody/antigen binding and/or interaction process underlying the response observed was reversible in nature, indicating that the electrodes could be used for multiple sensing protocols. Calibration profiles for BSA demonstrated linearity for a concentration range of 0-50 ppm but tended towards a plateau at higher concentrations. Factors relating to replicate sensor production, sample measurement and reproducibility are discusse
Open Access
Labeless Immunosensor Assay for Fluoroquinolone Antibiotics Based Upon an AC Impedance Protocol.
(Taylor & Francis, 2007-01-01T00:00:00Z) Garifallou, Goulielmos-Zois; Tsekenis, Georgios; Davis, Frank; Higson, Seamus P. J.; Millner, Paul A.; Pinacho, Daniel G.; Sanchez-Baeza, Francisco; Marco, M-Pilar; Gibson, Timothy D.
This paper describes the construction of a labeless immunosensor for the antibiotic ciprofloxacin and its interrogation using an AC impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Polyaniline was electrodeposited onto the sensors and then utilized to immobilize a biotinylated antibody for ciprofloxacin using classical avidin- biotin interactions. Electrodes containing the antibodies were exposed to solutions of antigen and interrogated using an AC impedance protocol. The faradaic component of the impedance of the electrodes was found to increase with increasing concentration of antigen. Control samples containing a non-specific IgG antibody were also studied and calibration curves obtained by subtraction of the responses for specific and non-specific antibody-based sensors, thereby eliminating the effects of non-specific adsorption of antigen.
Open Access
Langmuir and LB properties of two calix[4]resorcinarenes: Interactions with various analytes
(Elsevier Science B.V., Amsterdam., 2008-05-15T00:00:00Z) Sugden, Mark W.; Richardson, Tim H.; Davis, Frank; Higson, Seamus P. J.; Faul, Charl F. J.
The ability of calixarene-based molecules to interact with amino acids has been the basis of many studies. The Langmuir and LB properties of two calix [4]resorcinarenes have been investigated. The properties of the layer formed at the air–water interface were studied by surface pressure–area isotherms. LB deposition onto glass substrates has shown that multilayer assemblies can be built up. The UV–vis spectra of resulting LB films have been recorded, indicating that the compounds are coloured as a result of intra-molecular charge transfer bands. The sensitivity of the surface pressure–area isotherms has been investigated in relation to the exposure to various analytes delivered from the subphase (i.e. amino acids). Furthermore, exposure of the LB films to a wide range of vapours (e.g. amines, alcohols, thiols) has led to modified UV–vi
Open Access
Long period grating based toluene sensor for use with water contamination
(Elsevier Science B.V., Amsterdam., 2014-11-01T00:00:00Z) Partridge, Matthew; Wong, Rebecca; James, Stephen W.; Davis, Frank; Higson, Seamus P. J.; Tatam, Ralph P.
A demonstration of the use of a calix[4]resorcinarene coated optical fibre long period grating sensor for the detection of toluene in water is presented. Monitoring water quality both for domestic use and around industrial sites is critical to the preservation of clean water provision. Here we show that, by using a fibre optic based sensor system, water quality monitoring can be carried out without the requirement for water sampling or pre-concentration. The results presented demonstrate that this proof-of-concept sensor is capable of sensing ∼100ppm concentrations of toluene with semi-selectivity and low (<10ppm) variation.
Open Access
A membrane-based ELISA assay for the herbicide Isoproturon in soil samples
(Taylor & Francis, 2012-01-31T00:00:00Z) Baskeyfield, Damian E. H.; Davis, Frank; Magan, Naresh; Tothill, Ibtisam E.
A membrane based enzyme linked immunosorbent assay (MELISA) for the detection of a common herbicide, isoproturon is described. A heterogeneous competitive ELISA was the format chosen for isoproturon detection. An immunoassay system with a horseradish peroxidase (HRP) labeled polyclonal antibody preparation was developed and characterized before suitable sensitivity and selectivity for isoproturon were attained. After development as a microtiter plate immunoassay, the system was transferred to an affinity membrane sorbent based ELISA where the isoproturon/ovalbumin conjugate was immobilized on commercial membranes. Different porosities and immobilization conditions were utilized to optimize the MELISA, including sensitivity, selectivity, and stability studies. This enabled detection of isoproturon in the range 0.5ngml-1-20µgml-1, with an LLD90 of 0.5ngml-1. The use of acetonitrile extracts from soil samples was found to not overly impair the performance of the MELISA. Good correlation between ELISA and HPLC was obtained for extracts from spiked soil samples.