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Biomedical subjects

Frank Davis

Publications and source records attributed to Frank Davis.

8 recordsLinked to original sources
PubMed2006

Biofuel cells--recent advances and applications.

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.

Bioelectric Energy Sources↗
PubMed2005

Langmuir-Blodgett films of preformed polymers containing biphenyl groups.

Polymers containing liquid crystal groups have been studied previously as waveguides, and they have been deposited as spacer materials with various chromophores to form alternating films However, only a few members of this group of materials have been studied in any detail, and very little structural information has been obtained so far. Therefore, a more detailed examination of these materials as mono- and multilayers was undertaken. A new group of materials including the same mesogenic group, polymeric sulfones, was also studied. The polymers gave steep isotherms with high collapse pressures, indicating good packing of the monolayers, and could be deposited to form thick multilayers. X-ray diffraction showed that an ordered multilayer was formed, and the effects of the polymers chemical nature on the structure of the LB films are discussed. It appears that the dominant factor in monolayer structure is the nature of the polymer backbone rather than that of the liquid crystal side chains, which play a secondary role.

Biphenyl Compounds↗
PubMed2005

Species differentiation by DNA-modified carbon electrodes using an ac impedimetric approach.

A simple and novel electrochemical biosensor based approach is described for differentiating between differing species of fish on the basis of DNA hybridisation events. Screen-printed carbon electrodes modified with a variety of polymers were used to immobilise commercially available DNA in a single-stranded form. AC impedimetric measurements were firstly carried out on these systems and then upon exposure to single-stranded DNA solutions. When the electrode and solution DNA were complementary, a large drop in impedance was measured; this did not occur for non-matching DNA exposures. DNA hybridisation sensors for closely related species of fish were in the first instance developed as a demonstration for this approach. Species of fish such as herrings and salmon could be differentiated by this method. This sensor format offers great promise for many DNA hybridisation applications and lends itself to mass fabrication due to the simplicity and inexpensiveness of the materials and methods used. The hybridisation results were confirmed by use of ellipsometry to measure the characteristics of similar films deposited on silicon substrates.

Adsorption↗
PubMed2005

Sonochemically fabricated microelectrode arrays for biosensors. Part III. AC impedimetric study of aerobic and anaerobic response of alcohol oxidase within polyaniline.

A sonochemically fabricated alcohol oxidase enzyme micro-electrode array is reported. Sensors of this type were fabricated by first depositing an insulating polydiaminobenzene film on supporting gold electrodes. Sonication and subsequent ablation exposed discrete areas of the underlying conducting electrode, which collectively act as a microelectrode array. Electropolymerisation of aniline has been used to generate in situ polyaniline containing entrapped alcohol oxidase. The physical and electrochemical properties of these films were studied and reported within this paper. The final composites were shown to behave with microelectrode performance characteristics for the detection of aqueous ethanol concentrations.

Aerobiosis↗
PubMed2004

Structured thin films as functional components within biosensors.

This review provides an introduction to the field of thin films formed by Langmuir-Blodgett or self-assembly techniques and discusses applications in the field of biosensors. The review commences with an overview of thin films and methods of construction. Methods covered will include Langmuir-Blodgett film formation, formation of self-assembled monolayers such as gold-thiol monolayers and the formation of multilayers by the self-assembly of polyelectrolytes. The structure and forces governing the formation of the materials will also be discussed. The next section focussed on methods for interrogating these films to determine their selectivity and activity. Interrogation methods to be covered will include electrochemical measurements, optical measurements, quartz crystal microbalance, surface plasmon resonance and other techniques. The final section is dedicated to the functionality of these films, incorporation of biomolecules within these films and their effect on film structure. Species for incorporation will include antibodies, enzymes, proteins and DNA. Discussions on the location, availability, activity and stability of the included species are included. The review finishes with a short consideration of future research possibilities and applications of these films.

Biosensing Techniques↗
PubMed2004

Changing surface hydro- and oleophobicity with resorcinarene multilayers-a simple water/oil proofing process.

Resorcinarenes (resorcinol-aldehyde tetramers) of appropriate structures have been shown to change the hydro- and oleophilicities of a variety of surfaces. The phenomenon results from attachment of the rim of the bowl-like molecules to hydrophilic surfaces. Hydrophobic (alkyl) and oleophobic (perfluoro alkyl) "legs" attached to the bowls then determine the immediate surface property. Amounts required to modify surfaces are only between 2 and 10 mg m(-2) treated, and there is evidence of multilayer formation. Penetration of surfaces by a variety of liquids has been studied and cannot easily be understood as a function of density, viscosity, or surface tension.

Absorption↗
PubMed2004

Sonochemically fabricated microelectrode arrays for biosensors offering widespread applicability: Part I.

A novel and patented procedure is described for the sonochemical fabrication of a new class of microelectrode array based sensor with electrode element populations of up to 2 x 10(5) cm(-2). For some years it has been accepted that microelectrode arrays offer an attractive route for lowering minimum limits of detection and imparting stir (convectional mass transport) independence to sensor responses; despite this no commercial biosensors, to date, have employed microelectrode arrays, largely due to the cost of conventional fabrication routes that have not proved commercially viable for disposable devices. Biosensors formed by our sonochemical approach offer unrivalled sensitivity and impart stir independence to sensor responses. This format lends itself for mass fabrication due to the simplicity and inexpensiveness of the approach; in the first instance impedimetric and amperometric sensors are reported for glucose as model systems. Sensors already developed for ethanol, oxalate and a number of pesticide determinations will be reported in subsequent publications.

Biosensing Techniques↗