Biomedical subjects

B López-Ruiz

Publications and source records attributed to B López-Ruiz.

7 recordsLinked to original sources

PubMed2006

The application of methacrylate-based polymers to enzyme biosensors.

Enzyme electrodes based on methacrylates have received significant attention in the development of biosensors. This article reviews the use and application of methacrylate and its derivatives as an immobilization system for the preparation of enzyme electrodes. Resent examples, extracted from the literature, illustrate the superior performance of such materials in the fabrication of biosensors and bioreactors.

Biocompatible Materials↗

PubMed2006

Amperometric tyrosinase biosensor based on polyacrylamide microgels.

An amperometric enzyme sensor using tyrosinase (PPO) entrapped in polyacrylamide microgels has been developed for determination of phenolic compounds. Polyacrylamide microgels were obtained by the concentrated emulsion polymerization method. The crosslinking of the polymer matrix optimum to retain the enzyme and to allow the diffusion of the compounds involved in the enzyme reaction has been studied (4.0%) as well as the influence on the response of analytical parameters such as pH, temperature, enzyme load and working potential. The useful lifetime of the biosensor was 27 days and it was useful to determine monophenolics compounds (e.g. cresol, chlorophenol) and diphenolics compounds (e.g. catechol and dopamine) by amperometric measurements at -100mV (versus SCE) in a batch system. The results showed that the substrate structures have a great influence on the sensor response.

Acrylic Resins↗

PubMed2006

Organic phase enzyme electrodes.

In the development of biosensors, organic phase enzyme electrodes (OPEEs) have received considerable attention for the detection of substrates in organic media. This article reviews different enzymes, transductors and immobilization methods used for the preparation of OPEEs in the last decade.

Biosensing Techniques↗

PubMed2006

Amperometric glucose biosensor based on polymerized ionic liquid microparticles.

A glucose amperometric biosensor based on the immobilization of glucose oxidase (GOx) in microparticles prepared by polymerization of the ionic liquid 1-vinyl-3-ethyl-imidazolium bromide (ViEtIm+ Br-) using the concentrated emulsion polymerization method has been developed. The polymerization of the emulsion dispersed phase, in which the enzyme was dissolved together with the ionic liquid monomer, provides poly(ViEtIm+ Br-) microparticles with entrapped GOx. An anion-exchange reaction was carried out for synthesizing new microparticles of poly(ViEtIm+ (CF3SO2)2N-) and poly(ViEtIm+ BF4-). The enzyme immobilization method was optimized for biosensor applications and the following optimal values were determined: pH 4.0 for the synthesis medium, 1.23 M monomer concentration and 3.2% (w/w) cross-linking content. The performance of the biosensor as a function of some analytical parameters such as pH and temperature of the measuring medium, and enzymatic load of the microparticles was also investigated. The effect of the substances which are present in serum samples such as uric and ascorbic acid was eliminated by using a thin Nafion layer covering the electrode surface. The biosensor thus prepared can be employed in aqueous and in non-aqueous media with satisfactory results for glucose determination in human serum samples. The useful lifetime of this biosensor was 150 days.

Biosensing Techniques↗

PubMed2005

Biosensors based on acrylic microgels: a comparative study of immobilized glucose oxidase and tyrosinase.

Acrylic microgels are proposed as enzyme immobilizing support in amperometric biosensors. Two enzymes, glucose oxidase and tyrosinase, were entrapped in this matrix and their behaviour is compared. The optimum cross-linking of the polymeric matrix required to retain the enzyme, and to allow the diffusion of the substrate is different for each enzyme, 3.2% for glucose oxidase and 4.5% for tyrosinase. The effect of pH and temperature on the biosensor responses has been studied by experimental design methodology and predictions have been compared with independently performed experimental measurements. A quadratic effect of the variables studied (pH and T) on the biosensor response and the small or null interaction between them was confirmed. The pH results obtained with both methods are coincident revealing an reversible effect on the enzyme. However, the temperature optimum value obtained by experimental design was 10 degrees C lower as a result of an activity decay due to irreversible thermal denaturation of both enzymes.

Acrylic Resins↗

PubMed2004

Design of an amperometric biosensor using polypyrrole-microgel composites containing glucose oxidase.

A new material consisting of a water-dispersed complex of polypyrrole-polystyrensulfonate (PPy) embedded in polyacrylamide (PA) has been prepared and tested as enzyme immobilizing system for its use in amperometric biosensors. Glucose oxidase (GOx) and the water-dispersed polypyrrole complex were entrapped within polyacrylamide microgels by polymerization of acrylamide in the dispersed phase of concentrated emulsions containing GOx and PPy. Polymerization of the dispersed phase provides microparticles whose size lies between 3.5 and 7 microm. The aim of incorporating polypyrrole into the polyacrylamide microparticles was to facilitate the direct transfer of the electrons released in the enzymatic reaction from the catalytic site to the platinum electrode surface. The conductivity of the microparticles was measured by a four-point probe method and confirmed by the successful anaerobic detection of glucose by the biosensor. Thus, the polyacrylamide-polypyrrole (PAPPy) microparticles combine the conductivity of polypyrrole and the pore size control of polyacrylamide. The effects of the polyacrylamide-polypyrrole ratio and cross-linking on the biosensor response have been investigated, as well as the influence of analytical parameters such as pH and enzymatic loading. The PAPPy biosensor is free of interferences arising from ascorbic and uric acids, which allows its use for quantitative analysis in human blood serum.

Acrylic Resins↗

PubMed2000

Advances in the determination of inorganic anions by ion chromatography.

The time period covered for this review includes articles published from 1997 to 1999, with the addition of a few classic references. The purpose of the review is to include the most relevant works from each topic area of the determination of inorganic anions by ion chromatography, including new sample pretreatments, new separation methods, new detection systems and the latest applications in the field of environmental, water, foods, etc. samples. Experimental conditions such as stationary phase, eluent, detection mode, as well as matrix are summarized in a table.

Anions↗