Ricardo Mallavia

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The quantum efficiency and the molar-absorption coefficients of different phenothiazine dyes are obtained by means of fitting the experimental data of transmittance as a function of time. An analytical expression for the intensity transmitted in a photopolymerizable holographic material is obtained, and good agreement between theory and experience is also(More)
The interaction between the conjugated polyelectrolyte poly{[9,9-bis(6'-N,N,N-trimethylammonium)hexyl]fluorene-phenylene} bromide (HTMA-PFP) and human serum albumin (HSA) has been investigated from changes observed in both the spectroscopic properties of HTMA-PFP and the intrinsic fluorescence of HSA. Absorption and fluorescence spectra of HTMA-PFP suggest(More)
A study of the optimization and the characteristics of a dry film photopolymerizable recording material is presented. The effects of intensity, the thickness, and the variation of the concentration of each component have been studied. Diffraction efficiencies of 80%, with energetic sensitivities of 40 mJ/cm(2), have been obtained in photosensitive films of(More)
The presence of stilbenes in wine is becoming an important issue due to their claimed relation to a low incidence in coronary diseases and their increasing implication as cancer chemopreventive and neuroprotective agents. Total resveratrol content, quantified as glucoside and aglycone forms of resveratrol, has been determined in a survey of 45 Monastrell(More)
In this work we report the development of a highly sensitive fluorescent multienzymatic biosensor for quantitative xanthine detection. This biosensor is built by the simultaneous encapsulation of three enzymes, xanthine oxidase, superoxide dismutase and peroxidase, in a single sol-gel matrix coupled to the Amplex Red probe. The sol-gel chemistry yields a(More)
To enhance the advantages of fluorescent flow-through sensing for drinking water we have designed a novel sensing matrix based on molecularly imprinted polymers (MIPs). The synergic combination of a tailor-made MIP recognition with a selective room temperature fluorescence detection is a novel concept for optosensing devices and is assessed here for the(More)
A method is reported that makes use of holography to study the kinetics of the radical photopolymerization of acrylamide in a polyvinyl alcohol when the Kogelnik theory is applied. A mechanism of unimolecular termination by the radicals that initiate the polymerization reaction is postulated to calculate the quantum yield, the molar-extinction coefficient,(More)
One of the potential areas of research in the development of biosensors is the production of analytical devices based on the use of immobilized multienzymatic systems. In this work, we report the development of three analytical systems for superoxide radical detection using sol-gel technology to immobilize enzyme systems. These systems are based on the(More)
We provide a brief overview of the structural characteristics of the main groups of conjugated polyelectrolytes (CPEs) as well as the methods of synthesis and their behaviour in solution. Their tendency to form aggregates in solution, which is one of the key points to be taken into account for them to be used in polynucleotide sensing, is also considered(More)
In this work, a highly sensitive fluorescent biosensor for quantitative superoxide radical detection, based on the coupled reaction superoxide dismutase-peroxidase enzymes and the use of the probe Amplex red, is described. Superoxide anion radical was produced via oxidation of xanthine by xanthine oxidase. Dismutation of superoxide was catalyzed by(More)