Biomedical subjects

M E Díaz-García

Publications and source records attributed to M E Díaz-García.

7 recordsLinked to original sources

PubMed2005

Molecular imprinted ormosils for nafcillin recognition by room temperature phosphorescence optosensing.

Nafcillin imprinted sol-gels were used as specific binding materials for the room temperature phosphorescence (RTP) recognition of nafcillin using a flow injection system. Selective and reversible binding of the template to imprinted sol-gels could be observed by tailoring the hydrophobic/hydrophilic balance of the materials. Also, the possibility of minimizing non-specific interactions was evaluated by end-capping with trimethyl silyl groups. Control experiments were performed with non imprinted reference sol-gels. The recognition mechanism and the analytical potential of these materials for developing stable, selective and sensitive approaches for nafcillin recognition in real samples are outlined.

Biosensing Techniques↗

PubMed2002

Comparative study of the micellar enhanced spectrophotometric determination of beta-lactamic antibiotics by batch and flow injection analysis using a multisimplex design.

A study has been made on the spectrophotometric determination of the beta-lactamic antibiotics, amoxicillin and ampicillin, in micellar media using Cu ions as catalyst. Batch and flow injection approaches were compared. Multisimplex design was used to determine the optimal values of the flow injection analysis (FIA) system. Chemical (buffer, pH and Cu(II) concentrations) and physical (flow rate, temperature and reaction coil length) variables were considered. The analytical performance characteristics were as follows: the detection limits for batch and flow-through systems were 2.5 x 10(-7) and 2 x 10(-6) M, respectively, and a relative standard deviation less than 1% was found for both methods. The proposed FIA methodology was satisfactorily applied to the determination of the antibiotics in pharmaceutical formulations.

Amoxicillin↗

PubMed2001

Fluorescent competitive flow-through assay for chloramphenicol using molecularly imprinted polymers.

It is a fact that molecular imprinting techniques have reached tremendous importance in the research of new artificial recognition systems. These methods resemble the mechanism of natural recognition, generally based on non-covalent interactions, but improving their stability by means of a simple and inexpensive technique. Molecular imprinting polymers (MIPs) are easily obtained by copolymerisation of suitable functional monomers and crosslinkers in the presence of the print molecule. Removal of the template leaves a polymer that selectively recognises it. In this work, different imprinted polymers for chloramphenicol (CAP) obtained using different monomers and polymerisation conditions were tested in a HPLC system, in order to obtain a highly selective material for CAP. The optimised MIP was then used as recognition phase in a fluorescent competitive flow assay to determine chloramphenicol.

Biosensing Techniques↗

PubMed1999

Cyclodextrin-based optosensor for the determination of warfarin in waters.

A flow-through optosensor for warfarin is described. The sensor is developed in conjunction with flow analysis systems and uses a commercial bound beta-cyclodextrin material as the sensing phase. A strong fluorescence signal was observed as a result of the formation of an inclusion complex between warfarin and beta-cyclodextrin. The analytical performance characteristics of the proposed sensor for analysis of low levels of warfarin were as follows: the detection limits for continuous and flow injection analysis systems were 2 and 19 ppb, respectively; the observed relative standard deviations at 0. 5 ppm warfarin level were less than 2.3%. A study of the interference of other naphthalenic toxic substances was carried out. The continuous flow method was satisfactorily applied to the determination of the rodenticide in natural waters.

Agriculture↗

PubMed1998

Kalman filtering-aided time-resolved solid-surface room temperature phosphorimetry for simultaneous determination of anthracyclines in solution.

Daunorubicin, doxorubicin and epirubicin react with EuIII to form complexes which exhibit analytically useful room temperature phosphorescence (RTP). The RTP features of the three complexes are similar and the RTP spectra completely overlap. However, their three phosphorescence decay rates are different, and these differences were utilized to analyse the time-resolved RTP data by Kalman filtering. Simultaneous quantification of all three complexes is demonstrated and a method is proposed for the simultaneous determination of the three anthracyclines in mixtures by RTP optosensing. The analytical errors observed are within +/- 5%.

Antibiotics, Antineoplastic↗

PubMed1997

Fluorescent organofilms for oxygen sensing in organic solvents using a fiber optic system.

Oxygen quenching of the luminescence of the tris(2,2'-bipyridyl)ruthenium(II) complex [Ru(bpy)3]2+, entrapped in gelatin-containing microemulsion-based organogels, has been shown to be an accurate and precise method for measuring oxygen concentrations in organic solvents (such as toluene, hexane and isooctane). Film composition was investigated in order to obtain sensing phases with high sensitivity to oxygen and suitable response times. Using a fiber optic design combined with a continuous flow system configuration, the dynamic response of oxygen-sensing films was less than 1 min for a full signal change. A detection limit of 0.2 ppm of oxygen in hexane-5% chloroform was found.

Fiber Optic Technology↗

PubMedDate not supplied

Fluorometric monitoring of organic reactions on solid phase.

The direct monitoring of reaction progress on solid supports by fluorescence spectroscopy is described. An immobilized fluorescent tracer molecule (dansyl chloride) is used to monitor the reaction on OH resins (Argopore Wang, PS Wang, and Argogel Wang), both in batch and in parallel chemistry. Fluorescence measurements were obtained directly on solid phase. The method demonstrated to be a valuable tool for the quantitative determination of resin-bound hydroxyl groups, to study reaction kinetics and for continuously monitoring the progress of the conversion of the hydroxyl resins into the chlorinated ones. The procedure proposed is highly sensitive compared to the traditional ones. The system can be extended to monitor a variety of reactions on solid supports, and in conjunction with a well-established technique such as flow analysis, basic studies on solid-phase become possible.

Journal Article↗