Amperometric biosensor for the rapid determination of salicylate in whole blood

Polymer–graphite composite: a versatile use and throw plastic chip electrode

We report an efficient plastic chip electrode (PCE) fabricated from a composite of graphite and poly(methyl methacrylate) by a simple solution casting method and promoted as an economically inexpensive, multipurpose disposable electrode for various applications.

Electrochemical biosensors in pharmaceutical analysis

Given the increasing demand for practical and low-cost analytical techniques, biosensors have attracted attention for use in the quality analysis of drugs, medicines, and other analytes of interest in the pharmaceutical area. Biosensors allow quantification not only of the active component in pharmaceutical formulations, but also the analysis of degradation products and metabolites in biological fluids. Thus, this article presents a brief review of biosensor use in pharmaceutical analysis, focusing on enzymatic electrochemical sensors.

IR, Raman and SERS studies of methyl salicylate

The IR and Raman spectra of methyl salicylate (MS) were recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum was recorded in silver colloid. The vibrational wave numbers of the compound have been computed using the Hartree-Fock/6-31G* basis and compared with the experimental values. SERS studies suggest a flat orientation of the molecule at the metal surface.

A new enzyme electrode for quantification of salicylic acid in a FIA system

This work presents an amperometric biosensor incorporated into a flow configuration comprising salicylate hydroxylase that catalyses the irreversible hydroxylation of salicylate to catechol in the presence of NADH and molecular oxygen, and tyrosinase that further oxidises catechol giving o-quinone which is electrochemically reduced at -100 mV vs. Ag/AgCl yielding catechol and entering the catalytic oxidation and electrochemical reduction cycling which results in signal amplification and, consequently, low limits of detection. Additional incorporation of glucose dehydrogenase in the enzymatic sequence results in regeneration of NADH provided that glucose is present in the carrier stream and incorporation of a dialysis membrane provides operational stability to the biosensor. The analytical characteristics of this catalytic and electrochemical transduction sequence in a FIA system are: a limit of detection of 3.5 10(-6) M (S/N = 3), a sensitivity of 22.6 nA microM(-1) cm(-2), no loss of response at least after 5 h of continuous operation, and a sample frequency of 15 h(-1). Monitoring of salicylate after ingestion of 500 mg of acetylsalicylic acid has been followed in non-pretreated urine samples and the amount of salicylate in several drugs has been also successfully quantified.

Production, partial characterization, and potential diagnostic use of salicylate hydroxylase from Pseudomonas putida UUC-1

An unusual strain of Pseudomonas putida UUC-1 capable of growth at high salicylate concentration (10 gl-1) was investigated with the aim of developing an assay and a biosensor system for determining salicylate in body fluids by utilizing the salicylate hydroxylase enzyme. Medium and growth condition optimization were carried out under chemostat conditions. The highest biomass yield was at 4.0 gl-1 salicylate, 25 degrees C, pH 6.5, and 0.2 h-1 dilution rate. Growth occurred at up to 0.45 h-1 dilution rate, producing 236 Ul-1 enzyme activity and an output of 424 U h-1. The activity and productivity were higher than any reported in the literature for this enzyme. It had a Km value of 2.07 +/- 0.32 microM and an M(r) of approximately 43,000. In addition, its specific activity in the crude extract (0.8-0.9 U mg-1 protein) was similar to the commercially available enzyme. No plasmid DNA was detected in this strain, and no salicylate-negative isolates were obtained when curing with mitomycin C. It is therefore proposed that our strain has a chromosomally located inducible salicylate hydroxylase gene that enables it to grow at high salicylate. This strain also offers a means of cheaply producing large quantities of the enzyme through standard fermentation techniques.