Sol-Gel Films Doped with Enzymes and Banana Crude Extract as Sensing Materials for Spectrophotometric Determination.

Chromogenic enzymatic reactions are very convenient for the determination of various biochemically active compounds. Sol-gel films are a promising platform for biosensor development. The creation of sol-gel films with immobilized enzymes deserves attention as an effective way to create optical biosensors.

Silica Xerogel Doped with Iron(III) as Sensor Material for Salicylhydroxamic Acid Determination in Urine.

Salicylhydroxamic acid (SHA) is used as antimicrobic medicine and its concentration has to be monitored in urine. For the first time, silica xerogels doped with iron(III) have been proposed as sensor materials for SHA determination in biological samples. Three xerogels with iron(III) content in the range of 0.

Silica and Silica-Titania Xerogels Doped with Iron(III) for Total Antioxidant Capacity Determination.

In order to design a sensor material for total antioxidant capacity determination we have prepared silica and silica-titania xerogels doped with iron(III) and modified with 1,10-phenanthroline. Titanium(IV) tetraethoxyde content in the precursors (titanium(IV) tetraethoxyde and tetraethyl orthosilicate) mixtures has been varied from 0 to 12.5% vol.

Crude Extract: Characterization and Analytical Application.

In the present work crude extract (ABE) has been prepared and characterized by its tyrosinase activity, protein composition and substrate specificity. The presence of mushroom tyrosinase (PPO3) in ABE has been confirmed using two-dimensional electrophoresis, followed by MALDI TOF/TOF MS-based analysis. GH27 alpha-glucosidases, GH47 alpha-mannosidases, GH20 hexosaminidases, and alkaline phosphatases have been also detected in ABE.

Determination of Food Oxalates Using Silica-Titania Xerogel Modified with Eriochrome Cyanine R.

The interaction of silica-titania xerogel with triphenylmethane dyes (pyrocatechol violet, chrome azurol S, eriochrome cyanine R) has been investigated to create a new sensor material for solid phase spectrophotometric determination of food oxalates. The complex forming reaction between xerogel incorporated titanium(IV) and triphenylmethane dyes has been studied; half-reaction periods, complex composition, equilibrium constants, and xerogel sorption capacity have been calculated for each dye. Eriochrome cyanine R (ECR) is characterized by the shortest half-reaction period, the smallest equilibrium constant, and the greatest capacity; it has been chosen for the sensor material construction because titanium(IV)-ECR complex is formed faster and can be destroyed easier than other studied complexes.

Silica-titania xerogel doped with Mo,P-heteropoly compounds for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine.

Background: Ascorbic acid is one of the most important vitamins to monitor in dietary sources (juices and vitamins) and biological liquids.

Results: Silica and silica-titania xerogels doped with Mo,P-heteropoly compounds (HPC) have been synthesized varying titanium(IV) and HPC content in sol. Their surface area and porosity have been studied with nitrogen adsorption and scanning electron microscopy, their elemental composition has been studied with energy-dispersive X-ray analysis.

Silica-titania xerogel for solid phase spectrophotometric determination of salicylate and its derivatives in biological liquids and pharmaceuticals.

Background: Salicylic acid and its derivatives are widely used drugs with potential toxicity. The main areas of salicylate derivatives determination are biological liquids and pharmaceuticals analysis.

Results: Silica-titania xerogel has been used for solid phase spectrophotometric determination of various salicylate derivatives (salicylate, salicylamide, methylsalicylate).

Silica and silica-titania sol-gel materials: synthesis and analytical application.

This review describes last decade progress in the synthesis of sol-gel materials with analytically relevant properties and their application for the determination of metal ions, non-metal and organic compounds. The following types of materials are discussed: silica sol-gel materials doped with various analytical reagents, organofunctional silica sol-gel materials, and silica titania sol-gel materials. The variety of obtained materials allows their application for a wide range of analytical systems: electrochemical sensors, solid phase spectrophotometrical and SIA determination, and also for test determination including the employment of "length-of-stain" indicator tubes.