Optical Biosensor with Multienzyme System Immobilized onto Hybrid Membrane for Pesticides Determination

A construction of optical biosensor based on simultaneous immobilization of acetylcholinesterase and choline oxidase enzymes for the detection of pesticides residues is described. Different kinds of novel SiO2 hybrid membranes were synthesized to be suitable for optical biosensors using sol-gel techniques. The bioactive component of the sensor consists of a multi-enzyme system including acetylcholinesterase and choline oxidase covalently immobilized on new hybrid membranes. The sensor exhibited a linear response to acetylcholine in a concentration range of 2.5 - 30 mM. Inhibition plots obtained from testing carbamate (carbofuran) pesticides exhibited concentration dependent behaviour and showed linear profiles in concentration ranges between 5x10-8 - 5x10-7 M for carbofuran. The factors affecting the constructed optical biosensors were investigated

Effect of Hydrolysis Products of Different Proteins of Wheat on Antioxidant Enzymes

This paper presents a study of the effect of products of enzymatic hydrolysis of various proteins of wheat with a neutral proteinase (neutrase “Novozymes”, Denmark) on the activity of peroxidase from horseradish. It is shown that the hydrolysis products of albumin activate peroxidase activity, the constant of activation being 2.3 micromoles. At the same time with increasing the depth of hydrolysis of albumin the activating effect of peptides disappears. Peptides derived from the salt-soluble, alcohol-soluble alkali-soluble proteins had no effect on the activity of peroxidase

An Evaluation of Kinetic Parameters of Cadmium and Copper Biosorption by Immobilized Cells

Bioremediation is the use of living organisms to reduce or eliminate environmental hazards resulting from the accumulation of toxic chemicals and other hazardous wastes. This technology is based on the utilization of microorganisms to transform organic and inorganic compounds. The filamentous yeast Trichosporon cutaneum strain R57, immobilized and free cells was cultivated as batch culture on a liquid medium in the presence of various concentrations of cadmium and copper ions. The simultaneous uptake and accumulation of Cd2+ and Cu2+ ions by Tr. cutaneum cells depending on the initial concentration of Cd2+ and Cu2+ in the medium were studied. The potential use of the free and immobilized cells of Trichosporon cutaneum to remove cadmium and copper ions, from aqueous solutions was evaluated. Two important physicochemical aspects for the evaluation of the sorption process as a unit operation are the equilibrium of sorption and the kinetics. The Cd2+ and Cu2+ ions biosorption capacities of all tested adsorbent were presented as a function of the initial concentration of metal ions within the aqueous biosorption medium. The individual, as well as bicomponent sorption kinetics of copper and cadmium ions by immobilised cells of Trichosporon cutaneum R57 is presented. A second order kinetic model obtains kinetic parameters for the copper and cadmium ions

Constructing Optical Biosensor Based on Multienzyme System Tyrosinase/Horseradish Peroxidase

By using sol-gel method, hybrid membranes were synthesized based on SiO2 and cellulose derivatives. Membranes showed good physical and mechanical properties as well as good biocompatibility. Onto hybrid membranes tyrosinase and horse radish peroxidase were immobilized and optical biosensor was constructed. The working principle of constructed biosensor was detection of oxygen consumption. The properties of constructed biosensors like linear range, life time and sensitivity were defined by modeling substrate - L-3,4-dihydroxyphenylalanine. The factors affecting the constructed optical biosensors were investigated. The results showed that a multienzyme system is capable of improving the constructed biosensor properties

Valorization of hydrosol derived from Rosmarinus officinalis cultivated in Metouia oasis

Hydrosols, are by-products of the hydrodistillation of plants. They consist of the distillation water in which very small amounts of essential oils remain dispersed. The aim of this study is the valorization of the hydrosol of a Tunisian aromatic and medicinal plant, Rosmarinus officinalis, by evaluating its phenolic content, antioxidant properties and enzyme activities. Through pH measurements, it has been determined that the hydrolate possesses an acidic character, with pH value falling within the range of 4.9. Total phenolic content assay and antioxidant assays DPPH radical scavenging activity unequivocally demonstrated the presence of antioxidants in the hydrosol and highlighted its potential to combat free radicals. The results showed that Rosmarinus officinalis presented an interested tyrosinase, polyphenol oxidase and lipoxygenase activities. Detected enzymes are identified for the first time in plant hydrosol and are searched for health care and manufacturing industries

Covalent Immobilization of Peroxidase onto Hybrid Membranes for the Construction of Optical Biosensor

The aim of this study is to covalently immobilize horse radish peroxidase (HRP) onto new hybrid membranes synthesized by the sol-gel method based on silica precursors, dendrimers and cellulose derivatives. This new system will be used for designing biosensor. For investigation of the properties of membranes, HRP was used as a modeling enzyme. Kinetic parameters, pH and temperature optimum were determined, and the structure of the membranes surface was examined. Results showed higher relative and residual activity of HRP immobilized onto membranes with cellulose acetate butyrate with high molecular weight CAB/H. This novel biosensor could offer a simple, cheap and rapid tool with enhanced sensing performance as well as having potentials to find application in medicine, pharmacy, food and process control and environmental monitoring

Influence of Ni 2+ on urease activity produced by biofilms of Arthrobacter oxydans 1388

International audienc

Co-Immobilization of Peroxidase and Tyrosinase onto Hybrid Membranes Obtained by the Sol-Gel Method for the Construction of an Optical Biosensor

International audienc

Investigation on the proliferation of Gram negative bacterial cells onto sol-gel carriers

International audienceThis work is related to the synthesis and characterization of new hybrid sol-gel materials. Several carriers based on poly (N-acryloylglycine) (NAGly) composed of poly (ethylene glycol) dimethacrylate (PEGDM) were prepared. The effectiveness of biofilms formation of bacterial strains Escherichia coli and Pseudomonas fluorescents on the matrices was investigated by biochemical methods. Two types of hybrid gels were synthesized based on PEGDM, 2-hydroxyethyl acrylate (HEA) and N-acryloxysuccinimide ester (NAS) with incorporation of inorganic precursors. The rheological properties of the gels and formed biofilms were investigated by quartz crystal microbalance (qCM). The experimental results demonstrated that the obtained matrices are appropriate for biofilms formatio