Highly sensitive fluorescence quantification of picloram using immunorecognition liposome.

Picloram is a widely used chlorinated herbicide, which is quite persistent and mobile in soil and water with adverse health and environmental risks. A simple and efficient method with high sensitivity and good selectivity was developed in this work to analyze picloram. The aldehyde group functionalized quartz glass plate was used to catch picloram by Schiff base reaction, and reacted with the liposomes-labeled antibody. The fluorescein isothiocyanate (FITC) solution was encapsulated in the liposomes. After being released from the liposomes, the fluorescence of FITC was measured by a fluorimeter. It was found that the fluorescence intensity is linearly correlated to the logarithm of picloram concentration, ranging from 1.0 × 10(-4) to 100 ng mL(-1), with a detection limit of 1.0 × 10(-5) ng mL(-1). Picloram concentration in real wastewater samples were accurately measured by the proposed method and HPLC, the results of the two methods were approximately the same. The proposed method showed high sensitivity and good selectivity, and could be an efficient tool for picloram quantitative analysis.

[Lignin degradation by Penicillium simplicissimum].

A strain of fungi was isolated from soil, which was identified as Penicillium simplicissimum. This strain was capable of utilizing several lignin model compounds, making aromatic dyes decoloration and degrading natural lignin. All these results proved that Penicillium simplicissimum has ligninolytic ability. Three kinds of enzymes were believed to be the most important catalyzes in the biodegrading process. They are lignin peroxidase (LiP), laccase (Lac) and hemicellulase. And they always work synergistically. After 25 days' incubation, the amount of rice straw lignin decreased 0.23g, and the degrading rate was 14.94%. Different from the degrading mechanism of the white-rot fungi, the lignin degradation by P. simplicissimum mainly happened during the primary metabolism and it was greatly influenced by the pH of media, the concentration of Cu2+ and Mn2+.

Amperometric immunosensor based on polypyrrole/poly(m-pheylenediamine) multilayer on glassy carbon electrode for cytokinin N6-(Delta2-isopentenyl) adenosine assay.

A novel immunosensor based on a multilayer-coated glassy carbon electrode was designed to determine isopentenyl adenosine (iPA) in plants. The multilayer consists of polypyrrole and poly(m-phenylenediamine) with K4Fe(CN)6 and horseradish peroxidase (HRP) entrapped during electropolymerization. The ferrocyanide doped in polypyrrole functions as the mediator. The glucose oxidase bound on the immunosensor by the competitive immunoreaction involving iPA catalyzed the oxidation of the added glucose with the formation of H2O2, which is in turn reduced in the presence of HRP entrapped in poly(m-phenylenediamine). The current of the oxidized production of ferrocyanide reduced at -50 mV is inversely proportional to the concentration of iPA in the competitive immunoreaction. This immunosensor is able to be used about 40 times; after that its surface can be regenerated for a new immunosensor assembly by washing with 0.1M citrate-phosphate buffer (pH 4.6). The percentage of current response reduction (CR%) (y) is linearly related to the logarithm of the concentration of iPA (x) in the 5-300 microg/ml range, with a regression equation of the form y = 42.13x - 27.79 and a correlation coefficient of 0.9861. Five hybrid rice grain samples were analyzed with results in satisfactory agreement to those obtained by high-performance liquid chromatography.

Amperometric biosensor with HRP immobilized on a sandwiched nano-Au / polymerized m-phenylenediamine film and ferrocene mediator.

An amperometric biosensor has been developed for the determination of H(2)O(2) in plant samples. Horseradish peroxidase (HRP) is immobilized on a sandwiched nano-Au particle / m-phenylenediamine polymer film by glutaraldehyde cross-linking. The film is formulated on the carbon paste electrode (CPE) blended with ferrocene as an electron transfer mediator. On the low concentration range, the current response is related to the H(2)O(2) concentration linearly from 0 to 8x10(-6) M with a detection limit of 1.3x10(-7) M. On a wider concentration range of 8x10(-6) to 1.4x10(-4) M, the reciprocal of current response is linearly related to the reciprocal of H(2)O(2) concentration. The apparent Michaelis-Menten constant (K(m)(app)) was calculated to be 0.0334 mM. The sensor has been tested by determining H(2)O(2) concentration in plant leaf samples.