Studies On Electrochemical Biosensor Techniques For Endo-phytohormone Determination

Phytohormone is a natural substance which can regulate the life course and the physiological activities of plant. Phytohormone research is very significant to agriculture, horticulture and other related fields, and calls for a rapid, precise and convenient measurement procedure for phytohormone assay in plants. Exploring new simple, low-cost methods for phytohormone assay is of considerable interest.In this paper, we synthesized the antigen of IAA, iPA, GA3 with BSA as the carrier, immunized in the rabbit and obtained the antibody of these three kinds phytohormone. We developed the biosensor for IAA, iPA, GA3 determination by novel mechanism of biomatericals immobilization and sensing. The detailed materials are summarized as follows:1. Three styles of immunosensor for IAA determination: (1) By using a competitive immunoreaction and amplification effect, a QCM immunosensor was designed, which is capable of detecting IAA in dilute solution in the range of 0.5 ng / ml ~ 5 g / ml. (2) Based on the ordered, stable mercapto sel-assembled monolayer formed on the golden surface of the microelectrode, an amperomrtric immunosensor was prepared for detecting IAA in the mungbean sprout in the range of 5.68 10 - ~ 2.83 10 - mol / 1. (3) Using sol-gel technology in conjunction with an enzyme-linked competitive immunoreaction, an amperometric immunosensor was developed to determine IAA, with a detecting range of 5 g / ml~ 500g /ml.2. The immunosensor for iPA determination: an amperometric immunosensor was constructed by use of electropolymerization for enzyme immobilization, couple with an enzyme-labeled competitive immunoreaction to determine iPA in plant samples, in the range of 5 g /ml ~ 300 g /ml.3. The electrochemical immunosensor for GAs determination: Based on the competitive immunoreaction with copper cation labeled antigen and square wave stripping voltammetry technique, an electrochemical immunosensor was prepared to determine GAs in plant samples, in the range of 1 g / ml ~ 150 g/ ml.We applied these immunosensor in determination IAA, iPA, GAs in different hybrid rice grain samples with results in satisfactory agreement to those of HPLC, which demonstrated the reliability and the practical feasibility of these proposed immunosensor.4. Two styles of biosensor for H2O2 determination: (1) An amperometric sensor for H2O2 determination by immobilization of HRP on Nafion-ferrocene modified electrode. (2) An amperometric biosensor with HRP immobilized on a sandwich layer of poly m-phenylenediamine and nano-Au particles based on the ferrocene modified carbon paste electrode for H2O2 assay in plants.