Development Of Phytohormonal Sensors Based On Nano Particles

Phytohormones, also known as plant hormones are singnal molecules which play vital roles in plant growth regulation. They occur in extremely low concentration and are easy to be decomposed by heat, light and oxygen. However, traditional methods for detecting phytohormones all present certain kinds of disadvantages. Hence, plant physiologists urgently require a rapid, precise and convenient measurement procedure for the phytohormonal assay in plants. Exploring new simple, low-cost methods for phytohormone is of considerable interest.A porous nano-gold film is produced on the glassy carbon electrode by electrodeposition in hydrogen tetrachloroautate solution. The anti-ABA antibody was immobilized directly onto the porous nano-gold through electrostatic adsorption. Then bovine serum albumin was adopted onto the modified electrode surface to prevent non-specific adsorption by blocking the active binding sites for protein. The concentration increase of the antigen brought the decrease of the interfacial electron transfer, which also means the increase of the impedance signal. Different from former phytohormonal sensors, this immunosensor is free from any labeling. Experimental parameters as pH, antibody incubation time, antibody concentration were optimized. Under optimized parameters, a series of ABA with different concentration was detected. The direct detecting method showed good linearity with the content of ABA in the range of 0.5 ng/mL-5000 ng/mL by R=0.9942 with a detection limit at about 0.1 ng/mL. The immunosensor also showed good repeatability with RSD=2.21%. A comparasion with the HPLC of plant samples took place and obtained satisfying results.Based on nickel hexacyanoferrate nanoparticles's (NiNP) excellent electron transporation ability combined with carbon nanotube's (CNT) dynamic capability and high conductivity, a sensor for detecting IAA based on a glassy carbon electrode modified by a mixture of NiNP and CNT was established. Under proper conditions, the nitrogen atom at the pyrrole ring of IAA can be oxidized, consequently a current will occur. Synergy between CNT and NiNP improved the redox activity of the system, allowing current detection even of slight changes. The current increases as the concentration of IAA increase. Experimental parameters such as pH and differnet proportions of CNT and NiNP of the mixture were optimized. Under optimized parameters, a series of IAA with different concentration was detected The results showed good linearity with the content of IAA in the range of 0.5μg/mL-50μg/mL by R=0.9536 with a detection limit at 0.08μg/mL (S/N=3) .