Study On The Development Of Piezoelectric/Fluorescence IAA Biosensors

Phytohormone indole-3-acetic acid (IAA) is a trace organic substance, synthesized in plants, and regulates the processes of plant growth and development. The level of IAA in plant is very low, and easy to be photolyzed and oxidated; its physiological effects normally depend on the concentration gradient only across a few cells. Some existing detection methods and techniques for IAA have certain disadvantages, such as being unable to detect in real-time and in situ. Furthermore, the repeatability and stability of these detection methods can not be guaranteed.We developed a gold nanoparticle modified piezoelectric biosensor and a quantum dot-based fluorescent biosensor for IAA determination, and obtained the following results:(1) Gold nanoparticle modified IAA piezoelectric biosensorA piezoelectric competitive immunoassay method was developed to detect IAA. The linear concentration range for IAA is3.3-333.0ng/mL with a lower limit of detection of3.3ng/mL. The optimal conditions for IAA detection were determined as follows:9.0μg/mL BSA-IAA,9μL mouse anti-IAA antibody. The IAA sensor has good anti-interference ability. Moreover, the piezoelectric immuno-biosensor is easily to be regenerated without significant frequency signal loss after6repeated tests under the regeneration condition.(2) Quantum dots fluorescence IAA biosensorAnother method for IAA detection was developed based on the fluorescence resonance energy transfer principle (FRET). Fluorescence spectrophotometer was used to obtain the standard curve of different IAA concentrations vs. energy transfer rate. The sensor was used to detect the concentration of IAA in the range of0.1ng/mL-5μg/mL. The test results showed that the developed fluorescence biosensor has a minimum IAA detection concentration of0.1ng/mL. The optimal detection conditions were determined as follows:0.1μmol/mL DNA-IAA chain;1μmol/mL Cb;245nmol/mL QD605;0.5μmol/mL mouse anti-IAA antibody;37℃for Ni chain and Cb chain hybridization. Finally we applied the biosensor for the detection of IAA in fresh Arabidopsis thaliana leaves extracted by HPLC with a lower limit of detection of0.5ng/g.