A Novel Biosensor of Acetylcholinesterase Immobilized in Metal Organic Framework Based on Gold Nanoflower for Detection of Glyphosate

An electrochemical biosensor based on gold nanoflower ( GNF) and metal organic framework ( MOF) immobilized acetylcholinesterase ( AChE) was constructed and used for highly sensitive detection of glyphosate. Firstly , Nafion-Teflon polymer film was formed on glassy carbon electrode ( GCE) , and GNF with good dispersion was obtained by electrodeposition. Then p-aminothiophenol ( 4-ATP ) was self-assembled on the surface of GNF, and then AChE was immobilized on the electrode by the interaction of amide bond with 4-ATP. Finally, MOF was formed by electropolymerization in a solution containing AChE and 4-ATP functionalized gold nanoparticles ( Au@ 4-ATP) , and more AChE was immobilized to prepare AChE sensor (MOF/AChE/GNF/GCE ) . The biocatalytic activity of the sensor was investigated , and glyphosate was indirectly determined by voltammetry according to the inhibitory effect of glyphosate on the hydrolysis of thioacetylcholine iodide catalyzed by AChE. The logarithm of glyphosate concentration in the range of 5. 0 x 10(-16)-1. 0 x 10(-10) mol/L exhibited a good linear relationship with the current response of differential pulse voltammetry ( DPV) , and the detection limit was 1. 3 x 10(-16) mol/L (S/N = 3 ) . The results showed that the method overcame the deficiencies of low enzyme loading, easy aggregation , poor activity , and poor conductivity of MOF itself when conventional MOF was used to immobilize enzymes, and had extremely high sensitivity. The sensor was used for determination of glyphosate in vegetables.