Carboxylic silica nanosheet-platinum nanoparticle modified glass carbon electrodes for pesticide detection

Silica nanosheets were prepared from montmorillonite and carboxyl functionalized by a chemical method. Platinum nanoparticles (Pt NPs) were also synthesized on carboxylic silica nanosheets (CSNSs). An acetylcholinesterase (AChE) biosensor based on a Pt NP, CSNS, and Nafion nanocomposite-modified glass carbon electrode was successfully developed. The AChE biosensor showed favorable affinity to acetylthiocholine chloride (ATCl) and catalyzed the hydrolysis of ATCl with an apparent Michaelis-Menten constant value of 125 mu M. Under optimal conditions, the biosensor detected methyl parathion and carbaryl in the range of 1.0 x 10(-12) M to 1 x 10(-8) M. The detection limits for methyl parathion and carbaryl were 5.52 x 10(-13) and 5.65 x 10(-13) M, respectively. The developed biosensor was inexpensive and exhibited good sensitivity, stability, and reproducibility, thus providing a promising tool for the analysis of enzyme inhibitors. A simple and effective immobilization platform was also provided for effectively immobilizing the enzyme on the electrode surface.