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 μM. Under optimal conditions, the biosensor detected methyl parathion and carbaryl in the range of 1.0 × 10−12 M to 1 × 10−8 M. The detection limits for methyl parathion and carbaryl were 5.52 × 10−13 and 5.65 × 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.