A novel layer-by-layer assembled multi-enzyme/CNT biosensor for discriminative detection between organophosphorus and non-organophosphrus pesticides

摘要

Organophosphate compounds are heavily used in agriculture and military activities, while non-organophosphate pesticides are mostly used in agriculture and home defense. Discriminative detection of such toxic compounds is very challenging and requires sophisticated and bulky instrumentation. Meanwhile, multi-enzyme biosensors may offer an effective solution to the problem and may become a versatile analytical tool for discriminative detection of different neurotoxins. In this study, we report for the first time a novel hi-enzyme biosensing system incorporating electrostatically interacted enzyme-armored MWCNT-OPH and MWCNT-AChE along with a set of cushioning bilayers consisting of MWCNT-polyethyleneimine and MWCNT-DNA on glassy carbon electrode for discriminative detection of organophosphorus (OP) and non-organophosphorus (non-OP) pesticides. LbL interfaces were characterized by surface plasmon resonance and electrochemical impedance spectroscopy, demonstrating stepwise assembly and electron conductivity studies. The detection limit was found to be similar to 0.5 for OP pesticide paraoxon and 1 mu M for non-OP pesticide carbaryl, in a wide linear range. The biosensor performance was also validated using apple samples. Remarkable discriminative and straightforward detection between OP and non-OP neurotoxins was successfully achieved with cyclic voltammetry (CV) and UV-vis methods on the MWCNT-(PEI/DNA)(2)/OPH/AChE biosensor, showing great potential in large screening of OP and non-OP pesticides in practical applications. (C) 2014 Elsevier B.V. All rights reserved.