TiO2-decorated graphene nanohybrids for fabricating an amperometric acetylcholinesterase biosensor

Abstract

This work describes a highly sensitive and rapid amperometric biosensor for organophosphate compounds (OPs) based on immobilization of acetylcholinesterase (AChE) on a novel TiO(2)-decorated graphene (TiO(2)-G) nanohybrid, which was constructed by in situ growth of TiO(2) nanoparticles (NPs) on the graphene sheet. The well-dispersed TiO(2) NPs eliminated the restacking of TiO(2)-G nanohybrids. Due to the integrating of TiO(2)-G nanohybrids, the as-prepared biosensor showed high affinity to acetylthiocholine (ATCl) with a Michaelis-Menten constant (K(m)) value of 0.22 mM, and rapid inhibition time (3 min). Further, based on the inhibition of OPs on the enzymatic activity of the immobilized AChE, and using carbaryl as a model compound, the inhibition of carbaryl was proportional to its concentration ranging from 0.001 to 0.015 and 0.015 to 2 μg mL(-1) with a detection limit of 0.3 ng mL(-1) (S/N = 3). The developed biosensor exhibited a good performance for organophosphate pesticide detection, including good reproducibility and acceptable stability, which provided a new and promising tool for the analysis of enzyme inhibitors.

Recent advances in biosensors based on enzyme inhibition

“…Although the sensitivity was enhanced, the applied potential was high when compared with electrodes modified with electrochemical mediators or carbon nanotubes (Arduini et al, 2006, Zamfir et al, 2011Liu and Lin, 2006). In order to reduce the applied potential, the graphene was also employed with other nanomaterials such as NiO nanoparticles (NiONPs) (Yang et al, 2013a), TiO 2 (Wang et al, 2011a), gold nanoparticles , gold nanoparticles and polypyrrole (Yang et al, 2014), 3-carboxyphenylboronic and gold nanoparticles , CdS (Wang et al, 2011b), boronic acid functionalized Fe@Au magnetic nanoparticles (Dong et al, 2012), platinum nanoparticles (Yang et al, 2013b), and ZnOdecorated nanotubes (Nayak et al, 2013). In the carbon nanomaterial field, the advantage to use nanopowder was also reported as in the case of alkaline phosphatase immobilized on nano-powder paste electrode.…”

Nanomaterials Based Electrochemical Sensing Applications for Safety and Security

“…TiO 2 decorated graphene -TiO 2 -G nanohybrid) and electrochemical impedance analysis (EIA) applied recently for organophosphate compounds (OPs) detection based on acetylcholinesterase (AChE) inhibition can also be considered. [81] EIA in relation to the use of nanomaterials and toxic/safety related application is mostly applied as a characterisation tool (i.e. for detection of methyl paraoxon, carbofuran and phoxim [82].…”

Evolution and Expectations of Enzymatic Biosensors for Pesticides

“…The advantage of these materials allows producing a synergetic effect derived of combining their individual properties, while are eliminated their particular drawbacks. The introduction of materials as the graphene will be strategic to design nanohybrids materials with fast detection due to the excellent electron-transfer, acceptable stability, good reproducibility, and higher affinity to the substrates used for placing the enzyme (Wang, K. et al, 2011). Therefore, a new generation of biosensors to fulfill the parameters of performance required will be developed as for example, must search that the detection of levels can be realized in smaller periods.…”