Detection of methyl salicylate using bi-enzyme electrochemical sensor consisting salicylate hydroxylase and tyrosinase

Abstract

Volatile organic compounds have been recognized as important marker chemicals to detect plant diseases caused by pathogens. Methyl salicylate has been identified as one of the most important volatile organic compounds released by plants during a biotic stress event such as fungal pathogen infection. Advanced detection of these marker chemicals could help in early identification of plant diseases and has huge significance for agricultural industry. This work describes the development of a novel bi-enzyme based electrochemical biosensor consisting of salicylate hydroxylase and tyrosinase enzymes immobilized on carbon nanotube modified electrodes. The amperometric detection using the bi-enzyme platform was realized through a series of cascade reactions that terminate in an electrochemical reduction reaction. Electrochemical measurements revealed that the sensitivity of the bi-enzyme sensor was 30.6±2.7µAcm(-2)µM(-1) and the limit of detection and limit of quantification were 13nM (1.80ppb) and 39nM (5.39ppb) respectively. Interference studies showed no significant interference from the other common plant volatile compounds. Synthetic analyte studies revealed that the bi-enzyme based biosensor can be used to reliably detect methyl salicylate released by unhealthy plants.

Non-Covalent Functionalization of Carbon Nanotubes for Electrochemical Biosensor Development

“…In addition to the monoenzymatic biosensors introduced above, our recent researches developed bi-enzymatic biosensors for the detection of methyl salicylate (Figure 13). Salicylate hydroxylase and tyrosinase were immobilized onto MWCNTs using PBSE as cross-linker, and the sensitivity and limit of detection were 30.6 µA −1 ·cm −2 ·µM −1 and 13 nM [125,126].…”

Rapid determination of salicylic acid at screen printed electrodes

“…The application of electrochemical techniques to the detection of salicylic acid has traditionally been beset by a number of issues -mainly the large anodic potentials required to oxidise the analyte and the subsequent fouling of the electrode by oligomeric/polymeric oxidation products. A variety of approaches have been taken to minimise the effects of the latter and include: carbon electrodes [17], carbon with gold/iron oxide nanoparticles [18], gold electrodes coated with copper nanoparticles [19], platinum electrodes [20,21], screen printed electrodes [22], graphene based systems [23,24] and enzyme electrodes [25,26]. Park and Eun (2016) have postulated that while passivating polymeric films can arise, a number of additional products will also be formed [27] and the various possibilities are outlined in Scheme 2.…”

Immobilization of Multi-Enzymes on Support Materials for Efficient Biocatalysis

“…This work showed the possibility of biocatalytic hydrogenations in continuous flow using enzymes immobilized on a CNT-lined quartz column. Furthermore, enzymes co-immobilized on CNTs have also been widely used in electrochemical cascade enzymatic reactions for biosensing (Huang et al, 2013 ; Lang et al, 2014 ; Fang et al, 2016 ).…”