Acetylcholinesterase biosensor for inhibitor measurements based on glassy carbon electrode modified with carbon black and pillar[5]arene.

New acetylcholinesterase (AChE) biosensor based on unsubstituted pillar[5]arene (P[5]A) as electron mediator was developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. The AChE from electric eel was immobilized by carbodiimide binding on carbon black (CB) placed on glassy carbon electrode. The working potential of 200mV was obtained in chronoamperometric mode with the measurement time of 180 s providing best inter-biosensors precision of the results. The AChE biosensor developed made it possible to detect 1×10(-11)-1×10(-6) M of malaoxon, 1×10(-8)-7×10(-6) M of methyl-paraoxon, 1×10(-10)-2×10(-6) M of carbofuran and 7×10(-9)-1×10(-5) M of aldicarb with 10 min incubation. The limits of detection were 4×10(-12), 5×10(-9), 2×10(-11) and 6×10(-10) M, respectively. The AChE biosensor was tested in the analysis of pesticide residuals in spiked samples of peanut and beetroot. The protecting effect of P[5]A derivative bearing quaternary ammonia groups on malaoxon inhibition was shown.

Cholinesterase sensor based on glassy carbon electrode modified with Ag nanoparticles decorated with macrocyclic ligands.

New acetylcholinesterase (AChE) sensor based on Ag nanoparticles decorated with macrocyclic ligand has been developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. AChE was immobilized by carbodiimide binding on carbon black (CB) layer deposited on a glassy carbon electrode. The addition of Ag nanoparticles decreased the working potential of the biosensor from 350 to 50 mV. The AChE sensor made it possible to detect 0.4 nM-0.2 µM of malaoxon, 0.2 nM-0.2 µM of paraoxon, 0.2 nM-2.0 µM of carbofuran and 10 nM-0.20 µM of aldicarb (limits of detection 0.1, 0.05, 0.1 and 10 nM, respectively) with 10 min incubation. The AChE sensor was tested for the detection of residual amounts of pesticides in spiked samples of peanut and grape juice. The protecting effect of new macrocyclic compounds bearing quaternary ammonia fragments was shown on the example of malaoxon inhibition.

A whole-cell amperometric herbicide biosensor based on magnetically functionalised microalgae and screen-printed electrodes.

We report the fabrication of an amperometric whole-cell herbicide biosensor based on magnetic retention of living cells functionalised with magnetic nanoparticles (MNPs) on the surface of a screen-printed electrode. We demonstrate that Chlorella pyrenoidosa microalgae cells coated with biocompatible MNPs and retained on the electrode with a permanent magnet act as a sensing element for the fast detection of herbicides. The magnetic functionalisation does not affect the viability and photosynthesis activity-mediated triazine herbicide recognition in microalgae. The current of ferricyanide ion was recorded during alternating illumination periods and biosensor fabricated was used to detect atrazine (from 0.9 to 74 µM) and propazine (from 0.6 to 120 µM) (the limits of detection 0.7 and 0.4 µM, respectively). We believe that the methodology presented here can be widely used in fabrication of a number of whole cell biosensors since it allows for efficient and reversible cells immobilisation and does not affect the cellular metabolism.