Amperometric biosensing of organophosphate and organocarbamate pesticides utilizing polypyrrole entrapped acetylcholinesterase electrode

• Published in: Biosensors & bioelectronics Vol. 52; pp. 166 - 172
• Main Authors: Dutta, Rekha Rani, Puzari, Panchanan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.02.2014; Elsevier
• Subjects: Acetylcholinesterase - chemistry; Acetylcholinesterase biosensor; Animals; Biological and medical sciences; Biosensing Techniques - methods; Biosensors; Biotechnology; Conducting polymer; Electrochemistry; Electrodes; Electroimmobilization; Enzymes, Immobilized; Ethylparaoxon; Fundamental and applied biological sciences. Psychology; Gelatin - chemistry; Methods. Procedures. Technologies; Organocarbamates; Organophosphates; Organophosphates - isolation & purification; Pesticides - isolation & purification; Polymers - chemistry; Pyrroles - chemistry; Swine; Various methods and equipments; Geltn; Organocarbamates; Conducting polymer; Glut; Ethylparaoxon; Acetylcholinesterase biosensor; Electroimmobilization; Organophosphates; Enzyme; Pesticides; Esterases; Acetylcholinesterase; Carboxylic ester hydrolases; Electrodes; Biosensor; Amperometry; Hydrolases; Organophosphorus compounds; Pyrrole polymer; gluteraldehyde; gelatin
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2013.08.050

The work presented here describes a novel, easy and low-cost method of fabrication of a highly sensitive acetylcholinesterase biosensor and its application to detect organophosphate and organocarbamate pesticides. Acetylcholinesterase was electro-immobilized into a thick conducting layer of polypyrrole. Porcine skin gelatin and gluteraldehyde mixture was used for stabilizing the system. Acetylthiocholine chloride was used as the substrate. Polypyrrole catalyzed the electrochemical oxidation of thiocholine and promoted the electron transfer, thus lowering the oxidation potential and increasing the detection sensitivity. Electro oxidation of thiocholine in polypyrrole matrix occurred at 0.1V under low potential scan rate. The thiocholine sensitivity of the electrode was found to be 143mA/M. The sensor was applied to detect the sample organophosphate pesticide ethylparaoxon and organocarbamate pesticide carbofuran. The detection limit for paraoxon was found to be 1.1ppb and that for carbofuran is 0.12ppb. The sensor showed good intra and inter state precision with relative standard deviation (RSD) 0.742% and 6.56% respectively. Both dry and wet storage stability were studied. The sensor stored at 0°C in dry condition had a good storage stability retaining 70% of its original activity for 4 months. During wet storage, the activity decrease followed the same trend, however, the operational stability at the end of the storage period was found to be less compared to the dry storage case. The developed biosensor is as a promising new tool for analysis of cholinesterase inhibitors. •AChE can be electro-immobilized in polypyrrole to fabricate a highly stable and highly sensitive biosensor.•Polypyrole lowers the oxidation potential of thiocholine to 100mV and amplifies the amperometric signal.•Gelatin can provide a biocompatible micro-environment to AChE inside polypyrrole matrix.•Lower counter-ion concentration gives higher reproducibility and stability to electro-entrapped AChE biosensors.