Multi-Strip Assay and Multimodal Biosensors for Environmental and Medical Monitoring of Neurotoxicants

Abstract

The present report describes two types of biosensor systems. The first is for direct monitoring of neurotoxicants. The second is for monitoring individuals exposed to cholinergic and/or neuropathic organophosphorus compounds (OPs) by analyzing activities of their blood esterases. Both systems are rapid, simple, and sensitive. Assemblies of synthetic polymers, biomolecules, nanoparticles, and electrochemical transducers allow the biosensor systems to be used at the point of care and for field measurements in environmental, medical toxicology, veterinary, and antiterrorist applications. The selective monitoring of anticholinesterase compounds is based on a simple analytical method: the residual cholinesterase (ChE) activity assay after incubation with inhibitors. The specially developed design includes “programmable” strips and an automatic flow-injection amperometric analyzer for ChE activity analysis based on biosensor technology for choline detection. Capabilities include estimating the general toxicity of a sample as well as carrying out selective quantitative and qualitative assays of OPs, and other antiChE agents in mixtures. Combining layer-by-layer electrostatic assembly of enzymes and polyelectrolytes with extremely sensitive amperometric detection of hydrogen peroxide based on carbon electrodes coated by nanoparticles of MnO2 yields a simple biosensor device capable of sensitive (< 0.1 pM) detection of neurotoxicants in 20 minutes. A new method of simultaneous quantitative determination of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in mixtures is also described in the report; the method is fast and precise. Average error of determination of enzyme activity is 8%. Highly sensitive tyrosinase and choline oxidase biosensors based on nanostructured polyelectrolyte films were developed for these purposes. The methodology of neuropathy target esterase (NTE) activity assay in whole human blood was realized using an amperometric analyzer coupled with a tyrosinase biosensor for phenol detection. These analytical approaches were developed to serve as a monitoring system for individuals exposed to cholinergic and/or neuropathic OPs. Thus, the technologies described here not only have enormous potential for use in responding to terrorist chemical threats, but they also have many civilian applications, which would likely be the larger market sector.Key wordsBiosensorsneurotoxinsblood esterasesmonitoring