Neurotoxin sensor

Bansal L, Khalil S, El-Sherif M (2002) Fiber optic neurotoxin sensor. Proceedings of the IEEE 28th Annual Northeast Philadelphia, pp 20-21... 

Nanodes (nanoelectrodes) 771 Nanoparticles 802, 809, 817, 943 Nanotubes 802 Native peroxidase 373 Natural water samples el4 Negative feedback 912 Neisseria meningitidis 102 Neomycin 817 Nernst equation 26, 359 Nernstian function 12 Neuronal cell 105 Neurotoxins 311 Neutravidin 808, 817 Newcastle disease virus 107 Nikolskii-Eisenman 31 expression 727 Nitrate reductase 917 sensor 79 Nitric oxide 428... 

Acetylcholine receptor from electric organ of Torpedo sp. Receptor protein noncovalently bound on the surface of a planar interdigitated capacitative sensor. Response was concentration dependent and specific for ACh and inhibited by (+ )-tubocurarine, amantidine and a-neurotoxin. [66]... 

The sodium channel is the target for several classes of natural neurotoxins. These toxins may affect channel function in a variety of ways by binding to specific receptor sites on the a subunit and interacting with specific portions of the channel protein. These toxins have been invaluable probes for channel structure and function and their specific sites have, in some cases, been localized on the channel protein. The inactivation gate is located in the inner loop between S6 of domain ///and SI of domain IV transmembrane segment S4 of each domain contains voltage sensors and several phosphorylation sites by protein kinase and protein kinase C are identified in the inner loops between domains / and //and between domains ///and IV (Figure 17). 

Thus, the electrode is primarily responsive to DA that is protonized at pH 7.4 on the side-chain amino-group[171j. The positive effect of Nafion is increased by the low value of dopamine diffusion coeflScient in this membrane (Doa = 1 x 10 m s ). Therefore, the diffusion layer is restricted to the interior of the film and the product of the oxidation, DOQ (a potential neurotoxine) cannot penetrate into the brain liquid. A further favorable consequence is that the diffusion-layer thickness is the same in vivo as in vitro where the calibration of the sensor is provided. 

Direct use can be made of electroactive receptor species, such as the acetylcholine receptor extracted from the electroplax organ of fish. The idea would be to purify the material for reconstitution in a membrane which is immobilized on a sensor structure. Such a system could be used as a negative sensor for neurotoxins. Naturally, the military branches of a number of governments are particularly interested in this route. 

Lariat ethers can also be used as detectors for toxins. Gawley, Leblanc, and coworkers reported a coumaryl derivative of aza-18-crown-6 that responded to saxitoxin, a neurotoxin originating in marine bacteria and puffer fish. The fluorescence of the lariat ether increased with increasing saxitoxin concentration but was unaffected by either Na" " or K+, the two main chemical species that affect the response of crown ether-based sensors. 

Cennamo et al. [103] developed a SPR based sensor with a MIP layer of about 150 nm. This sensor was able to specifically recognize L-nicotine and not D-nicotine at a low concentration relevant for samples in the field. Other examples of MIP based SPR sensors are the sensor by Verma and Gupta [104] detecting the antibiotics tetracycline and their vitamin B3 sensor [105] for which the MIPs were prepared in hydrogel. Lotierzo et al. [106] developed an SPR based sensor for domoic acid, a neurotoxin. They compared their sensor with a sensor based on monoclonal antibodies and found that the MIP based sensor could be regenerated without losing its functionality and had a three times lower detection limit compared to the immunosensor. 

Ye, W Guo, J. Cheng, S. Yang, M. Nanoporous membrane based impedance sensors to detect the enzymatic activity of botufinum neurotoxin A. J Mater Chem B 2013,1, 6544—6550. 

Although being sensitive and useful sensors for environmental monitoring, biosensors based on enzyme inhibition have some limitations. They have a Iraig and tedious protocol that requires long incubation with inhibitors prior to analysis for good sensitivity and require reactivation of the enzyme which is inhibited irreversibly by OPs. Since AChE is inhibited by neurotoxins, which include not only OP pesticides but also carbamate pesticides and many other compounds, these analytical tools are not selective and carmot be used for quantification of either an individual or a class of pesticides that may be required for monitoring detoxification processes. 

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