Immobilization, organophosphorus

A. Mulchandani, P. Mulchnadani, W. Chen, J. Wang, and L. Chen, Amperometric thick-film strip electrodes for monitoring organophosphate nerve agents based on immobilized organophosphorus hydrolase. Anal. Chem. 71, 2246-2249 (1999). 

In addition to being used in chemical sensors, as described in Chapter 3, immobilized organophosphorus hydrolase enzymes can also be used to deactivate or decontaminate nerve agents. Silica is an excellent choice for... 

Lei, C. H., M. M. Valenta, K. P. Saripalli, E. J. Ackerman, 2007. Biosensing paraoxon in simulated environmental samples by immobilized organophosphorus hydrolase in functionalized mesoporous silica. J Environ Quality 36 233-38. 

Durand P, Nicaud JM, Mallevialle J. 1984. Detection of organophosphorus pesticides with an immobilized cholinesterase electrode. J Anal Toxicol 8 112-117. 

In view of the conductive and electrocatalytic features of carbon nanotubes (CNTs), AChE and choline oxidases (COx) have been covalently coimmobilized on multiwall carbon nanotubes (MWNTs) for the preparation of an organophosphorus pesticide (OP) biosensor [40, 41], Another OP biosensor has also been constructed by adsorption of AChE on MWNTs modified thick film [8], More recently AChE has been covalently linked with MWNTs doped glutaraldehyde cross-linked chitosan composite film [11], in which biopolymer chitosan provides biocompatible nature to the enzyme and MWNTs improve the conductive nature of chitosan. Even though these enzyme immobilization techniques have been reported in the last three decades, no method can be commonly used for all the enzymes by retaining their complete activity. 

S. Andreescu, L. Barthelmebs, and J.L. Marty, Immobilization of acetylcholinesterase on screen-printed electrodes comparative study between three immobilization methods and applications to the detection of organophosphorus insecticides. Anal. Chim. Acta 464, 171—180 (2002). 

K.C. Gulla, M.D. Gouda, M.S. Thakur, and N.G. Karanth, Reactivation of immobilized acetyl cholinesterase in an amperometric biosensor for organophosphorus pesticide. Biochim. Biophys. Acta... 

Other enzymes have also been immobilized on CNTs for the construction of electrochemical biosensors. Deo et al. [115] have described an amperometric biosensor for organophosphorus (OP) pesticides based on a CNT-modified transducer and OP hydrolase, which is used to measure as low as 0.15 pM paraoxon and 0.8 pM parathion with... 

LeJeune et al. - - investigated this stabilizing effect of immobilization at the expense of activity. They immobilized an organophosphorus hydrolase by emulsifying a solution of the enzyme with a hydrophilic polyurethane prepolymer. They intended to study the enzymatically catalyzed hydrolysis of organophosphate nerve... 

The largest number of automated extraction-chromatographic separations for actinides have used TRU-Resin, and many of these have coupled the column to ICP-MS as an on-line separation (see Table 9.3). TRU-Resin is impregnated with the neutral bifunctional organophosphorus complexant, octyl(phenyl)-A,A-diisobu-tylcarbamoylmethylphosphine oxide (CMPO) in tri-n-butyl phosphate (TBP).26 127 128 The organic stationary phase in this resin binds trivalent, tetravalent, and hexavalent actinide nitrato complexes from nitric acid solutions (see Figure 9.11). The extraction equilibria for representative species are shown in Equations 9.3-9.5, where the bar above a species indicates that it is immobilized on the resin.4... 

Letant, S.E., Kane, S.R., Hart, B.R., Hadi, M.Z., Cheng, T-C., Rastogi, V.K., Reynolds, J.G. (2005). Hydrolysis of acer-ylcholinesterase inhibitors - organophosphorus acid anhydo-lase enzyme immobilization on phospholuminescent porous silicon platforms. Chem. Commun. 7 851-3. 

Applications. A biotinylated GOX-based biosensor was developed based on a new electropolymerized material consisting of a pol3rp3uidyl complex of ruthenium(II) functionalized with a pyrrole group [90]. Because histidine, lysine and arginine functions also coordinate Os /Os , biosensors based on co-electrodeposited GOX, HRP, soybean peroxidase (SBP) and laccase with redox Os /Os polymer have been developed [89]. A metal chelate formed by nickel and nitrilotriacetic acid was used to modify a screen-printed electrode surface. The functionalized support allowed stable attachment of acetylcholinesterase and the resulting biosensor was used for sensitive detection of organophosphorus insecticides [91]. This method is attractive because it ensures a controlled and oriented enzyme immobilization, considerably improving the sensitivity and the detection limit. 

Richins, R.D., A. Mulchandani, and W. Chen. 2000. Expression, immobilization, and enzymatic characterization of cellulose-binding domain-organophosphorus hydrolase fusion enzymes. Biotechnology and Bioengineering 69(6) 591-596. 

A second strategy that might prove useful for decontaminating pesticide wastes in soil has been the addition of hydrolytic enzymes derived from microorganisms (12,22). Organophosphorus insecticides such as parathion and diazinon are most susceptible to decontamination by enzymes. Some success has been realized with immobilization of degradative enzymes on inert surfaces through which wastewater is passed and detoxified. 

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