Immobilization of thin enzyme membranes to construct glass enzyme electrodes

Abstract

International audienceA technique of immobilizing very thin layer of enzymes over glass electrodes, resulting in response times as low as 5-10s, is described. The method involves the adsorption of enzyme molecules onto the sensitive end of the glass electrode followed by the formation of covalent bonds between the enzyme molecules, by means of spraying a dilute solution of glutaraldehyde over the surface. Enzymes immobilized in this manner over pH glass elctrodes are acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), penicillinase, and urease. The cross-sectional scanning electron micrograph of the fractured surface of the electrode shows the immobilized layer is not more than 1-2 µm thick. The technique could offer immense scope for immobilization of other protein substances as thin layers on different support surfaces

Determination of Organophosphorus and Carbamate Pesticides Using a Piezoelectric Biosensor

“…Because they represent an alternative to the above-mentioned techniques, enzymatic methods based on the inhibition of acetylcholinesterase (AChE) activity by the action of organophosphorus and carbamate pesticides have been the object of intense investigation due to their sensitivity and specificity. In addition, their use can be coupled to various analytical techniques by the use of different substrates. − Biosensors based on AChE or cholinesterase (ChE) activities as molecular recognition systems for the detection of these compounds have been designed by combining the biological system with a variety of transducers, including potentiometric, − spectrophotometric, − voltammetric, and piezoelectric . In this way, in previous work we demonstrated the determination of organophosphorus and carbamate pesticides with a biosensor based on AChE using 4-aminophenyl acetate as substrate amenable for amperometric detection.…”

Application and automation of flow injection analysis (FIA) using fastresponding enzyme glass electrodes to detect penicillin in fermentation broth andurea in human serum

“…This was similar to that for the enzyme electrode described previously [15]. However, to immobilize penicillinase, the combined pH electrode was immersed in a penicillinase solution containing 4 mg m1-1 of the enzyme.…”

“…However, the stability of the urease electrode due to the urease enzyme [15], is not as good. Figure 9.…”

Electrochemical biosensors for pesticide determination in food samples

“…For a long time, pH sensors were used for monitoring the amount of acetic or bu t y ric acid formed during hydrolysis of acetyl-or butyrylcholine, which is pro p o rtional to the enzymatic activ i t y. Seve ral enzyme immobilization techniques, including the use of crosslinking with glutara l d e hyde and albumine [17,18], a c t ivated acrylamide-based prepolymers [19], covalent immobilization on p re a c t ivated polyamide membrane [20], and glass beads coated with AChE [21] were used. Some approaches using salts of acetyl-or bu t y ry l ( t h i o ) choline (most commonly iodide) as substrates have been proposed.…”