Amperometric sensor for choline and acetylcholine based on a platinum electrode modified by a co-crosslinked bienzymic system

Electrosynthesized poly(pyrrole)/poly(2-naphthol) bilayer membrane as an effective anti-interference layer for simultaneous determination of acethylcholine and choline by a dual electrode amperometric biosensor

“…The flow rate dependences for both ACh and Ch (not shown) were those already reported and discussed elsewhere (Guerrieri et al, 1995;Guerrieri and Palmisano, 2001), i.e. a response increases with the flow rate decrease, due to an increased residence time of the substrate (and then of the conversion efficiency) in the flow cell that behaves as an enzymatic reactor.…”

“…2. suggesting a change in the rate determining step controlling the biosensors response, i.e. a rate of enzyme catalysis comparable or higher than diffusion of enzyme substrates in membrane (Guerrieri et al, 1995(Guerrieri et al, , 1998. The pH dependence of both sensitivities and K M values were those already reported elsewhere (Guerrieri et al, 1995), i.e.…”

“…Enzyme co-crosslinking (Guerrieri et al, 1995) was preferred to a simple crosslinking procedure mainly because it allowed a higher degree of intermolecular bonding and a lower extent of enzyme crowding and deactivation. No pre-derivatization of the electrode surface was required for covalent binding of the enzyme to the Pt surface.…”

“…Several amperometric biosensors, based on ChO and AChE immobilized by a variety of techniques have been described (for a review, see Larsson et al, 1998). A sensitive and fastresponding amperometric biosensor for ACh and Ch based on ChO and AChE immobilized on a platinum electrode by glutaraldehyde (GLU) co-crosslinking with bovine serum albumin (BSA) has been developed in our laboratory (Guerrieri et al, 1995). Since this simple immobilization procedure works well also on the working electrode of a thin-layer flow cell, the use of an amperometric ACh/Ch biosensor as a LC detector has been recently proposed (Guerrieri and Palmisano, 2001).…”

Evaluation of the inhibition of choline uptake in synaptosomes by capillary electrophoresis with electrochemical detection

“…Although not electroactive, Ch and ACh can be indirectly detected through the oxidation of hydrogen peroxide generated by their reaction with these enzymes [13]. The enzymes are chemically cross-linked with glutaraldehyde and physically adsorbed onto a microelectrode surface similar to electrode fabrication procedures used in detection methods for ACh and/or Ch in tandem with HPLC separation and flow injection analysis [14][15][16][17] or for stand-alone microsensors [18][19][20][21]. Our current strategy takes advantage of the high efficiency of capillary electrophoresis (CE) to separate and identify molecules in the small sample volumes of complicated biological matrices, while EC detection offers femtomole sensitivity for detecting trace analyte levels [11].…”