Glucose modified carbon paste

FIGURE 4-15 Cyclic voltanmiograms for 1.5 x 10 3 M ribose (a), glucose (b), galactose (c), and fructose (d) recorded at a Ru02-modified carbon-paste electrode. Dotted lines were obtained in carbohydrate-free solutions. (Reproduced with permission from reference 50.)... 

S.Q. Liu and H.X. Ju, Reagentless glucose biosensor based on direct electron transfer of glucose oxidase immobilized on colloidal gold modified carbon paste electrode. Biosens. Bioelectron. 19, 177-183 (2003). 

Figure 4. (left) Steady state response to 31.5 mM glucose of the ferrocene-modified poly(siloxane) / glucose oxidase / carbon paste electrodes at several applied potentials. The relay systems are indicated next to each curve, which is the mean result for four electrodes. 

Figure 8. (right) Glucose calibration curves for the ferrocene-modified poly(ethylene oxide)/glucose oxidase/carbon paste electrodes at E =... 

CEEC has been used extensively for the detection of small molecules in blood and urine. Pulsed amperometric detection at a gold electrode was used to detect glucose in blood following capillary electrophoresis separation [59]. It was also detected using a glucose oxidase-modified carbon paste electrode [33]. As previ-... 

The bioelectrocatalytic oxidation or reduction of substrates at biocatalyst electrodes can be accelerated by the presence of a small molecule which functions as an electron transfer mediator between the electrode and the prosthetic group of the immobilized enzyme " . Two types of the enzyme-modified electrode with entrapped mediator have been designed" , a carbon paste electrode and a porous electrode, both modified with enzyme and a reservoir of mediator. In the former type of electrode , where glucose oxidase (GOD) was immobilized on the surface of a carbon paste electrode along with p-benzoquinone (BQ) by coating the enzyme-loaded surface with a semipermeable membrane, BQ was dissolved into the immobilized enzyme layer and retained there effectively to serve as an electron transfer mediator between the carbon paste electrode and the immobilized enzyme. It has been shown " that the kinetics of the bioelectrocatalytic oxidation of D-glucose (Glc) at the membrane-coated GOD-modified carbon paste electrode with mixed-in BQ can be explained by theoretical equations in which the diffusion enzyme reaction of the substrate and mediator in the immobilized-enzyme layer and the diffusion of the substrate (and mediators) in the coating membrane are taken into account - . In this study, a number of quinone derivatives and a few ferrocene derivatives were examined as electron transfer mediators in the GOD electrode, and the mediator activity of the compounds was evaluated on the basis of theoretical equations. 

J. Wang, X.J. Zhang, and M. Prakash, Glucose microsensors based on carbon paste enzyme electrodes modified with cupric hexacyanoferrate. Anal. Chim. Acta 395,11—16 (1999). 

Karan et al. [10] reported glucose sensors using quinone modified poly-siloxane (Fig. 3.8a-A) and acrylonitrile-ethylene (Fig. 3.8a-B) co-polymers and glucose oxidase. Sensors constructed with glucose oxidase and quinone modified polysiloxane were considerably more efficient than those using acrylonitrile-ethylene system to transfer electrons from reduced glucose oxidase to a conventional carbon paste electrode. Their results coincide with those described previously for the ferrocene-modified polysiloxane system. The excellent flexibility of poly(siloxane) allows it to function as an efficient... 

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