Poly -modified electrodes

The catalytic activity of viologen modified polypyrrole electrodes in preparative elK tror luctions has been extended from vicinal to geminal poly-... 

Besides, potentiometric sensors with ion-selective ionophores in modified poly(vinyl chloride) (PVC) have been used to detect analytes from human serum [128], Cellular respiration and acidification due to the activity of the cells has been measured with CMOS ISFETS [129], Some potentiometric methods employ gas-sensing electrodes for NH3 (for deaminase reactions) and C02 (for decarboxylase reactions). Ion-selective electrodes have also been used to quantitate penicillin, since the penicillinase reaction may be mediated with I or GST. 

J.P. Lowry and R.D. O Neill, Partial characterization in vitro of glucose oxidase modified poly(phenylenediamine)-coated electrodes for neurochemical analysis in vivo. Electroanalysis 6, 369— 379 (1994). 

Figure 2.5 Schematic representation of the Au/MPS/PAH-Os/solution interface modeled in Refs. [118-120] using the molecular theory for modified polyelectrolyte electrodes described in Section 2.5. The red arrows indicate the chemical equilibria considered by the theory. The redox polymer, PAH-Os (see Figure 2.4), is divided into the poly(allyl-amine) backbone (depicted as blue and light blue solid lines) and the pyridine-bipyridine osmium complexes. Each osmium complex is in redox equilibrium with the gold substrate and, dependingon its potential, can be in an oxidized Os(lll) (red spheres) or in a reduced Os(ll) (blue sphere) state. The allyl-amine units can be in a positively charged protonated state (plus signs on the polymer...

The first demonstration of a PEM with electrochromic properties was disclosed by SchlenofFand coworkers [66], using poly(butanylviologen)/ PSS films. While this film exhibited strong electrochromic response, it still required the use of an outer electrolyte solution. DeLongchamp and Hammond disclosed for the first time a solid-state device comprised of two electrochromic PEM-modified ITO electrodes separated by a 200-p,m thick poly(2-acrylamido-methane-2-propanesulfonic acid), proton-conducting PAMPS membrane (see Eigure 2.30) [196]. Both PEMs used in... 

Deposition of Pb has also been carried out at modified gold electrodes. The films of 3-mercaptopropane sulfonate on poly-crystaUine gold electrodes were prepared from an acidic solution. At such electrodes,... 

M.J. Lobo Castanon, A.J. Miranda Ordieres and P. Tunon Blanco, Amperometric detection of ethanol with poly-(o-phenylenediamine)-modified enzyme electrodes, Biosens. Bioelectron., 12(6) (1997) 511-520. 

All potentials vs. screen-printed pseudo Ag/AgCl reference, except values marked with double-dagger (J), which are vs. screen-printed Ag/Pd, and 02 those marked with asterisk ( ), which are vs. Ag/3M AgCl double-junction reference electrode. Abbreviations LDH lactate dehydrogenase, LOD lactate oxidase, PVA-SbQ styrlpyridinium-modified poly(vinyl alcohol), FIA flow injection analysis. aLinear ranges using a dialysis system. 

MWCNTs were functionalized with iron phthalocyanines (FePc) to improve the sensitivity towards hydrogen peroxide. A highly sensitive glucose sensor with an FePc-MWCNT electrode based on the immobilization of GOx on poly(o-amino-phenol) (POAP)-electropolymerized electrode surface [219]. A hemin-modified MWCNT electrode to be used as a novel 02 sensor was obtained by adsorption of hemin at MWCNTs and the electrochemical properties of the electrode were characterized by cyclic voltammetry [220]. 

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 =... 

The time required for the electrode to attain a steady-state response after addition of an aliquot of NADH is of the order of seconds (—10 s for a film held at 0.1 V). Comparing this response time with those obtained in the mass transport-limited regime for a standard couple at a bare electrode, it is clear that the response time of the modified poly(aniline) electrodes is of the order of the mixing time for the system. 

The excellent stability and reproducibility of these modified poly(aniline) electrodes for NADH oxidation allows detailed kinetic studies of the system to be completed. To determine the mechanism of NADH oxidation the effects of film thickness, electrode potential, rotation rate and NAD concentration have been investigated. 

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... 

Poly(pyrrole/pyrrole-ODN) films electrosynthesized by Vieil and coworkers [59] were also used to modify QCM electrodes to monitor DNA hybridization. 

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