Claudia Danilowicz | Harvard University (original) (raw)
Papers by Claudia Danilowicz
Journal of The American Chemical Society, 2002
We report on the "molecular wiring" efficiency of glucose oxidase in organized self-assembled nan... more We report on the "molecular wiring" efficiency of glucose oxidase in organized self-assembled nanostructures comprised of enzyme layers alternating with layers of an osmium derivatized poly(allylamine) cationic polyelectrolyte, acting as redox relays. Varying the relative position of the active enzyme layer in nanostructures alternating active enzyme and inactive apoenzyme we have investigated the mechanisms of electrical signal generation from biomolecular recognition. The specific rate of bimolecular FADH 2 oxidation ("wiring efficiency") is limited by the diffusionlike electron hopping mechanism in the multilayers.
Journal of Electroanalytical Chemistry, 1998
Two new redox-active osmium complexes of the type (Os(bpy) 2 Cl(pyX)) + have been synthesised, wh... more Two new redox-active osmium complexes of the type (Os(bpy) 2 Cl(pyX)) + have been synthesised, where pyX corresponds to a pyridine derivative bearing a functional group (aldehyde, carboxylate). Their electrochemical behaviour and electronic spectra were studied in acetonitrile and aqueous solutions. The rate coefficients for the re-oxidation of glucose oxidase (GOx) by these new osmium complexes were obtained. The applicability to this system of the equation derived by Nicholson and Shain for an EC% mechanism is discussed. The mediator containing the carbonyl group was bound to poly(allyl)amine. The new electroactive polymer was wired with oxidases in the construction of glucose and lactate sensors, as an example of the capabilities of these new osmium complexes to build integrated chemical systems.
Analytical Chemistry, 1999
The electron-transfer behavior of electroactive hydrogels formed by cross-linking ferrocene poly(... more The electron-transfer behavior of electroactive hydrogels formed by cross-linking ferrocene poly(allylamine) (Fc-PAA) and glucose oxidase is investigated as a function of electrolyte ionic strength using several techniques. Cyclic voltammetry and electrochemical impedance spectroscopy show that the quantity cD(e)(1/2) increases with electrolyte concentration. Enhancement of enzyme catalysis for the oxidation of glucose mediated by Fc-PAA is also apparent at higher KNO(3) concentration. The electroactive redox center concentration, c, and the diffusion coefficient due to electron hopping in the gel, D(e), are independently measured by chronoamperometry at ultramicroelectrodes. Larger electrolyte ionic strength induces an increase in electroactive redox center concentration while D(e) slightly decreases. These results are rationalized in terms of the electrostatic interactions within the redox gel backbone due to water and ion exchange with the external electrolyte, producing swelling and shrinking of the hydrogel.
Physical Chemistry Chemical Physics, 2005
Supramolecular multilayer structures comprised of glucose oxidase (GOx), and Os complex derivatis... more Supramolecular multilayer structures comprised of glucose oxidase (GOx), and Os complex derivatised poly(allylamine) (PAH-Os) have been built by alternate layer-by-layer (LBL) electrostatic adsorption in a selfassembly process. The resulting modified electrodes with integrated mediator were tested as reagentless glucose biosensors. The enzyme kinetic parameters and the surface concentration of ''wired'' enzyme G E have been obtained by analysis of the catalytic current dependence on glucose concentrations for the ping-pong mechanism of glucose oxidation. An average osmium volume concentration was estimated by integration of the redox charge in the absence of glucose and the ellipsometric thickness. The total enzyme surface concentration was measured with a quartz crystal microbalance (QCM) during each adsoption step and the fraction of ''wired'' enzyme and the bimolecular rate constant for FADH 2 oxidation by the redox polymer for the different multilayers. The catalytic current increases with the number of LBL layers because the increase in the enzyme loading while the efficiency of enzyme FADH 2 oxidation by the Os redox polymer, except for the first dipping cycle remains almost constant at about 2 Â 10 4 M À1 s À1 .
Journal of The Chemical Society, Faraday Transactions, 1993
The kinetics of amperometric enzyme electrodes are reported for glwose oxidase immobilized in thr... more The kinetics of amperometric enzyme electrodes are reported for glwose oxidase immobilized in three different bovine serum albumin (BSA) hydrogel modified electrodes using as soluble electron mediator either ferrocene sulfonate or a pentammine(pyrazine)ruthenium complex. The effect of hydrogel layer thickness, enzyme loading, substrate and redox mediator concentrations on the amperometric response are reported.
Analytical Chemistry, 2001
The uptake of glucose oxidase (GOx) onto a polycationic redox polymer (PAA-Os)-modified surface, ... more The uptake of glucose oxidase (GOx) onto a polycationic redox polymer (PAA-Os)-modified surface, by adsorption from dilute aqueous GOx solutions, was followed by the quartz crystal microbalance (QCM) and shows double exponential kinetics. The electrochemistry of the layerby-layer-deposited redox-active polymer was followed by cyclic voltammetry in glucose-free solutions, and the enzyme catalysis mediated by the redox polymer was studied in -D-glucose-containing solutions. AFM studies of the different layers showed the existence of large two dimension enzyme aggregates on the osmium polymer for 1 µM GOx and less aggregation for 50 nM GOx solutions. When the short alkanethiol, 2,2'-diaminoethyldisulfide was preadsorbed onto gold, a monoexponential adsorption law was observed, and single GOx enzyme molecules could be seen on the surface where the enzyme was adsorbed from 50 nM GOx in water.
Analytical Chemistry, 1996
Different redox polymers based on poly(allylamine) with covalently attached ferrocene and pyridin... more Different redox polymers based on poly(allylamine) with covalently attached ferrocene and pyridine groups that coordinate iron and ruthenium complexes were prepared, and hydrogels were obtained by cross-linking them with epichlorohydrin. Charge propagation from the underlying electrode, through the redox polymer and electrical communication with the enzyme FADH 2 of glucose oxidase, was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The effects of electrolyte composition, concentration of enzyme and substrate, and electrode potential are reported. The role of different redox mediators covalently attached to the polymer backbone is discussed in terms of driving force and electrostatic barriers.
Faraday Discussions, 2000
Layer-by-layer supramolecular structures composed of alternate layers of negatively charged enzym... more Layer-by-layer supramolecular structures composed of alternate layers of negatively charged enzymes and cationic redox polyelectrolyte have been assembled. Glucose oxidase (GOx), lactate oxidase (LOx) and soybean peroxidase (SBP) have been electrically wired to the underlying electrode by means of poly(allylamine) with [Os(bpy)
Journal of The Chemical Society, Faraday Transactions, 1995
ABSTRACT
Analytical Letters, 1999
ABSTRACT The analytical performance of two modified electrodes (a tyrosinase biosensor and a glas... more ABSTRACT The analytical performance of two modified electrodes (a tyrosinase biosensor and a glassy carbon electrode (GCE) covered with poly [Ni-(protoporphyrin IX) dimethyl ester]) in comparison with the bare electrode has been evaluated in a flow injection ...
Electroanalysis, 1998
... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998),... more ... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998), Studies of the Interaction Between Metalloporphyrin Films and Phenols in a Preconcentration Type Sensor. ... Copyright © 1999–2011 John Wiley & Sons, Inc. All Rights Reserved.
Electroanalysis, 1998
... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998),... more ... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998), Studies of the Interaction Between Metalloporphyrin Films and Phenols in a Preconcentration Type Sensor. ... Copyright © 1999–2011 John Wiley & Sons, Inc. All Rights Reserved.
![Research paper thumbnail of Liquid chromatography/electrochemical detection of phenols at a Poly[Ni(Protoporphyrin IX)] chemically modified electrode](https://attachments.academia-assets.com/49782140/thumbnails/1.jpg)
](Analytica Chimica Acta, 1996
Numerous carbohydrates can be oxldlzed at low positive POtentlals at chemically modified carbon p... more Numerous carbohydrates can be oxldlzed at low positive POtentlals at chemically modified carbon paste electrodes containing added cobalt phthaiocyanlne (CoPC). Although no response is observed at plain carbon paste electrodes, a diverse group of carbohydrates including mono-and disaccharides, pyranose and furanose rings, and reduclng and nonreducing sugars are readily oxldlzed at the modlfled electrode surface. I n 0.15 M NaOH, the oxldatlons exhlblt a cyclic voltammetric peak potential of 4-0.40 V vs. Ag/AgCI, the waves decreasing In magnltude and shiftlng to more posltlve potentials at less baslc pH. The CoPC electrodes can be used for electrochemical detectlon of the carbohydrates In liquid chromatography as long as the applled potentlal Is regularly pulsed to -0.3 V or lower. Detection Umlts obtained in this manner range from 100 pmol injected for glucose and maltose to 500 pmoi Injected for fructose and sucrose.
Journal of The American Chemical Society, 2002
We report on the "molecular wiring" efficiency of glucose oxidase in organized self-assembled nan... more We report on the "molecular wiring" efficiency of glucose oxidase in organized self-assembled nanostructures comprised of enzyme layers alternating with layers of an osmium derivatized poly(allylamine) cationic polyelectrolyte, acting as redox relays. Varying the relative position of the active enzyme layer in nanostructures alternating active enzyme and inactive apoenzyme we have investigated the mechanisms of electrical signal generation from biomolecular recognition. The specific rate of bimolecular FADH 2 oxidation ("wiring efficiency") is limited by the diffusionlike electron hopping mechanism in the multilayers.
Journal of Electroanalytical Chemistry, 1998
Two new redox-active osmium complexes of the type (Os(bpy) 2 Cl(pyX)) + have been synthesised, wh... more Two new redox-active osmium complexes of the type (Os(bpy) 2 Cl(pyX)) + have been synthesised, where pyX corresponds to a pyridine derivative bearing a functional group (aldehyde, carboxylate). Their electrochemical behaviour and electronic spectra were studied in acetonitrile and aqueous solutions. The rate coefficients for the re-oxidation of glucose oxidase (GOx) by these new osmium complexes were obtained. The applicability to this system of the equation derived by Nicholson and Shain for an EC% mechanism is discussed. The mediator containing the carbonyl group was bound to poly(allyl)amine. The new electroactive polymer was wired with oxidases in the construction of glucose and lactate sensors, as an example of the capabilities of these new osmium complexes to build integrated chemical systems.
Analytical Chemistry, 1999
The electron-transfer behavior of electroactive hydrogels formed by cross-linking ferrocene poly(... more The electron-transfer behavior of electroactive hydrogels formed by cross-linking ferrocene poly(allylamine) (Fc-PAA) and glucose oxidase is investigated as a function of electrolyte ionic strength using several techniques. Cyclic voltammetry and electrochemical impedance spectroscopy show that the quantity cD(e)(1/2) increases with electrolyte concentration. Enhancement of enzyme catalysis for the oxidation of glucose mediated by Fc-PAA is also apparent at higher KNO(3) concentration. The electroactive redox center concentration, c, and the diffusion coefficient due to electron hopping in the gel, D(e), are independently measured by chronoamperometry at ultramicroelectrodes. Larger electrolyte ionic strength induces an increase in electroactive redox center concentration while D(e) slightly decreases. These results are rationalized in terms of the electrostatic interactions within the redox gel backbone due to water and ion exchange with the external electrolyte, producing swelling and shrinking of the hydrogel.
Physical Chemistry Chemical Physics, 2005
Supramolecular multilayer structures comprised of glucose oxidase (GOx), and Os complex derivatis... more Supramolecular multilayer structures comprised of glucose oxidase (GOx), and Os complex derivatised poly(allylamine) (PAH-Os) have been built by alternate layer-by-layer (LBL) electrostatic adsorption in a selfassembly process. The resulting modified electrodes with integrated mediator were tested as reagentless glucose biosensors. The enzyme kinetic parameters and the surface concentration of ''wired'' enzyme G E have been obtained by analysis of the catalytic current dependence on glucose concentrations for the ping-pong mechanism of glucose oxidation. An average osmium volume concentration was estimated by integration of the redox charge in the absence of glucose and the ellipsometric thickness. The total enzyme surface concentration was measured with a quartz crystal microbalance (QCM) during each adsoption step and the fraction of ''wired'' enzyme and the bimolecular rate constant for FADH 2 oxidation by the redox polymer for the different multilayers. The catalytic current increases with the number of LBL layers because the increase in the enzyme loading while the efficiency of enzyme FADH 2 oxidation by the Os redox polymer, except for the first dipping cycle remains almost constant at about 2 Â 10 4 M À1 s À1 .
Journal of The Chemical Society, Faraday Transactions, 1993
The kinetics of amperometric enzyme electrodes are reported for glwose oxidase immobilized in thr... more The kinetics of amperometric enzyme electrodes are reported for glwose oxidase immobilized in three different bovine serum albumin (BSA) hydrogel modified electrodes using as soluble electron mediator either ferrocene sulfonate or a pentammine(pyrazine)ruthenium complex. The effect of hydrogel layer thickness, enzyme loading, substrate and redox mediator concentrations on the amperometric response are reported.
Analytical Chemistry, 2001
The uptake of glucose oxidase (GOx) onto a polycationic redox polymer (PAA-Os)-modified surface, ... more The uptake of glucose oxidase (GOx) onto a polycationic redox polymer (PAA-Os)-modified surface, by adsorption from dilute aqueous GOx solutions, was followed by the quartz crystal microbalance (QCM) and shows double exponential kinetics. The electrochemistry of the layerby-layer-deposited redox-active polymer was followed by cyclic voltammetry in glucose-free solutions, and the enzyme catalysis mediated by the redox polymer was studied in -D-glucose-containing solutions. AFM studies of the different layers showed the existence of large two dimension enzyme aggregates on the osmium polymer for 1 µM GOx and less aggregation for 50 nM GOx solutions. When the short alkanethiol, 2,2'-diaminoethyldisulfide was preadsorbed onto gold, a monoexponential adsorption law was observed, and single GOx enzyme molecules could be seen on the surface where the enzyme was adsorbed from 50 nM GOx in water.
Analytical Chemistry, 1996
Different redox polymers based on poly(allylamine) with covalently attached ferrocene and pyridin... more Different redox polymers based on poly(allylamine) with covalently attached ferrocene and pyridine groups that coordinate iron and ruthenium complexes were prepared, and hydrogels were obtained by cross-linking them with epichlorohydrin. Charge propagation from the underlying electrode, through the redox polymer and electrical communication with the enzyme FADH 2 of glucose oxidase, was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The effects of electrolyte composition, concentration of enzyme and substrate, and electrode potential are reported. The role of different redox mediators covalently attached to the polymer backbone is discussed in terms of driving force and electrostatic barriers.
Faraday Discussions, 2000
Layer-by-layer supramolecular structures composed of alternate layers of negatively charged enzym... more Layer-by-layer supramolecular structures composed of alternate layers of negatively charged enzymes and cationic redox polyelectrolyte have been assembled. Glucose oxidase (GOx), lactate oxidase (LOx) and soybean peroxidase (SBP) have been electrically wired to the underlying electrode by means of poly(allylamine) with [Os(bpy)
Journal of The Chemical Society, Faraday Transactions, 1995
ABSTRACT
Analytical Letters, 1999
ABSTRACT The analytical performance of two modified electrodes (a tyrosinase biosensor and a glas... more ABSTRACT The analytical performance of two modified electrodes (a tyrosinase biosensor and a glassy carbon electrode (GCE) covered with poly [Ni-(protoporphyrin IX) dimethyl ester]) in comparison with the bare electrode has been evaluated in a flow injection ...
Electroanalysis, 1998
... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998),... more ... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998), Studies of the Interaction Between Metalloporphyrin Films and Phenols in a Preconcentration Type Sensor. ... Copyright © 1999–2011 John Wiley & Sons, Inc. All Rights Reserved.
Electroanalysis, 1998
... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998),... more ... How to Cite. Dall'Orto, VC, Danilowicz, C., Hurst, J., Balbo, AL and Rezzano, I. (1998), Studies of the Interaction Between Metalloporphyrin Films and Phenols in a Preconcentration Type Sensor. ... Copyright © 1999–2011 John Wiley & Sons, Inc. All Rights Reserved.
Analytica Chimica Acta, 1996
Numerous carbohydrates can be oxldlzed at low positive POtentlals at chemically modified carbon p... more Numerous carbohydrates can be oxldlzed at low positive POtentlals at chemically modified carbon paste electrodes containing added cobalt phthaiocyanlne (CoPC). Although no response is observed at plain carbon paste electrodes, a diverse group of carbohydrates including mono-and disaccharides, pyranose and furanose rings, and reduclng and nonreducing sugars are readily oxldlzed at the modlfled electrode surface. I n 0.15 M NaOH, the oxldatlons exhlblt a cyclic voltammetric peak potential of 4-0.40 V vs. Ag/AgCI, the waves decreasing In magnltude and shiftlng to more posltlve potentials at less baslc pH. The CoPC electrodes can be used for electrochemical detectlon of the carbohydrates In liquid chromatography as long as the applled potentlal Is regularly pulsed to -0.3 V or lower. Detection Umlts obtained in this manner range from 100 pmol injected for glucose and maltose to 500 pmoi Injected for fructose and sucrose.