Arshak Poghossian - Academia.edu (original) (raw)
Papers by Arshak Poghossian
Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which... more Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect either a physical or (bio-)chemical parameter. Therefore, such systems include a more complicated fabrication technology and measuring set-up. In this work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilized as transducer for the detection of both (bio-)chemical
Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which... more Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect only one physical or (bio-)chemical parameter. In the present work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilised for the flow velocity and flow direction measurement for the first time. The proposed flow sensor presents a chemical
MRS Proceedings, 2006
Abstract The possibility of a label-free electrical detection of charged macromolecules using sem... more Abstract The possibility of a label-free electrical detection of charged macromolecules using semiconductor field-effect sensors offers a new approach for the development of DNA chips with fast and direct electrical readout. A deep understanding of the adsorption and ...
An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) ... more An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) gate with two input and two output signals. Reversible conversion of NAD + and NADH cofactors was used to perform a XOR logic operation, while biocatalytic hydrolysis of p-nitrophenyl phosphate resulted in an Identity operation working in parallel. The first biomolecular realization of a CNOT gate is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.
Die Entwicklung miniaturisierter Systeme für die (bio-)chemische Analyse tritt zunehmend auf den ... more Die Entwicklung miniaturisierter Systeme für die (bio-)chemische Analyse tritt zunehmend auf den Gebieten der Chemie, Biotechnologie, medizinischen Diagnostik, Lebenswissenschaften, Umweltanalytik und Mikrosystemtechnik in den Fokus wissenschaftlicher und wirtschaftlicher Interessen. Solche Systeme integrieren Sensoren zur Erfassung und Kontrolle von (bio-)chemischen und physikalischen Messgrößen, wie beispielsweise pH-Wert, Analytkonzentration, Elektrolytleitfähigkeit, Temperatur, Druck und Flussrate, zu Sensorarrays [1]. Oftmals basieren die eingesetzten Sensoren auf elektrochemischen oder optischen Transducerprinzipien. Ein genereller Vorteil miniaturisierter Systeme im Vergleich zu herkömmlichen Labormethoden ist der geringere Verbrauch an Reagenzien bzw. Bedarf an Probevolumen, die Möglichkeit der Echtzeitmessung sowie der reduzierte Aufwand für Wartung und Kalibrierung. Chipbasierte Sensoren können in diesem Zusammenhang eine entscheidende Rolle spielen und stellen aufgrund ih...
Die Erfindung betrifft eine Vorrichtung zum Nachweis von geladenen Makromolekülen, umfassend eine... more Die Erfindung betrifft eine Vorrichtung zum Nachweis von geladenen Makromolekülen, umfassend eine ionensensitive Schicht, an dessen Oberfläche ein Probenmolekül zum Nachweis eines Target-Moleküls immobilisiert ist. Probenmoleküle und nachzuweisendes Target-Molekül vermögen eine spezifische Bindung einzugehen. Die Vorrichtung ist dadurch gekennzeichnet, dass die Probenmoleküle in einem Mindestabstand voneinander auf der ionensensitiven Schicht immobilisiert sind in der Weise, dass während der Bindung mit dem Target-Molekül eine Umverteilung der Zonenkonzentration in den intermolekularen Zwischenräumen induziert wird. Ein Verfahren zum Nachweis geladener Makromoleküle mit der erfindungsgemäßen Vorrichtung ist offenbart.
In vitro Untersuchungen des Degradationsverlaufs sind essentiell für die Entwicklung und Optimier... more In vitro Untersuchungen des Degradationsverlaufs sind essentiell für die Entwicklung und Optimierung implantierbarer Medizinprodukte auf der Basis von biodegradierbaren Polymeren. Erstmals wurde mit Hilfe eines halbleiterbasierten kapazitiven Feldeffektsensors, der über Impedanzspektren ausgelesen wird, ein Sensorsystem realisiert, das die Echtzeitmessung der Degradation in situ ermöglicht. In einem Modellversuch wurde die Funktionalität des System demonstriert, indem die Degradation eines kommerziell erhältlichen, biodegradierbaren Polymers (Poly-D,L-Milchsäure) in Echtzeit verfolgt wurde. Dazu wurde das Polymer mittels Spin-Coating auf den Sensor aufgebracht und zunächst einer neutralen Pufferlösung (pH 7) zur Degradation ausgesetzt. Nach einer Zeit von 53,5 h wurde der pH-Wert auf pH 9 erhöht, um die hydrolytische Degradation zu beschleunigen. Die derart erzeugte Veränderung der Degradationsrate des Polymers konnte in einer beschleunigten Abnahme der Impedanzwerte des Sensorsigna...
An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was... more An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was evaluated theoretically and studied experimentally, taking into account the presence of oxygen vacancies in ferroelectric film as well as non-linear dependence of the ferroelectric films dielectric permittivity on the electric field for different values of oxygen vacancies concentration and doping levels in silicon.
Procedia Engineering
Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au struct... more Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au structure, respectively, have been tested for a label-free electrical detection of DNA (deoxyribonucleic acid) hybridization. Three different strategies for immobilizing single-stranded probe DNA (ssDNA) molecules on a LAPS surface have been studied and compared: (a) immobilization of thiol-modified ssDNA on the patterned Au surface via gold-thiol bond, (b) covalent immobilization of amino-modified ssDNA onto the SiO2 surface functionalized with 3-aminopropyltriethoxysilane and (c) layer-by-layer adsorption of negatively charged ssDNA on a positively charged weak polyelectrolyte layer of poly(allylamine hydrochloride).
Analytical Chemistry, 2015
Designing novel or optimizing existing biodegradable polymers for biomedical applications require... more Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.
Chemical communications (Cambridge, England), Jan 31, 2015
Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an el... more Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time.
Sensors and Actuators B: Chemical, 2015
The characterization of the degradation kinetics of biodegradable polymers is mandatory with rega... more The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al-p-Si-SiO 2 -Ta 2 O 5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13).
physica status solidi (a), 2013
ABSTRACT Investigation of the degradation kinetics of biodegradable polymers is essential for the... more ABSTRACT Investigation of the degradation kinetics of biodegradable polymers is essential for the development of implantable biomedical devices with predicted biodegradability. In this work, an impedimetric sensor has been applied for real-time and in situ monitoring of degradation processes of biopolymers. The sensor consists of two platinum thin-film electrodes covered by a polymer film to be studied. The benchmark biomedical polymer poly(D,L-lactic acid) (PDLLA) was used as a model system. PDLLA films were deposited on the sensor structure from a polymer solution by using the spin-coating method. The degradation kinetics of PDLLA films have been studied in alkaline solutions of pH 9 and 12 by means of an impedance spectroscopy (IS) method. Any changes in a polymer capacitance/resistance induced by water uptake and/or polymer degradation will modulate the global impedance of the polymer-covered sensor that can be used as an indicator of the polymer degradation. The degradation rate can be evaluated from the time-dependent impedance spectra. As expected, a faster degradation has been observed for PDLLA films exposed to pH 12 solution.
Procedia Chemistry, 2009
An array of individually addressable nanoplate field-effect capacitive (bio-)chemical sensors bas... more An array of individually addressable nanoplate field-effect capacitive (bio-)chemical sensors based on an SOI (silicon-oninsulator) structure has been developed for multi-parameter detection. An isolation of the individual capacitors was achieved by forming a trench in the top Si layer with various thicknesses of 30-350 nm. The feasibility of the proposed approach has been demonstrated by realising sensors for the detection of pH as well as for the label-free electrical monitoring of adsorption and binding of charged macromolecules.
Sensors and Actuators, B: Chemical, 2005
A critical evaluation of the possibilities and limitations of the label-free detection of deoxyri... more A critical evaluation of the possibilities and limitations of the label-free detection of deoxyribonucleic acid (DNA) hybridization by means of field-effect-based devices is discussed. A new DNA-detection method is introduced, which utilizes an ion-sensitive field-effect device as transducer. The upon the DNA hybridization induced redistribution of the ion concentration within the intermolecular spaces and/or the alteration of the ion sensitivity of the device is proposed as detection mechanism. The theoretical calculations predict a substantial change in the average ion concentration within the intermolecular spaces induced upon hybridization that are enough to obtain a detectable sensor signal.
Technisches Messen, 2007
... Michael J. Schöning, Maryam H. Abouzar, Arshak Poghossian, Fachhochschule Aachen, Standort Jü... more ... Michael J. Schöning, Maryam H. Abouzar, Arshak Poghossian, Fachhochschule Aachen, Standort Jülich, Yinhua Han, Andreas Offenhäusser, Sven Ingebrandt ... zur Detektion von SNPs mit einem FET-Chip verwendeten 20-bp ss-DNA-Sequenzen, sind in Ta-belle 1 aufgeführt. ...
AIP Conference Proceedings, 2009
The Journal of Physical Chemistry C, 2011
A capacitive field-effect electrolyte-insulator-semiconductor (EIS) device was applied for the fi... more A capacitive field-effect electrolyte-insulator-semiconductor (EIS) device was applied for the first time to trace the charge of supported gold nanoparticles (Au-NPs) induced by oxygen plasma treatment or due to storing in aqueous oxidation and reduction solutions. In addition, X-ray photoelectron spectroscopy (XPS) has been used as a reference method to establish the various charge states of the Au-NPs resulting from the different treatment steps. After the oxygen-plasma treatment, a shift of the capacitancevoltage (C-V) curve (and flatband potential) of the Au-NP-covered p-Si-SiO 2 EIS structure by about -300 mV was found. The exposure of the EIS sensor surface to an oxidative and a reductive solution resulted in a shift of the C-V curve for -85 and þ81 mV, respectively. These observations correlate well with corresponding binding energy shifts in Au 4f core spectra in XPS experiments. The obtained results may open new opportunities for biosensing and biochips based on nanoparticle-charge-gated field-effect devices.
The Analyst, 2014
An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) ... more An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) gate with two input and two output signals. Reversible conversion of NAD + and NADH cofactors was used to perform a XOR logic operation, while biocatalytic hydrolysis of p-nitrophenyl phosphate resulted in an Identity operation working in parallel. The first biomolecular realization of a CNOT gate is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.
Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which... more Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect either a physical or (bio-)chemical parameter. Therefore, such systems include a more complicated fabrication technology and measuring set-up. In this work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilized as transducer for the detection of both (bio-)chemical
Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which... more Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect only one physical or (bio-)chemical parameter. In the present work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilised for the flow velocity and flow direction measurement for the first time. The proposed flow sensor presents a chemical
MRS Proceedings, 2006
Abstract The possibility of a label-free electrical detection of charged macromolecules using sem... more Abstract The possibility of a label-free electrical detection of charged macromolecules using semiconductor field-effect sensors offers a new approach for the development of DNA chips with fast and direct electrical readout. A deep understanding of the adsorption and ...
An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) ... more An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) gate with two input and two output signals. Reversible conversion of NAD + and NADH cofactors was used to perform a XOR logic operation, while biocatalytic hydrolysis of p-nitrophenyl phosphate resulted in an Identity operation working in parallel. The first biomolecular realization of a CNOT gate is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.
Die Entwicklung miniaturisierter Systeme für die (bio-)chemische Analyse tritt zunehmend auf den ... more Die Entwicklung miniaturisierter Systeme für die (bio-)chemische Analyse tritt zunehmend auf den Gebieten der Chemie, Biotechnologie, medizinischen Diagnostik, Lebenswissenschaften, Umweltanalytik und Mikrosystemtechnik in den Fokus wissenschaftlicher und wirtschaftlicher Interessen. Solche Systeme integrieren Sensoren zur Erfassung und Kontrolle von (bio-)chemischen und physikalischen Messgrößen, wie beispielsweise pH-Wert, Analytkonzentration, Elektrolytleitfähigkeit, Temperatur, Druck und Flussrate, zu Sensorarrays [1]. Oftmals basieren die eingesetzten Sensoren auf elektrochemischen oder optischen Transducerprinzipien. Ein genereller Vorteil miniaturisierter Systeme im Vergleich zu herkömmlichen Labormethoden ist der geringere Verbrauch an Reagenzien bzw. Bedarf an Probevolumen, die Möglichkeit der Echtzeitmessung sowie der reduzierte Aufwand für Wartung und Kalibrierung. Chipbasierte Sensoren können in diesem Zusammenhang eine entscheidende Rolle spielen und stellen aufgrund ih...
Die Erfindung betrifft eine Vorrichtung zum Nachweis von geladenen Makromolekülen, umfassend eine... more Die Erfindung betrifft eine Vorrichtung zum Nachweis von geladenen Makromolekülen, umfassend eine ionensensitive Schicht, an dessen Oberfläche ein Probenmolekül zum Nachweis eines Target-Moleküls immobilisiert ist. Probenmoleküle und nachzuweisendes Target-Molekül vermögen eine spezifische Bindung einzugehen. Die Vorrichtung ist dadurch gekennzeichnet, dass die Probenmoleküle in einem Mindestabstand voneinander auf der ionensensitiven Schicht immobilisiert sind in der Weise, dass während der Bindung mit dem Target-Molekül eine Umverteilung der Zonenkonzentration in den intermolekularen Zwischenräumen induziert wird. Ein Verfahren zum Nachweis geladener Makromoleküle mit der erfindungsgemäßen Vorrichtung ist offenbart.
In vitro Untersuchungen des Degradationsverlaufs sind essentiell für die Entwicklung und Optimier... more In vitro Untersuchungen des Degradationsverlaufs sind essentiell für die Entwicklung und Optimierung implantierbarer Medizinprodukte auf der Basis von biodegradierbaren Polymeren. Erstmals wurde mit Hilfe eines halbleiterbasierten kapazitiven Feldeffektsensors, der über Impedanzspektren ausgelesen wird, ein Sensorsystem realisiert, das die Echtzeitmessung der Degradation in situ ermöglicht. In einem Modellversuch wurde die Funktionalität des System demonstriert, indem die Degradation eines kommerziell erhältlichen, biodegradierbaren Polymers (Poly-D,L-Milchsäure) in Echtzeit verfolgt wurde. Dazu wurde das Polymer mittels Spin-Coating auf den Sensor aufgebracht und zunächst einer neutralen Pufferlösung (pH 7) zur Degradation ausgesetzt. Nach einer Zeit von 53,5 h wurde der pH-Wert auf pH 9 erhöht, um die hydrolytische Degradation zu beschleunigen. Die derart erzeugte Veränderung der Degradationsrate des Polymers konnte in einer beschleunigten Abnahme der Impedanzwerte des Sensorsigna...
An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was... more An-amorphous BaxSr1-x TiO3/ polycrystalline (pc) silicon anis-type heterojunction capacitance was evaluated theoretically and studied experimentally, taking into account the presence of oxygen vacancies in ferroelectric film as well as non-linear dependence of the ferroelectric films dielectric permittivity on the electric field for different values of oxygen vacancies concentration and doping levels in silicon.
Procedia Engineering
Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au struct... more Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au structure, respectively, have been tested for a label-free electrical detection of DNA (deoxyribonucleic acid) hybridization. Three different strategies for immobilizing single-stranded probe DNA (ssDNA) molecules on a LAPS surface have been studied and compared: (a) immobilization of thiol-modified ssDNA on the patterned Au surface via gold-thiol bond, (b) covalent immobilization of amino-modified ssDNA onto the SiO2 surface functionalized with 3-aminopropyltriethoxysilane and (c) layer-by-layer adsorption of negatively charged ssDNA on a positively charged weak polyelectrolyte layer of poly(allylamine hydrochloride).
Analytical Chemistry, 2015
Designing novel or optimizing existing biodegradable polymers for biomedical applications require... more Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(d,l-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.
Chemical communications (Cambridge, England), Jan 31, 2015
Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an el... more Capacitive field-effect sensors modified with a multi-enzyme membrane have been applied for an electronic transduction of biochemical signals processed by enzyme-based AND-Reset and OR-Reset logic gates. The local pH change at the sensor surface induced by the enzymatic reaction was used for the activation of the Reset function for the first time.
Sensors and Actuators B: Chemical, 2015
The characterization of the degradation kinetics of biodegradable polymers is mandatory with rega... more The characterization of the degradation kinetics of biodegradable polymers is mandatory with regard to their proper application. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) field-effect sensors have been applied for in-situ monitoring of the pH-dependent degradation kinetics of the commercially available biopolymer poly(d,l-lactic acid) (PDLLA) in buffer solutions from pH 3 to pH 13. PDLLA films of 500 nm thickness were deposited on the surface of an Al-p-Si-SiO 2 -Ta 2 O 5 structure from a polymer solution by means of spin-coating method. The PMEIS sensor is, in principle, capable to detect any changes in bulk, surface and interface properties of the polymer induced by degradation processes. A faster degradation has been observed for PDLLA films exposed to alkaline solutions (pH 9, pH 11 and pH 13).
physica status solidi (a), 2013
ABSTRACT Investigation of the degradation kinetics of biodegradable polymers is essential for the... more ABSTRACT Investigation of the degradation kinetics of biodegradable polymers is essential for the development of implantable biomedical devices with predicted biodegradability. In this work, an impedimetric sensor has been applied for real-time and in situ monitoring of degradation processes of biopolymers. The sensor consists of two platinum thin-film electrodes covered by a polymer film to be studied. The benchmark biomedical polymer poly(D,L-lactic acid) (PDLLA) was used as a model system. PDLLA films were deposited on the sensor structure from a polymer solution by using the spin-coating method. The degradation kinetics of PDLLA films have been studied in alkaline solutions of pH 9 and 12 by means of an impedance spectroscopy (IS) method. Any changes in a polymer capacitance/resistance induced by water uptake and/or polymer degradation will modulate the global impedance of the polymer-covered sensor that can be used as an indicator of the polymer degradation. The degradation rate can be evaluated from the time-dependent impedance spectra. As expected, a faster degradation has been observed for PDLLA films exposed to pH 12 solution.
Procedia Chemistry, 2009
An array of individually addressable nanoplate field-effect capacitive (bio-)chemical sensors bas... more An array of individually addressable nanoplate field-effect capacitive (bio-)chemical sensors based on an SOI (silicon-oninsulator) structure has been developed for multi-parameter detection. An isolation of the individual capacitors was achieved by forming a trench in the top Si layer with various thicknesses of 30-350 nm. The feasibility of the proposed approach has been demonstrated by realising sensors for the detection of pH as well as for the label-free electrical monitoring of adsorption and binding of charged macromolecules.
Sensors and Actuators, B: Chemical, 2005
A critical evaluation of the possibilities and limitations of the label-free detection of deoxyri... more A critical evaluation of the possibilities and limitations of the label-free detection of deoxyribonucleic acid (DNA) hybridization by means of field-effect-based devices is discussed. A new DNA-detection method is introduced, which utilizes an ion-sensitive field-effect device as transducer. The upon the DNA hybridization induced redistribution of the ion concentration within the intermolecular spaces and/or the alteration of the ion sensitivity of the device is proposed as detection mechanism. The theoretical calculations predict a substantial change in the average ion concentration within the intermolecular spaces induced upon hybridization that are enough to obtain a detectable sensor signal.
Technisches Messen, 2007
... Michael J. Schöning, Maryam H. Abouzar, Arshak Poghossian, Fachhochschule Aachen, Standort Jü... more ... Michael J. Schöning, Maryam H. Abouzar, Arshak Poghossian, Fachhochschule Aachen, Standort Jülich, Yinhua Han, Andreas Offenhäusser, Sven Ingebrandt ... zur Detektion von SNPs mit einem FET-Chip verwendeten 20-bp ss-DNA-Sequenzen, sind in Ta-belle 1 aufgeführt. ...
AIP Conference Proceedings, 2009
The Journal of Physical Chemistry C, 2011
A capacitive field-effect electrolyte-insulator-semiconductor (EIS) device was applied for the fi... more A capacitive field-effect electrolyte-insulator-semiconductor (EIS) device was applied for the first time to trace the charge of supported gold nanoparticles (Au-NPs) induced by oxygen plasma treatment or due to storing in aqueous oxidation and reduction solutions. In addition, X-ray photoelectron spectroscopy (XPS) has been used as a reference method to establish the various charge states of the Au-NPs resulting from the different treatment steps. After the oxygen-plasma treatment, a shift of the capacitancevoltage (C-V) curve (and flatband potential) of the Au-NP-covered p-Si-SiO 2 EIS structure by about -300 mV was found. The exposure of the EIS sensor surface to an oxidative and a reductive solution resulted in a shift of the C-V curve for -85 and þ81 mV, respectively. These observations correlate well with corresponding binding energy shifts in Au 4f core spectra in XPS experiments. The obtained results may open new opportunities for biosensing and biochips based on nanoparticle-charge-gated field-effect devices.
The Analyst, 2014
An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) ... more An enzyme system organized in a flow device was used to mimic a reversible Controlled NOT (CNOT) gate with two input and two output signals. Reversible conversion of NAD + and NADH cofactors was used to perform a XOR logic operation, while biocatalytic hydrolysis of p-nitrophenyl phosphate resulted in an Identity operation working in parallel. The first biomolecular realization of a CNOT gate is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.