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Papers by Antonia Mallardi
Bollettino della Società italiana di biologia sperimentale, 1988
The Italian journal of biochemistry, 2007
The core complex formed by the reaction center and the light harvesting complex 1 (RC-LH1) was pu... more The core complex formed by the reaction center and the light harvesting complex 1 (RC-LH1) was purified from the photosynthetic bacterium Rhodobacter sphaeroides. We analyzed the lipid and ubiquinone (UQ) complements copurifying with the RC-LH1 complex and with the peripheral antenna (LH2). In RC-LH1 UQ was almost ten times more concentrated than in the LH2 and in the native membranes from which the complexes were extracted. The fractional lipid composition of the RC-LH1 complex also differed from that of the intact membranes, exhibiting a marked increase in cardiolipin concentration. We propose that the confinement of cardiolipin and ubiquinone observed within the RC-LH1 complex, plays a role in vivo in the stabilization of the light-induced charge separation catalyzed by the RC.
Progress in Colloid & Polymer Science, 1998
An integral membrane protein, the photosynthetic reaction center (RC) from Rb. sphaeroides, has b... more An integral membrane protein, the photosynthetic reaction center (RC) from Rb. sphaeroides, has been solubilized in n-hexane phospholipid reverse micelles. The interaction between this protein and its liposoluble exchangeable cofactor (Ubiquinone-10) has been investigated by means of flash absorption spectroscopy. The kinetic behavior of the RC has been studied as a function of quinone concentration and temperature, demonstrating that quinone
2009 3rd International Workshop on Advances in sensors and Interfaces, 2009
A novel bottom-gate top-contact OTFT architecture has been fabricated. In this device, a lipid bi... more A novel bottom-gate top-contact OTFT architecture has been fabricated. In this device, a lipid bilayer structure embedding a photosynthetic membrane protein extracted from Rhodobacter Sphaeroides has been deposited onto the organic semiconductor film (alpha,omega-dihexylsexythiophene) prior to the evaporation of source and drain gold contacts. The figures of merit of this device were extracted and compared to those obtained for the
Organic Electronics, 2012
and sharing with colleagues.
ACS Nano, 2014
An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamell... more An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamellae is proposed for an in-depth study of the proton translocation processes occurring as the bioelectronic device is exposed either to light or to low concentrations of general anesthetic vapors. The study involves the morphological, structural, electrical, and spectroscopic characterizations necessary to assess the functional properties of the device as well as the bR biological activity once integrated into the functional biointerlayer (FBI)-OFET structure. The electronic transduction of the protons phototranslocation is shown as a current increase in the p-type channel only when the device is irradiated with photons known to trigger the bR photocycle, while Raman spectroscopy reveals an associated CdC isomer switch. Notably, higher energy photons bring the cis isomer back to its trans form, switching the proton pumping process off. The investigation is extended also to the study of a PM FBI-OFET exposed to volatile general anesthetics such as halothane. In this case an electronic current increase is seen upon exposure to low, clinically relevant, concentrations of anesthetics, while no evidence of isomer-switching is observed. The study of the direct electronic detection of the two different externally triggered proton translocation effects allows gathering insights into the underpinning of different bR molecular switching processes.
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT To satisfy the demand for fast and smart analytical systems a great interest has been fo... more ABSTRACT To satisfy the demand for fast and smart analytical systems a great interest has been focused on the study and development of novel bio-sensing devices. Electronic transduction can open new perspectives for point-of-care diagnosis actuated by fast, sensitive, selective and reliable biosensors. Recently our group demonstrated the feasibility of the coupling of a biological recognition element to an organic field-effect device [3, 4]. As a further step, investigations on different deposition techniques have been developed, to improve the adhesion and the homogeneity of the biological element onto the organic semiconductor.
2010 IEEE International Symposium on Industrial Electronics, 2010
ABSTRACT Organic thin film transistor (OTFT) technology can be implemented to develop cost-effect... more ABSTRACT Organic thin film transistor (OTFT) technology can be implemented to develop cost-effective and label-free bio-affinity sensor chips, having a field-effect transport directly coupled to a bio-sensing process, useful to high-throughput testing and point-of-care applications. Biological recognition elements such as antibodies or other proteins can be integrated in OTFT devices to confer specificity. In this study the use of lipid bilayers as support for biomolecules immobilization is investigated. Preliminary results in terms of electrical resistance and capacitance of the lipid bilayers are presented.
Functional Supramolecular Architectures, 2011
ABSTRACT This chapter contains sections titled: Introduction Supramolecular Architectures for Org... more ABSTRACT This chapter contains sections titled: Introduction Supramolecular Architectures for Organic Thin-Film Field-Effect Sensing Transistors Bioactive Sensing Layer Sensing Devices with Polyelectrolyte Multilayer Architectures Electronic Sensing Devices with Phospholipid Layer Architectures Conclusions and Perspectives
Advanced Materials, 2014
Electrolyte-gated organic field-effect transistors are successfully used as biosensors to detect ... more Electrolyte-gated organic field-effect transistors are successfully used as biosensors to detect binding events occurring at distances from the transistor electronic channel that are much larger than the Debye length in highly concentrated solutions. The sensing mechanism is mainly capacitive and is due to the formation of Donnan's equilibria within the protein layer, leading to an extra capacitance (C DON ) in series to the gating system.
Topics in Molecular Organization and Engineering, 1994
ABSTRACT
Analytical Chemistry, 2015
A general method to obtain the efficient entrapment of mixtures of glyco-enzymes in calcium algin... more A general method to obtain the efficient entrapment of mixtures of glyco-enzymes in calcium alginate hydrogel is proposed in this paper. As a proof of principle, three glyco-enzymes acting in series (trehalase, glucose oxidase and horseradish peroxidase) have been co-immobilized in calcium alginate beads. The release of the enzymes from the hydrogel mesh (leakage) is avoided by exploiting the enzymes aggregation induced by the concanavalin A. The aggregation process has been monitored by dynamic light scattering technique, while both enzyme encapsulation efficiency and leakage have spectrophotometrically been quantified. Obtained data show an encapsulation efficiency above 95% and a negligible leakage from the beads when enzyme aggregates are larger than 300 nm. Operational stability of "as prepared" beads has been largely improved by a coating of alternated shells of polycation poly(diallyldimethylammonium chloride) and of alginate. As a test for the effectiveness of the overall procedure, analytical bio-assays exploiting the enzyme containing beads have been developed for the optical determination of glucose and trehalose and Limit of Detection values of 0.2 μM and of 40 μM respectively have been obtained.
Photosynthesis: from Light to Biosphere, 1995
Sensors and Actuators B: Chemical, 2012
The design and characterization of an optical biosensor based on a photosynthetic protein deposit... more The design and characterization of an optical biosensor based on a photosynthetic protein deposited on a quartz surface is here presented. The protein reaction center (RC), purified from Rhodobacter sphaeroides, has been immobilized in alternate layers with the cationic ...
Progress in Colloid & Polymer Science, 1996
An integral membrane protein, the photosynthetic bacterial reaction center (RC), has been incorpo... more An integral membrane protein, the photosynthetic bacterial reaction center (RC), has been incorporated in reverse micelle viscoelastic gels made of phosphatidylcholine and phosphatidylserine. Due to the dynamic nature of the gels, the use of a technique which shares the same timescale of the charge recombination is advised, in order to correlate the kinetic behaviour of the RC to the hosting-system properties. Self-diffusion and conductivity measurements have been used to investigate the properties of the model system lecithin/cyclohexane/water. The results indicate that such techniques can describe the properties of the system on a long characteristic time-scale. As a consequence, the kinetic behaviour of the RC has been studied by means of flash-spectro-photometry and related to the structural properties of the hosting gel, investigated by means of conductivity. The conductivity data are consistent with a water-induced sphere-to-rod transition of the phospholipid aggregates. Furthermore, increasing the ratio [water]/[lipid], a maximum in the hydrodynamic dimension of the giant worm-like reverse micelles is found. The experimental P+ decay has been resolved into three exponential components which are strongly affected by the system composition. The functionality of the binding site QB is dependent on the ratio [water]/[lipid] supporting the hypothesis of a water role in the binding process.
Field-Effect Transistors comprising layers of lipids have been developed and characterized from t... more Field-Effect Transistors comprising layers of lipids have been developed and characterized from the electrical point of view. Lipid layers-OTFT are proposed as novel devices for perspective application in the detection of analytes from aqueous samples.
Bollettino della Società italiana di biologia sperimentale, 1988
The Italian journal of biochemistry, 2007
The core complex formed by the reaction center and the light harvesting complex 1 (RC-LH1) was pu... more The core complex formed by the reaction center and the light harvesting complex 1 (RC-LH1) was purified from the photosynthetic bacterium Rhodobacter sphaeroides. We analyzed the lipid and ubiquinone (UQ) complements copurifying with the RC-LH1 complex and with the peripheral antenna (LH2). In RC-LH1 UQ was almost ten times more concentrated than in the LH2 and in the native membranes from which the complexes were extracted. The fractional lipid composition of the RC-LH1 complex also differed from that of the intact membranes, exhibiting a marked increase in cardiolipin concentration. We propose that the confinement of cardiolipin and ubiquinone observed within the RC-LH1 complex, plays a role in vivo in the stabilization of the light-induced charge separation catalyzed by the RC.
Progress in Colloid & Polymer Science, 1998
An integral membrane protein, the photosynthetic reaction center (RC) from Rb. sphaeroides, has b... more An integral membrane protein, the photosynthetic reaction center (RC) from Rb. sphaeroides, has been solubilized in n-hexane phospholipid reverse micelles. The interaction between this protein and its liposoluble exchangeable cofactor (Ubiquinone-10) has been investigated by means of flash absorption spectroscopy. The kinetic behavior of the RC has been studied as a function of quinone concentration and temperature, demonstrating that quinone
2009 3rd International Workshop on Advances in sensors and Interfaces, 2009
A novel bottom-gate top-contact OTFT architecture has been fabricated. In this device, a lipid bi... more A novel bottom-gate top-contact OTFT architecture has been fabricated. In this device, a lipid bilayer structure embedding a photosynthetic membrane protein extracted from Rhodobacter Sphaeroides has been deposited onto the organic semiconductor film (alpha,omega-dihexylsexythiophene) prior to the evaporation of source and drain gold contacts. The figures of merit of this device were extracted and compared to those obtained for the
Organic Electronics, 2012
and sharing with colleagues.
ACS Nano, 2014
An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamell... more An organic field-effect transistor (OFET) integrating bacteriorhodopsin (bR) nanoassembled lamellae is proposed for an in-depth study of the proton translocation processes occurring as the bioelectronic device is exposed either to light or to low concentrations of general anesthetic vapors. The study involves the morphological, structural, electrical, and spectroscopic characterizations necessary to assess the functional properties of the device as well as the bR biological activity once integrated into the functional biointerlayer (FBI)-OFET structure. The electronic transduction of the protons phototranslocation is shown as a current increase in the p-type channel only when the device is irradiated with photons known to trigger the bR photocycle, while Raman spectroscopy reveals an associated CdC isomer switch. Notably, higher energy photons bring the cis isomer back to its trans form, switching the proton pumping process off. The investigation is extended also to the study of a PM FBI-OFET exposed to volatile general anesthetics such as halothane. In this case an electronic current increase is seen upon exposure to low, clinically relevant, concentrations of anesthetics, while no evidence of isomer-switching is observed. The study of the direct electronic detection of the two different externally triggered proton translocation effects allows gathering insights into the underpinning of different bR molecular switching processes.
2011 IEEE SENSORS Proceedings, 2011
ABSTRACT To satisfy the demand for fast and smart analytical systems a great interest has been fo... more ABSTRACT To satisfy the demand for fast and smart analytical systems a great interest has been focused on the study and development of novel bio-sensing devices. Electronic transduction can open new perspectives for point-of-care diagnosis actuated by fast, sensitive, selective and reliable biosensors. Recently our group demonstrated the feasibility of the coupling of a biological recognition element to an organic field-effect device [3, 4]. As a further step, investigations on different deposition techniques have been developed, to improve the adhesion and the homogeneity of the biological element onto the organic semiconductor.
2010 IEEE International Symposium on Industrial Electronics, 2010
ABSTRACT Organic thin film transistor (OTFT) technology can be implemented to develop cost-effect... more ABSTRACT Organic thin film transistor (OTFT) technology can be implemented to develop cost-effective and label-free bio-affinity sensor chips, having a field-effect transport directly coupled to a bio-sensing process, useful to high-throughput testing and point-of-care applications. Biological recognition elements such as antibodies or other proteins can be integrated in OTFT devices to confer specificity. In this study the use of lipid bilayers as support for biomolecules immobilization is investigated. Preliminary results in terms of electrical resistance and capacitance of the lipid bilayers are presented.
Functional Supramolecular Architectures, 2011
ABSTRACT This chapter contains sections titled: Introduction Supramolecular Architectures for Org... more ABSTRACT This chapter contains sections titled: Introduction Supramolecular Architectures for Organic Thin-Film Field-Effect Sensing Transistors Bioactive Sensing Layer Sensing Devices with Polyelectrolyte Multilayer Architectures Electronic Sensing Devices with Phospholipid Layer Architectures Conclusions and Perspectives
Advanced Materials, 2014
Electrolyte-gated organic field-effect transistors are successfully used as biosensors to detect ... more Electrolyte-gated organic field-effect transistors are successfully used as biosensors to detect binding events occurring at distances from the transistor electronic channel that are much larger than the Debye length in highly concentrated solutions. The sensing mechanism is mainly capacitive and is due to the formation of Donnan's equilibria within the protein layer, leading to an extra capacitance (C DON ) in series to the gating system.
Topics in Molecular Organization and Engineering, 1994
ABSTRACT
Analytical Chemistry, 2015
A general method to obtain the efficient entrapment of mixtures of glyco-enzymes in calcium algin... more A general method to obtain the efficient entrapment of mixtures of glyco-enzymes in calcium alginate hydrogel is proposed in this paper. As a proof of principle, three glyco-enzymes acting in series (trehalase, glucose oxidase and horseradish peroxidase) have been co-immobilized in calcium alginate beads. The release of the enzymes from the hydrogel mesh (leakage) is avoided by exploiting the enzymes aggregation induced by the concanavalin A. The aggregation process has been monitored by dynamic light scattering technique, while both enzyme encapsulation efficiency and leakage have spectrophotometrically been quantified. Obtained data show an encapsulation efficiency above 95% and a negligible leakage from the beads when enzyme aggregates are larger than 300 nm. Operational stability of "as prepared" beads has been largely improved by a coating of alternated shells of polycation poly(diallyldimethylammonium chloride) and of alginate. As a test for the effectiveness of the overall procedure, analytical bio-assays exploiting the enzyme containing beads have been developed for the optical determination of glucose and trehalose and Limit of Detection values of 0.2 μM and of 40 μM respectively have been obtained.
Photosynthesis: from Light to Biosphere, 1995
Sensors and Actuators B: Chemical, 2012
The design and characterization of an optical biosensor based on a photosynthetic protein deposit... more The design and characterization of an optical biosensor based on a photosynthetic protein deposited on a quartz surface is here presented. The protein reaction center (RC), purified from Rhodobacter sphaeroides, has been immobilized in alternate layers with the cationic ...
Progress in Colloid & Polymer Science, 1996
An integral membrane protein, the photosynthetic bacterial reaction center (RC), has been incorpo... more An integral membrane protein, the photosynthetic bacterial reaction center (RC), has been incorporated in reverse micelle viscoelastic gels made of phosphatidylcholine and phosphatidylserine. Due to the dynamic nature of the gels, the use of a technique which shares the same timescale of the charge recombination is advised, in order to correlate the kinetic behaviour of the RC to the hosting-system properties. Self-diffusion and conductivity measurements have been used to investigate the properties of the model system lecithin/cyclohexane/water. The results indicate that such techniques can describe the properties of the system on a long characteristic time-scale. As a consequence, the kinetic behaviour of the RC has been studied by means of flash-spectro-photometry and related to the structural properties of the hosting gel, investigated by means of conductivity. The conductivity data are consistent with a water-induced sphere-to-rod transition of the phospholipid aggregates. Furthermore, increasing the ratio [water]/[lipid], a maximum in the hydrodynamic dimension of the giant worm-like reverse micelles is found. The experimental P+ decay has been resolved into three exponential components which are strongly affected by the system composition. The functionality of the binding site QB is dependent on the ratio [water]/[lipid] supporting the hypothesis of a water role in the binding process.
Field-Effect Transistors comprising layers of lipids have been developed and characterized from t... more Field-Effect Transistors comprising layers of lipids have been developed and characterized from the electrical point of view. Lipid layers-OTFT are proposed as novel devices for perspective application in the detection of analytes from aqueous samples.