Sabrina Conoci - Academia.edu (original) (raw)
Papers by Sabrina Conoci
Materials Science and Engineering: C, 2002
A Surface-Enhanced Raman Spectroscopy (SERS) study on self-assembled mercapto-aldehyde derivative... more A Surface-Enhanced Raman Spectroscopy (SERS) study on self-assembled mercapto-aldehyde derivative—4-(methylmercapto)benzaldehyde (SBZA)—is reported. This molecule was adsorbed onto silver surface, previously roughened to give SERS effect. The spectroscopic characterization of the adsorbed layer has shown a complete chemisorption of each molecule along with the presence of free aldehydic functionality. It is a group able to interact in several different reactions. In
Silicon based semiconductors techniques are creating a solid base for a new category of micro ele... more Silicon based semiconductors techniques are creating a solid base for a new category of micro electro mechanical systems (MEMS) with reliable structures for microfluidic funtions, handling either electrical signals or mechanical/physical parameters. A particular category of these early developed devices is constituted by Bio-MEMS, providing electro-microfluidic features in order to integrate in one system all the functional elements needed for
Organic Field-Effect Transistors III, 2004
Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configurati... more Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configuration, with Langmuir-Schafer (LS) or cast thin films of regioregular poly[1,4-(2,5-dioctyloxyphenylene )-2,5-thiophene], synthesized via an organometallic protocol, as active layers. The ...
Thin Solid Films, 2008
The correlations between morphological features and field-effect properties of poly(alkoxyphenyle... more The correlations between morphological features and field-effect properties of poly(alkoxyphenylene-thiophene) thin LangmuirSchäfer film deposited on differently terminated gate dielectric surfaces, namely bare and methyl functionalized thermal silicon dioxide ...
The Journal of Physical Chemistry B, 2008
The electrochemical behavior of 4-trifluoromethylacetophenone (TFMA) has been studied in aqueous ... more The electrochemical behavior of 4-trifluoromethylacetophenone (TFMA) has been studied in aqueous (2 5 pH 5 lo), micellar, and ethanolic solutions using polarographic techniques. A slow hydration process of the carbonyl group has been observed by means of polarography and UV-visible spectrophotometry. Besides the well-known pH dependence of the electroreduction of aromatic ketones, C-F bond cleavages concomitant to the ketone reduction occur under electrolysis conditions in alkaline medium (pH = 10) at a very negative potential (-1.7 V), leading to the formation of 4-methylacetophenone, which is reduced at this potential with formation of the carbinol and of symmetrical and dissymmetrical pinacols. Finally, the reduction of TFMA has been performed in the presence of chiral surfactants in order to test their ability to induce an asymmetric induction.
The Journal of Physical Chemistry B, 2006
This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin d... more This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin dimers (1) in Langmuir-Schäfer (LS) thin films by combining scanning force microscopy (SFM) with film balance, UV-vis absorption, fluorescence, and nanosecond laser flash photolysis measurements. Results show that depending on the surface pressure the Langmuir films of pure 1 can be arranged in two different condensed phases, whereas SFM of the LS films shows characteristic fractal networks constituted by nanoscopic aggregates. The spectral findings agree with a picture in which 1 is apparently present in the anti conformation but aggregated in a sort of H-type structure whose optical features resemble those of the syn conformer. This type of structure is not responsive to light stimuli. By diluting 1 in arachidic acid the porphyrin aggregation is significantly minimized with 1 exhibiting almost exclusively the anti conformation. As a result the LS films become photoresponsive, showing fluorescence emission and triplet-triplet transient absorption.
Surface Science, 2004
The behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the... more The behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the airwater interface. The molecular organization of floating films of pure 1 and its mixture with amphiphilic substances, such as arachidic acid and n-octadecylamine, was ...
Solid-State Electronics, 2005
Organic electrically bistable materials exhibiting conductance switching have been investigated a... more Organic electrically bistable materials exhibiting conductance switching have been investigated and their potential exploitation in nonvolatile memory applications has been tested. Theoretical modelling of both geometrical and electronic structure of such materials has been carried out and tentatively correlated to the mechanisms responsible of the bistable switching property.
Soft Matter, 2013
ABSTRACT A Langmuir film of bis(zinc octaethylporphyrin) (ZnPP) was characterised at the air–wate... more ABSTRACT A Langmuir film of bis(zinc octaethylporphyrin) (ZnPP) was characterised at the air–water interface and its syn–anti conformation switching induced upon addition of aromatic amines was studied by infrared and UV–vis reflection spectroscopic methods. The highly specific interaction of ZnPP with aromatic amines was maintained even after the floating film was transferred onto solid supports by the Langmuir–Schaefer (LS) technique, enabling us to selectively sense aromatic amines at concentrations as low as 20 ppb. Furthermore, LS ZnPP active layer selectivity was evaluated in the presence of aliphatic amines.
Sensors and Actuators B: Chemical, 2013
ABSTRACT Feasibility studies and examples of integration of Si-based miniaturized biosensors are ... more ABSTRACT Feasibility studies and examples of integration of Si-based miniaturized biosensors are discussed. We investigated three main issues: (i) device surface functionalization, (ii) biological molecule functionality after immobilization and (iii) biosensor working principle using electrical transduction mechanism in order to fabricate electrolyte-insulator-semiconductor (EIS) and, in the near future, ion-sensitive field-effect transistor (ISFET) biosensors.We compared a well established method for the immobilization of bio-molecules on Si oxide with a new immobilization protocol, both providing a covalent bonding on SiO2 surfaces of proteins (metallothioneines) enzymes (glucose oxidase, horse radish peroxidase), or DNA strands. The process steps were characterized by means of contact angle, XPS and TEM measurements. The compatibility with Ultra Large Scale Integration (ULSI) technology of the two protocols was also studied. The results strongly encourage to use the new optimized protocol to accomplish both ULSI compatibility and biological molecules correct functionalization. The electrical characterization of MOS-like capacitors with ssDNA anchored on the SiO2 dielectric, allowed us to conclude that the structures tested are sensitive to DNA immobilization and hybridization, as demonstrated by a positive shift in the VFB of +0.47 ± 0.04 V after ssDNA immobilization and by a further +0.07 ± 0.02 V shift when hybridization occurs. Device working principle was proved in this way. However, our results seem to indicate that bare SiO2 surfaces cannot be used as anchoring sites for DNA in transistor applications. In fact, the immersion in solution causes the migration of H+ ions in the oxide and the formation of defects at the SiO2/Si interface.
New Journal of Chemistry, 2008
... Fiorella L. Callaria, Salvatore Petraliab, Sabrina Conocib and Salvatore Sortino*a. a Diparti... more ... Fiorella L. Callaria, Salvatore Petraliab, Sabrina Conocib and Salvatore Sortino*a. a Dipartimento di Scienze Chimiche, Università di Catania, Viale Andrea Doria 8, I-95125 Catania, Italy. ... 9, F. Caruso, E. Rodda, DF Furlong, K. Niikura and Y. Okahata, Anal. ...
New Journal of Chemistry, 2003
A new calix[4]pyrrole-based macrocycle, meso-tetra(methyloctyl)calix[4]pyrrole (MTP), has been sy... more A new calix[4]pyrrole-based macrocycle, meso-tetra(methyloctyl)calix[4]pyrrole (MTP), has been synthesized and fully characterized. Thin films of MTP have been transferred onto hydrophobized quartz and silicon oxide sheets by using the LangmuirSchäfer (LS) method (horizontal ...
Materials Science and Engineering: C, 2003
Self-assembled monolayers (SAMs) of functional Ru II complexes on optically transparent ultrathin... more Self-assembled monolayers (SAMs) of functional Ru II complexes on optically transparent ultrathin Pt films (10-nm nominal thicknesses) have been prepared. We have demonstrated that reversible Ru III/II redox switching of these SAMs can be achieved by using appropriate oxidizing or reducing agents. Such a switching in molecular properties has been simply detected by transmission spectroscopy with a conventional spectrophotometer following the appearance/disappearance of the optical absorption metal-to-ligand charge-transfer (MLCT) band in the visible region. In light of their potential multifunctional properties, these SAMs on an optically transparent metal electrode are appealing candidates in the perspective of integrated molecular switch nanodevices. D
![Research paper thumbnail of Structural study of meso-octaethylcalix[4]pyrrole Langmuir–Blodgett films used as gas sensors](https://attachments.academia-assets.com/45118398/thumbnails/1.jpg)
](Materials Science and Engineering: C, 2002
Ž . Monolayers of meso-octaethylcalix 4 pyrrole MOP have been prepared at the airrwater interface... more Ž . Monolayers of meso-octaethylcalix 4 pyrrole MOP have been prepared at the airrwater interface by the Langmuir-Blodgett LB technique. LB isotherms indicate that during the barrier compression the MOP monolayer slowly goes towards a closely packed system consisting of molecules whose molecular area is consistent with a calix-like shape. A significant molecular area loss, suggesting the Ž . Ž . occurrence of self-assembling phenomena, has been observed by: a increasing the molecular concentration; b performing cyclic Ž . compression-decompression curves; c recording constant-pressure relaxation curves. By means of the LB dipping method, MOP thin films have been built-up by transferring four and eight layers on solid surfaces. Model-flat silicon oxide and nanostructured silver Ž . surfaces, both hydrophobized by three LB layers of cadmium arachidate, have been used as substrates. Scanning force microscopy SFM images performed on these systems showed surfaces constituted by the ensemble of MOP ellipsoidal aggregates tens of nanometers in size. The films transferred on silver have been found to be very useful for the molecular sensing of alcohol vapours by using the surface Ž . plasmon resonance SPR spectroscopy as transduction method. The film structure has been correlated to the SPR performance. q
Langmuir, 2003
This contribution reports on a novel self-assembled monolayer (SAM) on a gold surface, able to im... more This contribution reports on a novel self-assembled monolayer (SAM) on a gold surface, able to immobilize double-strand DNA and to induce its cleavage upon light excitation. DNA binding with the SAM is mainly driven by a highly favored electrostatic interaction, and it is shown that DNA immobilization takes place without impairing its intrinsic high order. SAM irradiation leads to an uncommon defluorination reaction, and it is unambiguously demonstrated that DNA breakage is strictly interrelated to this photochemical pathway. The photocleavage process is very efficient, is exclusively controlled by illumination conditions, seems to be non-base-specific, and does not require external additives. These features, together with the low excitation energy required, the prolonged thermal stability under physiological conditions, and the ease of preparation, make the SAM presented herein an appealing model system for designing nanodevices for applications where efficient, non-base-specific, and externally tunable cleavage of nanoscaled DNA arrays is required.
Journal of the American Chemical Society, 2007
Research on compounds able to deliver nitric oxide (NO) has undergone a tremendous growth in rece... more Research on compounds able to deliver nitric oxide (NO) has undergone a tremendous growth in recent years, 1 owing to the exciting discoveries related to the multiple roles NO plays in a broad array of physiological processes such as neurotransmission, hormone secretion, and vasodilatation. 2 Furthermore, NO has also recently proven to be an effective anticancer agent 3 as well as a chain breaking antioxidant in free radical-induced lipid oxidation. In this context, dispenser substances releasing NO under light stimuli are more appealing than those based on spontaneous thermolysis. Indeed, the easy manipulation of light associated with the fast response of the photochemical reactions allows a precise spatial and temporal control of NO delivery. Although a number of NO photogenerators have appeared in the literature in recent years, 5 only a few examples have addressed their integration in appropriate materials. NO photorelease in a very small area has been in fact demonstrated in the case of polymer films, 6 hydrogels, 7 and selfassembled monolayers on two-dimensional (2D) gold surfaces. 8 Thiol-stabilized metal nanoparticles, commonly referred to as monolayer-protected clusters (MPCs), are fascinating hybrid systems with intriguing properties and multifaceted applications in different fields. 9 In particular, the unique sizes, the excellent stability, and the easy modification of their exterior with the introduction of appropriate functional units have generated widespread interest in the use of MPCs in biomedicine spanning from biosensing to drug delivery. 9 Schoenfisch and co-workers have recently reported on the synthesis of NO releasing gold nanoparticles, ca. 2 nm in diameter. 10 On the basis of these properties, the achievement of metal nanoparticles with photoactiVable NO release is a worthwhile objective to pursue that can represent a significant step forward in the perspective of biomedical applications requiring targeted delivery of NO. Construction of these 3D nanoarchitectures is also expected to offer a 2-fold advantage as compared to the 2D self-assembled monolayers on noble metals. In fact, unlike their bulk counterparts, they would exhibit improved light-harvesting efficiency as well as reduced quenching effects on the excited states of the photoactive units. 11 With this goal in mind, we report herein on the preparation of ultrasmall (ca. 1 nm) and water soluble monolayer-protected platinum nanoparticles MPC-3 ( ) as delivery vehicles able to supply NO under the control of visiblelight stimuli.
Journal of the American Chemical Society, 2007
Thin films consisting of two fulleropyrrolidine derivatives 1 or 2 and a water-soluble porphyrin,... more Thin films consisting of two fulleropyrrolidine derivatives 1 or 2 and a water-soluble porphyrin, TPPS4, were prepared by the Langmuir-Schäfer (LS, horizontal lifting) method. In particular, a solution of the fulleropyrrolidine in chloroform and dimethyl sulfoxide was spread on the water surface, while the porphyrin (bearing peripheral anionic sulfonic groups) was dissolved into the aqueous subphase. To the best of our knowledge, such a versatile method for film fabrication of fullerene/porphyrin mixed composite films has never been used by other researchers. Evidence of the effective interactions between the two components at the air-water interface was obtained from the analysis of the floating layers by means of surface pressure vs area per molecule Langmuir curves, Brewster angle microscopy, and UV-visible reflection spectroscopy. The characterization of the LS films by UV-visible spectroscopy reveals that in each case the two constituents behave as strongly interacting pi systems. The use of polarized light suggests the existence of a preferential direction of the TPPS4 macrocyclic rings with an edge-on arrangement with respect to the substrate surface, regardless which fulleropyrrolidine derivative is in the composite film. Atomic force microscopy investigations give evidence of morphologically flat layers even for LS transfer at low surface pressures. Photoaction spectra were recorded from films deposited by only one horizontal lifting onto indium-tin-oxide (ITO) electrodes, and the observed photocurrent increased notably with increasing transfer surface pressure for both 1/TPPS4 and 2/TPPS4 composite films. IPCE values are larger for 2/TPPS4 systems in comparison with 1/TPPS4 composite layers. Finally, a nonconventional approach to photoinduced phenomena is proposed by differential spectroscopy in the FT-IR attenuated total reflectance (ATR) mode.
Journal of the American Chemical Society, 2003
We report the first example of a reversible redox-molecular switch based on dipolar ruthenium(III... more We report the first example of a reversible redox-molecular switch based on dipolar ruthenium(III/II) pentaammine(4,4'-bipyridinium) complexes self-assembled on an optically transparent metal electrode, whose change in molecular properties can be simply detected by transmission spectroscopy with a conventional spectrophotometer.
Journal of Porphyrins and Phthalocyanines, 2009
Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable sub... more Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable substrates by Langmuir-Blodgett deposition technique in order to realize optical-sensitive active layers using Surface Plasmon Resonance (SPR) technique as transduction methodology. ...
Journal of Materials Chemistry, 2004
With the aim to prepare photoactive azobenzene SAMs, 4-[(11-dodecylsulfanyl-undecyloxy)phenyl ]ph... more With the aim to prepare photoactive azobenzene SAMs, 4-[(11-dodecylsulfanyl-undecyloxy)phenyl ]phenyl-diazene (1, see ESI) was synthesized. In fact, the presence of the unsubstituted alkyl chain in 1 provides the sweep volume to a feasible photoisomerization.8 SAMs of 1 ...
Materials Science and Engineering: C, 2002
A Surface-Enhanced Raman Spectroscopy (SERS) study on self-assembled mercapto-aldehyde derivative... more A Surface-Enhanced Raman Spectroscopy (SERS) study on self-assembled mercapto-aldehyde derivative—4-(methylmercapto)benzaldehyde (SBZA)—is reported. This molecule was adsorbed onto silver surface, previously roughened to give SERS effect. The spectroscopic characterization of the adsorbed layer has shown a complete chemisorption of each molecule along with the presence of free aldehydic functionality. It is a group able to interact in several different reactions. In
Silicon based semiconductors techniques are creating a solid base for a new category of micro ele... more Silicon based semiconductors techniques are creating a solid base for a new category of micro electro mechanical systems (MEMS) with reliable structures for microfluidic funtions, handling either electrical signals or mechanical/physical parameters. A particular category of these early developed devices is constituted by Bio-MEMS, providing electro-microfluidic features in order to integrate in one system all the functional elements needed for
Organic Field-Effect Transistors III, 2004
Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configurati... more Organic Thin Film Transistors (OTFTs) have been fabricated, in a standard bottom gate configuration, with Langmuir-Schafer (LS) or cast thin films of regioregular poly[1,4-(2,5-dioctyloxyphenylene )-2,5-thiophene], synthesized via an organometallic protocol, as active layers. The ...
Thin Solid Films, 2008
The correlations between morphological features and field-effect properties of poly(alkoxyphenyle... more The correlations between morphological features and field-effect properties of poly(alkoxyphenylene-thiophene) thin LangmuirSchäfer film deposited on differently terminated gate dielectric surfaces, namely bare and methyl functionalized thermal silicon dioxide ...
The Journal of Physical Chemistry B, 2008
The electrochemical behavior of 4-trifluoromethylacetophenone (TFMA) has been studied in aqueous ... more The electrochemical behavior of 4-trifluoromethylacetophenone (TFMA) has been studied in aqueous (2 5 pH 5 lo), micellar, and ethanolic solutions using polarographic techniques. A slow hydration process of the carbonyl group has been observed by means of polarography and UV-visible spectrophotometry. Besides the well-known pH dependence of the electroreduction of aromatic ketones, C-F bond cleavages concomitant to the ketone reduction occur under electrolysis conditions in alkaline medium (pH = 10) at a very negative potential (-1.7 V), leading to the formation of 4-methylacetophenone, which is reduced at this potential with formation of the carbinol and of symmetrical and dissymmetrical pinacols. Finally, the reduction of TFMA has been performed in the presence of chiral surfactants in order to test their ability to induce an asymmetric induction.
The Journal of Physical Chemistry B, 2006
This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin d... more This work reports on the structural and spectroscopic properties of ethane-bridged Zn porphyrin dimers (1) in Langmuir-Schäfer (LS) thin films by combining scanning force microscopy (SFM) with film balance, UV-vis absorption, fluorescence, and nanosecond laser flash photolysis measurements. Results show that depending on the surface pressure the Langmuir films of pure 1 can be arranged in two different condensed phases, whereas SFM of the LS films shows characteristic fractal networks constituted by nanoscopic aggregates. The spectral findings agree with a picture in which 1 is apparently present in the anti conformation but aggregated in a sort of H-type structure whose optical features resemble those of the syn conformer. This type of structure is not responsive to light stimuli. By diluting 1 in arachidic acid the porphyrin aggregation is significantly minimized with 1 exhibiting almost exclusively the anti conformation. As a result the LS films become photoresponsive, showing fluorescence emission and triplet-triplet transient absorption.
Surface Science, 2004
The behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the... more The behavior of the symmetrical ethane-bridged bis(Zn porphyrin) (1) has been investigated at the airwater interface. The molecular organization of floating films of pure 1 and its mixture with amphiphilic substances, such as arachidic acid and n-octadecylamine, was ...
Solid-State Electronics, 2005
Organic electrically bistable materials exhibiting conductance switching have been investigated a... more Organic electrically bistable materials exhibiting conductance switching have been investigated and their potential exploitation in nonvolatile memory applications has been tested. Theoretical modelling of both geometrical and electronic structure of such materials has been carried out and tentatively correlated to the mechanisms responsible of the bistable switching property.
Soft Matter, 2013
ABSTRACT A Langmuir film of bis(zinc octaethylporphyrin) (ZnPP) was characterised at the air–wate... more ABSTRACT A Langmuir film of bis(zinc octaethylporphyrin) (ZnPP) was characterised at the air–water interface and its syn–anti conformation switching induced upon addition of aromatic amines was studied by infrared and UV–vis reflection spectroscopic methods. The highly specific interaction of ZnPP with aromatic amines was maintained even after the floating film was transferred onto solid supports by the Langmuir–Schaefer (LS) technique, enabling us to selectively sense aromatic amines at concentrations as low as 20 ppb. Furthermore, LS ZnPP active layer selectivity was evaluated in the presence of aliphatic amines.
Sensors and Actuators B: Chemical, 2013
ABSTRACT Feasibility studies and examples of integration of Si-based miniaturized biosensors are ... more ABSTRACT Feasibility studies and examples of integration of Si-based miniaturized biosensors are discussed. We investigated three main issues: (i) device surface functionalization, (ii) biological molecule functionality after immobilization and (iii) biosensor working principle using electrical transduction mechanism in order to fabricate electrolyte-insulator-semiconductor (EIS) and, in the near future, ion-sensitive field-effect transistor (ISFET) biosensors.We compared a well established method for the immobilization of bio-molecules on Si oxide with a new immobilization protocol, both providing a covalent bonding on SiO2 surfaces of proteins (metallothioneines) enzymes (glucose oxidase, horse radish peroxidase), or DNA strands. The process steps were characterized by means of contact angle, XPS and TEM measurements. The compatibility with Ultra Large Scale Integration (ULSI) technology of the two protocols was also studied. The results strongly encourage to use the new optimized protocol to accomplish both ULSI compatibility and biological molecules correct functionalization. The electrical characterization of MOS-like capacitors with ssDNA anchored on the SiO2 dielectric, allowed us to conclude that the structures tested are sensitive to DNA immobilization and hybridization, as demonstrated by a positive shift in the VFB of +0.47 ± 0.04 V after ssDNA immobilization and by a further +0.07 ± 0.02 V shift when hybridization occurs. Device working principle was proved in this way. However, our results seem to indicate that bare SiO2 surfaces cannot be used as anchoring sites for DNA in transistor applications. In fact, the immersion in solution causes the migration of H+ ions in the oxide and the formation of defects at the SiO2/Si interface.
New Journal of Chemistry, 2008
... Fiorella L. Callaria, Salvatore Petraliab, Sabrina Conocib and Salvatore Sortino*a. a Diparti... more ... Fiorella L. Callaria, Salvatore Petraliab, Sabrina Conocib and Salvatore Sortino*a. a Dipartimento di Scienze Chimiche, Università di Catania, Viale Andrea Doria 8, I-95125 Catania, Italy. ... 9, F. Caruso, E. Rodda, DF Furlong, K. Niikura and Y. Okahata, Anal. ...
New Journal of Chemistry, 2003
A new calix[4]pyrrole-based macrocycle, meso-tetra(methyloctyl)calix[4]pyrrole (MTP), has been sy... more A new calix[4]pyrrole-based macrocycle, meso-tetra(methyloctyl)calix[4]pyrrole (MTP), has been synthesized and fully characterized. Thin films of MTP have been transferred onto hydrophobized quartz and silicon oxide sheets by using the LangmuirSchäfer (LS) method (horizontal ...
Materials Science and Engineering: C, 2003
Self-assembled monolayers (SAMs) of functional Ru II complexes on optically transparent ultrathin... more Self-assembled monolayers (SAMs) of functional Ru II complexes on optically transparent ultrathin Pt films (10-nm nominal thicknesses) have been prepared. We have demonstrated that reversible Ru III/II redox switching of these SAMs can be achieved by using appropriate oxidizing or reducing agents. Such a switching in molecular properties has been simply detected by transmission spectroscopy with a conventional spectrophotometer following the appearance/disappearance of the optical absorption metal-to-ligand charge-transfer (MLCT) band in the visible region. In light of their potential multifunctional properties, these SAMs on an optically transparent metal electrode are appealing candidates in the perspective of integrated molecular switch nanodevices. D
Materials Science and Engineering: C, 2002
Ž . Monolayers of meso-octaethylcalix 4 pyrrole MOP have been prepared at the airrwater interface... more Ž . Monolayers of meso-octaethylcalix 4 pyrrole MOP have been prepared at the airrwater interface by the Langmuir-Blodgett LB technique. LB isotherms indicate that during the barrier compression the MOP monolayer slowly goes towards a closely packed system consisting of molecules whose molecular area is consistent with a calix-like shape. A significant molecular area loss, suggesting the Ž . Ž . occurrence of self-assembling phenomena, has been observed by: a increasing the molecular concentration; b performing cyclic Ž . compression-decompression curves; c recording constant-pressure relaxation curves. By means of the LB dipping method, MOP thin films have been built-up by transferring four and eight layers on solid surfaces. Model-flat silicon oxide and nanostructured silver Ž . surfaces, both hydrophobized by three LB layers of cadmium arachidate, have been used as substrates. Scanning force microscopy SFM images performed on these systems showed surfaces constituted by the ensemble of MOP ellipsoidal aggregates tens of nanometers in size. The films transferred on silver have been found to be very useful for the molecular sensing of alcohol vapours by using the surface Ž . plasmon resonance SPR spectroscopy as transduction method. The film structure has been correlated to the SPR performance. q
Langmuir, 2003
This contribution reports on a novel self-assembled monolayer (SAM) on a gold surface, able to im... more This contribution reports on a novel self-assembled monolayer (SAM) on a gold surface, able to immobilize double-strand DNA and to induce its cleavage upon light excitation. DNA binding with the SAM is mainly driven by a highly favored electrostatic interaction, and it is shown that DNA immobilization takes place without impairing its intrinsic high order. SAM irradiation leads to an uncommon defluorination reaction, and it is unambiguously demonstrated that DNA breakage is strictly interrelated to this photochemical pathway. The photocleavage process is very efficient, is exclusively controlled by illumination conditions, seems to be non-base-specific, and does not require external additives. These features, together with the low excitation energy required, the prolonged thermal stability under physiological conditions, and the ease of preparation, make the SAM presented herein an appealing model system for designing nanodevices for applications where efficient, non-base-specific, and externally tunable cleavage of nanoscaled DNA arrays is required.
Journal of the American Chemical Society, 2007
Research on compounds able to deliver nitric oxide (NO) has undergone a tremendous growth in rece... more Research on compounds able to deliver nitric oxide (NO) has undergone a tremendous growth in recent years, 1 owing to the exciting discoveries related to the multiple roles NO plays in a broad array of physiological processes such as neurotransmission, hormone secretion, and vasodilatation. 2 Furthermore, NO has also recently proven to be an effective anticancer agent 3 as well as a chain breaking antioxidant in free radical-induced lipid oxidation. In this context, dispenser substances releasing NO under light stimuli are more appealing than those based on spontaneous thermolysis. Indeed, the easy manipulation of light associated with the fast response of the photochemical reactions allows a precise spatial and temporal control of NO delivery. Although a number of NO photogenerators have appeared in the literature in recent years, 5 only a few examples have addressed their integration in appropriate materials. NO photorelease in a very small area has been in fact demonstrated in the case of polymer films, 6 hydrogels, 7 and selfassembled monolayers on two-dimensional (2D) gold surfaces. 8 Thiol-stabilized metal nanoparticles, commonly referred to as monolayer-protected clusters (MPCs), are fascinating hybrid systems with intriguing properties and multifaceted applications in different fields. 9 In particular, the unique sizes, the excellent stability, and the easy modification of their exterior with the introduction of appropriate functional units have generated widespread interest in the use of MPCs in biomedicine spanning from biosensing to drug delivery. 9 Schoenfisch and co-workers have recently reported on the synthesis of NO releasing gold nanoparticles, ca. 2 nm in diameter. 10 On the basis of these properties, the achievement of metal nanoparticles with photoactiVable NO release is a worthwhile objective to pursue that can represent a significant step forward in the perspective of biomedical applications requiring targeted delivery of NO. Construction of these 3D nanoarchitectures is also expected to offer a 2-fold advantage as compared to the 2D self-assembled monolayers on noble metals. In fact, unlike their bulk counterparts, they would exhibit improved light-harvesting efficiency as well as reduced quenching effects on the excited states of the photoactive units. 11 With this goal in mind, we report herein on the preparation of ultrasmall (ca. 1 nm) and water soluble monolayer-protected platinum nanoparticles MPC-3 ( ) as delivery vehicles able to supply NO under the control of visiblelight stimuli.
Journal of the American Chemical Society, 2007
Thin films consisting of two fulleropyrrolidine derivatives 1 or 2 and a water-soluble porphyrin,... more Thin films consisting of two fulleropyrrolidine derivatives 1 or 2 and a water-soluble porphyrin, TPPS4, were prepared by the Langmuir-Schäfer (LS, horizontal lifting) method. In particular, a solution of the fulleropyrrolidine in chloroform and dimethyl sulfoxide was spread on the water surface, while the porphyrin (bearing peripheral anionic sulfonic groups) was dissolved into the aqueous subphase. To the best of our knowledge, such a versatile method for film fabrication of fullerene/porphyrin mixed composite films has never been used by other researchers. Evidence of the effective interactions between the two components at the air-water interface was obtained from the analysis of the floating layers by means of surface pressure vs area per molecule Langmuir curves, Brewster angle microscopy, and UV-visible reflection spectroscopy. The characterization of the LS films by UV-visible spectroscopy reveals that in each case the two constituents behave as strongly interacting pi systems. The use of polarized light suggests the existence of a preferential direction of the TPPS4 macrocyclic rings with an edge-on arrangement with respect to the substrate surface, regardless which fulleropyrrolidine derivative is in the composite film. Atomic force microscopy investigations give evidence of morphologically flat layers even for LS transfer at low surface pressures. Photoaction spectra were recorded from films deposited by only one horizontal lifting onto indium-tin-oxide (ITO) electrodes, and the observed photocurrent increased notably with increasing transfer surface pressure for both 1/TPPS4 and 2/TPPS4 composite films. IPCE values are larger for 2/TPPS4 systems in comparison with 1/TPPS4 composite layers. Finally, a nonconventional approach to photoinduced phenomena is proposed by differential spectroscopy in the FT-IR attenuated total reflectance (ATR) mode.
Journal of the American Chemical Society, 2003
We report the first example of a reversible redox-molecular switch based on dipolar ruthenium(III... more We report the first example of a reversible redox-molecular switch based on dipolar ruthenium(III/II) pentaammine(4,4'-bipyridinium) complexes self-assembled on an optically transparent metal electrode, whose change in molecular properties can be simply detected by transmission spectroscopy with a conventional spectrophotometer.
Journal of Porphyrins and Phthalocyanines, 2009
Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable sub... more Thin films of meso-octaethylporphyrinogen with different thickness were deposited on suitable substrates by Langmuir-Blodgett deposition technique in order to realize optical-sensitive active layers using Surface Plasmon Resonance (SPR) technique as transduction methodology. ...
Journal of Materials Chemistry, 2004
With the aim to prepare photoactive azobenzene SAMs, 4-[(11-dodecylsulfanyl-undecyloxy)phenyl ]ph... more With the aim to prepare photoactive azobenzene SAMs, 4-[(11-dodecylsulfanyl-undecyloxy)phenyl ]phenyl-diazene (1, see ESI) was synthesized. In fact, the presence of the unsubstituted alkyl chain in 1 provides the sweep volume to a feasible photoisomerization.8 SAMs of 1 ...