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Valentina Benfenati,
Stefano Toffanin,
Simone Bonetti,
Guido Turatti,
Assunta Pistone,
Michela Chiappalone,
Anna Sagnella,
Andrea Stefani,
Gianluca Generali,
Giampiero Ruani,
Davide Saguatti,
Roberto Zamboni, Michele Muccini
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ABSTRACT: Real-time stimulation and recording of neural cell bioelectrical activity could provide an unprecedented insight in understanding the functions of the nervous system, and it is crucial for developing advanced in vitro drug screening approaches. Among organic materials, suitable candidates for cell interfacing can be found that combine long-term biocompatibility and mechanical flexibility. Here, we report on transparent organic cell stimulating and sensing transistors (O-CSTs), which provide bidirectional stimulation and recording of primary neurons. We demonstrate that the device enables depolarization and hyperpolarization of the primary neuron membrane potential. The transparency of the device also allows the optical imaging of the modulation of the neuron bioelectrical activity. The maximal amplitude-to-noise ratio of the extracellular recording achieved by the O-CST device exceeds that of a microelectrode array system on the same neuronal preparation by a factor of 16. Our organic cell stimulating and sensing device paves the way to a new generation of devices for stimulation, manipulation and recording of cell bioelectrical activity in vitro and in vivo.
Nature Material 05/2013; · 32.84 Impact Factor
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Valentina Benfenati,
Assunta Pistone,
Anna Sagnella,
Katja Stahl,
Laura Camassa,
Carolina Gomis-Perez,
Stefano Toffanin,
Reidun Torp,
David L Kaplan,
Giampiero Ruani,
Fiorenzo G Omenetto,
Roberto Zamboni, Michele Muccini
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ABSTRACT: Purpose: Biomaterials that enable the control of bioelectrical signals in neural cells have major potential for use in tissue engineering, targeted drug release or stem cell based neuroregenerative medicine. In this rapidly emerging area, particular attention is devoted to the engineering and use of interfaces that could be integrated in biocompatible electronic devices. In recent years, silk fibroin from Bombyx mori cocoon has been extensively studied for new biomedical applications, such as functional tissue engineering and drug delivery and in electronic devices intended for neuroregenerative medicine. However, achieving a thorough biocompatibility can be challenging because of the complex nature of the biological response to interaction with biomaterials. In particular an interface suitable for nerve regeneration should support neurite outgrowth and preserve/promote the functional recovery of neuronal cells (bio-functional interface), by enabling neuronal conduction of action potential. Moreover, attention should be given to modulation of bioelectrical activity of non-excitable (namely glial cells), in view of their central role in the inflammatory reaction occurring upon prothesic implantation at injury sites.
On this basis our lab's activity was targeted to define the effect of bio-derived biomaterials thin films (as silk fibroin), on the growth and electrophysiologic properties of peripheral neurons and glial cells.
Methods: Silk fibroin was extracted and thin films were prepared by means of previously reported protocols. Primary cultures of dorsal root ganglion (DRG) neurons (1) and cortical astrocytes (2) were plated on those films. Morphometric analyses were performed by optical and confocal imaging. Functional analyses were performed by means of single cell whole cell patch-clamp.
Results: In our work we have demonstrated that SF films are a favorable substrate to support in vitro studies on neuron and astrocytes. In particular, SF 1) promote adhesion and neurite outgrowth of peripheral neuron culture in vitro 2) preserve the capability of these neuronal cells to fire. 3) Preserve bioelectrical properties of astrocytes. By functionalization with specific trophic molecules, we demonstrated that bioelectrical properties of astrocytes could be specifically modulated. Moreover, we showed that NGF-silk films enable increased neurite outgrowth and modulation of firing properties of cultured neurons.
Conclusions: Silk fibroin is a biomaterial platform with major potential in neuroregenerative medicine, especially the Central and Peripheral Nervous System.
Journal of applied biomaterials & functional materials. 12/2012; 10(3):315-323.
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Margherita Durso,
Denis Gentili,
Cristian Bettini,
Alberto Zanelli,
Massimiliano Cavallini,
Filippo De Angelis,
Maria Grazia Lobello,
Viviana Biondo, Michele Muccini,
Raffaella Capelli,
Manuela Melucci
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ABSTRACT: The synthesis and characterization of two thieno(bis)imide based n-type semiconductors with electron mobilities of up to 0.3 cm(2) V(-1) s(-1) are described. The relationships between the electronic features of the π-inner core and the functional properties of the new materials are also discussed.
Chemical Communications 11/2012; · 6.17 Impact Factor
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European Workshop on Heterostructure Technology (HeTech), Barcelona, Spain; 11/2012
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ABSTRACT: Silk is a natural biocompatible material that can be integrated in a variety of photonic systems and optoelectronic devices. The silk replication of patterned substrates with features down to tens of nanometers is exploited to realize highly transparent, mechanically stable, and free-standing structures with optical wavelength size. We demonstrate organic lasing from a blue-emitting stilbene-doped silk film spin-coated onto a one-dimensional distributed feedback grating (DFB). The lasing threshold is lower than that of organic DFB lasers based on the same active dye. These findings pave the way to the development of an optically active biocompatible technological platform based on silk.
Applied Physics Letters 08/2012; 101(9):091110. · 3.84 Impact Factor
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ABSTRACT: Ionic transition metal complexes (iTMCs) have already been demonstrated to be a promising type of material to fabricate low-cost light sources, which are much more competitive in terms of realization costs with respect to standard organic light emitting diodes. The device performance, optical and morphological properties of thin films of two different complexes [Ir(phenylpyridine)(2)(5-Me-1,10-phen)][PF(6)] and [Ir(phenylquinoline)(2)(5-Me-1,10-phen)][PF(6)] have been measured and compared. The use of an ionic liquid as part of the processing procedure shows advantages in terms of low operation voltage, which is as low as 3.5 Volts. However, it leads to drawbacks in terms of device lifetime, limited to t(1/2) = 2 min, and maximum achievable brightness (1425 cd m(-2) vs. 3040 cd m(-2) without ionic liquid, for the complex [Ir(phenylpyridine)(2)(5-Me-1,10-phen)][PF(6)]).
Dalton Transactions 06/2012; 41(30):9227-31. · 3.84 Impact Factor
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Valentina Benfenati,
Katja Stahl,
Carolina Gomis-Perez,
Stefano Toffanin,
Anna Sagnella,
Reidun Torp,
David L Kaplan,
Giampiero Ruani,
Fiorenzo G Omenetto,
Roberto Zamboni, Michele Muccini
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ABSTRACT: Silk fi broin (SF) is a biocompatible and slowly biodegradable material with
excellent mechanical properties and huge potential for use as biofunctional
interface in electronic devices that aim to stimulate and control neural
network activity and peripheral nerve repair. It is shown that SF fi lms act
as material interfaces that support the adherence and neurite outgrowth of
dorsal root ganglion (DRG) neurons and preserve neuronal functions. Silk
fi lms preserve the capability of neuronal cells to fi re and DRG neurons on
silk fi lms retain the intracellular free Ca 2 + concentration ([Ca 2 + ] i ) response to
capsaicin, a typical noxious stimulus for this neuronal culture model. It is
also demonstrated that nerve growth factor (NGF)-functionalized silk fi lms
promote neurite outgrowth and modulate functional properties of DRG
neurons. The results show that silk preserves DRG neuronal physiology and
is a promising biomaterial platform for the future development of devices
with goals including functional recovery of injured neurons, neurite functional
outgrowth in vitro, or functional electrostimulation in vivo.
Advanced Functional Materials 05/2012; 22:1871-1884. · 10.18 Impact Factor
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ABSTRACT: The design, synthesis and structure-property investigation of a new thienopyrrolyl dione substituted oligothiophene material showing reduced band gap energy, low lying LUMO energy level and ambipolar semiconducting behaviour is described.
Chemical Communications 09/2011; 47(43):11840-2. · 6.17 Impact Factor
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ABSTRACT: In this paper, we present a study of the effects of the influence of the substrate platform on the properties of a three-layer vertical hetero-junction made of thin films of α, ω-diperfluorohexyl-4T (DHF4T), a blend of tris(8-hydroxyquinoline)aluminium (Alq3) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) and α, ω-dihexyl-quaterthiophene (DH4T). The hetero-junction represents the active component of an organic light-emitting transistor (OLET). The substrate platforms investigated in this study are glass/indium-tin-oxide/poly(methyl-methacrylate) (PMMA) and Si++/silicon oxide (SiO2)/PMMA. The first platform is almost completely transparent to light and therefore is very promising for use in OLET applications. The second one has been chosen for comparison as it employs standard microelectronic materials, i.e. Si++/SiO2. We show how different gate materials and structure can affect the relevant field-effect electrical characteristics, such as the charge mobility and threshold voltage. By means of an atomic force microscopy analysis, a systematic study has been made in order to correlate the morphology of the active layers with the electrical properties of the devices.
Journal of Physics D Applied Physics 05/2011; 44(22):224018. · 2.54 Impact Factor
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ABSTRACT: Astroglial cell survival and ion channel activity are relevant molecular targets for the mechanistic study of neural cell interactions with biomaterials and/or electronic interfaces. Astrogliosis is the most typical reaction to in vivo brain implants and needs to be avoided by developing biomaterials that preserve astroglial cell physiological function. This cellular phenomenon is characterized by a proliferative state and altered expression of astroglial potassium (K(+)) channels. Silk is a natural polymer with potential for new biomedical applications due to its ability to support in vitro growth and differentiation of many cell types. We report on silk interactions with cultured neocortical astroglial cells. Astrocytes survival is similar when plated on silk-coated glass and on poly-D-lysine (PDL), a well known polyionic substrate used to promote astroglial cell adhesion to glass surfaces. Comparative analyses of whole-cell patch-clamp experiments reveal that silk- and PDL-coated cells display depolarized resting membrane potentials (-40 mV), very high input resistance, and low specific conductance, with values similar to those of undifferentiated glial cells. Analysis of K(+) channel conductance reveals that silk-astrocytes express large outwardly delayed rectifying K(+) current (K(DR)). The magnitude of K(DR) in PDL- and silk-coated astrocytes is similar, indicating that silk does not alter the resting K(+) current. We also demonstrate that guanosine- (GUO) embedded silk enables the direct modulation of astroglial K(+) conductance in vitro. Astrocytes plated on GUO-embedded silk are more hyperpolarized and express inward rectifying K(+) conductance (K(ir)). The K(+) inward current increases and this is paralleled by upregulation and membrane polarization of K(ir)4.1 protein signal. Collectively these results indicate that silk is a suitable biomaterial platform for the in vitro studies of astroglial ion channel responses and related physiology.
Biomaterials 11/2010; 31(31):7883-91. · 7.40 Impact Factor
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Tiziana Benincori,
Valentina Bonometti,
Filippo De Angelis,
Luigi Falciola, Michele Muccini,
Patrizia R Mussini,
Tullio Pilati,
Giovanni Rampinini,
Simona Rizzo,
Stefano Toffanin,
Francesco Sannicolò
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ABSTRACT: The introduction of branching in multi-thiophene semiconductors, although granting the required solubility for processing, results in an increased molecular fluxionality and a higher level of distortion, thus hampering pi conjugation. Accordingly, branched oligothiophenes require rationalization of their structure-reactivity relationships for target-oriented design and optimization of the synthetic effort. Our current research on spiderlike oligothiophenes affords deep insight into the subject, and introduces new, easily accessible molecules with attractive functional properties. In particular, a regular series, T'X(Y), of five new multi-thiophene systems, T'5(3), T'8(4), T'11(5), T'14(6), and T'17(7), constituted by five, eight, 11, 14, and 17 thiophene units, respectively, their longest alpha-conjugated chain consisting of tri-, tetra-, penta-, hexa-, and heptathiophene moieties, respectively, has been synthesized and fully characterized from the structural, spectroscopic, and electrochemical point of view. The electronic properties of the monomers and their electropolymerization ability are discussed and rationalized as a function of their molecular structure, particularly in comparison with the series of 5-(2,2'-dithiophene)yl-persubstituted alpha-oligothiophenes (TX(Y)) previously reported by us. These oligothiophenes are easily accessible materials, with promising properties for applications as active layers in multifunctional organic devices including solar cells.
Chemistry 08/2010; 16(30):9086-98. · 5.93 Impact Factor
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ABSTRACT: The potential of organic semiconductor-based devices for light generation is demonstrated by the commercialization of display technologies based on organic light-emitting diodes (OLEDs). Nonetheless, exciton quenching and photon loss processes still limit OLED efficiency and brightness. Organic light-emitting transistors (OLETs) are alternative light sources combining, in the same architecture, the switching mechanism of a thin-film transistor and an electroluminescent device. Thus, OLETs could open a new era in organic optoelectronics and serve as testbeds to address general fundamental optoelectronic and photonic issues. Here, we introduce the concept of using a p-channel/emitter/n-channel trilayer semiconducting heterostructure in OLETs, providing a new approach to markedly improve OLET performance and address these open questions. In this architecture, exciton-charge annihilation and electrode photon losses are prevented. Our devices are >100 times more efficient than the equivalent OLED, >2x more efficient than the optimized OLED with the same emitting layer and >10 times more efficient than any other reported OLETs.
Nature Material 06/2010; 9(6):496-503. · 32.84 Impact Factor
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Microelectronics Reliability. 01/2010; 50:1861-1865.
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ABSTRACT: We report on the characteristics of a host-guest lasing system obtained by coevaporation of an oligo(9,9-diarylfluorene) derivative named T3 with the red-emitter 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (DCM). We demonstrate that the ambipolar semiconductor T3 can be implemented as an active matrix in the realization of a host-guest system in which an efficient energy transfer takes place from the T3 matrix to the lasing DCM molecules. We performed a detailed spectroscopic study on the system by systematically varying the DCM concentration in the T3 matrix. Measurements of steady-state photoluminescence (PL), PL quantum yield (PLQY), time-resolved picosecond PL, and amplified spontaneous emission (ASE) threshold are used to optimize the acceptor concentration at which the ASE from DCM molecules takes place with the lowest threshold. The sample with a DCM relative deposition ratio of 2% shows an ASE threshold as low as 0.6 kW/cm(2) and a net optical gain measured by femtosecond time-resolved pump-and-probe spectroscopy as high as 77 cm(-1). The reference model system Alq(3):DCM sample measured in exactly the same experimental conditions presents an one-order-of-magnitude higher ASE threshold. The ASE threshold of T3:DCM is the lowest reported to date for a molecular host-guest energy-transfer system, which makes the investigated blend an appealing system for use as an active layer in lasing devices. In particular, the ambipolar charge transport properties of the T3 matrix and its field-effect characteristics make the host-guest system presented here an ideal candidate for the realization of electrically pumped organic lasers.
The Journal of Physical Chemistry B 12/2009; 114(1):120-7. · 3.70 Impact Factor
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ABSTRACT: Two functional ethynyl-pyrene derivatives have been designed and synthesized by di- and tetra-substitutions of bromo pyrene derivatives with N-(4-ethynylphenyl)-3,4,5-tris(hexadecyloxy)benzamide fragments. The photoluminescence wavelength of the pyrene core can be tuned by the substitution pattern and the state of matter (solid, solution, gel, or liquid crystal). The disubstituted pyrene derivative 1 is not mesomorphic but produces robust and highly fluorescent gels in DMF, toluene, and cyclohexane. The well-defined fibers and ropes of the gel states were characterized by SEM and laser scanning confocal microscopy, and extended over several micrometers. The gels were integrated as active layers in field-effect transistors, which provided good bulk electron and hole charge mobilities as well as light emission generation. The tetra-substituted pyrene derivative is not a gelator but displays a stable liquid crystalline phase with 2D hexagonal symmetry between 20 and 200 degrees C. The pronounced luminescence properties of the mesophase allow one to observe original mesophase textures with flower-like patterns directly by fluorescence microscopy without crossed-polarizers.
Journal of the American Chemical Society 11/2009; 131(50):18177-85. · 9.91 Impact Factor
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ABSTRACT: We report on the triplet spectra and dynamics in two types of oligomeric films deposited by two different techniques: thermal evaporation and spin coating. The different molecular arrangement in both films is manifested in a red shift of the absorption, PL, and T1-Tn absorption spectra of the sublimated film relative to the spin-coated one. Triplet recombination dynamics studied with steady-state photoinduced absorption (PA) spectroscopy follow a dispersive bimolecular recombination model away from the trap filling regime. We obtained values for the triplet bimolecular recombination ratio (beta) of 3.4 x 10 (-14) and 1.1 x 10 (-15) cm3 s (-1) for evaporated and spin-coated film, respectively, the difference being attributed to diverse molecular arrangement in both films.
The Journal of Physical Chemistry B 09/2008; 112(37):11605-9. · 3.70 Impact Factor
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ABSTRACT: We report on the influence of the dielectric/organic interface properties on the electrical characteristics of field-effect transistors based on polyphenylenevinylene derivatives. Through a systematic investigation of the most common dielectric surface treatments, a direct correlation of their effect on the field-effect electrical parameters, such as charge carrier mobility, On/Off current ratio, threshold voltage, and current hysteresis, has been established. It is found that the presence of OH groups at the dielectric surface, already known to act as carrier traps for electrons, decreases the hole mobility whereas it does not substantially affect the other electrical characteristics. The treatment of silicon dioxide surfaces with gas phase molecules such as octadecyltrichlorosilane and hexamethyldisilazane leads to an improvement in hole mobility as well as to a decrease in current hysteresis. The effects of a dielectric polymer layer spin coated onto silicon dioxide substrates before deposition of the semiconductor polymer can be related not only to the OH groups density but also to the interaction between the dielectric and the semiconductor molecules. Specifically, the elimination of the OH groups produces the same effect observed with hexamethyldisilazane. The hole mobility values obtained with hexamethyldisilazane and polymer dielectrics are the highest reported to date for PPV-based field-effect transistors.
The Journal of Physical Chemistry B 08/2008; 112(33):10130-6. · 3.70 Impact Factor
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ABSTRACT: Careful analysis and comparison of optical and electrochemical data available in recent literature for multi-thiophene molecular assemblies suggested a few basic rules for the design of structurally simple and easily accessible oligothiophenes endowed with properties not far from those exhibited by much more complex and synthetically demanding architectures. The synthesis and computational investigation of three examples of a class of oligothiophenes (spider-like) tailored according to these indications are reported together with their exhaustive optical and electrochemical characterization. The new compounds (T9 5, T14 6, T19 7) are characterized by a thiophene, a 2,2'-bithiophene and a 2,2',5',2''-terthiophene unit (the spider body) fully substituted with 5-(2,2'-bithiophen)yl pendants (the spider legs). Absorption and electrochemical data are in good agreement and point to a high pi-conjugation level, comparable to those displayed by much larger assemblies. Electrode potential cycling in proximity of the first oxidation peak affords fast and reproducible formation of conducting, highly stable [TXn]m films, mainly consisting of dimers (m=2). Electrooxidation kinetic experiments on deuterium-labelled T9 5, coupled to laser-desorption-ionization mass spectroscopy on the resulting dimer demonstrated that the coupling process is extremely regioselective in the alpha positions of the more conjugated pentathiophene chain. The optical and the electrochemical properties of the films are reported and discussed. A peculiar feature is their impressive charge-trapping ability. Spider-like oligothiophenes are promising materials for applications as active layers in multifunctional organic devices.
Chemistry 02/2008; 14(2):459-71. · 5.93 Impact Factor
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Claudia Dragonetti,
Luigi Falciola,
Patrizia Mussini,
Stefania Righetto,
Dominique Roberto,
Renato Ugo,
Adriana Valore,
Filippo De Angelis,
Simona Fantacci,
Antonio Sgamellotti,
Miguel Ramon, Michele Muccini
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ABSTRACT: The photophysical and electrochemical properties of the novel complexes [Ir(ppy)(2)(5-X-1,10-phen)][PF(6)] (ppy = 2-phenylpyridine, phen = phenanthroline, X = NMe(2), NO(2)), [Ir(pq)(2)(5-X-1,10-phen)][PF(6)] (pq = 2-phenylquinoline, X = H, Me, NMe(2), NO(2)), [Ir(ppy)2(4-Me,7-Me-1,10-phen)][PF(6)], [Ir(ppy)2(5-Me,6-Me-1,10-phen)][PF(6)], [Ir(ppy)(2)(2-Me,9-Me-1,10-phen)][PF(6)], and [Ir(pq)2(4-Ph,7-Ph-1,10-phen)][PF(6)] have been investigated and compared with those of the known reference complexes [Ir(ppy)(2)(4-Me or 5-H or 5-Me-1,10-phen)][PF(6)] and [Ir(ppy)(2)(4-Ph,7-Ph-1,10-phen)][PF(6)], showing how the nature and number of the phenanthroline substituents tune the color of the emission, its quantum yield, and the emission lifetime. It turns out that the quantum yield is strongly dependent on the nonradiative decay. The geometry, ground state, electronic structure, and excited electronic states of the investigated complexes have been calculated on the basis of density functional theory (DFT) and time-dependent DFT approaches, thus substantiating the electrochemical measurements and providing insight into the electronic origin of the absorption spectra and of the lowest excited states involved in the light emission process. These results provide useful guidelines for further tailoring of the photophysical properties of ionic Ir(III) complexes.
Inorganic Chemistry 11/2007; 46(21):8533-47. · 4.60 Impact Factor
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Michele Muccini
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ABSTRACT: Field-effect transistors are emerging as useful device structures for efficient light generation from a variety of materials, including inorganic semiconductors, carbon nanotubes and organic thin films. In particular, organic light-emitting field-effect transistors are a new class of electro-optical devices that could provide a novel architecture to address open questions concerning charge-carrier recombination and light emission in organic materials. These devices have potential applications in optical communication systems, advanced display technology, solid-state lighting and electrically pumped organic lasers. Here, recent advances and future prospects of light-emitting field-effect transistors are explored, with particular emphasis on organic semiconductors and the role played by the material properties, device features and the active layer structure in determining the device performances.
Nature Material 09/2006; 5(8):605-13. · 32.84 Impact Factor
