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The growth of controlled 1D carbon-based nanostructures on metal surfaces is a multistep process whose path, activation energies and intermediate metastable states strongly depend on the employed substrate. Whereas this process has been extensively studied on gold, less work has been dedicated to silver surfaces, which have a rather different catalytic activity. In this work, we present an experimental and theoretical investigation of the growth of poly-$p$-phenylene (PPP) chains and subsequent narrow graphene ribbons starting from 4,4''-dibromo-$p$-terphenyl molecular precursors deposited at the silver surface. By combing scanning tunneling microscopy (STM) imaging and density functional theory (DFT) simulations, we describe the molecular morphology and organization at different steps of the growth process and we discuss the stability and conversion of the encountered species on the basis of calculated thermodynamic quantities. Unlike the case of gold, at the debromination step we observe the appearance of organometallic molecules and chains, which can be explained by their negative formation energy in the presence of a silver adatom reservoir. At the dehydrogenation temperature the persistence of intercalated Br atoms hinders the formation of well-structured graphene ribbons, which are instead observed on gold, leading only to a partial lateral coupling of the PPP chains. We numerically derive very different activation energies for Br desorption from the Ag and Au surfaces, thereby confirming the importance of this process in defining the kinetics of the formation of molecular chains and graphene ribbons on different metal surfaces.

This work is focused on the structural control of graphene nanoribbons (GNRs) and intermediate polymeric wires [poly(p-phenylene), PPP] during their thermoactivated bottom-up synthesis from room te...

Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) offer many opportunities for the development of low-cost and low-power electronics suitable for applications like sensors and point-of-care tests; however, EGOFETs can be affected by the drift of their operative point that causes signals distortion and loss of information during sensing applications. Here, a blend of 2,8-Difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES-ADT) and polystyrene (PS) is used as the active material for the fabrication of dual-gate EGOFETs. We exploited the dual-gate architecture to improve EGOFETs stability by implementing digital feedback that uses the back-gate electrode to compensate dynamically for the transistor threshold voltage allowing us to fix its operative point for prolonged tests (>10 h) with different aqueous solutions (Milli-Q water, NaCl 0.1 M and a physiological solution). The presented real-time threshold voltage compensation does not only allow to steady EGOFETs DC output current, but it also preserves EGOFETs sensing capability for the detection of signals with frequencies as low as 1 Hz., The research leading to these results has received funding from the University of Padua, Department of Chemical Sciences (Grants: P-DISC#09BIRD2019-UNIPD - SMOW -; P-DiSC#11NExuS_BIRD2020-UNIPD - CARBON-FET -). It is further funded by the Italian Ministry of Education, Universities and Research through the project entitled “Nanochemistry for Energy and Health, NExuS” (the national funding network termed “Dipartimenti di Eccellenza” awarded to the Department of Chemical Sciences at the University of Padua). This work was partially supported by the University of Padua, Department of Information Engineering, under the initiative Project PROACTIVE 2018, and by MIUR (Italian Minister for Education) under the initiative “Departments of Excellence” (Law 232/2016). This work was funded by the Spanish Ministry of Science and Innovation with the project GENESIS PID2019-111682RB-I00 and through the “Severo Ochoa” Programme for Centers of Excellence in R&D (FUNFUTURE CEX2019-000917-S), and the Generalitat de Catalunya (2017-SGR-918). S. R. acknowledges her FPI fellowship and is enrolled in the UAB PhD program., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

International audience; The monitoring of K+ in saliva, blood, urine, or sweat represents a future powerful alternative diagnostic tool to prevent various diseases. However, several K+ sensors are unable to meet the requirements for the development of point‐of‐care (POC) sensors. To tackle this grand‐challenge, the fabrication of chemiresistors (CRs) based on 3D networks of Au nanoparticles covalently bridged by ad‐hoc supramolecular receptors for K+, namely dithiomethylene dibenzo‐18‐crown‐6 ether is reported here. A multi‐technique characterization allows optimizing a new protocol for fabricating high‐performing CRs for real‐time monitoring of K+ in complex aqueous environments. The sensor shows exceptional figures of merit: i) linear sensitivity in the 10^–3 to 10^–6 m concentration range; ii) high selectivity to K+ in presence of interfering cations (Na+, Ca2+, and Mg2+); iii) high shelf‐life stability (>45 days); iv) reversibility of K+ binding and release; v) successful device integration into microfluidic systems for real‐time monitoring; vi) fast response and recovery times (

International audience; The development of novel, highly efficient, reliable, and robust surface enhanced Raman scattering (SERS) substrates containing a large number of hot spots with programmed size, geometry, and density is extremely interesting since it allows the sensing of numerous (bio-)chemical species. Herein, an extremely reliable, easy to fabricate, and label-free SERS sensing platform based on metal nanoparticles (NPs) thin-film is developed by the layer-by-layer growth mediated by polyelectrolytes. A systematic study of the effect of NP composition and size, as well as the number of deposition steps on the substrate's performance, is accomplished by monitoring the SERS enhancement of 1-naphtalenethiol (532 nm excitation). Distinct evidence of the key role played by the interlayer (poly(diallyldimethylammonium chloride) (PDDA) or PDDA-functionalized graphene oxide (GO@PDDA)) on the overall SERS efficiency of the plasmonic platforms is provided, revealing in the latter the formation of more uniform hot spots by regulating the interparticle distances to 5 ± 1 nm. The SERS platform efficiency is demonstrated via its high analytical enhancement factor (≈10^6) and the detection of a prototypical substance(tamoxifen), both in Milli-Q water and in a real matrix, viz. tap water, opening perspectives towards the use of plasmonic platforms for future high-performance sensing applications.

Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1&ndash, 3, ten prenylated derivatives (coded 4&ndash, 13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD50) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3&prime, dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4&ndash, 13, evidencing ester 13 as the most active. This compound presented MIC and LD50 values (62&ndash, 250 &micro, M and 7.8&ndash, 125 &micro, M, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy.

Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1–3, ten prenylated derivatives (coded 4–13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD50) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3′-dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4–13, evidencing ester 13 as the most active. This compound presented MIC and LD50 values (62–250 µM and 7.8–125 µM, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy.

The Met80Ala and Met80Ala/Tyr67Ala variants of S. cerevisiae iso-1 cytochrome c (ycc) and their adducts with cardiolipin immobilized onto a gold electrode coated with a hydrophobic self-assembled monolayer (SAM) of decane-1-thiol were studied through cyclic voltammetry and surface-enhanced resonance Raman spectroscopy (SERRS). The electroactive species - containing a six-coordinate His/His axially ligated heme and a five-coordinate His/- heme stable in the oxidized and reduced state, respectively - and the pseudoperoxidase activity match those found previously for the wt species and are only slightly affected by CL binding. Most importantly, the reduced His/- ligated form of these variants is able to catalytically reduce the nitrite ion, while electrode-immobilized wt ycc and other His/Met heme ligated variants under a variety of conditions are not. Besides the pseudoperoxidase and nitrite reductase functions, which are the most physiologically relevant abilities of these constructs, also axial heme ligation and the equilibria between conformers are strongly affected by the nature - hydrophobic vs. electrostatic - of the non-covalent interactions determining protein immobilization. Also affected are the catalytic activity changes induced by a given mutation as well as those due to partial unfolding due to CL binding. It follows that under the same solution conditions the structural and functional properties of immobilized ycc are surface-specific and therefore cannot be transferred from an immobilized system to another involving different interfacial protein-SAM interactions.

In this paper we report on the use of an Ullmann-like aryl halide homocoupling reaction to obtain long Graphyne Molecular Wires (GY MWs) organized in dense, ordered arrays. Instead of using highly reactive terminal alkynes, we resort to a precursor wherein the acetylenic functional group is internal, namely protected by two phenyl rings, each bearing a Br atom in the para position to allow for linear homocoupling. In addition, two further factors concur with the production of dense and highly ordered arrays of very long GY MWs, namely the geometric compatibility between the substrate and both the organometallic intermediates and the final polymeric products of the synthesis, coupled with the presence of surface-adsorbed bromine atoms separating the MWs, which minimize inter-wire cross-linking secondary reactions.

The aggregation of α-synuclein is a critical event in the pathogenesis of neurological diseases, such as Parkinson or Alzheimer. Here, we present a label-free sensor based on an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) integrated with microfluidics that allows for the detection of amounts of α-synuclein in the range from 0.25 pM to 25 nM. The lower limit of detection (LOD) measures the potential of our integrated device as a tool for prognostics and diagnostics. In our device, the gate electrode is the effective sensing element as it is functionalised with anti-(α-synuclein) antibodies using a dual strategy: i) an amino-terminated self-assembled monolayer activated by glutaraldehyde, and ii) the His-tagged recombinant protein G. In both approaches, comparable sensitivity values were achieved, featuring very low LOD values at the sub-pM level. The microfluidics engineering is central to achieve a controlled functionalisation of the gate electrode and avoid contamination or physisorption on the organic semiconductor. The demonstrated sensing architecture, being a disposable stand-alone chip, can be operated as a point-of-care test, but also it might represent a promising label-free tool to explore in-vitro protein aggregation that takes place during the progression of neurodegenerative illnesses., This work was funded by the EXPLORA project MAT2015-72760-EXP (Spanish Ministry) and ERC StG 2012–306826 e-GAMES (European Research Council FP7). The authors also thank the Spanish Ministry of Economy and Competitiveness, through the projects FANCY CTQ2016-80030-R, GENESIS PID2019-111682RB-I00 and “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV-2015-0496), the Generalitat de Catalunya (2017-SGR-918) and the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN). S. R. is enrolled in the PhD program of the Universitat Autònoma of Barcelona (UAB). The research leading to these results has also received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007–2013) under Research Executive Agency Grant Agreement No. 600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. The Surface Plasmon Resonance (SPR) measurements were performed through the ICTS NANBIOSIS platform, more specifically in the Biodeposition and Biodetection Unit of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN) at the Catalan Institute of Nanoscience and Nanotechnology (ICN2). The microfluidic device design and fabrication were performed with funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement 764281 (AiPBAND), and Marie Skłodowska-Curie grant agreement 813863 (BORGES).

Cellulose nanopaper (CNP) features appealing properties, including transparency, flatness, a low thermal expansion coefficient and thermal stability, often outperforming conventional paper. However, free-standing crystalline cellulose films usually swell in water or upon moisture sorption, compromising part of their outstanding properties. This remains a major problem whenever working in a water environment is required. Freestanding cellulose nanopaper is prepared by solution casting water suspensions of cellulose nanocrystals with an average width of 10 nm and an average aspect ratio of 28, isolated from Avicel by acid hydrolysis and extensively characterized by AFM and FE-SEM measurements and GPC detection of their degree of polymerization. We demonstrate by elemental analyses, FT-IR, Raman spectroscopy, XRD measurements and water contact angle detection that wet treatment with lauroyl chloride results in surface hydrophobization of nanopaper. The hydrophobized nanopaper, C12-CNP, shows a more compact surface morphology than the starting CNP, due to the effect of chemical functionalization, and presents enhanced resistance to water, as assessed by electrochemical permeation experiments. The new hydrophobized nanopaper is a promising substrate for thin film devices designed to work in a humid environment.

Cytochrome c is a small globular protein whose main physiological role is to shuttle electrons within the mitochondrial electron transport chain. This protein has been widely investigated, especially as a paradigmatic system for understanding the fundamental aspects of biological electron transfer and protein folding. Nevertheless, cytochrome c can also be endowed with a non-native catalytic activity and be immobilized on an electrode surface for the development of third generation biosensors. Here, an overview is offered of the most significant examples of such a functional transformation, carried out by either point mutation(s) or controlled unfolding. The latter can be induced chemically or upon protein immobilization on hydrophobic self-assembled monolayers. We critically discuss the potential held by these systems as core constituents of amperometric biosensors, along with the issues that need to be addressed to optimize their applicability and response.

International audience; Graphene is regarded as the ultimate material for future flexible, high‐performance, and wearable electronics. Herein, a novel, robust, all‐green, highly reliable (yield ≥ 99%), and upscalable technology is reported for wearable applications comprising reduced graphene oxide (rGO) as the electroactive component in liquid‐gated transistors (LGTs). rGO is a formidable material for future flexible and wearable applications due to its easy processability, excellent surface reactivity, and large‐area coverage. A novel protocol is established toward the high‐yield fabrication of flexible rGO LGTs combining high robustness (>1.5 h of continuous operation) with state‐of‐the‐art performances, being similar to those of their rigid counterparts operated under liquid gating, including field‐effect mobility of ≈10−1 cm2 V−1 s−1 and transconductance of ≈25 µS. Permeable membranes have been proven crucial to operate flexible LGTs under mechanical stress with reduced amounts of solution (

Electrolyte‐gated organic field‐effect transistors (EGOFETs) exploit the transduction of interfacial phenomena, such as biorecognition or redox processes, into detectable changes of electrical response. Here, it is shown that, beyond sensing applications, EGOFETs may act effectively as memory devices, through the functionalization of the gate electrode with a self‐assembly monolayer comprising a switching molecule undergoing a large and persistent change of dipole moment, upon application of a small (0.6 V) programming potential. This first example of a switchable EGOFET device with memory retention is based on a tetrathiafulvalene derivative self‐assembled on gold and an aqueous buffer as electrolyte in a microfluidic assembly. Changes of the self‐assembled monolayer redox state lead to variations of the gate electrochemical potential and, as a consequence, the EGOFET's threshold voltage undergoes reversible shifts larger than 100 mV. The distinctive electrical readout upon different redox states opens the possibility of writing and erasing information, thus making the transistor behave as a single memory cell., This work was funded by ITN iSwitch 642196 (V.P. and M.S.M.), ERC StG 2012‐306826 e‐GAMES, the EuroNanoMed III project “AMI,” the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER‐BBN), the Generalitat de Catalunya (2017‐SGR‐918) and the Spanish Ministry of Economy and Competitiveness, through the project FANCYCTQ2016‐80030‐R and “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV‐2015‐0496). V.P. is enrolled in the Molecular and Regenerative Medicine Programme of the Università di Modena and Reggio Emilia. M.S.M. and Q.Z. are enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. S.C. acknowledges the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007‐2013) under Research Executive Agency Grant Agreement No. 600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. Q.Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (11404266) and the Fundamental Research Funds for the Central Universities (Grant No. XDJK2011C041).

International audience; Conformationally rigid multipodal molecules should control the orientation and packing density of functional head groups upon self-assembly on solid supports. Common tripods frequently fail in this regard because of inhomogeneous bonding configuration and stochastic orientation. These issues are circumvented by a suitable tetrapodal diazatriptycene moiety, bearing four thiol-anchoring groups, as demonstrated in the present study. Such molecules form well-defined self-assembled monolayers (SAMs) on Au(111) substrates, whereby the tetrapodal scaffold enforces a nearly upright orientation of the terminal head group with respect to the substrate, with at least three of the four anchoring groups providing thiolate-like covalent attachment to the surface. Functionalization by condensation chemistry allows a large variety of functional head groups to be introduced to the tetrapod, paving the path toward advanced surface engineering and sensor fabrication.

descripción no proporcionada por scopus, The authors thank the ERC StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project BE-WELL CTQ2013-40480-R, the Generalitat de Catalunya (2014-SGR-17) and the Spanish Ministry of Economy and Competitiveness, through the ‘Severo Ochoa‘ Programme for Centres of Excellence in R&D (SEV- 2015-0496). F.L. gratefully acknowledges the “Juan de la Cierva” programme. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007-2013) under REA grant agreement no.600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. Q. Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (11404266) and the Fundamental Research Funds for the Central Universities (Grant No. XDJK2011C041). Q. Z. is enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. The authors gratefully acknowledge Prof. J. Puigdollers for the useful discussions

A switchable electrode, which relies on an indium-tin oxide conductive substrate coated with a self-assembled monolayer terminated with an anthraquinone group (AQ), is reported as an electrowetting system. AQ electrochemical features confer the capability of yielding a significant modulation of surface wettability as high as 26° when its redox state is switched. Hence, an array of planar electrodes for droplets actuation is fabricated and integrated in a microfluidic device to perform mixing and dispensing on sub-nanoliter scale. Vehiculation of cells across microfluidic compartments is made possible by taking full advantage of surface electrowetting in culture medium., This work was funded by the innovative training networks (ITN) iSwitch 642196, European research council (ERC) StG 2012-306826 e-GAMES, Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBER-BBN), the Spanish Ministry project FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2014-SGR-17) and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV-2015-0496). M.S.M. is enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. S.C. acknowledges the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007–2013) under Research Executive Agency Grant Agreement No. 600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ.

Hydroxylated biphenyl unit is embedded in many structures of bioactive natural products and some of them are present in compounds of high biological relevance. It is previously reported by us that generally dimers manifested higher antioxidant efficiency than those of the corresponding monomers [1]. In our laboratory we are actively engaged in the synthesis and biological evaluation of hydroxylated natural-like biphenyls [2]. 4-(4-hydroxyphenyl)-2-butanol, 4-(4-hydroxyphenyl)-2-butanone, 2-(4-hydroxyphenyl)ethanol, commonly known respectively as rhododendrol 1, raspberry ketone 2 and tyrosol 3 are natural phenols which displayed remarkable variety of biological activities. Rhododendrol, mostly present in Acer nikoense and Betula platyphylla, was developed as a tyrosinase inhibitor for lightening/whitening cosmetics [3]. Raspberry ketone, occuring on a variety of fruits, including raspberries, cranberries, and blackberries, sometimes used in perfumery and cosmetics, was proved to restrain oxidative stress and the lipid peroxidation reaction, and to prevent damage in liver cells [4]. Tyrosol is a natural phenolic antioxidant present in a variety of natural sources. It is one of the main natural phenols found in olive oil. As antioxidant, tyrosol can protect cells against injury due to oxidation [5]. We herein report the synthesis, by oxidative coupling reaction mediated by methyltributyl ammonium permanganate (MTBAP), of novel C2-symmetry 2,2?-dihydroxy-5,5?-disubstitued-1,1?-biphenyls (4-6) related to natural phenols rhododendrol, raspberry ketone and tyrosol (1-3). All synthesized compounds were obtained as air stable solids or oils and easily purified by flash chromatography. References: [1] Kancheva V., Kazakova A.S., Fabbri D., Dettori M.A., Delogu G., Janiak M-J. and Amarowic R. Food Chem. 2014, 157, 263-274. Profumo E., Buttari B., D'Arcangelo D., Tinaburri L., Dettori M.A., Fabbri D., Delogu G. and Riganò R. Oxid. Med. Cell. Longev, 2016, Article ID 1246485; [2] Pisano M., Palomba A., Tanca A., Pagnozzi D., Uzzau S., Addis M.F., Dettori M.A., Fabbri D., Palmieri G. and Rozzo C. BMC Cancer 2016, 16:317. Ruzza P., Serra P.A., Fabbri D., Dettori M.A., Rocchitta G. and Delogu G. Eur. J. Med. Chem. 2017, 126, 1034. Maioli M., Basoli V., Carta P., Fabbri D., Dettori M.A., Cruciani S., Serra P.A. and Delogu G. PlosOne 2018, 13(2): e0192178. [3] Sasaki M., Kondo M., Sato K., Umeda M., Kawabata K., Takahashi Y., Suzuki T., Matsunaga K. And Inoue S. Pigm. Cell Melanoma Res. 2014, 27; 754. [4] Wang L., Meng X. and Zhang F. J Med. Food. 2012, 15, 495. [5] Rodríguez-Morató J., Boronat A., Kotronoulas A., Pujadas M., Pastor A., Olesti E., Pérez-Mañá C., Khymenets O., Fitó M., Farré M. and & De la Torre R. Drug Metab. Rev. 2016, 48, 218.

Understanding the physics behind the operational mechanism of Electrolyte-Gated Organic Field-Effect Transistors (EGOFETs) is of paramount importance for the correct interpretation of the device response. Here, we report the systematic functionalization of the gate electrode of an EGOFET with self-assembled monolayers with a variety of dipolar moments showing that both the chemical nature and the monolayer density influence the electrical characteristics of the device., The authors thank the ERC StG2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2017-SGR-918), and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” programme for Centres of Excellence in R&D (SEV-2015-0496). F. L. gratefully acknowledges the “Juan de la Cierva” programme. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the Seventh Framework Programme of the European Union (FP7/2007-2013) under Research Executive Agency Grant Agreement No. 600388 (TECNIOSpring programme), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. A. T. is enrolled in the UAB PhD program and he thanks the Spanish Ministry for a FPU fellowship.

4-(4-hydroxyphenyl)-2-butanol, 4-(4-hydroxyphenyl)-2-butanone, 2-(4-hydroxyphenyl)ethanol, commonly known respectively as rhododendrol 1, raspberry ketone 2 and tyrosol 3 are natural phenols which displayed remarkable variety of biological activities. Rhododendrol, mostly present in Acer nikoense1a, was developed as a tyrosinase inhibitor for lightening/whitening cosmetics. Raspberry ketone, occuring on a variety of fruits, sometimes used in cosmetics, was proved to restrain oxidative stress and the lipid peroxidation reaction, and to prevent damage in liver cells1b. Tyrosol is a natural phenolic antioxidant present in a variety of natural sources. It is one of the main natural phenols found in olive oil. As antioxidant, tyrosol can protect cells against injury due to oxidation1c. In our laboratory we are actively engaged in the synthesis and biological evaluation of hydroxylated natural-like biphenyls2. Hydroxylated biphenyl unit is embedded in many structures of bioactive natural products and some of them are present in compounds of high biological relevance. It is previously reported by us that generally dimers manifested higher antioxidant efficiency than those of the corresponding monomers3.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), spotted-wing drosophila, has recently become a common and serious pest of temperate fruit crops (small fruits, cherries and kaki) in many countries [1]. Crop damage is caused when adult females, using a serrated ovipositor, lay eggs in ripe and partially ripe fruit before harvest. Developing larvae cause soft and unmarketable fruit, moreover oviposition wounds provide access to pathogens that may enhance fruit deterioration leading to increased risk of secondary rot infections with an economic loss up to 80%. Push-pull strategies (stimulus deterrent diversionary strategies) attempt to reduce crop injury by modifying pest distribution using adversative stimuli to push the pest organism away from the crop while also using attractive stimuli to pull the pest organism out of the crop [2]. A novel and more sustainable method for repelling D. suzukii was evaluated by spraying edible repellents (alone and in mixture) on fruit surface during ripening period in combination with conventional natural attractive traps.

A multilayer self-assembled monolayer (MuL-SAM) composed by i) cysteamine, ii) 4-formilphenyl boronic acid and iii) dopamine has been used to functionalize polycrystalline Au. Its electrochemical characterization shows how this surface engineering makes Au reactive toward dopamine. Kelvin probe measurements have shown how MuL-SAM tunes the surface potential of the bare Au. Such measurements are correlated with the electrical performances of organic field-effect transistors (OFETs), whose source/drain electrodes have been functionalized by MuL-SAM. Such devices, operated as charge-injection organic gauges (CIOGs), have shown sensitivity to the concentration of dopamine in the range of [1, 50] nM.

We describe a potentiometric sensor based on Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) for "in vitro'' detection of dopamine. The sensing element of this device resides at the Au gate-aqueous solution interface by means of a self-assembled monolayer (SAM) composed by cysteamine and 4-formylphenyl boronic acid. The covalent and selective adsorption of dopamine induces a surface dipole potential which shifts the electrode work function and modulates the double layer capacitance. As a result, our device is capable to detect dopamine up to pico-molar concentration showing higher sensitivity with respect to other approaches. For this reason the interface engineering of our EGOFET gate is a promising route for diagnostic applications. (c) 2012 Elsevier B.V. All rights reserved.

Surface doping allows tuning the electronic structure of semiconductors at near-surface regime and is normally accomplished through the deposition of an ultrathin layer on top or below the host material. Surface doping is particularly appealing in organic field-effect transistors (OFETs) where charge transport takes place at the first monolayers close to the dielectric surface. However, due to fabrication restrictions that OFET architecture imparts, this is extremely challenging. Here, it is demonstrated that mercury cations, Hg2+, can be exploited to control doping levels at the top surface of a thin film of a p-type organic semiconductor blended with polystyrene. Electrolyte- or water-gated field-effect transistors, which have its conductive channel at the top surface of the organic thin film, turn out to be a powerful tool for monitoring the process. A positive shift of the threshold voltage is observed in the devices upon Hg2+ exposure. Remarkably, this interaction has been proved to be specific to Hg2+ with respect to other divalent cations and sensitive down to nanomolar concentrations. Hence, this work also opens new perspectives for employing organic electronic transducers in portable sensors for the detection of an extremely harmful water pollutant without the need of using specific receptors., Q.Z. and F.L. contributed equally to this work. The authors thank the ERC-StG 2012-306826 e-GAMES project, the Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) project, FANCY CTQ2016-80030-R, the Generalitat de Catalunya (2014-SGR-17), and the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Program for Centres of Excellence in R&D (SEV-2015-0496). Q.Z. acknowledges the China Scholarship Council, the National Natural Science Foundation (NSF) of China (Grant No. 11404266). Q.Z. was enrolled in the Materials Science PhD Program of Universitat Autònoma de Barcelona. F.L. gratefully acknowledges the “Juan de la Cierva” program. The research leading to these results has received funding from the People Program (Marie Curie Actions) of the Seventh Framework Program of the European Union (FP7/2007-2013) under REA Grant Agreement No. 600388 (TECNIOSpring program), and from the Agency for Business Competitiveness of the Government of Catalonia, ACCIÓ. The authors thank E. Barrena and A. Pérez for useful discussions.

Self-assembly is possibly the most effective and versatile strategy for surface functionalization. Self-assembled monolayers (SAMs) can be formed on (semi-)conductor and dielectric surfaces, and have been used in a variety of technological applications. This work aims to review the strategy behind the design and use of self-assembled monolayers in organic electronics, discuss the mechanism of interaction of SAMs in a microscopic device, and highlight the applications emerging from the integration of SAMs in an organic device. The possibility of performing surface chemistry tailoring with SAMs constitutes a versatile approach towards the tuning of the electronic and morphological properties of the interfaces relevant to the response of an organic electronic device. Functionalisation with SAMs is important not only for imparting stability to the device or enhancing its performance, as sought at the early stages of development of this field. SAM-functionalised organic devices give rise to completely new types of behavior that open unprecedented applications, such as ultra-sensitive label-free biosensors and SAM/organic transistors that can be used as robust experimental gauges for studying charge tunneling across SAMs.

none 14 si Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNFα at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNFα concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNFα concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNFα in human-plasma derived samples as an example for point-of-care application. Berto, Marcello; Casalini, Stefano; Di Lauro, Michele; Marasso, Simone L; Cocuzza, Matteo; Perrone, Denis; Pinti, Marcello; Cossarizza, Andrea; Pirri, Candido F; Simon, Daniel T; Berggren, Magnus; Zerbetto, Francesco; Bortolotti, Carlo A; Biscarini, Fabio Berto, Marcello; Casalini, Stefano; Di Lauro, Michele; Marasso, Simone L; Cocuzza, Matteo; Perrone, Denis; Pinti, Marcello; Cossarizza, Andrea; Pirri, Candido F; Simon, Daniel T; Berggren, Magnus; Zerbetto, Francesco; Bortolotti, Carlo A; Biscarini, Fabio

Electrolyte-gated organic field-effect transistors (EGOFETs), based on ultrathin pentacene films on quartz, were operated with electrolyte solutions whose pH was systematically changed. Transistor parameters exhibit nonmonotonic variation versus pH, which cannot be accounted for by capacitive coupling through the Debye–Helmholtz layer. The data were fitted with an analytical model of the accumulated charge in the EGOFET, where Langmuir adsorption was introduced to describe the pH-dependent charge buildup at the quartz surface. The model provides an excellent fit to the threshold voltage and transfer characteristics as a function of the pH, which demonstrates that quartz acts as a second gate controlled by pH and is mostly effective from neutral to alkaline pH. The effective capacitance of the device is always greater than the capacitance of the electrolyte, thus highlighting the role of the substrate as an important active element for amplification of the transistor response.

Replacement of the axial Met80 heme ligand in electrode-immobilized cytochrome c with a noncoordinating Ala residue and alteration of the hydrogen bonding network in the region nearby following substitution of Tyr67 were investigated as effectors of the thermodynamics and kinetics of the protein-electrode electron transfer (ET) and the heme-mediated electrocatalytic reduction of H(2)O(2). To this end, the voltammetry of the Met80Ala, Met80Ala/Tyr67His, and Met80Ala/Tyr67Ala variants of yeast iso-1-cytochrome c chemisorbed on carboxyalkanethiol self-assembled monolayers was measured at varying temperature and hydrogen peroxide concentration. The thermodynamic study shows that insertion of His and Ala residues in place of Tyr67 results mainly in differences in protein-solvent interactions at the heme crevice with no relevant effects on the E degrees' values at pH 7, which for single and double variants range from approximately -0.200 to -0.220 V (vs SHE). On the contrary, both double variants show much lower ET rates compared to Met80Ala, most likely as a consequence of a change in the ET pathways. In the present nondenaturing immobilizing conditions, and with hydrogen peroxide concentrations in the micromolar range, the variants catalyze H(2)O(2) reduction at the electrode, whereas wild-type cytochrome c does not. H(2)O(2) electrocatalysis occurs with an efficient mechanism likely involving a fast catalase-like process followed by electrocatalytic reduction of the resulting dioxygen at the electrode. Comparison of Met80Ala/Tyr67His with Met80Ala/Tyr67Ala shows that the presence of a general acid-base residue for H(2)O(2) recognition and binding through H-bonding in the distal heme site is a key requisite for the reductive turnover of this substrate.

The reduction thermodynamics ( Δ H rc ∘ ′ and Δ S rc ∘ ′ ) and the kinetics of electron transfer for spinach plastocyanin adsorbed on a polycrystalline gold electrode coated with a mixed SAM made of 11-mercapto-1-undecanol and 11-mercapto-1-undecanoic acid were determined through cyclic voltammetry. The adsorbed protein experiences a marked enthalpic stabilization of the oxidized state, likely due to the electrostatic interaction of surface lysine(s) with the negatively charged SAM. The kinetic data indicate that the electron transfer process occurs through a tunnelling mechanism and that the distance between the protein and the electrode surface can be calculated by the Marcus equation. The ionic strength of the solution remarkably affects both the thermodynamics and the kinetics of the electron transfer process in a fashion which, for the former parameters, adheres to the Debye–Huckel model.

The organic field effect transistor (OFET) is a device where a thin film of an organic semiconductor (OS) bridges a channel between source and gate electrodes. The gate electrode, separated by a dielectric thin film from the organic semiconductor, controls the charge carrier density in the organic semiconductor by capacitive coupling. OFET responds with a current between source and drain to a voltage bias applied to the gate and drain electrodes, the source being grounded. Response of OFET is measured by a set of parameters that are extracted from the current voltage characteristics as a function of the gate voltage (transfer curves) or the drain voltage (output curves). The OFET has been studied for more than two decades because of its potential applications in flexible circuits, RFID tags, wearable electronics, and back-panel active matrix displays. Although organic electronics is the main technology driver, OFET plays a central role in the fundamental studies aimed to elucidate charge transport in organic semiconductors. OFET is widely used as an experimental gauge for probing charge mobility, carrier density, and doping levels in organic thin films and nanostructures. Despite the apparent simplicity of the architecture, the device physics is more subtle and elusive. OFET response cannot be simply elicited from molecular design and crystal packing, as it is dominated by the interactions of the OS with the device interfaces. At the OS/metal electrodes, charge injection/extraction occurs; at the OS/gate dielectric interface, charge carriers are capacitively accumulated, depleted, trapped, and transported; charge carriers cross organic semiconductor domain boundaries and are scattered/trapped by morphological/structural defects; the outer OS surface is exposed to the environment. The OFET response is extremely sensitive to any change occurring at these interfaces, happening either spontaneously (like in the case of charge trapping and bias stress), accidentally (a parasitic dopant), or by design (specific interaction of an analyte with species adsorbed or grafted at the interfaces). The effect of these interfaces is intertwined in the OFET response, and it is difficult to experimentally disentangle it. On one hand, the OFET inherent instability is detrimental to electronics applications; on the other hand, it makes the device interesting for exploring new paradigms of sensing and transduction. In the past five years, an increasing trend of publications with OFETs used as (bio-)sensors is observed [1]. Advantages of OFETs with respect to more robust and established devices as CMOS are: the ease of interface tailoring toward analytes, living cells, and tissues; the use of low-cost scalable fabrication (important for single shot sensing); technology transferrable on flexible substrates with tunable mechanical compliance; a library of biocompatible and biodegradable materials, the latter yet in nuce (both crucial features for implantable devices); fabrication of devices with minimal amounts of materials (semiconductors, conductors, dielectrics, recognition groups); upscaling and integration are simpler than for resistive or amperometric sensors. This chapter looks into the OFET as a low-dimensional device and how this distinctive feature can be exploited for

Vesicles of cationic amphiphilic β-cyclodextrins have been immobilized on polycrystalline gold by exploiting the chemical affinity between their amino groups and Au atoms. The presence of cyclodextrins has been widely investigated by means of AFM, XPS, kelvin probe and electrochemical measurements. This multi-functional coating confers distinct electrochemical features such as pH-dependent behavior and partial/total blocking properties towards electro-active species. The host-guest properties of β-cyclodextrins have been successfully exploited in order to trap drugs, like dopamine and levodopa. The further release of these drugs was successfully achieved by providing specific electrical stimuli. This proof-of-concept led us to fabricate an electronic device (i.e. an organic transistor) capable of dispensing both dopamine and levodopa in aqueous solution.

Four linear terarylene molecules (i) 4-nitro-terphenyl-4″-methanethiol (NTM), (ii) 4-nitro-terphenyl-3″,5″-dimethanethiol (NTD), (iii) ([1,1′;4′,1″] terphenyl-3,5-diyl)methanethiol (TM), and (iv) ([1,1′;4′,1″] terphenyl-3,5-diyl)dimethanethiol (TD) have been synthesized and their self-assembled monolayers (SAMs) have been obtained on polycrystalline gold. NTM and NTD SAMs have been characterized by X-ray photoelectron spectroscopy, Kelvin probe measurements, electrochemistry, and contact angle measurements. The terminal nitro group (−NO2) is irreversibly reduced to hydroxylamine (−NHOH), which can be reversibly turned into nitroso group (−NO). The direct comparison between NTM/NTD and TM/TD SAMs unambiguously shows the crucial influence of the nitro group on electrowetting properties of polycrystalline Au. The higher grade of surface tension related to NHOH has been successfully exploited for basic operations of digital μ-fluidics, such as droplets motion and merging.

A model system for the electrochemical investigation of vectorial electron transfer in biological systems was designed, assembled and characterized. Gold electrodes, functionalized with a - OCH3 terminated, aromatic self-assembled monolayer, were used as a substrate for the adsorption of variants of copper-containing, redox metalloprotein azurin. The engineered azurin bears a polyhistidine tag at its C-terminus. Thanks to the presence of the solvent exposed tag, which chelates Cu2+ ions in solution, we introduced an exogenous redox centre. The different reduction potentials of the two redox centres and their positioning with respect to the surface are such that electron transfer from the exogenous copper centre and the electrode is mediated by the native azurin active site, closely paralleling electron transfer processes in naturally occurring multicentre metalloproteins. (C) 2015 Elsevier Ltd. All rights reserved.

Organic electronic transistors are rapidly emerging as ultrahigh sensitive label-free biosensors suited for point-of-care or in-field deployed applications. Most organic biosensors reported to date are based on immunorecognition between the relevant biomarkers and the immobilized antibodies, whose use is hindered by large dimensions, poor control of sequence, and relative instability. Here, an electrolyte-gated organic field effect transistor (EGOFET) biosensor where the recognition units are surface immobilized peptide aptamers (Affimer proteins) instead of antibodies is reported. Peptide aptasensor for the detection of the pro-inflammatory cytokine tumor necrosis factor alpha (TNF alpha) with a 1 x 10(-12) M limit of detection is demonstrated. Ultralow sensitivity is met even in complex solutions such as cell culture media containing 10% serum, demonstrating the remarkable ligand specificity of the device. The device performances, together with the simple one-step immobilization strategy of the recognition moieties and the low operational voltages, all prompt EGOFET peptide aptasensors as candidates for early diagnostics and monitoring at the point-of-care. Funding Agencies|IT MIUR Bilateral Project Italy/Sweden "Poincare"; INFM-CNR Project "EOS - Organic electronics for innovative measuring instruments"; Life Science Department through "FAR"; "Fondazione di Vignola"

There is a quest for electronic biosensors operated in water for biomedical applications and environmental monitoring. Water is an aggressive medium for standard electronics materials and devices due to its strong polarizability and electrochemical activity. Thick dielectric encapsulation provides necessary stability while it damps the sensitivity of the device to sensing events occurring in the aqueous environment. Organic electronics provides materials that exhibit stable electronic conduction in direct contact with water combined with other desirable properties like mechanical softness, biocompatibility and processability onto flexible substrates. In this review, we introduce an emerging class of organic transistors, in which the current across the organic film is gated by the electric field of the Debye-Helmholtz layer. We discuss the device physics, the sensing mechanism and the relevant electrochemical processes. Applications of water-gated transistors range from the sensing of biologically relevant molecules like DNA, proteins or hormones to non-invasive recording and stimulation of electrical activity of neurons. Materials chemistry is crucial to control properties of electrically active films and to allow the introduction of specific chemical functionalities and receptors at sensing interfaces of the device. © 2013 The Royal Society of Chemistry.

Made available in DSpace on 2018-12-11T17:30:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01 Water-gated organic transistors have been successfully exploited as potentiometric transducers in a variety of sensing applications. The device response does not depend exclusively on the intrinsic properties of the active materials, as the substrate and the device interfaces play a central role. It is therefore important to fine-tune the choice of materials and layout in order to optimize the final device performance. Here, polyethylene naphthalate (PEN) has been chosen as the reference substrate to fabricate and test flexible transistors as bioelectronic transducers in liquid. PEN is a biocompatible substrate that fulfills the requirements for both bio-applications and micro-fabrication technology. Three different semiconducting or conducting polymer thin films employing pentacene, poly(3-hexylthiophene) or poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) were compared in terms of transconductance, potentiometric sensitivity and response time. The different results allow us to identify material properties crucial for the optimization of organic transistor-based transducers operating in water. Dipartimento di Scienze della Vita Università di Modena and Reggio Emilia (UNIMORE), Via Campi 103 Programa de Pós-graduação em Ciência e Tecnologia de Materiais (POSMAT) Universidade Estadual Paulista (UNESP) Istituto per Lo Studio Dei Materiali Nanostrutturati (ISMN) Consiglio Nazionale Delle Ricerche (CNR), Via Gobetti n.101 Departamento de Física Química e Matemática (DFQM) Universidade Federal de São Carlos (UFSCar) ST Microelectronics Analog and MEMS Group (AMG), Str. Primosole 50 ST Microelectronics Analog and MEMS Group (AMG), Via Remo de Feo 1 Faculdade de Ciências e Tecnologia (FCT) Universidade Estadual Paulista (UNESP) Laboratório Nacional de Nanotecnologia (LNNano) Centro Nacional de Pesquisa em Energia e Materiais (CNPEM) Institut de Ciéncia de Materials de Barcelona (ICMAB) Consejo Superior de Investigaciones Cientifica (CSIC) University of Cambridge Electrical Engineering Division, 9 JJ Thomson Avenue Programa de Pós-graduação em Ciência e Tecnologia de Materiais (POSMAT) Universidade Estadual Paulista (UNESP) Faculdade de Ciências e Tecnologia (FCT) Universidade Estadual Paulista (UNESP)

Pentacene ultra thin film transistors were exposed to water and operated with a conventional silicon/silicon oxide bottom gate and an electrolyte top gate controlled by a working electrode. The transistors are highly sensible (mu V) to the electrochemical potential of the aqueous electrolyte. We show that dual gate operation permits the measurement of the double layer capacitance, C-DL = 14.6 mu F/cm(2). The device exhibits a fast (4.6 ms) and stable response, without bias stress as opposed to conventional bottom gate operations, when controlled with the electrolyte gate. These features make the device a promising candidate for potentiometric transducers required for non-invasive electrophysiology. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3699218]

Self-Assembly Monolayers (SAMs) are considered a promising route for solving technolog-ical hindrances (such as bias-stress, contact resistance, charge trapping) affecting the elec-trical performances of the Organic Field-Effect Transistors (OFETs). Here we use an OFETbased on pentacene thin film to investigate the charge transport across conjugated SAMsat the Au/pentacene interface. We synthesized a homolog series of p -conjugated mole-cules, termed Tn-C8-SH, consisting of a n-unit oligothienyl Tn (n =1...4) bound to anoctane-1-thiol (C8-SH) chain that self-assembles on the Au electrodes. The multi-paramet-ric response of such devices yields an exponential behavior of the field-effect mobility ( l ),current density (J), and total resistivity (R), due to the SAM at the charge injection interface(i.e. Au-SAM-pentacene). The surface treatment of the OFETs induces a clear stabilization ofdifferent parameters, like sub-threshold slope and threshold voltage, thanks to standard-ized steps in the fabrication process. 2012 Elsevier B.V. All rights reserved.

The Met80Ala variant of yeast iso-1 -cytochrome c, immobilized on a gold electrode, is found to exchange electrons efficiently with it in nondenaturing conditions and to provide robust and persistent catalytic currents for O 2 and nitrite ion reduction from pH 3 to 11. Direct covalent protein linkage to gold yields the best electrochemical and electrocatalytic performances without drastically affecting the structural properties of the bound protein compared to the freely diffusing species. Therefore, this biocatalytic interface can be of use for the amperometric detection of the above species, which are of great environmental, industrial, and clinical interest, with particular reference to the exploitation in nanostructured biosensing devices. This work shows that the use of a small engineered electron transfer (ET) protein, featuring an axial heme iron coordination position available for the binding of exogenous ligands, in place of a large heme enzyme is a viable strategy for the improvement of the heterogeneous ET rate and the stability and efficiency of sensing gold-protein interfaces over a wide range of Tand pH.

The M80A variant of yeast i so- I -cytochrome c (cytc), which features a noncoordinating Ala residue in place of the axial heme iron Met ligand, was chemisorbed on a gold electrode coated with 4-mercaptopyridine or carboxyalkanethiol self-assembled monolayers (SAM) and investigated by cyclic voltammetry at varying conditions of temperature, pH, and 02 concentration. The E degrees' value (standard reduction potential for the heme Fe(III)/Fe(II) couple) of M80A cytc on both SAMs is of approximately-200 mV (vs the standard hydrogen electrode, SHE) at pH 7, which is more than 400 mV lower than that of native cytochrome c in the same conditions. The thermodynamics of Fe(III) to Fe(II) reduction and the kinetics of heterogeneous electron transfer (ET) are dominated by the presence of a hydroxide ion as the sixth axial heme iron ligand above pH 6. On both SAMs, protonation of the bound hydroxide ion is mainly responsible for the changes in these parameters at low pH, since the distances of ET between the heme and the electrode are found to be independent of pH in the range of 5-11 The invariance of the electrochemical features up to pH I I indicates that no changes in heme iron coordination occur at high pH, at variance with native cytc. Most notably, immobilized M80A cytc is found to act as an efficient biocatalyst for O-2 reduction from pH 5 to 11.0. This finding makes M80A cytc a suitable candidate as a constituent of a biocatalytic interface for O-2 biosensing and opens the way for the exploitation of engineered cytochrome c in the bio-based detection of chemicals of environmental and clinical interest.

Alkanethiol Self-Assembly Monolayers (SAMs) were investigated by means of BiModal Atomic Force Microscopy. Morphological and mechanical properties show a parabolic trend vs. the chain length n, which is ascribed to the disorder at the SAMs/Au interface. This explains the trend of charge injection across SAMs in organic field effect transistors.