Yazar "Osella, Silvio" seçeneğine göre listele

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    Diazonium-Based Covalent Molecular Wiring of Single-LayerGraphene Leads to Enhanced Unidirectional PhotocurrentGeneration through the p-doping Effect
    (Amer Chemical Soc, 2022) Jacquet, Margot; Osella, Silvio; Harputlu, Ersan; Palys, Barbara; Kaczmarek, Monika; Nawrocka, Ewa K.; Rajkiewicz, Adam A.
    Development of robust and cost-effective smart materials requiresrational chemical nanoengineering to provide viable technological solutions for awide range of applications. Recently, a powerful approach based on theelectrografting of diazonium salts has attracted a great deal of attention due to itsnumerous technological advantages. Several studies on graphene-based materialsreveal that the covalent attachment of aryl groups via the above approach could leadto additional beneficial properties of this versatile material. Here, we developed thecovalently linked metalorganic wires on two transparent, cheap, and conductivematerials:fluorine-doped tin oxide (FTO) and FTO/single-layer graphene (FTO/SLG). The wires are terminated with nitrilotriacetic acid metal complexes, whichare universal molecular anchors to immobilize His6-tagged proteins, such asbiophotocatalysts and other types of redox-active proteins of great interest inbiotechnology, optoelectronics, and artificial photosynthesis. We show for thefirsttime that the covalent grafting of a diazonium salt precursor on two differentelectron-rich surfaces leads to the formation of the molecular wires that promote p-doping of SLG concomitantly with a significantlyenhanced unidirectional cathodic photocurrent up to 1 mu Acm-2. Density functional theory modeling reveals that the exceptionallyhigh photocurrent values are due to two distinct mechanisms of electron transfer originating from different orbitals/bands of thediazonium-derived wires depending on the nature of the chelating metal redox center. Importantly, the novel metalorganic interfacesreported here exhibit minimized back electron transfer, which is essential for the maximization of solar conversion efficiency.
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    Enhancement of direct electron transfer in graphene bioelectrodes containing novel cytochrome c553 variants with optimized heme orientation
    (Elsevier Science Sa, 2021) Izzo, Miriam; Osella, Silvio; Jacquet, Margot; Kiliszek, Malgorzata; Harputlu, Ersan; Starkowska, Alicja; Lasica, Anna
    The highly efficient bioelectrodes based on single layer graphene (SLG) functionalized with pyrene self-assembled monolayer and novel cytochrome c(553) (cyt c(553)) peptide linker variants were rationally designed to optimize the direct electron transfer (DET) between SLG and the heme group of cyt. Through a combination of photoelectrochemical and quantum mechanical (QM/MM) approaches we show that the specific amino acid sequence of a short peptide genetically inserted between the cyt c(553) - holoprotein and the surface anchoring C-terminal His s -tag plays a crucial role in ensuring the optimal orientation and distance of the heme group with respect to the SLG surface. Consequently, efficient DET occurring between graphene and cyt c(553) leads to a 20-fold enhancement of the cathodic photocurrent output compared to the previously reported devices of a similar type. The QM/MM modeling implies that a perpendicular or parallel orientation of the heme group with respect to the SLG surface is detrimental to DET, whereas the tilted orientation favors the cathodic photocurrent generation. Our work confirms the possibility of fine-tuning the electronic communication within complex bio-organic nanoarchitectures and interfaces due to optimization of the tilt angle of the heme group, its distance from the SLG surface and optimal HOMO/LUMO levels of the interacting redox centers. (C) 2021 The Authors. Published by Elsevier B.V.
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    Molecular mechanism of direct electron transfer in the robust cytochrome-functionalised graphene nanosystem
    (Royal Soc Chemistry, 2021) Jacquet, Margot; Kiliszek, Malgorzata; Osella, Silvio; Izzo, Miriam; Sar, Jaroslaw; Harputlu, Ersan; Unlu, C. Gokhan
    Construction of green nanodevices characterised by excellent long-term performance remains high priority in biotechnology and medicine. Tight electronic coupling of proteins to electrodes is essential for efficient direct electron transfer (DET) across the bio-organic interface. Rational modulation of this coupling depends on in-depth understanding of the intricate properties of interfacial DET. Here, we dissect the molecular mechanism of DET in a hybrid nanodevice in which a model electroactive protein, cytochrome c(553) (cyt c(553)), naturally interacting with photosystem I, was interfaced with single layer graphene (SLG) via the conductive self-assembled monolayer (SAM) formed by pyrene-nitrilotriacetic acid (pyr-NTA) molecules chelated to transition metal redox centers. We demonstrate that efficient DET occurs between graphene and cyt c(553) whose kinetics and directionality depends on the metal incorporated into the bio-organic interface: Co enhances the cathodic current from SLG to haem, whereas Ni exerts the opposite effect. QM/MM simulations yield the mechanistic model of interfacial DET based on either tunnelling or hopping of electrons between graphene, pyr-NTA-M2+ SAM and cyt c(553) depending on the metal in SAM. Considerably different electronic configurations were identified for the interfacial metal redox centers: a closed-shell system for Ni and a radical system for the Co with altered occupancy of HOMO/LUMO levels. The feasibility of fine-tuning the electronic properties of the bio-molecular SAM upon incorporation of various metal centers paves the way for the rational design of the optimal molecular interface between abiotic and biotic components of the viable green hybrid devices, e.g. solar cells, optoelectronic nanosystems and solar-to-fuel assemblies.
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    Role of Metal Centers in Tuning the Electronic Properties of Graphene-Based Conductive Interfaces
    (Amer Chemical Soc, 2019) Osella, Silvio; Kiliszek, Malgorzata; Harputlu, Ersan; Unlu, Cumhur G.; Ocakoglu, Kasim; Trzaskowski, Bartosz; Kargul, Joanna
    A major bottleneck in the fabrication of efficient bio-organic nanoelectronic devices resides in the strong charge recombination that is present at the different interfaces forming the complex system. An efficient way to overcome this bottleneck is to add a self-assembled monolayer (SAM) of molecules between the biological material and electrode that promotes an efficient direct electron transfer while minimizing wasteful processes of charge recombination. In this work, the presence of a pyrene-nitrilotriacetic acid layer carrying different metal centers as the SAM is physisorbed on graphene is fully described by means of electrochemical analysis, field-emission scanning electron microscopy, photoelectrochemical characterization, and theoretical calculations. Our multidisciplinary study reveals that the metal center holds the key role in the efficient electron transfer at the interface. While Ni2+ is responsible for the electron transfer from the SAM to graphene, Co2+ and Cu2+ force an opposite transfer from graphene to SAM. Moreover, since Cu2+ inhibits the electron transfer due to a strong charge recombination, Co2+ seems to be the transition metal of choice for the efficient electron transfer.