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Highly Conductive Redox Protein–Carbon Nanotube Complex for Biosensing Applications

Authors

  • Chiara Baldacchini,

    Corresponding author
    1. Biophysics and Nanoscience Centre and CNISM, Facoltà di Scienze, Università della Tuscia, Largo dell’Università, 01100 Viterbo, Italy
    2. Institute of Agro-environmental and Forest Biology – IBAF, National Research Council – CNR, Via Marconi 2, 05010 Porano, TR, Italy
    • Biophysics and Nanoscience Centre and CNISM, Facoltà di Scienze, Università della Tuscia, Largo dell’Università, 01100 Viterbo, Italy.
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  • Maria Antonia Herrero Chamorro,

    1. Dipartimento di Scienze Farmaceutiche, Università di Trieste, Piazzale Europa 1, 34127 Trieste, Italy
    Current affiliation:
    1. Present address: Departamento de Química Orgánica – IRICA, Facultad de Química, IRICA, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
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  • Maurizio Prato,

    1. Dipartimento di Scienze Farmaceutiche, Università di Trieste, Piazzale Europa 1, 34127 Trieste, Italy
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  • Salvatore Cannistraro

    1. Biophysics and Nanoscience Centre and CNISM, Facoltà di Scienze, Università della Tuscia, Largo dell’Università, 01100 Viterbo, Italy
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Abstract

The integration of redox proteins with nanomaterials has attracted much interest in the past years, and metallic single-walled carbon nanotubes (SWNTs) have been introduced as efficient electrical wires to connect biomolecules to metal electrodes in advanced nano-biodevices. Besides preserving biofunctionality, the protein–nanotube connection should ensure appropriate molecular orientation, flexibility, and efficient, reproducible electrical conduction. In this respect, yeast cytochrome c redox proteins are connected to gold electrodes through lying-down functionalized metallic SWNTs. Immobilization of cytochromes to nanotubes is obtained via covalent bonding between the exposed protein thiols and maleimide-terminated functional chains attached to the carbon nanotubes. A single-molecule study performed by combining scanning probe nanoscopies ascertains that the protein topological properties are preserved upon binding and provides unprecedented current images of single proteins bound to carbon nanotubes that allow a detailed IV characterization. Collectively, the results point out that the use as linkers of suitably functionalized metallic SWNTs results in an electrical communication between redox proteins and gold electrodes more efficient and reproducible than for proteins directly connected with metal surfaces.

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