Aligned carbon nanotube thin films for genosensor development

Francesca Berti 1Giovanna Marrazza 1Ilaria Palchetti 1Marco Mascini 1Luca Lozzi 2Sandro Santucci 2Guido Faglia 3Giorgio Sberveglieri 3

1. Dipartimento di Chimica, Università di Firenze (UNIFI), Via della Lastruccia 3, Sesto Fiorentino (Firenze) 50019, Italy
2. Department of Physics, University of L'Aquila (Unita INFM), Coppito, L'Aquila 67020, Italy
3. INFM & UNIVERSITY OF BRESCIA (INFM), VIA VALOTTI 9, Brescia 25133, Italy

Abstract

In the last decade, the synthesis of various nanomaterials such as nanowires, nanotubes and nanocrystals has attracted immense attention due to their potential to serve as building blocks for the development of nanoscale biosensor devices. In this work carbon nanotube (CNTs) thin films were designed and tested as working electrode for DNA immobilisation and for the development of an electrochemical genosensor. Carbon nanotubes are promising materials for DNA electrochemical sensing due to their unique electric properties: high surface area, fast heterogeneous electron transfer, electrochemical stability. Self-assembled aligned CNT thin films were prepared by Chemical Vapor Deposition (CVD) onto silicon oxide substrate, using acetylene and ammonia as precursor gases and nickel particles as catalyst. The electrochemical characteristics of these surfaces were obtained studying the electron transfer rates of potassium ferricyanide redox couple under different experimental conditions in Cyclic Voltammetry (CV) experiments. Scanning Electrochemical Microscopy (SECM) has been employed in the feedback mode to increase the information regarding the electrochemical behaviour of the carbon nanostructured materials. The surface was then functionalised with oligonucleotide DNA-probe by covalent immobilisation. The immobilised oligonucleotides are complementary to the sequence of the most common inserts in the GMOs: the Promoter 35S. The biosensor format involves the immobilisation of a probe onto the carbon nanotubes sensor surface, the hybridisation reaction and the square wave voltammetric detection of the duplex formation. Careful attention to the probe immobilisation conditions is crucial for minimizing the signal due to non-specifically adsorbed sequences. Other relevant experimental parameters such as ionic strength, hybridisation time, the use of hybridisation accelerators were examined and optimised.

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Presentation: Short communication at SMCBS'2007 International Workshop, by Francesca Berti
See On-line Journal of SMCBS'2007 International Workshop

Submitted: 2007-08-29 18:13
Revised:   2009-06-07 00:44
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