Diamond Microelectrodes

Most biosensors are hybrid devices composed of a bioreceptor, responsible for the selective recognition of the analyte, and a transducer, transforming the signal generated by the recognition reaction into one suitable for further processing and electronic readout. The basic concept of an amperometric biosensor is shown schematically in the figure below. In this type of biosensor an enzymes serve as bioreceptors. Enzymes are proteins catalyzing chemical reactions – usually very selectively. For an enzymatic redox reaction, the associated charge transfer can be detected by measuring a current via the diamond electrode.
The nanocrystalline diamond (NCD) electrode serves as the transducer. Diamond exhibits outstanding properties which render it very well suited as an electrode material interfacing biological systems. Mechanical stability, chemical inertness, and the wide electrochemical window allow application in harsh environments. At the same time diamond shows excellent bio-compatibility. Nanocrystalline diamond films can be grown on various substrates by microwave plasma-assisted chemical vapor deposition (MPCVD). The electronic properties can be defined by doping with boron or phosphorous, which is achieved by mixing suitable precursor gases into the plasma during the growth. By selective nucleation with diamond nanoparticles, patterned diamond structures can be grown. Many of these small electrodes, which can all serve as individual biosensors, can be integrated on a single sensor chip.

Controlled immobilization of enzymes is essential in the design of this type of biosensor. The most common grafting technique is covalent attachment using self assembled monolayers (SAMs) of linker molecules. In cooperation with the Wacker Chair of Macromolecular Chemistry we investigate protein immobilization via polymer brushes. In a first step, polymers are grown on the diamond surface by self-initiated photo-grafting and photo-polymerization. With this technique no extensive pretreatment of the surface is necessary to initiate polymerization – a termination with hydroxyl groups is sufficient. Proteins can be directly tethered along polymers built up from monomers exhibiting suitable functional groups. Alternatively, in a second step side chains can be generated by graft-polymerization, providing additional functionalities, for example conductive groups to enhance charge transfer from proteins immobilized along the polymer farther away from the NCD electrode. The advantages of this approach include providing a more natural environment for the proteins, a higher loading density of proteins per surface area (hence a possibly stronger signal), and a more tunable system with respect to properties such as hydrophilicity, grafting density, additional functionalities, etc.

 

People on the project:

Andreas Reitinger, Franz Fuchs

 

Selected publications:

  • Microstructured poly(2-oxazoline) bottle-brush brushes on nanocrystalline diamond
    Naima A. Hutter, Andreas A. Reitinger, Ning Zhang, Marin Steenackers, Oliver A. Williams, Jose A. Garrido, Rainer Jordan
    Physical Chemistry Chemical Physics 12, 4360 – 4366 (2010)
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  • Nanostructured Polymer Brushes and Protein Density Gradients on Diamond by Carbon Templating
    Naima A. Hutter, Marin Steenackers, Andreas A. Reitinger, Oliver A. Williams, Jose A. Garrido, Rainer Jordan
    Submitted (2010)
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  • Submitted Protein-modified nanocrystalline diamond thin films for biosensor applications
    Andreas Härtl, Evelyn Schmich, Jose A. Garrido, Jorge Hernando, Silvia C.R. Catharino, Stefan Walter, Peter Feulner, Alexander Kromka, Doris Steinmüller, Martin Stutzmann
    Nature Materials 3, 736 – 742 (2004)
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  • Synthetic Nanocrystalline Diamond as a Third- Generation Biosensor Support
    Jorge Rubio-Retama, Jorge Hernando, Beatriz Lopez-Ruiz, Andreas Härtl, Doris Steinmüller, Martin Stutzmann, Enrique Lopez-Cabarcos, Jose Antonio Garrido
    Langmuir 22 (13), 5837 – 5842 (2006)
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  • Chemical Grafting of Biphenyl Self-Assembled Monolayers on Ultrananocrystalline Diamond
    Simon Q. Lud, Marin Steenackers, Rainer Jordan, Paola Bruno, Dieter M. Gruen, Peter Feulner, Jose A. Garrido, Martin Stutzmann
    Journal of the American Chemical Society 128 (51), 16884 – 16891 (2006)
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Cooperations:

WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München

Laboratoire Capteurs Diamant , Commissariat à l’énergie atomique (CEA LIST), France

Oliver Williams, Fraunhofer-Institut für Angewandte Festkörperphysik IAF Freiburg

Rainer Jordan, Professur Makromolekulare Chemie, Technische Universität Dresden

 

Funding:

International Graduate School of Science and Engineering (IGSSE), Project 2.12 “Diamond-based biosensor arrays”

MATCON

TUM Technische Universität München TUM Technische Universität München Physik Department Elektrotechnik und Informationstechnik TUM Technische Universität München
 

Upcoming Events

3.06.2013  
Benno Blaschke
Graphene SGFETs for biosensing applications

poster, Graphene Week 2013, Chemnitz, Germany

 

6.06.2013  
Jose A. Garrido
Graphene sensors for bioelectronic applications

plenary talk, Graphene Week 2013, Chemnitz, Germany

 

3.09.2013  
Roberta Caterino 
Novel functionalization of diamond surfaces for protein-based hybrid systems

talk, International Conference on Diamond and Carbons Materials, Riva del Garda, Italy

 

5.09.2013 
Roberta Caterino
Bio-photovoltaics based on hybrid systems of reaction centers and diamond

talk, International Conference on Diamond and Carbons Materials, Riva del Garda, Italy