PNA/DNA Hybridization on Si Nanowires

The central goal of this research project is the investigation and optimization of the structural, electronic and electrochemical properties of organophosphonate functionalized silicon-based nanowire field effect devices. The devices rely on detecting changes in the electrical surface potential that occur as a result of adsorbing charged DNA. This signal transduction mechanism is free from the need to modify the target DNA molecules by, for example, fluorescent dyes; hence it constitutes a label-free detection method. To minimize hampering electrolyte screening effects a suitable organic interface is needed to provide high density of receptor binding sites at a short distance to the semiconductor sensing surface. To this end, we focus our research on the biofunctionalization of silicon oxide-terminated surfaces with peptidic nucleic acid (PNA), an analogue of DNA.


XPS spectra of the N1s region of a SAMP modified only with the linker(black) and after additional modification with PNA (red).

Functionalization by attachment groups at the γ-points along the PNA backbone allows for multidentate binding of the PNA receptor in a lying configuration on the device surface, with potential advantages towards tackling the counter-ion screening problem at the sensor interface. PNA is chosen because of its high biological stability and its significantly higher affinity for complementary DNA, allowing for a greater signal-to-noise ratio detection capabilities. Current investigations are based on the detailed characterization of the novel functional interfaces by means of atomic force microscopy (AFM), ellipsometry, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and in particular by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Future work will focus on the reduction of non-specific DNA adsorption effects and monolithic integration of these sensor structures into microfluidic systems for reliable molecular DNA/RNA detection in disease diagnostics.

Selected Pubblications:

De A., Keim K., Tornow M.,Cattani-Scholz A. “Horizontal γ-PNA immobilization through organophosphonate chemistry for biosensing applications”, Nanotechnology IEEE Nano 2015, 1568-1571.

Cattani-Scholz, A.; Pedone, D.; Dubey, M.; Neppl, S.; Nickel, B.; Feulner, P.; Schwartz, J.; Abstreiter, G.; Tornow, M. “Organophosphonate-based PNA-functionalization of silicon nanowires for label-free DNA detection”, Acs Nano 2008,2, (8), 1653-1660.


Luca Selmi, DIEGM - Università di Udine, Italy

Marc Tornow, Molekularelektronik, Technische Universität München

Open Positions:

if you would like to join us as an internship or master student on this project, please contact Anna Cattani-Scholz


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

Events & News

17 Jan 2018

ERC Consolidator Grant for Gregor Koblmüller   more

16 Jan 2018

Light-steering of spin-polarized currents in topological insulators   more

10 Aug 2017

Best Poster Awards for Ganpath Veerabathran and Alexander Andrejew at iNOW 2017   more

27 Jun 2017

Best Poster Award at Nanowire Week for Jochen Bissinger   more

15 Mar 2017

Dr. Kai Müller admitted to the “Junges Kolleg” of the Bavarian Academy of Sciences   more


March 12, 2018

Two-dimensional coherent spectroscopy of a semiconductor microcavity   more

March 05, 2018

Diamond-organic photovoltaics   more