Aptamer Immobilization on SiC


Inorganic semiconductors combined with bio-organic systems offer the potential for the development of a wide range of novel hybrid devices. In particular in the emerging area of hybrid organic/inorganic semiconductor interfaces for bioelectronic devices, there is a continuous need of developing new functional materials with improved properties. In this context, wide band gap semiconductors have attained increased interest as particulary promising substrates  for the development of novel biosensing devices. SiC in particular is mechanically robust, chemically inert, non toxic and biocompatible and, thanks to its transparency for the visible light, can be used for in situ observation of living cell growth. The different polytypes of SiC are quite well matched to organic systems in terms of band gap and band alignment. In this project we have focused our first investigations on the covalent immobilization on 6H-SiC surfaces of peptide nucleic acid oligonucleotides, which are receptors for DNA hybridization.



 

Cyclic voltammetry for PNA functionalization on SiC and PNA/DNA hybrid formation.

In contrast to DNA, PNA does not have an anionic phosphate backbone, and is therefore uncharged at neutral pH. The lack of repulsion between PNA and DNA results in enhanced hybridization efficiency and increased melting temperatures, properties which make PNA an ideal receptor in many biosensing applications. Characterization by cyclic voltammetry shows that it is possible to detect electrochemically the attachment of a PNA single strand to 4H-SiC as well as the hybridization with a complementary DNA strand, because the oligonucleotides significantly influence the charge transfer characteristics across the interface. In the frame of this project we want to test further our platform to the designed immobilization of proteins on SiC trough aptamer hybridization. Aptamers are artificial nucleic acids with specific binding affinity and selectivity for amino acids, drugs, proteins, and other small molecules and have potential applications as a recognition element in analytical and diagnostic assays. Since aptamers can be synthesized at low cost via in vitro procedures, the easy modification of the aptamer sequence with a complementary tag for the specific binding to the PNA moieties can allow to regulate immobilization of different aptamer sequences on the device surface. In this sense preliminary studies, using a thrombine-aptamer complex immobilized on a 4H-SiC electrode, have shown the potentiality of this approach.

Selected Publications:

Auernhammer M.; Schoell S.J.; Sachsenhauser M.; Liao K.-C.; Schwartz J.; Sharp I. D.; Cattani-Scholz A. “Surface Functionalization of 6H-SiC Using Organophosphonate Monolayers”, Applied Physics Letters 2012, 100, 101601.

Cattani-Scholz, A.; Pedone, D.; Blobner, F.; Abstreiter, G.; Schwartz, J.; Tornow, M.; Andruzzi, L. “PNA-PEG Modified Silicon Platforms as Functional Bio-interfaces for Applications in DNA Microarrays and Biosensors”, Biomacromolecules2009, 10, 489-496.

Collaborations:

Matthias Sachsenhauser, WSI, Technische Universität München

Ian Sharp, Lawrence Berkeley National Laboratory, USA

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
 

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