Doctoral College TU-D Unravelling advanced 2D materials
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Surface modification and biosensing applications

H. Mikula, http://www.ias.tuwien.ac.at/home/

Research in the HM group focuses on bioorthogonal reactions, in vivo chemistry, chemical biology and novel chemical tools for the development of diagnostic tools including biosensors. We use fast and selective reactions for the design of chemical probes that can be used for molecular and medical imaging [HM 1, HM 2]. Furthermore, we are interested in small molecules as organic semiconductors that can be applied for the fabrication of electronic devices towards biosensing applications [HM 3]. Using click chemistry strategies we aim for easy and highly selective modification of sensor surfaces with biorecognition units (proteins, DNA/RNA aptamers, small molecules, antibodies, etc.). In collaboration with international partners we also focus on in vivo chemistry supported by nanoparticles.

PhD Project 1: Surface modifications using bioorthogonal chemistry

Co-supervisor: Ulrike Diebold

One of the greatest potentials of organic electronics is the realization of miniaturized, or even implanted, biosensors as low-cost point-of-care devices, capable of label-free, selective detection of analytes (e.g. biomarkers, pathogens) while creating an electronic read out for user friendly interaction. The materials of choice for these devices are 2D materials (e.g. graphene, CNTs) as they incorporate both superior electrical properties and extraordinary stability in biomedical relevant media. Key for realizing these sensitive and selective sensors is the endowment of highly specific biorecognition units such as antibodies, proteins or DNA/RNA aptamers onto the surface of the 2D materials.
This project is designed to use bioorthogonal click chemistry to achieve this functionalization by enabling a facile and highly versatile strategy toward various surface modifications. Bioorthogonal click chemistry is a very robust tool and does not require additional reagents or catalysts and can even be carried out in vivo. Additionally, site specific modifications of proteins open up the possibility of enhanced sensing performance as a result of optimized structure property investigations. The biosensors consist of a graphene-based field-effect transistor (gFET) (fabricated in collaboration with DK members DE and TM) endowed with covalently or non-covalently attached (bio)recognition units to the graphene surface, whose specific interactions with analytes changes the electrical current flowing between the electrodes. Extensive characterization of functionalized 2D surfaces will include XPS, ToF SIMS, XRD, STM and Raman-AFM techniques and are prerequisites for the final electrical characterization. As a first step toward novel biosensors first prototypes will be fabricated on commercially available rigid Si-wafers before moving to flexible substrates and implementation of microfluidic cells. In order to prevent non-specific binding interactions of the 2D materials with matrix elements, we will employ atomic layer deposition (ALD) as a unique and novel technique to deposit ultrathin, conformal coatings of high-k dielectrics onto the 2D materials.

PhD Project 2: Fabrication of self-assembled monolayers through click chemistry

Co-supervisor: Dominik Eder

This project focuses on the application of (dual) click chemistry strategies for the fabrication of self-assembled monolayers (SAM) as bottom-up 2D materials for surface modification and functionalization. Self-assembly is the autonomous organization of components into patterns and structures and holds great potential for a number of new applications. SAM molecules typically consist of an anchor group, a spacer and a functional head group. The anchor group is capable of attaching the SAM covalently to a metal oxide surface, thus eliminating other surface reactions and ensuring the formation of only a single layer. The spacers ensure the upright orientation of the molecules and a dense packing as a result of van-der-Waals forces between the chains. By varying the functional head groups a powerful tool for tuning surface chemistry is obtained leading to new properties and applications. Within this project click chemistry will be applied to modify interlayers of perovskite solar cells. As an example fullerenes (C60) will be used as carbon-based functional head groups to generate self-assembled monolayers with the aim of enhancing solar cell efficiency.


Literature

  1. Denk C., Svatunek D., Filip T., Wanek T., Lumpi D., Fröhlich J., Kuntner C. and Mikula H.* Development of a 18F-Labeled Tetrazine with Favorable Pharmacokinetics for Bioorthogonal PET Imaging. Angewandte Chemie International Edition 53, 9655–9659 (2014) DOI: 10.1002/anie.201404277
  2. Kim E., Yang K. S., Kohler R. H., Dubach J. M., Mikula H., Weissleder R. Optimized Near-IR Fluorescent Agents for in Vivo Imaging of Btk Expression. Bioconjugate Chemistry 26, 1513-1518 (2015) DOI: 10.1021/acs.bioconjchem.5b00152
  3. Bintinger J., Yang S., Mikula H., Fruhmann P., Holzer B., Stöger B., Svirkova A., Marchetti-Deschmann M., Horkel E., Hametner C., Kymissis I., Fröhlich J. Synthesis, Characterization and Printing Application of Alkylated Indolo[3,2-b]carbazoles. Submitted manuscript (2016)