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Ravi Kumar
Dr. Ravi Kumar
ravi kumarQti1∂kit edu

Immobilization via Click-Chemistry DPN and PPL


The currently most widely spread strategy for covalent attachment of molecules to surfaces by DPN is the use of thiol-gold binding. This method allows for very high resolution (<20 nm), but the limitation to gold surfaces can be problematic for many tasks. Therefore, we follow the approach to transfer reactions from the well established click chemistry tool box (e.g. the copper-catalized azide-alkyne-cycloaddition (CuAAC) or thiol-based click reactions) to DPN. This opens up the use of new classes of compounds as ink and new substrates. The fluorescence microscopy image on the right shows a alexa-555-azide structure on a modified glass substrate. The line width (measured by atomic force microscopy) is about 100 nm. The image below shows a multiplexed pattern of alexa-555-azide (red) and fluorescently labeled streptavidin (green) bound in solution over a biotin-thiol on a multivalent surface. The click-chemistry structures are bio-compatible and can be used for cell culture applications (below right). A click-chemistry DPN generated structure with alexa-555-azide.
         Cells on Protein Pattern

Left: An alexa-555-azide (red) / biotin-thiol structure on a multivalent surface coating. A fluorescent protein (green) was bound to the biotin in a second step. Right: Fibroblast cells on a biotin-azide / neutravidin / biotin-fibronectin sandwich structure.


Selected publications:

Click-Chemistry Based Multi-Component Microarrays by Quill-Like Pens

M. Hirtz, A. M. Greiner, T. Landmann, M. Bastmeyer, H. Fuchs
Adv. Mater. Interfaces 1 (2014) 1300129, DOI:10.1002/admi.201300129 

Facile modification of silica substrates provides a platform for direct-writing surface click chemistry
S. Oberhansl, M. Hirtz, A. Lagunas, R. Eritja, E. Martinez, H. Fuchs, J. Samitier
Small 8 (2012) 541–545, DOI:10.1002/smll.201101875 


Substrate-independent dip-pen nanolithography based on reactive coatings
H. Y. Chen, M. Hirtz, X. Deng, T. Laue, H. Fuchs, J. Lahann
J. Am. Chem. Soc. 132 (2010) 18023-18025, DOI:10.1021/ja108679m