The formation of defined structures on opportune substrates in the micro- and nano-metric scale is one of the major goal of modern science. Moreover, with the aim of miniaturized and integrated device fabrication, it is attractive to realize biological micropatterned surfaces.

 Scanning probe microscopy (SPM) has also been considered as a novel instrument for engineering of sophisticated nano and micrometer-scale material and devices. [1] Among various SPMs techniques, Scanning Electrochemical Microscopy (SECM) is a very flexible tool, which can be used for a wide variety of surface analyses; this technique is based on a ultramicroelectrode in close proximity to a substrate, this feature was proven to be a powerful means to obtain surface chemical information of conducting and not conducting surfaces with high spatial resolution. During the past decade SECM has widely used, not only for imaging surfaces, but also for local surface modifications. [2] In the present work we use SECM for in situ surface modification and patterning. Two different methods inducing reactivity in a substrate according to a specific pattern are reported.

The first method is based on local modification of self assembled monolayer (SAM) of thiols on gold. The SECM microelectrode is used for  local and defined desorption of thiols. [3] The realized pattern of discovered gold can be then filled with a thiol different from the initial one and holding moieties suitable to fix biological molecules, such as proteins.

   The second investigated method is based on direct chemisorption of a synthetic polymer on a conducting surface by in situ electrografting. As when the electrode is brought near a conducting surface  the electron transfer is confined to a small area on the surface, the SECM microelectrode is used for a local grafting. The electrografted polymer can then be easily post functionalized thanks to a good leaving group on its lateral chains. The substrates can be hence easily used for micropatterning a large variety of molecules. In particular the good capacity of this polymer in anchoring proteins has already been shown. [4]

 Using the aforesaid methods we obtained post-functionalizable microstructured substrates, this feature allows to adsorb biomolecule with high control of dimension and geometry of the final pattern. 

[1] H. Shiku, I. Uchida, T. Matsue,  Langmuir 1997, 13, 7239-7244.

[2] Allen j. Bard, Michael V. Mirkin, Scanning Electrochemical Microscopy, Ed. Marcel Dekker, inc, New York Basel, 2001.

[3] G. Wittstock, R. Hesse, W. Schuhmann, Electroanalysis, 1997, 9,746-750.

[4] C. Jérôme, S. Gabriel, S. Voccia, C. Detrembleur, M. Ignatova, R. Gouttebaron, R. Jérôme, Chem. Comm., 2003, 2500-2501.

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