Microcontact Printing of Macromolecules with Submicrometer Resolution by Means of Polyolefin Stamps Gabor Csucs,* ,†,‡ Tobias Ku ¨ nzler, †,§ Kirill Feldman, | Franck Robin, ⊥ and Nicholas D. Spencer § BioMicroMetricsGroup, BMMG, ETH Zu ¨ rich, Wagistrasse 4, CH-8952 Schlieren, Switzerland, Laboratory for Surface Science and Technology, Department of Materials, ETH Zu ¨ rich, Sonneggstrasse 5, CH-8092 Zu ¨ rich, Switzerland, Polymer Technology Group, Department of Materials, ETH Zu ¨ rich, Universita ¨ tstrasse 41, CH-8092 Zu ¨ rich, Switzerland, and Electromagnetic Fields and Microwave Electronics Laboratory, ETH Zu ¨ rich, Gloriastrasse 35, CH-8092 Zu ¨ rich, Switzerland Received February 18, 2003. In Final Form: May 15, 2003 Microcontact printing (μCP) is a simple and cost-effective method to create micrometer-scale chemical patterns on surfaces. By careful modification of the conventionally used stamping material (poly- (dimethylsiloxane) (PDMS)) and the stamping technique (e.g., “thin stamp μCP”), one can create surface chemical structures down to the submicrometer size range. In the present paper we report on the application of a new class of materialsspolyolefin plastomers (POPs) for μCP applications. We show that the POP stamps are well suited to print proteins or block copolymers. Comparative studies on reproducibility, homogeneity, and quality of printing between POP and conventional PDMS stamps were also performed. The results show a superior performance of the POP stamps in the nanometer range and an identical performance in the micrometer range compared to PDMS. Further advantages of the POP-based μCP are faster stamp production, the lack of monomeric contamination (typical for PDMS stamps), and the possibility of recycling the POP stamps. We believe that POPs offer a useful alternative to PDMS for μCP and open new possibilities in submicrometer-range printing. 1. Introduction During the past decade, microcontact printing (μCP) has become one of the most popular laboratory techniques for the fabrication of chemically microstructured surfaces. There are several reasons for this popularity: μCP is fast, is inexpensive, is simple, requires neither cleanroom instrumentation nor absolutely flat surfaces, and offers a way to create complex patterns, albeit with some geometrical constraints. 1 The achievable resolution is also remarkables30 nm being the current limit (for thiol-based systems). 2 Although μCP was originally used to print self- assembled monolayers of alkanethiolates on gold sur- faces, 1,3,4 it was soon extended to the stamping of proteins onto a variety of different surfaces. 5-7 The overwhelming majority of μCP studies have been carried out using poly- (dimethylsiloxane) (PDMS) as a stamping material. 1 Although PDMS is well suited for many stamping ap- plications, it has a number of serious drawbacks, which are partially connected to the softness (low mechanical stability) of the material. This softness sets serious geometrical constrains for the realizable structures and limits the achievable resolution of the standard PDMS- based technique. 1,8,9 To overcome these problems, two principal solutions have been introduced (and also com- bined with each other): (1) A supporting glass/plastic plate was used to increase the mechanical stability of the stamp. 6,10 (2) Special PDMS variants with better me- chanical properties for high-resolution μCP were used. 11 Another (often neglected) drawback of PDMS-based μCP is the frequently observed low-molecular-weight (“mono- mer”) PDMS contamination that is present on the stamped surface. 12,13 To solve these problems (mechanics/contami- nation), instead of creating new PDMS variants we have investigated the possibility of using a new class of materialsspolyolefin plastomers (POPs) in μCP applica- tions. In the present paper we describe the use of POPs for printing proteins (Alexa 488-fibrinogen) and block copolymerssfluorescein-poly-L-lysine-g-poly(ethylene gly- col) (PLL-g-PEG-fl*). 13 We compare μCP with POPs to the conventional PDMS-based approach, in terms of both quality and reproducibility. * To whom correspondence may be addressed. Fax: +41 1 633 1124. E-mail: csucs@biomech.mavt.ethz.ch. † These authors contributed equally to this work. ‡ BioMicroMetricsGroup, BMMG, ETH Zu ¨ rich. § Laboratory for Surface Science and Technology, Department of Materials, ETH Zu ¨ rich. | Polymer Technology Group, Department of Materials, ETH Zu ¨ rich. ⊥ Electromagnetic Fields and Microwave Electronics Laboratory, ETH Zu ¨ rich. (1) Xia, Y. N.; Whitesides, G. M. Annu. Rev. Mater. Sci. 1998, 28, 153-184. (2) Biebuyck, H. A.; Larsen, N. B.; Delamarche, E.; Michel, B. IBM J. Res. Dev. 1997, 41, 159-170. (3) Kumar, A.; Whitesides, G. M. Appl. Phys. Lett. 1993, 63, 2002- 2004. (4) Mrksich, M.; Chen, C. S.; Xia, Y. N.; Dike, L. E.; Ingber, D. E.; Whitesides, G. M. Proc. Natl. Acad. Sci. U.S.A. 1996, 93, 10775-10778. (5) Bernard, A.; Delamarche, E.; Schmid, H.; Michel, B.; Bosshard, H. R.; Biebuyck, H. Langmuir 1998, 14, 2225-2229. (6) James, C. D.; Davis, R. C.; Kam, L.; Craighead, H. G.; Isaacson, M.; Turner, J. N.; Shain, W. Langmuir 1998, 14, 741-744. (7) Bernard, A.; Renault, J. P.; Michel, B.; Bosshard, H. R.; Delama- rche, E. Adv. Mater. 2000, 12, 1067-1070. (8) Delamarche, E.; Schmid, H.; Michel, B.; Biebuyck, H. Adv. Mater. 1997, 9, 741-746. (9) Bietsch, A.; Michel, B. J. Appl. Phys. 2000, 88, 4310-4318. (10) Rogers, J. A.; Paul, K. E.; Whitesides, G. M. J. Vac. Sci. Technol., B 1998, 16, 88-97. (11) Schmid, H.; Michel, B. Macromolecules 2000, 33, 3042-3049. (12) Yang, Z. P.; Belu, A. M.; Liebmann-Vinson, A.; Sugg, H.; Chilkoti, A. Langmuir 2000, 16, 7482-7492. (13) Csucs, G.; Michel, R.; Lussi, J. W.; Textor, M.; Danuser, G. Biomaterials 2003, 24, 1713-1720. 6104 Langmuir 2003, 19, 6104-6109 10.1021/la0342823 CCC: $25.00 © 2003 American Chemical Society Published on Web 06/27/2003