by Keyword: Lithography

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Gállego, Isaac, Manning, Brendan, Prades, Joan Daniel, Mir, Mònica, Samitier, Josep, Eritja, Ramon, (2017). DNA-origami-driven lithography for patterning on gold surfaces with sub-10 nm resolution Advanced Materials 29, 1603233

Agusil, Juan Pablo, Torras, Núria, Duch, Marta, Esteve, Jaume, Pérez-García, Lluïsa, Samitier, Josep, Plaza, José A., (2017). Highly anisotropic suspended planar-array chips with multidimensional sub-micrometric biomolecular patterns Advanced Functional Materials 27, 1605912

Suspended planar-array (SPA) chips embody millions of individual miniaturized arrays to work in extremely small volumes. Here, the basis of a robust methodology for the fabrication of SPA silicon chips with on-demand physical and chemical anisotropies is demonstrated. Specifically, physical traits are defined during the fabrication process with special focus on the aspect ratio, branching, faceting, and size gradient of the final chips. Additionally, the chemical attributes augment the functionality of the chips with the inclusion of complete coverage or patterns of selected biomolecules on the surface of the chips with contact printing techniques, offering an extremely high versatility, not only with the choice of the pattern shape and distribution but also in the choice of biomolecular inks to pattern. This approach increases the miniaturization of printed arrays in 3D structures by two orders of magnitude compared to those previously demonstrated. Finally, functional micrometric and sub-micrometric patterned features are demonstrated with an antibody binding assay with the recognition of the printed spots with labeled antibodies from solution. The selective addition of physical and chemical attributes on the suspended chips represents the basis for future biomedical assays performed within extremely small volumes.

Keywords: Microcontact printing, Microparticles, Molecular multiplexing, Polymer pen lithography, Silicon chip technology

Credi, C., De Marco, C., Molena, E., Pla Roca, M., Samitier, J., Marques, J., Fernàndez-Busquets, X., Levi, M., Turri, S., (2016). Heparin micropatterning onto fouling-release perfluoropolyether-based polymers via photobiotin activation Colloids and Surfaces B: Biointerfaces 146, 250-259

A simple method for constructing versatile ordered biotin/avidin arrays on UV-curable perfluoropolyethers (PFPEs) is presented. The goal is the realization of a versatile platform where any biotinylated biological ligands can be further linked to the underlying biotin/avidin array. To this end, microcontact arrayer and microcontact printing technologies were developed for photobiotin direct printing on PFPEs. As attested by fluorescence images, we demonstrate that this photoactive form of biotin is capable of grafting onto PFPEs surfaces during irradiation. Bioaffinity conjugation of the biotin/avidin system was subsequently exploited for further self-assembly avidin family proteins onto photobiotin arrays. The excellent fouling release PFPEs surface properties enable performing avidin assembly step simply by arrays incubation without PFPEs surface passivation or chemical modification to avoid unspecific biomolecule adsorption. Finally, as a proof of principle biotinylated heparin was successfully grafted onto photobiotin/avidin arrays.

Keywords: Antifouling, Heparin, Malaria, Microcontact arrayer, Microcontact printing, Micropatterning, Perfluoropolyether, Photobiotin, Polymers, Soft lithography

Oberhansl, S., Garcia, A., Lagunas, A., Prats-Alfonso, E., Hirtz, M., Albericio, F., Fuchs, H., Samitier, J., Martinez, E., (2014). Mesopattern of immobilised bone morphogenetic protein-2 created by microcontact printing and dip-pen nanolithography influence C2C12 cell fate RSC Advances 4, (100), 56809-56815

Dip-pen nanolithography and microcontact printing were used to fabricate mesopatterned substrates for cell differentiation experiments. A biotin-thiol was patterned on gold substrates and subsequently functionalised with streptavidin and biotinylated bone morphogenetic protein-2 (BMP-2). The feasibility of mesopatterned substrates containing immobilised BMP-2 was proven by obtaining similar differentiation outcomes compared to the growth factor in solution. Therefore, these substrates might be suitable for replacing conventional experiments with BMP-2 in solution.

Keywords: Bone morphogenetic protein-2, C2C12 cells, Dip-pen nanolithography, Micro contact printing

Oberhansl, Sabine, Hirtz, Michael, Lagunas, Anna, Eritja, Ramon, Martinez, Elena, Fuchs, Harald, Samitier, Josep, (2012). Facile modification of silica substrates provides a platform for direct-writing surface click chemistry Small 8, (4), 541-545

Kuphal, M., Mills, C.A., Korri-Youssoufi, H., Samitier, J., (2012). Polymer-based technology platform for robust electrochemical sensing using gold microelectrodes Sensors and Actuators B: Chemical 161, (1), 279-284

Rapid and inexpensive development of electrochemical sensors with good exploitation potential may be produced using a polymer as a substrate material. However, fabrication of polymer-based sensors is challenging. Using photolithography and etching of gold-coated poly(ethylene-2,6-naphthalate) (PEN), we have succeeded in fabricating disk-shaped and interdigitated microelectrodes (uEs). The electrodes have an excellent adhesion to the polymer and are encapsulated using a novel room-temperature process, applicable for low-cost, high-throughput fabrication. The PEN surface has been characterized in respect of wettability, surface energy and surface roughness. Finally, the electrodes give stable and reproducible electrochemical impedance spectroscopy and cyclic voltammetry responses, using the redox couple ferrocyanide and ruthenium hexamine. The results demonstrate the robustness and functionality of the polymer-based sensor platform with minimum feature sizes of 6 um.

Keywords: Poly(ethylene naphthalate), Photolithography, Microelectrodes, Interdigitated electrodes, Electrochemical characterization, Electrochemical sensor

Martínez, E., Pla, M., Samitier, J., (2012). Micro/nanopatterning of proteins using a nanoimprint-based contact printing technique Nanotechnology in Regenerative Medicine - Methods and Protocols (Methods in Molecular Biology) (ed. Navarro, M., Planell, J. A.), Springer (New York, USA) 811, 79-87

Micro and nanoscale protein patterning based on microcontact printing technique on large substrates have often resolution problems due to roof collapse of the poly(dimethylsiloxane) (PDMS) stamps used. Here, we describe a technique that overcomes these issues by using instead a stamp made of poly(methyl methacrylate) (PMMA), a much more rigid polymer that do not collapse even using stamps with very high aspect ratios (up to 300:1). Conformal contact between the stamp and the substrate is achieved because of the homogeneous pressure applied via the nanoimprint lithography instrument, and it has allowed us to print lines of protein 150 nm wide, at a 400 nm period. This technique, therefore, provides an excellent method for the direct printing of high-density submicrometer scale patterns, or, alternatively, micro/nanopatterns spaced at large distances.

Keywords: Microcontact printing, Nanoimprint lithography, Poly(methyl methacrylate), Protein

Fernandez, Javier G., Samitier, Josep, Mills, Christopher A., (2011). Simultaneous biochemical and topographical patterning on curved surfaces using biocompatible sacrificial molds Journal of Biomedical Materials Research - Part A 98A, (2), 229-234

A method for the simultaneous (bio)chemical and topographical patterning of enclosed structures in poly(dimethyl siloxane) (PDMS) is presented. The simultaneous chemical and topography transference uses a water-soluble chitosan sacrificial mold to impart a predefined pattern with micrometric accuracy to a PDMS replica. The method is compared to conventional soft-lithography techniques on planar surfaces. Its functionality is demonstrated by the transference of streptavidin directly to the surface of the three-dimensional PDMS structures as well as indirectly using streptavidin-loaded latex nanoparticles. The streptavidin immobilized on the PDMS is tested for bioactivity by coupling with fluorescently labeled biotin. This proves that the streptavidin is immobilized on the PDMS surface, not in the bulk of the polymer, and is therefore accessible for use as signaling/binding element in micro and bioengineering. The use of a biocompatible polymer and processes enables the technique to be used for the chemical patterning of tissue constructions.

Keywords: Biotechnology, Chitosan, Microfabrication, MEMs, Soft lithography

Martinez, Elena, Samitier, Josep, (2011). Soft lithography and variants Generating micro- and nanopatterns on polymeric materials (ed. del Campo, Aranzazu , Arzt, Eduard), Wiley-VCH Verlag GmbH&Co (Weinheim) , 57-66

Caballero, D., Samitier, J., Errachid, A., (2009). Submerged nanocontact printing (SnCP) of thiols Journal of Nanoscience and Nanotechnology 9, (11), 6478-6482

Biological patterned surfaces having sub-micron scale resolution are of great importance in many fields of life science and biomedicine. Different techniques have been proposed for surface patterning at the nanoscale. However, most of them present some limitations regarding the patterned area size or are time-consuming. Micro/nanocontact printing is the most representative soft lithography-based technique for surface patterning at the nanoscale. Unfortunately, conventional micro/nanocontact printing also suffers from problems such as diffusion and stamp collapsing that limit pattern resolution. To overcome these problems, a simple way of patterning thiols under liquid media using submerged nanocontact printing (SnCP) over large areas (similar to cm(2)) achieving nanosize resolution is presented. The technique is also low cost and any special equipment neither laboratory conditions are required. Nanostructured poly(dimethyl siloxane) stamps are replicated from commercially available digital video disks. SnCP is used to stamp patterns of 200 nm 1-octadecanethiol lines in liquid media, avoiding ink diffusion and stamp collapsing, over large areas on gold substrates compared with conventional procedures. Atomic force microscopy measurements reveal that the patterns have been successfully transferred with high fidelity. This is an easy, direct, effective and low cost methodology for molecule patterning immobilization which is of interest in those areas that require nanoscale structures over large areas, such as tissue engineering or biosensor applications.

Keywords: Submerged Nanocontact Printing, Replica Molding, Nanopatterning, Large Area, Dip-pen nanolithography, High-aspect-ratio, Soft lithography, Submicronscale, Nanoimprint lithography, Thin-film, Surfaces, Fabrication, Proteins, Nanofabrication

Fernandez, J. G., Mills, C. A., Martinez, E., Lopez-Bosque, M. J., Sisquella, X., Errachid, A., Samitier, J., (2008). Micro- and nanostructuring of freestanding, biodegradable, thin sheets of chitosan via soft lithography Journal of Biomedical Materials Research - Part A 85A, (1), 242-247

A technique for imparting micro- and nano-structured topography into the surface of freestanding thin sheets of chitosan is described. Both micro- and nanometric surface structures have been produced using soft lithography. The soft lithography method, based on solvent evaporation, has allowed structures similar to 60 nm tall and similar to 500 X 500 nm(2) to be produced on freestanding similar to 0.5 mm thick sheets of the polymer when cured at 293 K, and structures similar to 400 nm tall and 5 X 5 mu m(2) to be produced when cured at 283 K. Nonstructured chitosan thin sheets (similar to 200 mu m thick) show excellent optical transmission properties in the visible portion of the electromagnetic spectrum. The structured sheets can be used for applications where optical microscopic analysis is required, such as cell interaction experiments and tissue engineering.

Keywords: Chitin/chitosan, Microstructure, Nanotopography, Polymerization, Soft lithography

Lopez, M. J., Caballero, D., Campo, E. M., Perez-Castillejos, R., Errachid, A., Esteve, J., Plaza, J. A., (2008). Focused ion beam-assisted technology in sub-picolitre micro-dispenser fabrication Journal of Micromechanics and Microengineering 18, (7), 8

Novel medical and biological applications are driving increased interest in the fabrication of micropipette or micro-dispensers. Reduced volume samples and drug dosages are prime motivators in this effort. We have combined microfabrication technology with ion beam milling techniques to successfully produce cantilever-type polysilicon micro-dispensers with 3D enclosed microchannels. The microfabrication technology described here allows for the designing of nozzles with multiple shapes. The contribution of ion beam milling has had a large impact on the fabrication process and on further customizing shapes of nozzles and inlet ports. Functionalization tests were conducted to prove the viability of ion beam-fabricated micro-dispensers. Self-assembled monolayers were successfully formed when a gold surface was patterned with a thiol solution dispensed by the fabricated micro-dispensers.

Keywords: Dip-pen nanolithography, Silicon, Deposition, Microneedles, Delivery, Arrays, Polysilicon, Capillary, Systems, Gene

Mills, C. A., Fernandez, J. G., Errachid, A., Samitier, J., (2008). The use of high glass temperature polymers in the production of transparent, structured surfaces using nanoimprint lithography Microelectronic Engineering 85, (9), 1897-1901

Polymers with high glass transition temperatures, fluorinated ethylene propylene copolymer (FEP) and poly(ethylene naphthalate) (PEN), have been used in imprint lithography as a protective support layer and as a secondary mould, to imprint superficial structures into a polymer with a lower glass transition temperature, namely poly(methyl methacrylate) (PMMA). As a support layer, FEP replaces fragile silicon based supports for the production of freestanding, structured sheets of PMMA, useful, for example, in biomedical applications where transmittance optical microscopy is required. Secondary PEN moulds, produced by imprinting using silicon-based primary moulds, have been used to transfer sub-micrometer tall structures to a freestanding PMMA sheet. Similarly, hole structures, with different dimensions, have been embossed in both sides of a PMMA sheet simultaneously.

Keywords: Polymer engineering, Embossing, Nanoimprint lithography, Biomedical applications

Pla, M., Fernandez, J. G., Mills, C. A., Martinez, E., Samitier, J., (2007). Micro/nanopatterning of proteins via contact printing using high aspect ratio PMMA stamps and NanoImprint apparatus Langmuir 23, (16), 8614-8618

Micro- and nanoscale protein patterns have been produced via a new contact printing method using a nanoimprint lithography apparatus. The main novelty of the technique is the use of poly(methyl methacrylate) (PMMA) instead of the commonly used poly(dimethylsiloxane) (PDMS) stamps. This avoids printing problems due to roof collapse, which limits the usable aspect ratio in microcontact printing to 10:1. The rigidity of the PMMA allows protein patterning using stamps with very high aspect ratios, up to 300 in this case. Conformal contact between the stamp and the substrate is achieved because of the homogeneous pressure applied via the nanoimprint lithography instrument, and it has allowed us to print lines of protein similar to 150 nm wide, at a 400 nm period. This technique, therefore, provides an excellent method for the direct printing of high-density sub-micrometer scale patterns, or, alternatively, micro-/nanopatterns spaced at large distances. The controlled production of these protein patterns is a key factor in biomedical applications such as cell-surface interaction experiments and tissue engineering.

Keywords: Soft lithography, Cell-adhesion, Microstructures, Fabrication, Stability, Patterns

Mills, C. A., Pla, M., Martin, C., Lee, M., Kuphal, M., Sisquella, X., Martinez, E., Errachid, A., Samitier, J., (2007). Structured thin organic active layers and their use in electrochemical biosensors Measurement & Control 40, (3), 88-91

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