Microcontact Printing Technique Research Articles

A novel micropatterning of luminescent barium carbonate nanowires controlled by a phosphonated copolymer

Novel luminescent BaCO3 nanowires have been successfully synthesized in the presence of mixed additives of a phosphonated copolymer and an organic dye. The nanowires show a time-dependent self-assembly into various microstructures over different length scales. With the combination of a microcontact printing technique, the selective growth of uniform NWs was achieved through application of substrates with different wettability and roughness. In this strategy, microstructures, location and growth orientation of BaCO3 NWs are well controlled.

In vitro neuronal networks of controlled architectures

Event Abstract Back to Event In vitro neuronal networks of controlled architectures Joséphine Lantoine1, Thomas Grevesse1 and Sylvain GABRIELE1* 1 université de mons, Belgium Understanding brain pathologies requires pertinent in vitro platforms which are even more useful when an architecture evoking the in vivo network organization can be enforced. To address this challenge, we developed a robust microcontact printing technique for designing in vitro networks of cortical neurons with a controlled architecture. Protein micropatterns al-low to impose the geometry of the neuronal assembly by controlling important network fea-tures such as the total number of cells, their positions, the number and the length of connec-tions. Our results demonstrate that neuronal networks are formed in vitro through a spontane-ous migration process directed by the geometry of laminin micropatterns. Neuronal migration leads to the accumulation of cell bodies on circular islands, which are connected together through axonal elongation directed by thin laminin tracks. First, we combined fluorescence microscopy and pharmacological inhibitors to demonstrate that microtubules play a funda-mental role in the neuronal migration process. Then, we used soft hydrogels (E=5 kPa) and intermediate elastomers (E=500 kPa) to investigate the influence of the matrix rigidity on the network formation. Our results indicate shorter maturation times for neuronal networks grown on soft environments, suggesting that the motility of cortical neurons is a stiffness-dependent process. Furthermore, we used confocal microscopy and synapsin immunostaining to measure quantitatively the formation of synapses, demonstrating a functional activity of these neuronal networks. Acknowledgements Josephine Lantoine acknowledges FRIA for doctoral grant Keywords: neuronal network, Synapses, stiffness, Migration, microcontact printing Conference: 11th National Congress of the Belgian Society for Neuroscience, Mons, Belgium, 22 May - 22 May, 2015. Presentation Type: Poster presentation Topic: Neuroscience Citation: Lantoine J, Grevesse T and GABRIELE S (2015). In vitro neuronal networks of controlled architectures. Front. Neurosci. Conference Abstract: 11th National Congress of the Belgian Society for Neuroscience. doi: 10.3389/conf.fnins.2015.89.00003 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 05 May 2015; Published Online: 05 May 2015. * Correspondence: Mr. Sylvain GABRIELE, université de mons, mons, 7000, Belgium, sylvain.gabriele@umons.ac.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joséphine Lantoine Thomas Grevesse Sylvain GABRIELE Google Joséphine Lantoine Thomas Grevesse Sylvain GABRIELE Google Scholar Joséphine Lantoine Thomas Grevesse Sylvain GABRIELE PubMed Joséphine Lantoine Thomas Grevesse Sylvain GABRIELE Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Fabrication of Highly Ordered Two-Dimensional Graphene Arrays on Patterned Substrate

We report a facial and straightforward method to fabricate highly ordered two-dimensional graphene arrays. A monolayer molecule pattern with alternative hydrophilic/hydrophobic wetting property was first formed by using micro-contact printing (μCP) and self-assembly techniques. Water droplets were condensed on the hydrophilic areas under saturated water atmosphere, which could be used to construct the ordered graphene arrays. The optical microscopy and atom force microscopy results indicate that ring and porous arrays of graphene can be obtained with low and high concentration of graphene solutions, respectively. Without the water droplet template, graphene patterns with square structure were produced.

Extending microcontact printing for patterning of thick polymer layers: semi-drying of inks and contact mechanisms

We investigate the applicability of the microcontact printing technique for the patterning of polymeric etch-resistant layers with thicknesses in the order of micrometers. In contrast to small molecular materials such as thiols and silane coupling agents typically used in microcontact printing, the patterning of thick layers requires tuning of the rheological properties of an ink film to prevent pattern deformation and attain high-quality transfer. By evaluating the swelling rate of a microcontact stamp material (i.e. poly(dimethylsiloxane) (PDMS)) and the evaporation rate of solvents, we find an optimal ink formulation to attain the desired semi-dried state for the printing of polymer layers. In polymer films with solid content below the optimal limit, split- or wrinkle-type deformations were found depending on the adhesion force and deformability of ink films, while overly-dried polymer films failed to be transferred. These phenomena are in qualitative agreement with deformation curves obtained from colloidal probe microscopy measurements that successfully revealed the deformability and adhesion of semi-dried polymer films. Further investigation of the effects of stamp stiffness on pattern formation reveals that a pattern region in which the thickness profile has a small curvature radius failed to be transferred when a stiffer PDMS stamp was used. This type of defect is thought to be caused by incomplete contact between the film and substrate due to a semi-circular cap structure of the polymer film and insufficient deformation of the stamp. Herein, a detailed contacting mechanism for high-quality patterning is discussed on the basis of the Hertz contact model. Using the developed etch-resistant ink and optimized printing process conditions, a finely defined etched structure for a silicon substrate is obtained.

Dopamine-Based Copper-Free Click Kit for Efficient Surface Functionalization

Strain-promoted azide-alkyne cycloaddition reactions are combined with a dopamine functional species to generate a highly efficient method for surface modification. The resulting conjugate containing 4-dibenzocyclooctynol (DIBO) and dopamine results in a versatile surface labeling technology that can replicate patterns generated from photolithography and microcontact printing techniques.

The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands.

We prepare and investigate two-dimensional (2D) single-layer arrays and multilayered networks of gold nanoparticles derivatized with conjugated hetero-aromatic molecules, i.e., S-(4-{[2,6-bipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)thiolate (herein S-BPP), as capping ligands. These structures are fabricated by a combination of self-assembly and microcontact printing techniques, and are characterized by electron microscopy, UV–visible spectroscopy and Raman spectroscopy. Selective binding of the S-BPP molecules to the gold nanoparticles through Au–S bonds is found, with no evidence for the formation of N–Au bonds between the pyridine or pyrazole groups of BPP and the gold surface. Subtle, but significant shifts with temperature of specific Raman S-BPP modes are also observed. We attribute these to dynamic changes in the orientation and/or increased mobility of the molecules on the gold nanoparticle facets. As for their conductance, the temperature-dependence for S-BPP networks differs significantly from standard alkanethiol-capped networks, especially above 220 K. Relating the latter two observations, we propose that dynamic changes in the molecular layers effectively lower the molecular tunnel barrier for BPP-based arrays at higher temperatures.

Protein patterning on hydrogels by direct microcontact printing: application to cardiac differentiation

An extended microcontact printing technique to chemically pattern hydrogels is reported. The procedure employs standard polydimethylsiloxane stamps and requires minor pre-processing of the hydrogels by freeze-drying. Micropatterned Matrigel™ and gelatin hydrogels induce NIH-3T3 cell alignment and elongation. Furthermore, human embryonic stem cells cultured on fibronectin-patterned hydrogels display beating foci earlier than those cultured on non-patterned substrates.

Luminescent gold surfaces for sensing and imaging: patterning of transition metal probes.

Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium(II), RubpySS, osmium(II), OsbpySS, and cyclometalated iridium(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications.

Spatially Resolved Energy Transfer in Patterned Colloidal Quantum Dot Heterostructures

Spatial uniformity is a key consideration in high-resolution displays and light-emitting structures fabricated from colloidal quantum dots (QDs). We report spatially and spectrally resolved transient photoluminescence measurements of laterally patterned QD heterostructures. We show, using a microcontact printing technique, that spatially uniform energy transfer can be achieved in a QD donor-acceptor bilayer system, highlighting the promising potential of colloidal QDs as flexible photonic components in next-generation optoelectronic technologies.

Electroformation of Uniformly Sized Giant Liposomes with Functional Membrane Proteins

Giant proteoliposomes mimic natural cell membranes and provide excellent models for membrane biophysical studies such as membrane phase separation, lipid-protein interactions, and functional studies of membrane proteins. Here, we present a simple and versatile approach for producing a large number of uniformly-sized giant proteoliposomes in a parallel fashion. This approach that combines the versatile technique of hydrogel-based microcontact printing and the commonly used technique of electroformation is efficient, low-cost, and doesn't require any specialized equipment. The resulting liposomes are attached to the surface in an array format, enabling rapid data collection for statistical analysis of membrane processes. We applied these vesicles for monitoring lipid-protein and protein-protein binding interactions. Alternatively, liposomes can be easily detached from the surface to produce a large number of giant liposomes with functional membrane proteins. We employed these vesicles for studying the channel activity of aquaporin protein and for monitoring material transport across lipid membranes. This approach may further be applicable to produce giant polymerosomes with increased stability compared to liposomes. The presented method can, hence, be useful in biomaterials, biotechnology, and biosensing applications as well as in the biophysical fundamental studies.View Large Image | View Hi-Res Image | Download PowerPoint Slide

Electroless Copper Deposition on PET Sheets

This paper describes metallization of PET surface by Sn-free electroless deposition (ELD) of thin copper layer. Prior to introduction to ELD process, the PET surface was plasma-pretreated in argon atmosphere. ELD is a multi-step process involving silanization with TMS, activation with PdCl2 and copper deposition. Contact angle measurement and XPS analysis were carried out at each stage in order to confirm the chemical change of the PET surface after modification. XPS analysis revealed that the copper surface consisted mainly of Cu2O, combined with Cu0, making Cu-coated PET sheet suitable for the use as substrate for electropolymerization of pyrrole. This study offers an alternative to preparing flexible sensors. This process could be further applied to micro-contact printing technique to fabricate flexible patterned electrodes.

The Regulation of Cellular Adhesion Geometry on Apoptosis of Mesenchymal Stem Cell

The mechanical stimulation from extracellular matrix could regulate physiological behavior of cells through the mechanism of mechanotransduction. Previous researches had shown that apoptosis could be regulated by the size of the cell adhesion area.However, the regulation of cell apoptosis by different adhesion shape with the same area is still unclear. This workfocused on the regulation of apoptosis for bone marrow mesenchymal stem cells (MSCs) by different circularity and area of adhesion geometry. We manufactured micro-pattern surface which was suitable for adhesion of MSCs by the technique of micro-contact printing. Three typesof geometry for individual is land of micro-pattern were designed. We adopted terminal-deoxynucleoitidyl transfer as emediated nick end labeling (TUNEL) method to detectcell apoptosis. This research shows that the adhesion geometry which has smaller area and greater circularity will promote apoptosis of MSCs. This indicates that MSCsmay prefer to live on the surface without any restrict. Ourstudies focused on the significantly important problem about interaction between extracellular matrix and physiological behavior of mesenchymal stem cells.

Wafer-scale directed self-assembly of nanostructures using self-assembled monolayer based controlled-wetting

Controlled spatial placement of nanostructure (NS) at micro/nano scale has attracted much attention since the last decade due to their applications in NS based device fabrication. Different processes like, chemical interaction based to solvent driven patterned assembly of NS have been reported. This work is about the large scale patterned assembly of different NS; cobalt and diamond nano particles and ZnO nanorods at micro/nano scale by controlling the surface wetting properties. Wettable and non-wettable patterned regions were created on gold/silicon surface using patterns of self-assembled monolayer (SAM). Patterns of SAMs with terminal end of CH3 were used to create non-wettable regions on wettable gold/silicon surfaces. Micro-contact printing, e-beam lithography, and simple scratch techniques were used to create SAM patterns of different shapes and sizes. Dipping the SAM patterned surface in the NS solution or by putting a droplet of the NS solution on the patterned surface the NS assembled according to SAM patterns only in the wettable, Au/silicon regions. I observed that wettability behavior of the surface plays a dominant role in the NS assembly in comparison to van der Waals’ and other interactions between surface and the NS.

Change of laminin density stimulates axon branchingviagrowth cone myosin II-mediated adhesion

Axon branching enables neurons to contact with multiple targets and respond to their microenvironment. Owing to its importance in neuronal network formation, axon branching has been studied extensively during the past decades. The chemical properties of extracellular matrices have been proposed to regulate axonal development, but the effects of their density changes on axon branching are not well understood. Here, we demonstrate that both the sharp broadening of substrate geometry and the sharp change of laminin density stimulate axon branching by using microcontact printing (μCP) and microfluidic printing (μFP) techniques. We also found that the change of axon branching stimulated by laminin density depends on myosin II activity. The change of laminin density induces asymmetric extensions of filopodia on the growth cone, which is the precondition for axon branching. These previously unknown mechanisms of change of laminin density-stimulated axon branching may explain how the extracellular matrices regulate axon branching in vivo and facilitate the establishment of neuronal networks in vitro.

Improved-Throughput Traction Microscopy Based on Fluorescence Micropattern for Manual Microscopy

Traction force microscopy (TFM) is a quantitative technique for measuring cellular traction force, which is important in understanding cellular mechanotransduction processes. Traditional TFM has a significant limitation in that it has a low measurement throughput, commonly one per TFM dish, due to a lack of cell position information. To obtain enough cellular traction force data, an onerous workload is required including numerous TFM dish preparations and heavy cell-seeding activities, creating further difficulty in achieving identical experimental conditions among batches. In this paper, we present an improved-throughput TFM method using the well-developed microcontact printing technique and chemical modifications of linking microbeads to the gel surface to address these limitations. Chemically linking the microbeads to the gel surface has no significant influence on cell proliferation, morphology, cytoskeleton, and adhesion. Multiple pairs of force loaded and null force fluorescence images can be easily acquired by means of manual microscope with the aid of a fluorescence micropattern made by microcontact printing. Furthermore, keeping the micropattern separate from cells by using gels effectively eliminates the potential negative effect of the micropattern on the cells. This novel design greatly improves the analysis throughput of traditional TFM from one to at least twenty cells per petri dish without losing unique advantages, including a high spatial resolution of traction measurements. This newly developed method will boost the investigation of cell-matrix mechanical interactions.

Multilayered heparin hydrogel microwells for cultivation of primary hepatocytes.

The biomaterial scaffolds for regenerative medicine need to be rationally designed to achieve the desired cell fate and function. This paper describes the development of hydrogel microstructures for cultivation of primary hepatocytes. Four different micropatterned surfaces are tested: 1) poly(ethyelene glycol) (PEG) microwells patterned on glass, 2) heparin hydrogel microwells patterned on glass, 3) PEG microwells patterned on heparin hydrogel-coated substrates, and 4) heparin hydrogel microwells patterned on heparin hydrogel-coated substrates. The latter surfaces are constructed by a combination of micromolding and microcontact printing techniques to create microwells with both walls and floor composed of heparin hydrogel. Individual microwell dimensions are 200 μm diameter and 20 μm in height. In all cases, the floor of the microwells is modified with collagen I to promote cell adhesion. Cultivation of hepatocytes followed by analysis of hepatic markers (urea production, albumin synthesis, and E-cadherin expression) reveals that the all-heparin gel microwells are most conducive to hepatic phenotype maintenance. For example, ELISA analysis shows 2.3 to 13.1 times higher levels of albumin production in all-heparin gel wells compared with other micropatterned surfaces. Importantly, hepatic phenotype expression can be further enhanced by culturing fibroblasts on the heparin gel walls of the microwells. In the future, multicomponent all-heparin gel microstructures may be employed in designing hepatic niche for liver-specific differentiation of stem cells.

Controlled Wetting on Electrodeposited Oxide Thin Films: From Hydrophilic to Superhydrophobic

We have explored how surface morphology and structure affect wetting properties of electrodeposited oxide thin films notwithstanding chemical modifications. Microstripes of self-assembled monolayers (SAMs) on gold were prepared using a microcontact printing (μCP) technique, which served as molecular templates to guide the electrochemical deposition of zirconia in aqueous solution. The wetting properties of the thus-prepared zirconia oxide thin films are shown to be tunable; i.e., a wide range of wettabilities from hydrophilic to superhydrophobic can be obtained by simply varying the SAM template and the electrodeposition conditions (potential scan rate and number of cycles). In particular, a “two-tier” micro/nanoscale roughness was achieved on the gold substrate patterned with alternating stripes of 1-octadecanethiol and 6-mercapto-1-hexanol SAMs, which leads to a superhydrophobic surface (water contact angle ∼150°). Of great significance is the demonstrated ability herein to convert an intrinsically hydrophilic into a hydrophobic surface by changing the conditions for materials fabrication, which does not involve any chemical modifications.

Interdigitated Multicolored Bioink Micropatterns by Multiplexed Polymer Pen Lithography

Multiplexing, i.e., the application and integration of more than one ink in an interdigitated microscale pattern, is still a challenge for microcontact printing (μCP) and similar techniques. On the other hand there is a strong demand for interdigitated patterns of more than one protein on subcellular to cellular length scales in the lower micrometer range in biological experiments. Here, a new integrative approach is presented for the fabrication of bioactive microarrays and complex multi-ink patterns by polymer pen lithography (PPL). By taking advantage of the strength of microcontact printing (μCP) combined with the spatial control and capability of precise repetition of PPL in an innovative way, a new inking and writing strategy is introduced for PPL that enables true multiplexing within each repetitive subpattern. Furthermore, a specific ink/substrate platform is demonstrated that can be used to immobilize functional proteins and other bioactive compounds over a biotin-streptavidin approach. This patterning strategy aims specifically at application by cell biologists and biochemists addressing a wide range of relevant pattern sizes, easy pattern generation and adjustment, the use of only biofriendly, nontoxic chemicals, and mild processing conditions during the patterning steps. The retained bioactivity of the fabricated cm(2) area filling multiprotein patterns is demonstrated by showing the interaction of fibroblasts and neurons with multiplexed structures of fibronectin and laminin or laminin and ephrin, respectively.

Space-confined fabrication of silver nanodendrites and their enhanced SERS activity

Here we report a controllable method based on electrodeposition to fabricate Ag nanodendrites (NDs) on a microwell patterned electrode. The microwell patterns on the ITO electrode are fabricated via the microcontact printing technique. By varying the microwell size and electrodeposition time, the morphology of metal deposits on the microwell patterned ITO electrode can be tuned from boulders to dendrites. At the edge of the microwells, the current density was strengthened, which incurs rapid nucleation. The nucleus develops into dendrites because of Mullins-Sekerka instability. However, only boulders were observed at the center of microwells. By reducing the size of the microwells, only NDs were fabricated due to the edge effect. On the basis of understanding the underlying mechanism for dendritic growth in a confined space, our method is used for fabricating other noble metal (Au, Pt) nanodendrites. The controllable synthesis of Au and Pt NDs indicates the universality of this method. Compared with Ag film obtained from electron beam evaporation, the as-prepared Ag NDs exhibit highly enhanced surface-enhanced Raman scattering (SERS) sensitivity when they are used to detect rhodamine 6G (R6G). This approach provides a very controllable, reliable and general way for space-confined fabricating the noble metal nanodendrite arrays which show great promise in catalysis, sensing, biomedicine, electronic and magnetic devices.

Directing polypyrrole growth by chemical micropatterns: A study of high-throughput well-ordered arrays of conductive 3D microrings

An array of well-ordered conducting polypyrrole microrings doped with cobaltabisdicarbollide [Co(C2B9H11)2]− anions was fabricated by means of electropolymerization and submerged micro-contact printing techniques. The different conductive properties of the micropatterned thiols acted as a template for directing the electrochemical 3D growth of the microstructures over large areas. X-ray photoelectron spectroscopy characterization confirmed the presence of this unusual doping anion within the polymer. Its intrinsic properties together with hydrophobic interactions with the thiols guided the formation of the ring structures. A topographic study by atomic force microscopy gave insights into the PPy/[Co(C2B9H11)2]− growing mechanism which is in agreement with the theoretical model of metal growth. Finally, the conductive properties of the microstructures were addressed by conductive-atomic force microscopy, showing a highly conductive behaviour. This methodology using cobaltabisdicarbollide as dopant anion could have important applications in organic microelectronics for the development of biosensors, in cell microarrays and for the fabrication of polymer-based microencapsulators.