Covalent microcontact printing of proteins for cell patterning

We describe a straightforward approach to the covalent immobilization of cytophilic proteins by microcontact printing, which can be used to pattern cells on substrates. Cytophilic proteins are printed in micropatterns on reactive self-assembled monolayers by using imine chemistry. An aldehyde-terminated monolayer on glass or on gold was obtained by the reaction between an amino-terminated monolayer and terephthaldialdehyde. The aldehyde monolayer was employed as a substrate for the direct microcontact printing of bioengineered, collagen-like proteins by using an oxidized poly(dimethylsiloxane) (PDMS) stamp. After immobilization of the proteins into adhesive "islands", the remaining areas were blocked with amino-poly(ethylene glycol), which forms a layer that is resistant to cell adhesion. Human malignant carcinoma (HeLa) cells were seeded and incubated onto the patterned substrate. It was found that these cells adhere to and spread selectively on the protein islands, and avoid the poly(ethylene glycol) (PEG) zones. These findings illustrate the importance of microcontact printing as a method for positioning proteins at surfaces and demonstrate the scope of controlled surface chemistry to direct cell adhesion.     

Positioning and alignment of lipid tubules on patterned Au substrates

This paper presents a method for positioning and aligning self-assembled tubules of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphochloline (DC(8,9)PC) by withdrawing a patterned Au substrate from tubule solution. The patterned Au substrates with alternating bare Au stripes and thiol monolayer stripes are formed by microcontact printing. We find that the lipid tubules selectively adsorb on the bare Au stripes but show no orientation order. By withdrawing the patterned Au substrates at the direction along the stripes from tubule solution, the lipid tubules are found to be aligned along the direction of the Au stripes. The angular distribution and the density of the aligned lipid tubules depend on the withdrawal rates and the adsorption time, respectively. We conclude that forces causing tubule alignment that originate in the surface tension associated with the moving meniscus dominate alignment forces exerted by the patterned Au substrates.     

Early and intermediate stages of guided dewetting in polystyrene thin films

We investigated the early and intermediate stages of the guided dewetting of polystyrene (PS) thin films on chemically patterned silicon, achieved by micro-contact printing of non-wettable self-assembling monolayers of an alkylsilane. Two different types of ordered patterns could be achieved depending on the annealing temperature and time. Study of the dynamics of hole growth revealed a deviation of the growth profile from the trend on homogeneous substrates, attributed to the pinning of the PS rims on the borders of the hydrophobic regions. The ordered patterns produced could be useful in applications that require spatially localized features of controlled surface chemistry, such as studies in proteomics, single cell studies, and biosensors.     

Anomalous uniform domain in a twisted nematic cell constructed from micropatterned surfaces

We have discovered an optically uniform type of domain that occurs in twisted nematic (TN) cells that are constructed from substrates chemically patterned with stripes via microcontact printing of self-assembled monolayers; such domains do not occur in TN cells constructed from uniform substrates. In such a cell, the azimuthal anchoring at the substrates is due to the elastic anisotropy of the liquid crystal rather than the conventional rubbing mechanism. A model is presented that predicts the relative stability of the twisted and anomalous states as a function of the material and design parameters.     

Selective atomic layer deposition of titanium oxide on patterned self-assembled monolayers formed by microcontact printing

We demonstrate a selective atomic layer deposition of TiO2 thin films on patterned alkylsiloxane self-assembled monolayers. Microcontact printing was done to prepare patterned monolayers of the alkylsiloxane on Si substrates. The patterned monolayers define and direct the selective deposition of the TiO2 thin film using atomic layer deposition. The selective atomic layer deposition is based on the fact that the TiO2 thin film is selectively deposited only on the regions exposing the silanol groups of the Si substrates because the regions covered with the alkylsiloxane monolayers do not have any functional group to react with precursors.     

利用去湿现象制备图案化的离子刻蚀聚合物保护层

微米和纳米尺度的图案化表面的制备在微电子、光学、生物、化学和材料科学等领域具有重要的科学意义和应用价值 [1～ 3 ] .由于需要复杂昂贵的设备和苛刻的工作环境 ,光刻技术难以广泛应用于微电子以外的领域 ,因此 ,发展简单、便宜、适用于普通实验室 (尤其是化学实验室 )的表面图案化技术已成为一个涉及众多学科领域的课题 .在近年来不断涌现出来的物理、化学和生物的表面图案化技术 [4～ 6]中 ,最具代表性的是由 Whitesides等 [7]发明的以表面具有微观图案的聚二甲基硅氧烷 (PDMS)弹性体作为模具或印章的软光刻技术 .结合溶胶 -凝胶、…     

Recycling and reusing patterned self-assembled monolayers for cell culture

Patterned self-assembled monolayers (SAMs) have been widely utilized for the study of cellular growth and behavior. While microcontact printing is a straightforward method of producing patterned substrates, the process is time consuming and requires the use of many techniques and specialized equipment. Here we present a method by which patterned substrates can be reused up to 15 times, saving both time and valuable resources.     

Nanoscopic Pd line arrays using nanocontact printed dendrimers

High-density Pd line arrays with 55 nm line-width were obtained using nanocontact-printed dendrimer monolayers. Elastomeric PDMS stamps for nanocontact printing were replicated from silicon master molds which were fabricated by UV nanoimprinting in combination with reactive ion etching. The fabrication method effectively controlled the aspect ratios of high-density lines for resolving the problems encountered in both replicating silicon masters to PDMS stamps and printing with the replicated PDMS stamps. Using the PDMS nanostamp with an optimized aspect ratio, a self-assembled monolayer of dendrimer was patterned on a Pd film via nanocontact printing, which was facilitated by the strong interaction between Pd and amine groups of the dendrimer. The patterned self-assembled monolayer was used as an etch-resist mask against the wet etchant of Pd, leaving behind a high-density Pd line array over large areas. The resulting functional Pd nanopattern is of practical significance in microelectronics and bio- or gas-sensing devices.     

Direct patterning of silanized-biomolecules on semiconductor surfaces

A novel approach to pattern silanized-biomolecules directly onto glass (SiO(x)) substrates via Dip-Pen nanolithography (DPN) and microcontact printing (μCP) is presented. Subsequent hybridization reactions of DPN patterned silanized-DNA with its complementary strands provide "proof-of-concept" that the patterned oligonucleotides maintain their biological activities. The fabrication strategy does not require premodification of substrates and offers a cheap and robust way to immobilize molecules on electronically important semiconductor surfaces.     

Direct printing of self-assembled lipid tubules on substrates

Lipid tubules formed by rolled-up bilayer sheets have shown promise in drug delivery systems, nanofluidics, and microelectronics. Here we report a method for directly printing lipid tubules on substrates. Preformed lipid tubules of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine are aligned in the recessed channels of a thin poly(dimethylsiloxane) (PDMS) stamp. The aligned lipid tubules then serve as an "ink" for microcontact printing. We demonstrate that two-dimensional (2-D) arrays of aligned lipid tubules can be transferred onto planar, patterned, and curved substrates from the recessed channels of the PDMS stamp by bringing the tubule-inked PDMS stamp into contact with these substrates. We show that the 2-D array of aligned lipid tubules can be transcribed into a 2-D array of aligned silica cylinders through templated sol-gel condensation of tetraethoxysilane.     

Inkjet-printed monolayers as platforms for tethered polymers

Combining inkjet printing and atom-transfer radical polymerization (ATRP) provides a straightforward and versatile method for producing patterned polymer surfaces that may serve as platforms for a variety of applications. We report the use of drop-on-demand technology to print binary chemical gradients and simple patterns onto solid substrates and, by using surface-confined ATRP, amplify these patterns and gradients. Chemically graded monolayers prepared by inkjet printing dodecanethiol and backfilling with 11-mercaptoundecanol showed continuous changes in the water contact angle along the gradient. These samples also exhibited a distinct change in the intensity of methyl group and C-O stretching modes along the gradient. Graded or patterned polymer layers were produced by growing, with ATRP, tethered poly(methyl methacrylate) (PMMA) layers from gradient or patterned printed monolayers that contained a bromo-capped initiator. Atomic force microscopy and optical microscopy confirmed that the PMMA layers amplified the underlying printed initiator layer with remarkable fidelity.     

Microstructured silicone substrate for printable and stretchable metallic films

Stretchable electronics (i.e., hybrid inorganic or organic circuits integrated on elastomeric substrates) rely on elastic wiring. We present a technique for fabricating reversibly stretchable metallic films by printing silver-based ink onto microstructured silicone substrates. The wetting and pinning of the ink on the elastomer surface is adjusted and optimized by varying the geometry of micropillar arrays patterned on the silicone substrate. The resulting films exhibit high electrical conductivity (～11?000 S/cm) and can stretch reversibly to 20% strain over 1000 times without failing electrically. The stretchability of the ≥200 nm thick metallic film relies on engineered strain relief in the printed film on patterned PDMS.     

Micropatterning of cell-repellent polymer on a glass substrate for the highly resolved virus microarray

The development of a simple and easily accessible method to control cellular behavior under a spatially controlled surface is critical for fundamental studies in biotechnology. We fabricated a microarray of Spodoptera frugiperda 9 (Sf9) cells on a glass surface by microcontact printing cell-repellent polymeric molecules of poly(ethylene glycol)-branched-poly(methyl methacrylate) as a template for cell micropatterning. The polymer micropatterns enabled the stable confinement of Sf9 cells on the surface, resulting in the formation of a cell microarray. Subsequently, the patterned Sf9 cells were infected with recombinant baculovirus modified with green fluorescent protein (GFP) to form a virus microarray, and GFP expression in the virus microarray was verified with confocal fluorescence microscopy.     

Ultrathin coatings from isocyanate terminated star PEG prepolymers: patterning of proteins on the layers

This study presents the easy and fast patterning of low molecular weight molecules that act as binding partners for proteins on Star PEG coatings. These coatings are prepared from isocyanate terminated star shaped prepolymers and form a highly cross-linked network on the substrate in which the stars are connected via urea groups and free amino groups are present. Streptavidin has been patterned on these layers by microcontact printing (muCP) of an amino reactive biotin derivative and consecutive binding of streptavidin to the biotin. Patterns of Ni(2+)-nitriltriacetic acid (NTA) receptors have been prepared by printing amino functional NTA molecules in freshly prepared Star PEG layers that still contain amino reactive isocyanate groups. Complexation of the NTA groups with Ni(II) ions enabled the binding of His-tag enhanced green fluorescent protein (EGFP) in the desired pattern on the substrates. Since the unmodified Star PEG layers prevent unspecific protein adsorption, His-EGFP could selectively be bound to the sample by immersion into crude, nonpurified His-tag EGFP containing cell lysate.     

Selective deposition in multilayer assembly: SAMs as molecular templates

Self-assembled monolayers (SAMs) on surfaces may be used as molecular templates for the selective deposition of polymer multilayer films. SAMs of ω-functionalized alkane thiolates are patterned onto gold surfaces with micron scale features using the microcontact printing method; glass substrates can also be patterned with trichloroalkylsilane SAMs. Patterned polymeric monolayer and multilayer films are adsorbed atop the SAM from dilute polymer solutions using ionic macromolecular self-assembly techniques which have been developed recently. The effects of polymer molecular weight and ionic content, as well as the use of a second SAM in the unpatterned regions to promote selectivity are discussed. Surface roughness, selectivity and other film properties are presented. It is demonstrated that this technique can be used successfully in the patterning of micron scale features with multilayers of low molecular weight upon adsorption from dilute solution.     

Patterning catalyst via inkjet printing to grow single-walled carbon nanotubes

We demonstrated a method to pattern catalyst via inkjet printing to grow SWNTs, using metal salt solutions as the inks and an ordinary office-use printer. We printed water solutions of cobalt acetate on hydrophilic Si substrates and grew high quality SWNT films.     

Micropatterning of bioactive glass nanoparticles on chitosan membranes for spatial controlled biomineralization

Bioactive glass nanoparticles (BG-NPs) capable of inducing apatite precipitation upon immersion in simulated body fluid (SBF) were patterned on free-standing chitosan membranes by microcontact printing using a poly(dimethylsiloxane) (PDMS) stamp inked in a BG-NPs pad. Formation of the patterns was characterized by scanning electron microscopy (SEM). Mineralization of the bioactive glass patterns was induced in vitro by soaking the samples in SBF over different time points up to 7 days. The confined apatite deposition in the patterned regions with diameters of 50 μm was confirmed by Fourier-transformed infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX) analysis, and SEM. In vitro tests confirmed the preferential attachment and proliferation of L929 cells to the areas printed with BG-NPs of the membranes. This approach permits one to spatially control the properties of biomaterials at the microlevel and could be potentially used in guided tissue regeneration for skin, vascular, articular, and bone tissue engineering and in cellular cocultures or to develop substrates able to confine cells in regions with controlled geometry at the cell's length scale.     

Patterned self-assembled film guided electrodeposition

Conjugated polymers can be the alternatives to metals to manufacture the integrated circuit in nano/micro electromechanical systems (NEMS/ MEMS)[1], while patterning is the basis for such an application. It has been well known that the electro-deposition on a template[2—10] represents the simplest method to construct a patterned conducting polymer structure as compared with the conventional ap-proaches such as photolithography, e-beam writing, screen-printing, and ink-jet printing[11]. For…     

Solid-supported monolayers and bilayers of amphiphilic beta-cyclodextrins

This paper describes the adsorption and spreading of beta-cyclodextrin (CD) vesicles on hydrophobic and hydrophilic substrates, which involves a transition from bilayer vesicles to planar molecular monolayers or bilayers. On substrates that are patterned with self-assembled monolayers by microcontact printing (muCP), the CD vesicles preferentially adsorb on hydrophobic areas instead of hydrophilic (nonionic) areas, and on cationic areas instead of hydrophilic (nonionic) areas. Supported monolayers of amphiphilic cyclodextrins CD1 and CD2 were obtained by adsorption of CD vesicles to hydrophobic substrates, and supported bilayers of amphiphilic cyclodextrins CD1 and CD2 were prepared by adsorption of CD vesicles on cationic substrates. Contact angle goniometry, atomic force microscopy and confocal fluorescence microscopy (CFM) were used to analyze the supported CD layers. The fluidity of the supported CD layers was verified using fluorescence recovery after photobleaching experiments. The supported layers function as a supramolecular platform that can bind suitable guest molecules through inclusion in the CD host cavities. Additionally, the CD host layers were patterned with fluorescent guest molecules by supramolecular muCP on the supported CD layers. The host-guest interactions were investigated with CFM and fluorescence resonance energy transfer experiments.     

Mussel-inspired anchoring for patterning cells using polydopamine

This Article introduces a simple method of cell patterning, inspired by the mussel anchoring protein. Polydopamine (PDA), artificial polymers made from self-polymerization of dopamine (a molecule that resembles mussel-adhesive proteins), has recently been studied for its ability to make modifications on surfaces in aqueous solutions. We explored the interfacial interaction between PDA and poly(ethylene glycol) (PEG) using microcontact printing (μCP). We patterned PDA on several substrates such as glass, polystyrene, and poly(dimethylsiloxane) and realized spatially defined anchoring of mammalian cells as well as bacteria. We applied our system in investigating the relationship between areas of mammalian nuclei and that of the cells. The combination of PDA and PEG enables us to make cell patterns on common laboratorial materials in a mild and convenient fashion.