Soft Lithography

Xia, Younan; Whitesides, George M.

doi:10.1002/(sici)1521-3773(19980316)37:5<550::aid-anie550>3.0.co;2-g

Cited by 4,481 publications

(1,344 citation statements)

References 161 publications

(357 reference statements)

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“…This geometry, consisting of two channels that intersect at 90 , is a convenient platform for generating a planar extensional flow. Masters for the cross-slots used for the cell experiments were made from SU-8 patterned on silicon wafers according to standard soft lithography approaches (25). Briefly, silicon wafers were precleaned with piranha solution (3:1 sulfuric acid to hydrogen peroxide), washed with deionized water, and baked at 120 C for 20 min to remove any moisture.…”

Section: Microfluidic Device Fabricationmentioning

confidence: 99%

Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device

Guillou

Dahl

Lin

et al. 2016

Biophysical Journal

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The quantification of cellular mechanical properties is of tremendous interest in biology and medicine. Recent microfluidic technologies that infer cellular mechanical properties based on analysis of cellular deformations during microchannel traversal have dramatically improved throughput over traditional single-cell rheological tools, yet the extraction of material parameters from these measurements remains quite complex due to challenges such as confinement by channel walls and the domination of complex inertial forces. Here, we describe a simple microfluidic platform that uses hydrodynamic forces at low Reynolds number and low confinement to elongate single cells near the stagnation point of a planar extensional flow. In tandem, we present, to our knowledge, a novel analytical framework that enables determination of cellular viscoelastic properties (stiffness and fluidity) from these measurements. We validated our system and analysis by measuring the stiffness of cross-linked dextran microparticles, which yielded reasonable agreement with previously reported values and our micropipette aspiration measurements. We then measured viscoelastic properties of 3T3 fibroblasts and glioblastoma tumor initiating cells. Our system captures the expected changes in elastic modulus induced in 3T3 fibroblasts and tumor initiating cells in response to agents that soften (cytochalasin D) or stiffen (paraformaldehyde) the cytoskeleton. The simplicity of the device coupled with our analytical model allows straightforward measurement of the viscoelastic properties of cells and soft, spherical objects.

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Section: Microfluidic Device Fabricationmentioning

confidence: 99%

Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device

Guillou

Dahl

Lin

et al. 2016

Biophysical Journal

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“…Alternatively, PDMS stamp molds were also fabricated by spin coating SU-8 negative photoresist (MicroChem, Newton, MA) onto a silicon wafer, exposing photoresist to UV through a mask for 10 s, and then developing the photoresist following the manufacturer's instructions. The mask was prepared using a computer drawing program to create a pattern that was printed onto a transparency [24,25], also with 1 mm features. PDMS (5.5 g) was poured onto the photolithographic mold, cured at 60 °C for 1-3 h, and then carefully peeled away from mold.…”

Section: Patterned Sams and Complex Depositionmentioning

confidence: 99%

“…SAMs can be used in conjugation with μCP, a soft lithographic technique, to imprint substrates with specific patterns of SAMs [21,22,24]. A PDMS stamp was used to imprint gold surfaces with specific patterns of hydrophilic alkanethiols (50% MUA) in a background of methylterminated alkanethiols (DT10).…”

Section: Patterned Sams and Complex Depositionmentioning

confidence: 99%

“…Furthermore, the flexibility in surface chemistry of SAMs permits preparation of patterned surfaces with varying degrees of surface charge and wettability. Microcontact printing (μCP), a soft lithographic technique, was used to imprint gold substrates with specific patterns of SAMs using an elastomeric stamp [21][22][23][24], creating regions of different surface properties. Here, we demonstrate the ability to use micropatterning to pattern DNA complex immobilization and transfection.…”

Section: Introductionmentioning

confidence: 99%

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Substrate-mediated delivery from self-assembled monolayers: Effect of surface ionization, hydrophilicity, and patterning

2005

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Gene transfer has many potential applications in basic and applied sciences. In vitro, DNA delivery can be enhanced by increasing the concentration of DNA in the cellular microenvironment through immobilization of DNA to a substrate that supports cell adhesion. Substrate-mediated delivery describes the immobilization of DNA, complexed with cationic lipids or polymers, to a biomaterial or substrate. As surface properties are critical to the efficiency of the surface delivery approach, selfassembled monolayers (SAMs) of alkanethiols on gold were used to correlate surface chemistry of the substrate to binding, release, and transfection of non-specifically immobilized complexes. Surface hydrophobicity and ionization were found to mediate both DNA complex immobilization and transfection, but had no effect on complex release. Additionally, SAMs were used in conjunction with soft lithographic techniques to imprint substrates with specific patterns, resulting in patterned DNA complex deposition and transfection, with transfection efficiencies in the patterns nearing 40%. Controlling the interactions between complexes and substrates, with the potential for patterned delivery, can be used to locally enhance or regulate gene transfer, with applications to tissue engineering scaffolds and transfected cell arrays.

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“…Eliminating such a problem in real devices, at large dimensional scales, is impractical during both fabrication and performance, requiring additional steps including the use of the traditional patterning techniques involving multiple lithography steps and cleaning procedures, or always necessitating the wiring of the devices beforehand. [17][18][19] To overcome these limitations, our unique approach utilizes inorganic solid-binding peptides that are molecular linkers, functionalizing the QDots, and have specific material selectivity property, essential for selective spatial assembly. To demonstrate how this approach works, we show here the directed assembly of peptide-functionalized QDots only on the targeted optical windows of a nanocrystal-based color-conversion LED.…”

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confidence: 99%

Spatially Selective Assembly of Quantum Dot Light Emitters in an LED Using Engineered Peptides

et al. 2011

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Cataloged from PDF version of article.Semiconductor nanocrystal quantum dots are utilized in numerous applications in nano- and biotechnology. In device applications, where several different material components are involved, quantum dots typically need to be assembled at explicit locations for enhanced functionality. Conventional approaches cannot meet these requirements where assembly of nanocrystals is usually material-nonspecific, thereby limiting the control of their spatial distribution. Here we demonstrate directed self-assembly of quantum dot emitters at material-specific locations in a color-conversion LED containing several material components including a metal, a dielectric, and a semiconductor. We achieve a spatially selective immobilization of quantum dot emitters by using the unique material selectivity characteristics provided by the engineered solid-binding peptides as smart linkers. Peptide-decorated quantum dots exhibited several orders of magnitude higher photoluminescence compared to the control groups, thus, potentially opening up novel ways to advance these photonic platforms in applications ranging from chemical to biodetection. © 2011 American Chemical Society

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Soft Lithography

Cited by 4,481 publications

References 161 publications

Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device

Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device

Substrate-mediated delivery from self-assembled monolayers: Effect of surface ionization, hydrophilicity, and patterning

Spatially Selective Assembly of Quantum Dot Light Emitters in an LED Using Engineered Peptides

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