Surface-Bound Gradients for Studies of Soft Materials Behavior

Genzer, Jan

doi:10.1146/annurev-matsci-070511-155050

Cited by 89 publications

(90 citation statements)

References 225 publications

(237 reference statements)

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“…Such materials have been used to study cell adhesion and migration, directed transport, and protein adsorption among other phenomena as described in a number of reviews [1][2][3][4][5][6]. An one-component gradient, however, may not be sufficient for a number of applications, particularly those that rely on the interaction of an analyte species with more than one functional group located in close proximity to each other on a surface.…”

Section: Introductionmentioning

confidence: 99%

Amine-phenyl multi-component gradient stationary phases

Dewoolkar

Kannan

Ashraf

et al. 2015

Journal of Chromatography A

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Continuous multi-component gradients in amine and phenyl groups were fabricated using controlled rate infusion (CRI). Solutions prepared from either 3-aminopropyltriethoxysilane (APTEOS) or phenyltrimethoxysilane (PTMOS) were infused, in a sequential fashion, at a controlled rate into an empty graduated cylinder housing a vertically aligned thin layer chromatography (TLC) plate. The hydrolyzed precursors reacted with an abundance of silanol (SiOH) groups on the TLC plates, covalently attaching the functionalized silane to its surface. The extent of modification by phenyl and amine was determined by the kinetics of each reaction and the exposure time at each point along the TLC plate. The local concentrations of phenyl and amine were measured using diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy, respectively. The profile of the multi-component gradients strongly depended on the order of infusion, the direction of the gradient and the presence of available surface silanol groups. A slightly higher amount of phenyl can be deposited on the TLC plate by first modifying its surface with amine groups as they serve as a catalyst, enhancing condensation. Separation of water- and fat-soluble vitamins and the control of retention factors were demonstrated on the multi-component gradient TLC plates. Uniformly modified and single-component TLC plates gave different separations compared to the multi-component gradient plates. The retention factors of the individual vitamins depended on the order of surface modification, the spotting end, and whether the multi-component gradients align or oppose each other.

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Section: Introductionmentioning

confidence: 99%

Amine-phenyl multi-component gradient stationary phases

Dewoolkar

Kannan

Ashraf

et al. 2015

Journal of Chromatography A

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“…1 As described in recent reviews, 1−8 many different approaches have been used to form gradient materials. Historically, such materials have been used to drive and control transport and as high-throughput tools to study protein adsorption and crystallization, cell adhesion, charge interactions, and phase separation.…”

Section: ■ Introductionmentioning

confidence: 99%

Chelation Gradients for Investigation of Metal Ion Binding at Silica Surfaces

2014

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Centimeter-long surface gradients in bi- and tridentate chelating agents have been formed via controlled rate infusion, and the coordination of Cu(2+) and Zn(2+) to these surfaces has been examined as a function of distance by X-ray photoelectron spectroscopy (XPS). 3-(Trimethoxysilylpropyl)ethylenediamine and 3-(trimethoxysilylpropyl)diethylenetriamine were used as precursor silanes to form the chelation gradients. When the gradients were exposed to a metal ion solution, a series of coordination complexes formed along the length of the substrate. For both chelating agents at the three different concentrations studied, the amine content gradually increased from top to bottom as expected for a surface chemical gradient. While the Cu 2p peak area had nearly the same profile as nitrogen, the Zn 2p peak area did not and exhibited a plateau along much of the gradient. The normalized nitrogen-to-metal peak area ratio (N/M) was found to be highly dependent on the type of ligand, its surface concentration, and the type of metal ion. For Cu(2+), the N/M ratio ranged from 8 to 11 on the diamine gradient and was ∼4 on the triamine gradient, while for Zn(2+), the N/M ratio was 4-8 on diamine and 5-7 on triamine gradients. The extent of protonation of amine groups was higher for the diamine gradients, which could lead to an increased N/M ratio. Both 1:1 and 1:2 ligand/metal complexes along with dinuclear complexes are proposed to form, with their relative amounts dependent on the ligand, ligand density, and metal ion. Collectively, the methods and results described herein represent a new approach to study metal ion binding and coordination on surfaces, which is especially important to the extraction, preconcentration, and separation of metal ions.

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“…1,13–15 Such surface-bound gradients are comprehended by functionality, 15–18 dimensionality, 19,20 directionality, 21,22 length scale, 23,24 and temporal dependency. 13,25,26 Specifically, functional gradients featuring various soft material building blocks enable systematic screening of interactions between biological macromolecules, i.e., proteins and platelets, with various supports that are vital in the development of blood compatible coatings for medical devices, e.g., ventricular assist devices (VAD).…”

mentioning

confidence: 99%

“…Alternatively, assemblies of long chain molecules offer substantially thicker films extending to variation of surface concentrations of functional moieties as described in recent reviews. 13,15 …”

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confidence: 99%

Surface-Anchored Poly(N-isopropylacrylamide) Orthogonal Gradient Networks

2016

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We present a versatile synthetic route leading toward generating surface-attached polyacrylamide gels, in which the cross-link density varies continuously and gradually across the substrate in two orthogonal directions. We employ free radical polymerization to synthesize random copolymers comprising ~5% of photoactive methacrylyloxybenzophenone (MABP), ~5% of thermally active styrene sulfonyl azide (SSAz), and ~90% of N-isopropylacrylamide (NIPAAm) units. The presence of MABP and SSAz in the copolymer facilitates control over the cross-link density of the gel in an orthogonal manner using photoactivated and thermally activated cross-linking chemistries, respectively. Spectroscopic ellipsometry is employed to determine the degree of swelling of the gel in water and methanol as a function of position on the substrate. Network swelling varies continuously and gradually across the substrate and is high in regions of low gel fractions and low in regions of high gel fractions.

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Surface-Bound Gradients for Studies of Soft Materials Behavior

Cited by 89 publications

References 225 publications

Amine-phenyl multi-component gradient stationary phases

Amine-phenyl multi-component gradient stationary phases

Chelation Gradients for Investigation of Metal Ion Binding at Silica Surfaces

Surface-Anchored Poly(N-isopropylacrylamide) Orthogonal Gradient Networks

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