Dynamic Monolayer Gradients:  Active Spatiotemporal Control of Alkanethiol Coatings on Thin Gold Films

Spatiotemporally Controlled Formation of Two‐Component Counterpropagating Lateral Graft Density Gradients of Mixed Polymer Brushes on Planar Au Surfaces

“…[7,8] A number of techniques to generate gradients on various substrates have been reported, including diffusion-controlled vapor deposition, [1] cross diffusion, [9,10] corona discharge, [11,12] photoimmobilization, [13,14] electrochemical-potential gradients, [5,[15][16][17] the use of microfluidic devices, [18,19] and, more recently, surface-initiated polymerization through atom-transfer radical polymerization (ATRP). [7,8,[20][21][22][23][24][25][26] ATRP is of special interest because of its versatility, robustness, controllability, the living nature of the polymerization, [27][28][29][30] and as a facile route to surface-grafted polymers, which are attractive because they can be used to tailor surface properties such as wettability, biocompatibility, adhesion, adsorption, corrosion resistance, and friction.…”

“…Electrochemical-potential gradients are able to generate chemical-composition gradients of organothiol SAMs on thin Au electrodes, [5,16,17,[35][36][37][38][39][40] with tunable gradient properties, such as the position and slope of the transition region on samples with a broad range of physical sizes. The electrochemical-gradient approach is extended here to generate mixed polymer-brush gradients of poly(N-isopropylacrylamide) (PNIPAAm) and poly(2-hydroxyethyl methacrylate) (PHEMA), as shown in Scheme 1.…”

A Haptotaxis Assay for Leukocytes Based on Surface-Bound Chemokine Gradients

“…An assay for migration on a surface poses a basis for research of the response of neutrophils to immobilized chemokines and would complement the existing chemotaxis assays. Microcontact printing has been widely used to immobilize protein gradients and patterns on surfaces (32)(33)(34) and to determine the influence of immobilized proteins on cell adhesion, growth, and migration (35,36). It was shown that the biological activity of the chemokine can be preserved upon immobilization on a surface (37,38).…”

Surface-chemical and -morphological gradients

“…7,37,38 In 2000, Terrill et al presented a method that relied on the electrochemical desorption of alkanethiols from a fully covered SAM by application of a potential. 39 The width of the potential window and the position of the electrodes thereby determine the width and slope of the gradients (see Fig. 2).…”