Assembly of Nanoparticles using Surface‐Grafted Orthogonal Polymer Gradients

Abstract

Summary: We report on preparing poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) gradient substrate, wherein molecular weight (MW) and grafting density (σ) of the surface‐anchored PDMAEMA chains vary continuously in two orthogonal directions. Such a specimen is used to control the assembly of charged gold nanoparticles. Increasing MW and σ of the grafted PDMAEMA cause an enhanced binding of the nanoparticles to PDMAEMA, thus leading to an orthogonal number density gradient of surface‐bound gold nanoparticles.magnified image

Tailoring Cell Adhesion Using Surface‐Grafted Polymer Gradient Assemblies

“…The linear gradient in MW of grafted PHEMA was prepared using a polymerization solution draining method [31]. Orthogonal gradients in molecular weight and grafting density of PHEMA were produced by combining methodologies for forming molecular weight [31] and grafting density [32] gradients, as outlined in references [33] and [42]. The dry-thickness profile of a polymer grown at various points on the linear as well as on orthogonal gradient was measured by VASE (J.…”

“…[16,22,26,27] While there is no consensus on the relative importance of MW and r in imparting protein resistance to a grafted polymer surface, [22,29,30] it has been demonstrated experimentally that protein adsorption systematically decreases upon an increase in either the MW and/or r of the anchored chains. [18,21,22,28] Recently, our group designed novel gradient substrates wherein polymer MW, [31] r, [32] or a combination of these two parameters, [33] can be continuously varied. Here, we utilize these polymer-gradient substrates to manipulate protein adsorption and consequently tailor the adhesion of cells.…”

“…[33] Since protein adsorption depends also on the grafting density of the anchored polymer, we studied deposition of FN on a sample in which MW and r of PHEMA vary orthogonally. In Figure 2a we present a contour plot of PHEMA thickness, grafted at various points on the orthogonal substrate.…”

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. Therefore, extensive research has been dedicated to understanding the behavior of tethered polymer chains at interfaces.…”

Brush in the bath of active particles: Anomalous stretching of chains and distribution of particles

“…The interplay between polymer brush and nanoparticles is an important aspect due to the applications in nanomaterials [19][20][21][22] and the relevance to biotechnology such as protein adsorption, cell adhesion and drug encapsulation, etc. 6,[23][24][25][26][27][28] Theoretical and simulation studies have shown that the solubility, the size and the shape of particles greatly influence their spatial organization on the brush.…”