Chain-End Functionalized Nanopatterned Polymer Brushes Grown via in Situ Nitroxide Free Radical Exchange

Abstract

The patterning of biologically active materials has been accomplished by the use of imprint lithography of functional photopolymer resins to create controlled nanoscale patterns of a cross-linked photopolymer containing embedded initiator groups. Functionalized polymer brushes consisting of polystyrene and poly(N,N-dimethylacrylamide) were grown from these patterned layers by nitroxide-mediated polymerization. Chain-end functionalization of the brush layer was accomplished by nitroxide radical exchange during the polymerization. Accordingly, brush layers terminated by pyrene and biotin functional groups were obtained by exchange with the appropriate alkoxyamines. The presence of pyrene functionality at the chain ends of the brushes was confirmed by fluorescent emission measurements. Fluorescently labeled streptavidin protein was selectively attached with high selectivity to the patterned biotinylated brush layer through biotin−streptavidin interactions. The functionalized polymer grafted surfaces and nanopatterns have been successfully characterized using a fluorescence spectrophotometer, AFM, SEM, confocal microscopy, and water contact angle measurements.

Fabrication of Arbitrary Three‐Dimensional Polymer Structures by Rational Control of the Spacing between Nanobrushes

“…We believe the present method can be directly applied to create biomimic surfaces for studying cell adhesion, differentiation, and signaling as well as protein interactions. In principle, this strategy can be used with other nanolithographic tools such as e-beam lithography, [20,27,28] nanoimprint lithography, [29,30] nano-shaving/grafting, [31][32][33] dip-pen nanolithography, [34][35][36] and polymer pen lithography. [37] Received: April 12, 2011 Published online: June 9, 2011 .…”

A carbon network backbone polymer functionalized with polymer brushes

“…Free radical initiators, such as AIBN, could be used to abstract hydrogen or bromine radicals from the backbone surface, 26 leaving initiation sites suitable for free radical polymerization and growth of oligomeric/polymeric side chains from 1. 22,[27][28][29] As this kind of reactivity had not been explored with 1, proving that radical initiators could actually effect a reaction at the surface of the polymer was considered to be the starting point.…”

Chain End‐Functionalized Polymer Brushes with Switchable Fluorescence Response

“…End anchoring of polymer chains at a high density to a surface to form polymer brushes is a powerful way to prepare functional coatings . Fluorescent dye‐labeled polymer brushes have been prepared and utilized in ion sensing and organic light emitting diode (OLED) development or in studying the degrafting kinetics of brushes . In this context, responsive polymer brushes, which undergo conformational change upon certain, for example, pH, temperature, ionic strength, and solvent have been modified with fluorescent probes and widely used in the design of sensors .…”

“…So far, only a limited number of studies have reported chain‐end functionalization of polymer brushes with fluorescent labels. These include converting alkyl bromide end groups into amines before reacting with isothiocyanate‐functionalized dye as well as nitroxide radical exchange during polymerization . A straightforward alternative to these synthetic routes could be “click chemistry,” which was previously used to modify chain‐ends of polymer brushes with, for example, recognition elements, DNA, and polyethylene glycol (PEG) …”