am8b11525_si_002.avi (2.49 MB)
Substrate-Independent Micropatterning of Polymer Brushes Based on Photolytic Deactivation of Chemical Vapor Deposition Based Surface-Initiated Atom-Transfer Radical Polymerization Initiator Films
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posted on 2018-09-04, 00:00 authored by Ramya Kumar, Alexander Welle, Fabian Becker, Irina Kopyeva, Joerg LahannPrecise microscale
arrangement of biomolecules and cells is essential
for tissue engineering, microarray development, diagnostic sensors,
and fundamental research in the biosciences. Biofunctional polymer
brushes have attracted broad interest in these applications. However,
patterning approaches to creating microstructured biointerfaces based
on polymer brushes often involve tedious, expensive, and complicated
procedures that are specifically designed for model substrates. We
report a substrate-independent, facile, and scalable technique with
which to prepare micropatterned biofunctional brushes with the ability
to generate binary chemical patterns. Employing chemical vapor deposition
(CVD) polymerization, a functionalized polymer coating decorated with
2-bromoisobutyryl groups that act as atom-transfer radical polymerization
(ATRP) initiators was prepared and subsequently modified using UV
light. The exposure of 2-bromoisobutyryl groups to UV light with wavelengths
between 187 and 254 nm resulted in selective debromination, effectively
eliminating the initiation of ATRP. In addition, when coatings incorporating
both 2-bromoisobutyryl and primary amine groups were irradiated with
UV light, the amines retained their functionality after UV treatment
and could be conjugated to activated esters, facilitating binary chemical
patterns. In contrast, polymer brushes were selectively grown from
areas protected from UV treatment, as confirmed by atomic force microscopy,
time-of-flight secondary ion mass spectrometry, and imaging ellipsometry.
Furthermore, spatial control over biomolecular adhesion was achieved
in three ways: (1) patterned nonfouling brushes resulted in nonspecific
protein adsorption to areas not covered with polymer brushes; (2)
patterned brushes decorated with active binding sides gave rise to
specific protein immobilization on areas presenting polymer brushes;
(3) and primary amines were co-patterned along with clickable polymer
brushes bearing pendant alkyne groups, leading to bifunctional reactivity.
Because this novel technique is independent of the original substrate’s
physicochemical properties, it can be extended to technologically
relevant substrates such as polystyrene, polydimethylsiloxane, polyvinyl
chloride, and steel. With further work, the photolytic deactivation
of CVD-based initiator coatings promises to advance the utility of
patterned biofunctional polymer brushes across a spectrum of biomedical
applications.
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Chemical Vapor Depositionpendant alkyne groupsCVD-based initiator coatings2- bromoisobutyryl groupsbiofunctional polymer brusheschemical patternsion mass spectrometryBiofunctional polymer brushespolymer brushesfunctionalized polymer coatingclickable polymer brushesATRPSurface-Initiated Atom-Transfer Radical Polymerization Initiator Filmsmicropatterned biofunctional brushesUV treatmentUV lightEmploying chemical vapor deposition
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