Substrate-Independent Micropatterning of Polymer Brushes Based on Photolytic Deactivation of Chemical Vapor Deposition Based Surface-Initiated Atom-Transfer Radical Polymerization Initiator Films

Abstract

Precise 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.

Protein Patterning on Microtextured Polymeric Nanobrush Templates Obtained by Nanosecond Fiber Laser

“…Post protein adsorption, a clear change of depth (around 0.5 µm) was evident on the textured surface as viewed from the three dimensional projected images and comparing their line profiles (before and after protein adsorption) captured by AFM (Figure 5e). A 135 nm change in surface roughness ( R q ) [ 70 ] of textured area upon protein adsorption further affirmed the selective protein patterning on textured area having no polyPEGMA brush (Figure 5e).…”

Materiomically Designed Polymeric Vehicles for Nucleic Acids: Quo Vadis?

“…During in vitro screening experiments, transfection assays are typically miniaturized to 384- or 1536-well plates to reduce reagent consumption and to boost throughput . Cellular microarrays obtained using micropatterned protein-coated cell culture substrates − have also emerged as promising platforms for studying material–cell interactions. To circumvent problems arising from evaporation of small volumes in well-plate and microarray based studies, microfluidic tools (Figure ) have been developed to boost the experimental throughput during in vitro transfection. − Candiani and co-workers developed a microfluidic device wherein lipoplex dilution and formulation, cell culture, and transfection operations could be performed serially in a single device consisting of connected chambers .…”

The Bioanalytical and Biomedical Applications of Polymer Modified Substrates

“…Because of their inherent antibiofouling nature, the fabrication of microarrays on the polymer brush modified substrates allows biomolecular immobilization and recognition with low nonspecific interactions, resulting in a significant improvement of the specificity and reproducibility of microarray [77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95]. In addition, the 3D structure of polymer brush modified substrates provide a high biomolecule immobilization capacity and accessible scaffolds with sufficient space for biomolecule binding, leading to an increase in the sensitivity of microarrays.…”