Switchable Oligo(glycidyl ether) Acrylate Bottlebrushes "Grafted-from" Polystyrene Surfaces: A Versatile Strategy toward Functional Cell Culture Substrates

Thermoresponsive brushes based on linear poly(glycidyl ether)s (PGEs) have already shown to be functional coatings for cell sheet fabrication. In here, we introduce a method to functionalize polystyrene (PS) tissue culture substrates with thermoresponsive coatings comprising glycidyl ether-based bottlebrush architectures. Utilizing the UV-induced "grafting-from" approach, thermoresponsive oligo(glycidyl ether) acrylate (OGEA) macromonomers were polymerized from PS substrates under bulk conditions. Applying ellipsometry, water contact angle (CA), and atomic force microscopy (AFM) measurements, we found that OGEA coatings exhibit a complex, gel-like structure comprising nanosized roughness and exhibit a temperature-dependent phase transition in water through the reversible hydration of OGEA bottlebrush side chains. To assess the utility of the coatings as functional substrates for cell sheet fabrication, human dermal fibroblast (HDF) adhesion and detachment were investigated. By adjusting the bottlebrush properties via the grafting procedure and coating structure, we were able to harvest confluent HDF sheets from functionalized PS substrates in a temperature-triggered, controlled manner. As the first report on surface-grafted bottlebrushes comprising thermoresponsive side chains with molecular weight of up to 1 kDa, this study demonstrates the potential of OGEA-based coatings for cell sheet fabrication.

Controlling the surface chemistry and chromatographic properties of methacrylate-ester-based monolithic capillary columnsviaphotografting

Preparation of monolithic capillary columns for separations in the CEC mode using UV-initiated polymerization of the plain monolith followed by functionalization of its pore surface by photografting has been studied. The first step enabled the preparation of generic poly(butyl methacrylate-co-ethylene dimethacrylate) monoliths with optimized porous properties, controlled by the percentages of porogens 1-decanol and cyclohexanol in the polymerization mixture, irradiation time, and UV light intensity. Ionizable monomers [2-(methacryloyloxy)ethyl]trimethylammonium chloride or 2-acryloamido-2-methyl-1-propanesulfonic acid were then photografted onto the monolithic matrix, allowing us to control the direction of the EOF in CEC. Different strategies were applied to control the grafting density and, thereby, the magnitude of the EOF. To control the hydrophobic properties, two approaches were tested: (i) cografting of a mixture of the ionizable and hydrophobic monomers and (ii) sequential grafting of the ionizable and hydrophobic monomers. Cografting resulted in similar retention but higher EOF. With sequential grafting, more than 50% increase in retention factors was obtained and a slight decrease in EOF was observed due to shielding of the ionizable moieties.