Thermoresponsive Poly(glycidyl ether) Brush Coatings on Various Tissue Culture Substrates-How Block Copolymer Design and Substrate Material Govern Self-Assembly and Phase Transition.

Daniel David Stöbener,Marie Weinhart

doi:10.3390/polym12091899

Daniel David Stöbener, Marie Weinhart

Open Access

https://doi.org/10.3390/polym12091899

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Journal: Polymers	Publication Date: Aug 24, 2020
Citations: 9	License type: CC BY 4.0

Affiliation: Leibniz University Hannover, Freie Universität Berlin

Abstract

Thermoresponsive poly(glycidyl ether) brushes can be grafted to applied tissue culture substrates and used for the fabrication of primary human cell sheets. The self-assembly of such brushes is achieved via the directed physical adsorption and subsequent UV immobilization of block copolymers equipped with a short, photo-reactive benzophenone-based anchor block. Depending on the chemistry and hydrophobicity of the benzophenone anchor, we demonstrate that such block copolymers exhibit distinct thermoresponsive properties and aggregation behaviors in water. Independent on the block copolymer composition, we developed a versatile grafting-to process which allows the fabrication of poly(glycidyl ether) brushes on various tissue culture substrates from dilute aqueous-ethanolic solution. The viability of this process crucially depends on the chemistry and hydrophobicity of, both, benzophenone-based anchor block and substrate material. Utilizing these insights, we were able to manufacture thermoresponsive poly(glycidyl ether) brushes on moderately hydrophobic polystyrene and polycarbonate as well as on rather hydrophilic polyethylene terephthalate and tissue culture-treated polystyrene substrates. We further show that the temperature-dependent switchability of the brush coatings is not only dependent on the cloud point temperature of the block copolymers, but also markedly governed by the hydrophobicity of the surface-bound benzophenone anchor and the subjacent substrate material. Our findings demonstrate that the design of amphiphilic thermoresponsive block copolymers is crucial for their phase transition characteristics in solution and on surfaces.

Highlights

Coatings based on thermoresponsive polymers consistently prove to be a valuable foundation for cell sheet engineering purposes [1,2,3]
Thermal hysteresis and broader phase transition regimes are likely caused by the distinct aggregation behavior of poly(glycidyl ether)s (PGEs)-O-BPs in aqueous solution, which slows down the dissociation of the mesoglobules formed above the Cloud point temperatures (CPTs)
Thermoresponsive coatings based on PGE block copolymers can be fabricated through a viable adsorption/immobilization

Summary

Introduction

Coatings based on thermoresponsive polymers consistently prove to be a valuable foundation for cell sheet engineering purposes [1,2,3] Due to their physical response to changes in temperature under aqueous conditions, such coatings can switch from a rather hydrophobic, protein- and cell-adhesive state into a more hydrophilic, protein- and cell-repellant state upon cooling [4,5]. This phase transition is characterized by an increase in coating hydration, which is usually accompanied by the swelling of the thermoresponsive polymer layer. Besides extensively discussed and investigated poly(N-isopropyl acrylamide) (PNIPAm) gel [8] and brush [9]

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