Institute of Chemistry and Biochemistry, Freie Universitaet Berlin, Takustr. 3, Berlin 14195, Germany.
Institute of Physical Chemistry and Electrochemistry, Leibniz Universitaet Hannover, Callinstr. 3A, Hannover 30167, Germany.
Langmuir. 2021 Jun 15;37(23):7087-7096. doi: 10.1021/acs.langmuir.1c00695. Epub 2021 Jun 2.
Thermoresponsive coatings that exhibit "switchable" protein- and cell-adhesive properties are frequently used for the fabrication of cell sheets. Among other architectures, polymer brush coatings have shown to be especially viable due to their distinct phase transition behavior, which can be tailored via a manifold of adjustable brush characteristics, such as the (co)monomer composition, polymer chain length, and grafting density. Brush coatings based on poly(glycidyl ether)s (PGEs) have shown to efficiently mediate cell sheet fabrication when tethered to various tissue culture substrates. Herein, we report the phase transition of self-assembled PGE brushes with respect to polymer molecular weight (: 10 and 22 kDa) and grafting density (0.07-0.5 chains nm) on gold model substrates studied by quasi-static QCM-D temperature ramp measurements. The brush grafting density can be tuned via the applied grafting conditions, and all brushes investigated feature broad phase transition regimes (Δ ∼15 °C) with volume phase transition temperatures (VPTTs) close to the cloud point temperatures (CPTs) of the PGEs in solution. We further demonstrate that brush coatings with a low grafting density (0.07-0.12 chains nm) exhibit a continuous brush-to-mushroom transition, whereas brushes with medium grafting densities (0.3-0.5 chains nm) undergo a brush-to-brush transition comprising vertical phase separation during the phase transition progress. These insights help to understand the transition behavior of thin, thermoresponsive brushes prepared via grafting-to strategies and contribute to their rational design for improved functional surfaces.
具有“可切换”蛋白质和细胞附着特性的温敏涂层常用于细胞片的制备。在其他结构中，聚合物刷涂层因其独特的相转变行为而显示出特别的可行性，这种行为可以通过多种可调刷特性来调整，例如（共）单体组成、聚合物链长和接枝密度。基于聚（缩水甘油醚）（PGEs）的刷涂层在与各种组织培养基质结合时，已被证明可以有效地介导细胞片的制备。在此，我们报告了在金模型基底上自组装的 PGE 刷的相转变，涉及聚合物分子量（10 和 22 kDa）和接枝密度（0.07-0.5 个链 nm），通过准静态 QCM-D 温度斜坡测量进行研究。刷接枝密度可以通过施加的接枝条件进行调整，所有研究的刷都具有宽的相转变区域（Δ约 15°C），其体积相转变温度（VPTT）接近溶液中 PGE 的浊点温度（CPT）。我们进一步证明，低接枝密度（0.07-0.12 个链 nm）的刷涂层表现出连续的刷-蘑菇转变，而中等接枝密度（0.3-0.5 个链 nm）的刷涂层经历了包括垂直相分离的刷-刷转变在相转变过程中。这些见解有助于理解通过接枝到策略制备的薄的温敏刷的转变行为，并有助于它们的合理设计以改善功能表面。
