Akiyama Yoshikatsu
Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University (TWIns), 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8886, Japan.
Heliyon. 2021 Mar 16;7(3):e06520. doi: 10.1016/j.heliyon.2021.e06520. eCollection 2021 Mar.
A previous report shows that poly(-isopropylacrylamide) (PIPAAm) gel grafted onto poly(dimethylsiloxane) (PDMS) (PI-PDMS) surfaces with large PIPAAm graft density (Lar-PI-PDMS), is prepared by using electron beam irradiation, demonstrating that applied mechanical stretching affects properties of the Lar-PI-PDMS surface. However, the influence of PIPAAm graft density on the properties of PI-PDMS surfaces and their stability are not understood. To provide insight into these points, the properties of PI-PDMS surfaces with low PIPAAm graft density (Low-PI-PDMS) surfaces with stretched (stretch ratio = 20%) and unstretched states were examined as stretchable temperature-responsive cell culture surface using contact angle measurement and cell attachment/detachment assays, compared to those with Lar-PI-PDMS, as previously reported. Long-term contact angle measurements (61 days) for unstretched Low-PI-PDMS and Lar-PI-PDMS surfaces indicated that the cross-linked structure of the grafted PIPAAm gel suppressed hydrophobic recovery of the basal PDMS surface. The cell attachment assay revealed that the stretched Low-PI-PDMS surface was less cell adhesive than that of the unstretched Low-PI-PDMS surface despite of a larger amount of adsorbed fibronectin (FN). The lower cell adhesiveness was possibly explained by denaturation of adsorbed FN, which was induced by the strong hydrophobic property of the stretched Low-PI-PDMS surface. The cell detachment assay revealed that dual stimuli, low temperature treatment and mechanical shrinking stress applied to the stretched Low-PI-PDMS surface promoted cell detachment compared to a single stimulus, low temperature treatment or mechanical shrinking stress. These results suggested that the PIPAAm gelgrafted PDMS surface was chemically stable and did not suffer from hydrophobic recovery. External mechanical stretching stress not only strongly dehydrated grafted PIPAAm chains, but also denatured the adsorbed FN when the grafted PIPAAm layer was extremely thin, as in Low-PI-PDMS surfaces. Thus, PI-PDMS may be utilized as a stretchable temperature-responsive cell culture surface without significant hydrophobic recovery.
先前的一份报告显示，通过电子束辐照制备了接枝密度大的聚（N-异丙基丙烯酰胺）（PIPAAm）凝胶接枝到聚二甲基硅氧烷（PDMS）（PI-PDMS）表面上（Lar-PI-PDMS），这表明施加的机械拉伸会影响Lar-PI-PDMS表面的性能。然而，PIPAAm接枝密度对PI-PDMS表面性能及其稳定性的影响尚不清楚。为了深入了解这些问题，与先前报道的Lar-PI-PDMS相比，使用接触角测量和细胞附着/脱离试验，研究了具有低PIPAAm接枝密度（Low-PI-PDMS）的PI-PDMS表面在拉伸（拉伸比=20%）和未拉伸状态下作为可拉伸温度响应性细胞培养表面的性能。对未拉伸的Low-PI-PDMS和Lar-PI-PDMS表面进行的长期接触角测量（61天）表明，接枝的PIPAAm凝胶的交联结构抑制了基底PDMS表面的疏水恢复。细胞附着试验表明，尽管吸附的纤连蛋白（FN）量较多，但拉伸后的Low-PI-PDMS表面的细胞粘附性低于未拉伸的Low-PI-PDMS表面。较低的细胞粘附性可能是由于拉伸后的Low-PI-PDMS表面的强疏水性导致吸附的FN变性所致。细胞脱离试验表明，与单一刺激（低温处理或机械收缩应力）相比，施加于拉伸后的Low-PI-PDMS表面的双重刺激（低温处理和机械收缩应力）促进了细胞脱离。这些结果表明，PIPAAm凝胶接枝的PDMS表面化学稳定，不会发生疏水恢复。外部机械拉伸应力不仅使接枝的PIPAAm链强烈脱水，而且当接枝的PIPAAm层极薄时（如在Low-PI-PDMS表面），还会使吸附的FN变性。因此，PI-PDMS可作为一种可拉伸的温度响应性细胞培养表面，且不会有明显的疏水恢复。
