Switchable phase transition behavior of thermoresponsive substrates for cell sheet engineering

• Published in: Journal of polymer science. Part B, Polymer physics Polymer physics, 2018-12, Vol.56 (23), p.1567-1576
• Main Authors: Mokhtarinia, Kiana, Nourbakhsh, Mohammad Sadegh, Masaeli, Elahe, Entezam, Mehdi, Karamali, Fereshteh, Nasr‐Esfahani, Mohammad Hossein
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Biomedical materials; cell adhesion; cell sheet engineering; Chemical composition; Critical temperature; Cultivation; Fourier transforms; Grafting; Hydrophobicity; Infrared reflection; Infrared spectroscopy; Isopropylacrylamide; Microscopy; Nonlinear response; Organic chemistry; Phase transitions; poly(N‐isopropylacrylamide); Substrates; thermoresponsive polymers; Thickness; Tissue engineering; Wettability
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/polb.24744

ABSTRACT Recently, there are significant interests in the development of biomaterials with nonlinear response to an external stimulus. Thermoresponsive polymers as a well‐known class of stimuli‐responsive materials represent reversible hydrophilicity/hydrophobicity characteristics around a critical temperature. This switchable behavior applies for nondestructive cellular detachment from cultivation substrates. In this study, poly (N‐isopropylacrylamide) (PNIPAAm)‐grafted dishes were made up to harvest retinal pigmented epithelial (RPE) and periodontal ligament cell (PDLC) sheets. Wettability assessments verified that all functionalized surfaces were inverted from hydrophilic to hydrophobic state when the temperature rises from lower critical solution temperature (LCST) at 37 °C. Other physicochemical characteristics such as chemical composition, grafting thickness, and surface topography were investigated through attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and atomic force microscopy (AFM). ATR‐FTIR results showed typical peaks of amide group corresponding to successful PNIPAAm polymerization. AFM microscopy results also proved creating a rough PNIPAAm layer with thickness of 29.2 nm after grafting process in the mixture of methanol and water. Cell culture experiments showed an irreversible cellular attachment/detachment from modified surfaces upon temperature changes. These results introduced thermoresponsive TCPS to noninvasively harvest RPE and PDLCs sheets especially for application in scaffold‐free tissue engineering decorations. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1567–1576 In this study, a uniform polymeric layer with appropriate thickness (15 nm) was polymerized and grafted on the surface of TCPS substrate using electron beam irradiation at the static mode in the mixture of methanol/water solvents. Given the inherent intelligence of PNIPAAm and the versatility of the grafting method, obtained smart surfaces showed promising future in cell sheet engineering, particularly for periodontal tissue regeneration and treatment of sight‐threatening diseases caused by retina degeneration.