Monitoring Cell\nAdhesion on Polycaprolactone–Chitosan\nFilms with Varying Blend Ratios by Quartz Crystal Microbalance with\nDissipation

Abstract

A detailed\nunderstanding\nof the cell adhesion on polymeric surfaces\nis required to improve the performance of biomaterials. Quartz crystal\nmicrobalance with dissipation (QCM-D) as a surface-sensitive technique\nhas the advantage of label-free and real-time monitoring of the cell–polymer\ninterface, providing distinct signal patterns for cell–polymer\ninteractions. In this study, QCM-D was used to monitor human fetal\nosteoblastic (hFOB) cell adhesion onto polycaprolactone (PCL) and\nchitosan (CH) homopolymer films as well as their blend films (75:25\nand 25:75). Complementary cell culture assays were performed to verify\nthe findings of QCM-D. The thin polymer films were successfully prepared\nby spin-coating, and relevant properties, <i>i.e.</i>, surface\nmorphology, ζ-potential, wettability, film swelling, and fibrinogen\nadsorption, were characterized. The adsorbed amount of fibrinogen\ndecreased with an increasing percentage of chitosan in the films,\nwhich predominantly showed an inverse correlation with surface hydrophilicity.\nSimilarly, the initial cell sedimentation after 1 h resulted in lesser\ncell deposition as the chitosan ratio increased in the film. Furthermore,\nthe QCM-D signal patterns, which were measured on the homopolymer\nand blend films during the first 18 h of cell adhesion, also showed\nan influence of the different interfacial properties. Cells fully\nspread on pure PCL films and had elongated morphologies as monitored\nby fluorescence microscopy and scanning electron microscopy (SEM).\nCorresponding QCM-D signals showed the highest frequency drop and\nthe highest dissipation. Blend films supported cell adhesion but with\nlower dissipation values than for the PCL film. This could be the\nresult of a higher rigidity of the cell–blend interface because\nthe cells do not pass to the next stages of spreading after secretion\nof their extracellular matrix (ECM) proteins. Variations in the QCM-D\ndata, which were obtained at the blend films, could be attributed\nto differences in the morphology of the films. Pure chitosan films\nshowed limited cell adhesion accompanied by low frequency drop and\nlow dissipation.