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A Comparison of the Cell Compatibility of Poly(ethyleneimine) with that of other Cationic Biopolymers Used in Applications at Biointerfaces

Poly(ethyleneimine) (PEI) is used as an initiating base layer or intermediate layer for layer‐by‐layer (LBL) technology. Since PEI is potentially cytotoxic in solution, it is necessary to investigate the influence of the physical properties of PEI layers on osteoblast cells. Therefore, the first aim of this study was to test the hypothesis that there is no statistically significant difference of cell adhesion, proliferation, and viability in response to nanometer thin polymer layers of PEI compared to other well‐known polymers. The second aim of this study was to test the hypothesis that the amine‐substituted dextran (aminodextran (AMD)) adheres well on Ti and can be used as a polymer coating in biomaterials applications. Titanium samples were coated with PEI, poly‐L‐lysine (PLL), or AMD using dip coating. The polymer films were investigated with ellipsometry, atomic force microscopy, contact angle measurements, and X‐ray‐photoelectron spectroscopy (XPS). Cell adhesion, proliferation, and viability tests were carried out using osteoblast‐like cells (CAL‐72). Thin polymer layers below 10 nm layer thickness were found on the Ti surfaces. It was shown for the first time that base layers of PEI with nanometer thickness do not affect the bone cell reaction negatively. PEI, therefore, can be used as a functional base layer for LBL functionalization of metallic implants. AMD can be used in biomedical applications but does not adhere on titanium without an adhesion promoter.