Photochemical coating of Kapton® with hydrophilic polymers for the improvement of neural implants

The polyimide Kapton (R) was coated photochemically with hydrophilic polymers to prevent undesirable cell growth on the polyimide surface. The polymer coatings were generated using photochemically reactive polymers synthesized by a simple and modular strategy. Suitable polymers or previously synthesized copolymer precursors were functionalized with photoactive arylazide groups by a polymer analogous amide coupling reaction with 4-azidobenzoic acid. A photoactive chitosan derivative (chitosan-Az) and photochemically reactive copolymers containing DMAA, DEAA or MTA as primary monomers were synthesized using this method. The amount of arylazide groups in the polymers was adjusted to approximately 5%, 10% and 20%. As coating on Kapton (R) all polymers effect a significantly reduced water contact angle (WCA) and consequently a rise of the surface hydrophilicity compared to the untreated Kapton (R). The presence of the polymer coatings was also proven by ATR-IR spectroscopy. Coatings with chitosan-Az and the DEAA copolymer cause a distinct inhibition of the growth of fibroblasts. In the case of the DMAA copolymer even a strong anti-adhesive behavior towards fibroblasts was verified. Biocompatibility of the polymer coatings was proven which enables their utilization in biomedical applications. (C) 2017 Elsevier B.V. All rights reserved.