A simple one-step modification of various materials for introducing effective multi-functional groups.

Covalent immobilization of various biomolecules is a desired strategy for bio-multifunctional surface modification. Multi-functionalization of a material surface is considered to be the premise of immobilizing a variety of biomolecules. However, currently adopted methods, used to introduce proper reactive functional groups on material surfaces, mostly are hard to be carried out and frequently can only introduce insufficient functional groups. In this work, we successfully develop the films (GAHD films) prepared via the simple copolymerization of gallic acid (GA) and hexamethylenediamine (HD), which can be deposited on different kinds of material surfaces including metals, ceramics and polymers by a one-step dip-coating method. Moreover, these copolymerized GAHD films possess high concentration of multi-functional groups like carboxyl (COOH), primary amine (-NH2) and quinone groups on the surfaces. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results prove either the occurrence of Michael addition reaction, Schiff base reaction in the film-forming process, or the existence of COOH, NH2 and quinone groups on the surfaces. The maximum contents of carboxyl and amine on the GAHD film are 24.9 nmol/cm(2) and 31.7 nmol/cm(2) respectively. After dynamical immersion for 30 days, slight swellings can be observed, which reveals that the GAHD films possess good stability. Moreover, Heparin (Hep), fibronectin (Fn) and laminin (Ln) are successfully immobilized on the GAHD film surfaces. The results of cell counting kit-8 (CCK-8) and rhodamine fluorescence photograph indicate that the 1:1.62 GAHD film has good cytocompatibility.