Facile fabrication of ultrathin antibacterial hydrogel films via layer-by-layer “click” chemistry

We report a facile strategy to fabricate ultrathin hydrogel films via a layer-by-layer (LbL) technique and “click” chemistry. Poly[oligo(ethylene glycol)fumarate]-co-poly[dodecyl bis(2-hydroxyethyl)methylammonium fumarate] (POEGDMAM) containing multi-enes and poly[oligo(ethylene glycol)mercaptosuccinate] (POEGMS) containing multi-thiols were synthesized by polycondensation, which were used as precursors for a LbL thiol–ene “click” reaction under ambient conditions without any metal catalyst or light irradiation. Due to the presence of ammonium groups with long alkyl chains in the POEGDMAM, the ultrathin hydrogel films exhibited excellent antibacterial activity against both Staphylococcus aureus and Escherichia coli, which was enhanced by increasing the number of layers. These kinds of biocompatible, antibacterial, ultrathin hydrogel films are promising candidates for biomedical applications.