Antibacterial coatings and methods of making the antibacterial coatings are described herein. A first branched polyethylenimine (BPEI) layer is formed and a first glyoxal layer is formed on a surface of the BPEI layer. The first BPEI layer and the first glyoxal layer are cured to form a crosslinked BPEI coating. The first BPEI layer can be modified with superhydrophobic moieties, superhydrophilic moieties, or negatively charged moieties to increase the antifouling characteristics of the coating. The first BPEI layer can be modified with contact-killing bactericidal moieties to increase the bactericidal characteristics of the coating.