The chains and segments of unordered cationic polypeptides are complex and may produce unexpected biological activities. Herein, the Ugi's 4CC reaction is adopted to synthesize a cationic alternating copolymer comprising ornithine and glycine (poly(Orn-alter-Gly)) with an ordered sequence for enhanced bacterial resistance. In this technique, potassium isocyanate, 4-(N-carbobenzyloxyamino)-1-butyraldehyde and 1-(4-Methoxyphenyl)ethylamine react to produce MPEsubstituted poly(Orn-alter-Gly) in one step without using a catalyst and then poly(Orn-alter-Gly) is obtained by removing the N-(1-p-methoxyphenethyl) (MPE) group. 1 H NMR, Fourier transform infrared spectroscopy, and automatic amino acid analysis confirm that ornithine and glycine are linked alternately in the poly(Orn-alter-Gly) chains. Both MPE-substituted poly(Orn-alter-Gly) and poly(Orn-alter-Gly) have excellent antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa as well as excellent biocompatibility. The synthesis strategy and materials provide new information on how to obtain ordered sequence cationic polypeptides.

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Bacterial infection and blockage are severe problems for polyurethane (PU) catheters and there is an urgent demand for surface-functionalized polyurethane. Herein, a cationic alternating copolymer comprising allyl-substituted ornithine and glycine (allylsubstituted poly(Orn-alter-Gly)) with abundant carbon−carbon double bond functional groups (CC) is designed. Polyurethane is prepared with a large quantity of CC groups (PU-D), and different amounts of allyl-substituted poly(Orn-alter-Gly) are grafted onto the PU-D surface (PU-D-2%AMPs and PU-D-20% AMPs) via the CC functional groups. The chemical structures of the allyl-substituted poly(Orn-alter-Gly) and polyurethane samples (PU, PU-D, PU-D-2%AMPs, and PU-D-20%AMPs) are characterized and the results reveal that allyl-substituted poly(Orn-alter-Gly) is decorated on the polyurethane. PU-D-20%AMPs shows excellent antibacterial activity against Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus because of the high surface potential caused by cationic allyl-substituted poly(Orn-alter-Gly), and it also exhibits excellent long-term antibacterial activity and antibiofilm properties. PU-D-20%AMPs also has excellent antifouling properties because the cationic copolymer is fixed at multiple reactive sites, thus avoiding the formation of movable long chain brush. A strong surface hydration barrier is also formed to prevent adsorption of proteins and ions, and in vivo experiments reveal excellent biocompatibility. This flexible strategy to prepare dualfunctional polyurethane surfaces with antibacterial and antifouling properties has large potential in biomedical implants.