A novel amphiphilic polypeptoid based ultrafiltration membrane with excellent biocompatible property

Polysarcosine (PSar), a polypeptoid with a chemical structure resembling natural amino acids, stands out as a prominent non-ionic polypeptoid due to its outstanding water solubility and biocompatibility. These extraordinary properties make PSar a highly appealing material for a wide range of biomedical applications, especially in biocompatible membranes. However, due to its high-water solubility, PSar is inherently not stable enough for membranes. It is an effective way to apply PSar in membrane field by improving its stability while ensuring the hydrophilicity. Here, a novel copolymer, consisting of PSar and polysulfone (PSF) blocks (PSF-b-PSar, denoted as PSbS), is presented and synthesized by ring-opening polymerization (ROP) of N-phenyloxycarbonyl-sarcosine (Sar-NPC), which is used as a functional skin layer on PSF substrates. The results demonstrated that the PSbS performed a highly hydrated layer on the membrane surface, thus mitigating interactions between biomolecules and biological entities. Notably, the PSbS/PSF membrane showed improved antifouling, biocompatibility, hemocompatibility and stability. Moreover, the hemolysis rate of the composite membrane was reduced to 0.56%, and the activated partial thromboplastin time (APTT) was effectively prolonged. In summary, this work proposed a strategy for solidifying PSar on the membrane surface as the non-water-soluble amphiphilic polymer, which is promising in the biomedical applications, especially in biocompatible membranes.