Development Of New Polyurethane With Zwitterionic Brush Side Chains And Their Protein Resistance

"Biological fouling", the undesired attachment of nonspecific protein, biomolecular and microorganism on surfaces is a great challenge in many applications ranging from biomedical devices to marine coatings. For medical devices and implants, nonspecific protein adsorption lead to unwanted fouling, degrades the performance of surface-based diagnostic devices and initiate subsequent adverse inflammatory responses, thus resulting in implantable device failure and adverse outcomes to the patients. On the other hand, marine biofouling caused by the colonization of unwanted marine organisms on the submerged surfaces had been a global problem for maritime industries and Navy ships. Biofouling lead to waste of fuel and future emissions of greenhouse gas. So, developing anti-fouling coatings which are resistant to the attachment of marine organisms is urgent and meaningful.In my research, polyurethane (PU) with zwitterionic side chains based on poly(carboxybetaine) ester analogue is developed for marine coatings and biomedical applications. First, The carboxybetaine ester (CB-ester) analogue is prepared, Then dihydroxy-terminated poly(carboxybetaine) ester analogue (PCB(OH)2) is synthesized by free radical polymerization with 3-mercapto-1,2-propanediol as the chain transfer agent, which polyadds with diisocyanate to yield PUs with poly(carboxybetaine) ester analogue side chains (PCB-PU). The mew polymer exhibit excellent resistance to non-specific protein adsorption, bacterial adhesion and HUVEC cell attachment after a quick hydrolysis. Attenuated total reflectance infrared (ATR-IR) and Static contact angle measurement show the surface structure and hydrophilicity of PUs before and after hydrolysis. ELISA shows the PUs have different protein resistance depending on the content of CB ester analogue and different structures of side chains. Adhesion test according to ISO 4624 and GB/T 5210 shows strong pull-off strength of the material. Furthermore, the self-regeneration test demonstrated the polymer could heal the damaged surfaces by slow and controllable hydrolysis of the hydrophobic matrix. At last, we tested the protein resistance property of the material after 30 days hydrolysis in weak alkaline solution, the result demonstrated the long-term nonfouling performance of the material. After all, the excellent resistance to non-specific protein adsorption and good coating ability make this material an ideal candidate for marine and medical device coatings.