(309c) Molecular Understanding, Design and Development of Ultralow Fouling Zwitterionic Materials

An important challenge in many biomedical and engineering applications is the prevention of unwanted nonspecific biomolecular and macromolecular attachment on surfaces from drug delivery carriers and implants to ship hulls and membranes. Poly(ethylene glycol) (PEG) has been a gold standard as nonfouling materials for 45 years although it suffers stability and immunogenicity issues. It is challenging to develop nonfouling materials beyond PEG. Using molecular simulation methods and statistical mechanical theories I learned from Prof. Keith Gubbins when I did my PhD work under his guidance at Cornell, our group revealed molecular nonfouling mechanisms, applied molecular principles learned to the design of new nonfouling materials, and developed a new class of nonfouling materials based on zwitterionic materials. These zwitterionic materials include poly(carboxybetaine), poly(sulfobetaine), poly(trimethylamine N-oxide), and glutamic acid (E) and lysine (K)-containing poly(peptides). Unlike amphiphilic PEG, zwitterionic materials are super-hydrophilic and non-immunogenetic. Furthermore, unlike PEG, there exist diversified zwitterionic molecular structures to accommodate various properties and applications.

In this talk, I will discuss the fundamental understanding and applications of zwitterionic materials. With zwitterionic materials and surfaces, we demonstrate new technological capabilities that are never been achieved with PEG and other existing biomaterials: (a) no capsule formation upon subcutaneous implantation in mice up to one year, (b) expansion of hematopoietic stem and progenitor cells (HSPCs) without differentiation, (c) no anti-coagulants needed for artificial lungs in sheep, (d) no antibodies generated against zwitterionic polymers; (e) long-term resistance to marine biofoulants. I will also discuss the important role and opportunities of zwitterionic materials in immunoengineering.