NAMS 2002 Workshop - ICOM 2008

Biomedical and Biotechnology II – 5
Wednesday July 16, 11:45 AM-12:15 PM, Honolulu/Kahuku
Anti-Biofouling Membrane Surface with Grafted Zwitterionic
Polysulfobetaine for Improved Blood Compatibility
Y. Chang (Speaker), R&D Center for Membrane Technology and Department of Chemical
Engineering, Taoyuan, Taiwan - yungchang0307@gmail.com
One of the most important requirements for membranes in biomedical
applications is to reduce the nonspecific adsorption of biomolecules when living
systems encounter membrane surfaces. Biofouling of membranes prepared from
hydrophobic materials will lead to a change in biomolecular structure selectively
decreasing the permeate flux with time, especially in the filtration of protein,
platelet, or cell-containing solutions. In general, ester group in poly(ethylene
glycol) (PEG)- based material is the ideal choice of surface functional moiety with
anti-biofouling characteristics. However, it has been recognized that PEG
decomposes in the presence of oxygen and transition metal ions found in most
biochemically relevant solutions. Whereas, PEG exhibits an excellent nonfouling
capability, but it faces the problem of long-term stability for biomedical uses.
Therefore, materials containing zwitterionic phosphotidylcholine headgroups
have become one of the popular synthetic materials for developing anti-biofouling
surfaces. Recently, our works have shown that material surfaces containing
similar zwitterionic structure to phosphorylcholine, such as sulfobetaine are ideal
for resisting protein adsorption when the surface density and chain length of
zwitterionic groups is controlled. In our current research, it was further
demonstrated that a surface with well-packed grafted zwitterionic
polysulfobetaine performs highly stable anti- biofouling properties for plasma
protein repulsion. This work is aimed at addressing two important issues for
polysulfobetaine (PSBMA) stability, i.e., (i) protein adsorption on PSBMA
surfaces at different ionic strengths, solution pH values, and temperatures, (ii)
PSBMA blood compatibility in the human body temperature. The results were
systematically studied by surface plasmon resonance and will be summarized in
the first part of the giving talk. This work concluded that zwitterionic PSBMA
provides a significant impact and opportunity in searching for alternative stable
nonbiofouling materials other than PEG. In this extended study, the strategy for
creating zwitterionic PSBMA surface will be introduced to prepare anti-biofouling
membranes. The general idea was performed by two different surface
modification approaches for the case of segmented polyurethane (SPU)
membrane, which will be presented in the second part of the giving talk. For the
first case system, interpenetrating polymer networks (IPNs) on the prepared
membrane surface were prepared by the modification of a SPU with a crosslinked
sulfobetaine methacrylate (SBMA) polymer. The IPN membrane surfaces
that were prepared can effectively resist nonspecific protein adsorption when the