Surface Functionalization of MEMS for a Bioartificial Kidney

Figure 1. Schematic representation of the surface modification strategy to minimize protein fouling.

Silicon nanoporous membranes (SNM) with monodisperse slit-shaped pores have potential application in medical procedures where membranes are used, such as hemodialysis, plasmapheresis, and membrane oxygenation. Blood compatibility is a critical concern in translating SNM, or any novel biomaterial, from bench to biomedical applications. Membrane biofouling is a process that starts immediately upon contact of an implanted device with the body and occurs when proteins, cells, and other biological components adhere to the artificial surface, and eventually clot the pores of the material. The nonspecific adsorption of proteins from blood (e.g., fibrinogen), even at a very low level, will cause platelet adhesion, aggregation, and thrombosis, leading to device failure. Therefore, membrane surface chemistry should be controlled to prevent protein fouling and activation of the blood coagulation cascade. Hydrophilic poly(ethylene glycol) (PEG) based polymers, zwitterionic polymers, and polymers incorporating oligosaccharide moieties are inherently anti-biofouling in nature. The ultimate objective of this work is to develop stable thin film coatings with nonfouling characteristics on silicon nanoporous membranes for applications as hemofiltration.

Figure 2. Three potential surface coating materials: PEG, Polyzwitterions, and oligosaccharide surfactant polymers.

Goals:

1. Development of biocompatible materials

2. In vitro biocompatibility evaluations

3. Filtration studies on coated SNM substrates

Figure 3. Comparison of fibinogen adsoption on various biomaterials.