PNNL

Abstract

We report an effective approach to patterning cells on a gold-silicon substrate with high precision, selectivity, stability, and reproducibility. This technique is based on photolithography and surface molecular engineering and does not involve a cell positioning or delivery device, thus reducing potential damage to cells. Cell patterning is achieved by activating the gold regions with functionalized thiols that covalently bind proteins to guide the subsequent cell adhesion and passivating the silicon regions with polyethylene glycol (PEG) to resist cell adhesion. Time-of-light secondary ion mass spectrometry (TOF-SIMS), a powerful surface chemical state imaging technique that allows simultaneous chemical and spatial characterization, was used to characterize the chemistry of the cell-adhesive and cell-resistant regions of the surface at key stages in the device fabrication. Fourier transform infrared (FTIR) reflectance spectroscopy was used to verify the immobilization of proteins on model surfaces. Proteins were tagged with Rhodamine fluorescent probes to characterize patterned surfaces by fluorescence microscopy. Finally, the ability of the engineered surfaces to guide cell adhesion was illustrated by differential interference contrast (DIC) reflectance microscopy. The cell patterning technique introduced in this study is compatible with micro- and photo- electronics, and may have numerous medical, environmental, and defense applications.