Abstract:
The ability of streptavidin (SA) to simultaneously bind four biotins is often used in linker layers, where
a biotinylated molecule is linked to a biotin-functionalized surface via SA. For biosensor and array
applications, it is desirable that the SA linker layer be stable to drying and rehydration. In this study it
was observed that a significant decrease in binding capacity of a SA layer occurred when that layer was
dried. For this study a SA linker layer was constructed by binding SA to a biotin-containing alkylthiolate
monolayer (BAT/OEG) self-assembled onto gold. Its stability after drying was investigated using surface
plasmon resonance (SPR). Approximately a quarter of the SA layer was removed from the BAT/OEG
surface upon drying and rehydration, suggesting disruption of SA-biotin binding when dry. This resulted
in the dried SA layer losing 40% of its biotinylated ferritin (BF) binding capacity. Coating the layer with
trehalose before drying was found to inhibit the loss of SA from the BAT/OEG surface. SPR showed that
the trehalose-protected SA linker layer retained 91% of its original BF binding capacity after drying and
rehydration. Atomic force microscopy, which was used to image individual surface-bound SA and BF
molecules, qualitatively confirmed these observations.
