Protein delivery with nanoscale precision

Abstract

A novel assay of protein delivery to a surface with nanoscale precision was established. This was achieved by combining recent advancements in atomic force microscopy (AFM) and bioconjugation. We utilized a heterobifunctional photocleavable cross linker to functionalize an AFM tip with proteins. Upon irradiation, the proteins were released from the tip due to a photolytic reaction of the cross linker. These proteins bound tightly to their binding partners on a substrate. When tip functionalization is carefully controlled, proteins can be locally delivered to a desired area. Importantly, the result of protein delivery can be examined immediately by high-resolution imaging in the same area using the protein-free tip. Successful protein delivery was also confirmed by fluorescence imaging and was proved to be reproducible. The approach allows protein delivery and subsequent imaging to be performed in the same local area with the same AFM tip, thus opening up the possibility of monitoring protein functions in living cells in real time.