5)Proteindeliverywithnanoscaleprecision.docVIP

5) Protein delivery with nanoscale precisionQiling Tang, Yuexing Zhang, Liaohai Chen, Funing Yan and Rong Wang INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY Nanotechnology 16 (2005) 1062–1068 doi:10.1088/0957-4484/16/8/011 Protein delivery with nanoscale precision Qiling Tang1, Yuexing Zhang2, Liaohai Chen2, Funing Yan1 and Rong Wang1,3 1 Illinois Institute of Technology, Chicago, IL 60616, USA 2 Argonne National Laboratory, Argonne, IL 60439, USA E-mail: wangr@iit.edu Received 2 December 2004, in final form 11 March 2005 Published 12 May 2005 Online at stacks.iop.org/Nano/16/1062 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. (Some figures in this article are in colour only in the electronic version) 1. Introduction The examination of living cells on the nanometre scale has attracted a lot of interest in recent years. This is because the elucidation of cellular functions at the molecular level can provide novel strategies for correcting cell dysfunction, thus opening up ne