Functionalized Self-Assembled Monolayers on Ultraflat Gold as Platforms for Single Molecule Force Spectroscopy and Imaging

详细信息    查看全文

• 作者：Vamsi K. Yadavalli ; Jeffrey G. Forbes ; Kuan Wang
• 刊名：Langmuir
• 出版年：2006
• 出版时间：August 1, 2006
• 年：2006
• 卷：22
• 期：16
• 页码：6969 - 6976
• 全文大小：652K
• 年卷期：v.22,no.16(August 1, 2006)
• ISSN：1520-5827

文摘

Single molecule force spectroscopy is a valuable tool for studying unfolding and nanomechanical properties ofproteins. The common practice is to stretch proteins from a surface that was dosed to give a reasonable hit rate andto analyze the curves that exhibit the expected characteristics of a single polymer. Whether the surface-bound proteinsare indeed single and isolated remains unclear, and the undesirable protein/surface interactions that obscure informativefeatures of the force curves are implicitly assumed to be absent. In this study, mixed self-assembled monolayers(SAMs) consisting of N-hydroxysuccinimide (NHS) and oligoethylene glycol (OEG) terminated thiols on an ultraflatgold surface were used to covalently immobilize proteins via lysine residues. By the optimization of attachment sitesvia lysine-NHS linkages amidst a protein-resistant layer of the OEG SAM, it was possible to isolate single proteinsfor study in a controlled fashion. The single protein distribution on the surface is clearly demonstrated by atomic forcemicroscopy (AFM) imaging. The OEG also significantly reduces nonspecific tip-surface interactions between thecantilever and surface. Stretching covalently attached single proteins produces high-quality and reproducible force-extension curves. This experimental strategy is an attractive platform with which to study protein structure, interactions,and nanomechanical properties of single proteins.