Electrochemical Atomic-Force Microscopy Using a Tip-Attached Redox Mediator. Proof-of-Concept and Perspectives for Functional Probing of Nanosystems

Autor:	Agnès Anne, Cédric Goyer, Christophe Demaille
Rok vydání:	2009
Předmět:	chemistry.chemical_classification Chemistry General Engineering General Physics and Astronomy Substrate (chemistry) Nanotechnology Polymer Electrochemistry Redox chemistry.chemical_compound Ferrocene Microscopy General Materials Science Reactivity (chemistry) Nanoscopic scale
Zdroj:	ACS Nano. 3:819-827
ISSN:	1936-086X 1936-0851
Popis:	This paper presents the first steps toward the development of a new type of high-resolution AFM-SECM microscopy which relies on the use of tip-attached redox-labeled polymer chains as mediators to probe the local electrochemical reactivity of a planar substrate at the nanoscale. Submicrometer-sized combined gold AFM-SECM probes were functionalized by linear, nanometer-sized, flexible, PEG3400 chains bearing a ferrocene (Fc) redox label at their free end. Analysis of the force and current approach curves recorded when such Fc-PEGylated probes (tips) were approached to a bare gold substrate allowed the presence of the Fc-PEG chains at the very tip end of the combined probes to be specifically demonstrated. It also allowed the chain coverage, configuration, and dynamics to be determined. When the Fc-PEGylated probe is positioned some approximately 5 nm above the substrate, only a few hundred chains are actually electrochemically contacting the surface, thus reducing the size of the tip-substrate interaction area to 20-40 nm. Most importantly, we have shown that the tip-borne PEG chains are flexible enough to allow their Fc heads to efficiently "sense" locally the electrochemical reactivity of the substrate, thus validating the working principle of the new AFM-SECM microscopy we propose. This innovative microscopy, we label Tarm (for tip-attached redox mediator)/AFM-SECM, should be particularly suitable for probing the activity of slowly functioning nanometer-sized active sites on surfaces, such as individual enzyme molecules, because it is, by design, free of the diffusional constraints which hamper the characterization of such nanosystems by classical SECM.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1c7d67bbdc1101337cd732b5622aadd4 https://doi.org/10.1021/nn8007788 Zobrazit plný text záznamu