Issue 16, 2024

Amplifying the electrochemical footprint of <1000 molecules in a dissolving microdroplet

Abstract

The ability of analytical strategies to detect and positively identify molecules under extremely dilute conditions is important for the growth and expansion of analytical techniques and instrumentation. At present, few measurement science techniques can robustly approach the measurement of just a few thousand molecules. Here, we present an electrochemical platform for the detection and positive identification of fewer than 1000 molecules of decamethylferrocene ((Cp*)2FeII). We achieve this remarkable detection threshold by trapping (Cp*)2FeII in a 1,2-dichloroethane microdroplet, which is allowed to dissolve into an aqueous continuous phase while on a gold microelectrode (radius ∼6.25 μm). Because electrochemistry is not sensitive enough to observe the charge of less than 1000 molecules, we dissolved μM amounts hexacyanoferrate(III) in the aqueous continuous phase. The biphasic reaction between hexacyanoferrate(III) and Cp2*(Fe)II allows for a feedback loop when the microelectrode is biased sufficiently negative to reduce Cp2*(Fe)III. This feedback loop, a typical EC′ catalytic mechanism, amplifies the electrochemical signal of Cp2*(Fe)II when the droplet is of small enough dimensions for feedback to occur. Our results demonstrate that clever biphasic reactions can be coupled with dissolving microdroplets to access extremely low limits of quantitation in electroanalysis.

Graphical abstract: Amplifying the electrochemical footprint of <1000 molecules in a dissolving microdroplet

Supplementary files

Article information

Article type
Paper
Submitted
03 Apr 2024
Accepted
17 May 2024
First published
17 May 2024
This article is Open Access
Creative Commons BY license

Analyst, 2024,149, 4222-4229

Amplifying the electrochemical footprint of <1000 molecules in a dissolving microdroplet

J. H. Nguyen, A. Rana and J. E. Dick, Analyst, 2024, 149, 4222 DOI: 10.1039/D4AN00504J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements