Direct Measurement of Total Vesicular Catecholamine Content with Electrochemical Microwell Arrays
Journal article, 2020

We have designed and fabricated a microwell array chip (MWAC) to trap and detect the entire content of individual vesicles after disruption of the vesicular membrane by an applied electrical potential. To understand the mechanism of vesicle impact electrochemical cytometry (VIEC) in microwells, we simulated the rupture of the vesicles and subsequent diffusion of entrapped analytes. Two possibilities were tested: (i) the vesicle opens toward the electrode, and (ii) the vesicle opens away from the electrode. These two possibilities were simulated in the different microwells with varied depth and width. Experimental VIEC measurements of the number of molecules for each vesicle in the MWAC were compared to VIEC on a gold microdisk electrode as a control, and the quantified catecholamines between these two techniques was the same. We observed a prespike foot in a significant number of events (similar to 20%) and argue this supports the hypothesis that the vesicles rupture toward the electrode surface with a more complex mechanism including the formation of a stable pore intermediate. This study not only confirms that in standard VIEC experiments the whole content of the vesicle is oxidized and quantified at the surface of the microdisk electrode but actively verifies that the adsorbed vesicle on the surface of the electrode forms a pore in the vicinity of the electrode rather than away from it. The fabricated MWAC promotes our ability to quantify the content of vesicles accurately, which is fundamentally important in bioanalysis of the vesicles.

Author

Elias Ranjbari

University of Gothenburg

Zahra Taleat

University of Gothenburg

Mokhtar Mapar

Chalmers, Physics, Biological Physics

Mohaddeseh Aref

University of Gothenburg

Johan Dunevall

University of Gothenburg

Andrew Ewing

University of Gothenburg

Analytical Chemistry

0003-2700 (ISSN) 1520-6882 (eISSN)

Vol. 92 16 11325-11331

Subject Categories

Analytical Chemistry

Materials Chemistry

Other Chemistry Topics

DOI

10.1021/acs.analchem.0c02010

PubMed

32692153

More information

Latest update

10/1/2020