Computer-Assisted Processing of Current Step Signals in Single Blocking Impact Electrochemistry

Current step signals
related to single-entity collisions in blocking
impact electrochemistry were analyzed by computer-assisted processing
for estimating the size distributions of various particles. In this
work, three different types of entities were studied by single blocking
impact electrochemistry: polystyrene nanospheres (350 nm diameter)
and microspheres (1 μm diameter), phospholipid liposomes (300
nm diameter) and two different strains of Gram-negative bacillus bacteria
(Escherichia coli and Shewanella oneidensis). The size estimations of these
different entities from the current step signal analysis were compared
and discussed according to the shape and size of each entity. From
the magnitude of the current step transient, the size distribution
of each entity was calculated by a new computer program assisting
in the detection and analysis of single impact events in chronoamperometry
measurements. The data processing showed that the size distributions
obtained from the electrochemical data agreed with the dynamic light
scattering and atomic force microscopy data for nanospheres and liposomes.
In contrast, the size estimation calculated from the electrochemical
data was underestimated for microspheres and bacteria. We demonstrated
that our computer program was efficient for detecting and analyzing
the collision events in single blocking impact electrochemistry for
various entities from spherical hard nanoparticles to micrometer-sized
rod-shaped living bacteria.