A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II)
salicylaldiimine metallodendrimer (SDD-Co(II)) doped with electro-synthesized silver nanoparticles
(AgNPs) for microcystin-LR (L, L-leucine; R, L-arginine), or MC-LR, detection in the nanomolar
range. The GCE|SDD-Co(II)|AgNPs aptatoxisensor was fabricated with 5' thiolated aptamer through
self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response
was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on
GCE|SDD-Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric
hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of
the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and
1.1 ug L-1 and the calculated limit of detection (LOD) was 0.04 ug L-1. In the detection of MC-LR
in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in
the presence of interfering analog and was comparable to the conventional analytical techniques.
The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine
quantification of MC-LR in freshwater and environmental samples.