Electrochemical Aptatoxisensor Responses on Nanocomposites Containing Electro-Deposited Silver Nanoparticles on Poly(Propyleneimine) Dendrimer for the Detection of Microcystin-LR in Freshwater

Abstract

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 µg·L−1 and the calculated limit of detection (LOD) was 0.04 µg·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.

Aptamers as the Agent in Decontamination Assays (Apta-Decontamination Assays): From the Environment to the Potential Application In Vivo

“…Akin to the capture assay application as reviewed by Citartan et al [ 27 ], the very first step for the application of the aptamers for the biodecontamination is the immobilization of the aptamers on the surface of the platforms. To enable this immobilization, aptamers are first functionalized with specific functional groups (e.g., thiol, amine, and biotin) [ 22 , 33 ]. Interaction of these functional groups with the functional groups on the surface of the platforms immobilizes the aptamer.…”

Electrochemical Biosensing of Algal Toxins in Water: The Current State-of-the-Art

“…52,57 Without using any electroactive probes/ mediators in the solution, one study demonstrated that the linear range of MC-LR concentration to CV current response was very limited (i.e., 0.1 to 1.1 μg/L) before it began to plateau. 54 It should also be noted that in the case of voltammetry sensor using negatively charged aptamers, their electrostatic interaction with electroactive probes chosen (i.e., repulsion or attraction) could play a more important role than steric/conformational changes into locked structure upon binding with algal toxins. For example, when using negatively charged [Fe(CN) 6 ] 3-/4as electroactive probes, it was observed that redox current increased with the amount of MC-LR binding to aptamers.…”

Determination of microcystin-LR, employing aptasensors

“…AgNPs to design a electrochemical aptasensor for MC-LR detection at nanomolar levels (Bilibana et al 2016). In the proposed system, a thin film of SDD-Co (II) was deposited onto a GCE surface and then AgNPs were electro-synthesized on the surface of film.…”

“…The sensing platform demonstrated linearity between 0.1 and 1.1 µg L -1 with a LOD of 0.04 µg L -1 . Employing standard spiking methods, the average recoveries were calculated as between 94 to 115% in water samples (Bilibana et al 2016).…”