Ultrasensitive electrochemical microcystin-LR immunosensor using gold nanoparticle functional polypyrrole microsphere catalyzed silver deposition for signal amplification

Abstract

This work designed an ultrasensitive electrochemical immunosensor for microcystin-LR (MC-LR) detection using gold nanoparticle functional polypyrrole microsphere (AuNP/PPyMS) as a novel signal tag to induce silver enhancement for signal amplification. The dispersed polypyrrole microsphere (PPyMS) synthesized with a chemical oxidative polymerization was used to load AuNP for labeling signal antibodies, which enhanced the detection signal due to large surface area. The proposed MC-LR immunosensor was constructed by coating a polyethylene glycol film on a carbon nanotubes modified electrode and then immobilizing MC-LR antigen on the film. With a competitive immunoassay format, coated MC-LR competed for MC-LR antibody with added target MC-LR to form antibody-antigen immunocomplex. Subsequently, the immunocomplex reacted with AuNP/PPyMS labeled signal antibodies. The MC-LR immunoreaction monitoring was achieved by the electrochemical stripping signal of the deposited silver catalyzed by AuNP/PPyMS. AuNP/PPyMS-mediated silver enhancement along with carbon nanotubes-promoted electron transfer led to high detection sensitivity of MC-LR. Under optimal conditions, the MC-LR immunoassay had a wide linear range of 0.25 ng L-1 to 50 μg L-1 , low detection limit of 0.1 ng L-1 , and good precision, reproducibility and stability. The designed amplification strategy has potential application in the ultrasensitive electrochemical detection of other algae toxins.

Label‐free Immunosensor for the Determination of Microcystin‐LR in Water

“…The limit of detection (LOD), calculated as three times the standard deviation of the intercept/slope, was 0.053 ng mL À 1 . Table 1 shows a brief comparison of the linear ranges and detection limits of the GCE/MGNnP-PEI-anti-MC-LR and other immunosensors for MC-LR detection, recently published in the literature [12,14,[16][17][18][32][33][34][35]. It can be observed that the LOD of the proposed immunosensor is close to that of previously reported LOD values.…”

“…Thin-layer chromatography, high-performance liquid chromatography, enzyme-linked immunosorbent assay, liquid chromatography/mass spectrometry and protein phosphatase inhibition assays are the techniques generally applied to detect low concentrations of MC-LR [12,13]. Recently, electrochemical immunosensors and label-free fluorescent probes for MC-LR detection have been developed as an alternative to traditional techniques, offering low detection limits, no need for sample pretreatment and easy manipulation [14][15][16][17][18][19][20].…”

Applications of Gold Nanoparticles in Non-Optical Biosensors

“…Recently, Zhang et al used polypyrrole microsphere (PPyMS) to immobilize more AuNPs for the amplification of silver label signal. A low detection limit of 0.1 ng·L −1 and a wide linear range of 0.25 ng·L −1 to 50·L −1 was obtained for microcystin-LR (MC-LR) detection [133].…”

Tunable electrochemistry of gold-silver alloy nanoshells

“…Secondly, when analysing the CVs of the different phases of GRR, a weak but clearly defined reduction peak appears at +0.44 vs RHE only in the case of the latest GRR stages (Figure 3 -B, blue curve): this well-known and studied feature corresponds to the UPD of Ag + ions onto the NSs' surface [32] , [33] exploited successfully in the electrochemical silver-enhanced method with Au NPs. [34] , [35] , [36] The metal cations electrodeposition mechanism onto other metallic surfaces has been largely investigated at the macro-scale, while few examples of metal UPD over MNPs are found in literature. [37] , [38] During the UPD process metal ions in solution can adsorb onto the MNPs surface altering the local surface charge density of the metal.…”