Dual-Mode Electrochemical Immunoassay for Insulin Based on Cu₇S₄–Au as a Double Signal Indicator

Abstract

The detection of insulin by electrochemical (EC) immunoassay is desirable but highly challenged due to the obstacle of improving its accuracy, especially in a single-response system. In this work, based on Cu 7 S 4 −Au as a dual signal indicator, we fabricated a dual-mode electrochemical immunoassay for insulin. Especially, Cu 7 S 4 presents a strong differential pulse voltammetry (DPV) signal for the electron transfer between Cu 2+ and Cu + , without the addition of K 3 [Fe(CN) 6 ] or other electron transfer mediators. Furthermore, Cu 7 S 4 displays high sensitivity and high electrocatalytic activity toward the reduction of H 2 O 2 through chronoamperometry (CA). The introduction of Au nanoparticles can not only link on the surface of Cu 7 S 4 by the chemical bond of Au−SH, but also connect the second antibody (Ab 2 ) by the chemical bond of Au−N. Due to the superior electroconductivity of Au nanoparticles and the synergistic effect between the Au nanoparticles and Cu 7 S 4 , a high sensitivity is achieved by means of DPV and CA. To improve the loading capacity of antibodies, nanofiber polyaniline covalently grafted graphene (GS−PANI) linked with Au nanoparticles (GS− PANI−Au) as the matrix material was prepared. Based on Cu 7 S 4 −Au as a double signal indicator, the developed EC immunoassay for insulin exhibits a wide linear response for insulin detection in the range from 0.1 pg/mL to 50 ng/mL, with a low detection limit of 35.8 and 12.4 fg/mL through DPV and CA modes, respectively. Furthermore, the immunosensor displays an excellent analytical capability for insulin and promises application in quantitative detection of other disease markers in clinical diagnosis.

Gold Microstructures/Polyaniline/Reduced Graphene Oxide/ Prussian Blue Composite as Stable Redox Matrix for Label-free Electrochemical Immunoassay of α-Fetoprotein

“…The SEM images also reveal that rGO exhibited a single layer and fold structure, which could provide more active nucleation sites for PANI (Fig. 1B) 21 . A dendritic structure was observed after the electropolymerization of aniline on rGO/PB/GCE, suggesting the formation of PANI film on the surface of rGO/PB/GCE (Fig.…”

“…PB usually exhibits poor stability under alkaline or neutral environments [12][13][14] . The presence of the PANI not only prevented the leakage of PB, but also enhanced the analytical performances of the immunosensor 21,24 . With the aid of PANI, the DPV response was significantly strengthened in comparison with HFG/rGO/PB.…”

“…GO with various oxygen functional groups (such as hydroxyl, epoxy, and carbonyl groups) can act as anchor sites and attach the subsequent in situ polymerization of PANI to the surface and edge of the GO sheets. Therefore, the PANI-GO nanocomposite can significantly improve the conductivity and sensitivity of the immunosensor [21][22][23] . In comparison with GO, reduced graphene oxide (rGO) converts the sp 3 hybridized carbon to sp 2 , resulting in the restoration of conjugation and hence a higher electrical conductivity can be realized 24 .…”

Enzyme‐free Electrochemical Detection of Hydrogen Peroxide Based on the Three‐Dimensional Flower‐like Cu‐based Metal Organic Frameworks and MXene Nanosheets†

“…Electrochemically active nanomaterials not only have the above advantages, but can provide outstanding electrochemical responses for analysis. [ 10‐11 ] To this end, they can be used for the determination of other species that can change the electrochemical signals, or the substances that can be catalytically oxidized or reduced by the electrochemically active nanomaterials. [ 12 ] Therefore, the development of sensing platforms based on electrochemically active nanomaterials has broad application prospects.…”

The TDs/aptamer cTnI biosensors based on HCR and Au/Ti3C2-MXene amplification for screening serious patient in COVID-19 pandemic

“… Li et al, 2018 ; Liu et al, 2019 ; Tan et al, 2021 ; Wang et al, 2019 ; Yang et al, 2019 ; Zhang et al, 2020 ; Zhang et al, 2020 ; Zhang et al, 2016 .…”