An ultrasensitive label-free electrochemical immunosensor based on signal amplification strategy of multifunctional magnetic graphene loaded with cadmium ions

Abstract

Herein, a novel and ultrasensitive label-free electrochemical immunosensor was proposed for quantitative detection of human Immunoglobulin G (IgG). The amino functionalized magnetic graphenes nanocomposites (NH2-GS-Fe3O4) were prepared to bond gold and silver core-shell nanoparticles (Au@Ag NPs) by constructing stable Au-N and Ag-N bond between Au@Ag NPs and -NH2. Subsequently, the Au@Ag/GS-Fe3O4 was applied to absorb cadmium ion (Cd2+) due to the large surface area, high conductivity and exceptional adsorption capability. The functional nanocomposites of gold and silver core-shell magnetic graphene loaded with cadmium ion (Au@Ag/GS-Fe3O4/Cd2+) can not only increase the electrocatalytic activity towards hydrogen peroxide (H2O2) but also improve the effective immobilization of antibodies because of synergistic effect presented in Au@Ag/GS-Fe3O4/Cd2+, which greatly extended the scope of detection. Under the optimal conditions, the proposed immunosensor was used for the detection of IgG with good linear relation in the range from 5 fg/mL to 50 ng/mL with a low detection limit of 2 fg/mL (S/N = 3). Furthermore, the proposed immunosensor showed high sensitivity, special selectivity and long-term stability, which had promising application in bioassay analysis.

Ratiometric ultrasensitive electrochemical immunosensor based on redox substrate and immunoprobe

“…Antigens were subsequently recognized by the substrate and probe 24 25 26 . If the substrate was fabricated by redox material 27 28 , the analyte can be detected simultaneously by the signals of substrate and probe, respectively. In this case, the DNA-free ratiometric immunoassay was presented and its principle was illustrated in Fig.…”

Functional Magnetic Graphene Composites for Biosensing

“…Most MGCs were built via in situ reduction of metal precursors on the surface of GO [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77]79,80]. For magnetic materials, metal precursors, including FeCl 2 , FeCl 3 , Fe(acac) 3 , (NH 4 ) 2 Fe(SO 4 ) 2 and more, which would bind with GO surfaces for electrostatic interactions between positive charges of metal ions with negative charges of groups on GO surfaces.…”

Multimodal/Multifunctional Nanomaterials in (Bio)electrochemistry: Now and in the Coming Decade

“…A variety of electrochemical (bio)sensors have been reported in the literature where the presence of magnetic particles not only facilitates the preparation of the sensor but also provides other functionalities related to higher sensitivity, through enhanced electrical conductivity, and/or better selectivity derived from electrocatalytic effects toward redox processes involved in the detection scheme. Table 2 summarizes the main characteristics of recently reported electrochemical biosensing strategies involving magnetic carbon nanomaterials [ 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 ].…”