A sensitive label–free amperometric immunosensor for alpha-fetoprotein based on gold nanorods with different aspect ratio

Abstract

A simple and accurate label–free amperometric immunosensor for α–fetoprotein (AFP) detection is developed based on gold nanorods (GNRs) with different aspect ratio and compared with gold particles (GNPs). The positively charged GNRs and GNPs due to the surface immobilized cetyltrimethyl ammonium bromide (CTAB) can adsorb the negatively charged AFP antibody (Ab) directly. The presence of the GNRs not only enhanced the immobilized amount of biomolecules, but also improved the electrochemical properties of the immunosensor. With the aid of GNRs, the electrochemical signal was greatly enhanced in comparison with GNPs. Under optimal conditions, the proposed immunosensor could detect AFP in a linear range from 0.1 to 200 ng/mL with a detection limit of 0.04 ng/mL (signal–to–noise ratio = 3), and it also possessed good reproducibility and storage stability. Moreover, the detection of AFP in five human serum samples also showed satisfactory accuracy. The proposed methodology was potentially attractive for clinical immunoassay.

Electrochemical Biosensing in Cancer Diagnostics and Follow‐up

“…Anti‐PSA antibodies were immobilized by physical and chemical binding. Besides AuNPs, other subtypes of gold nanomaterials were also reported to improve the sensor performance: gold nanorods (AuNRs) and nanoporous gold (NPG), that can also be used to efficiently immobilize the bioreceptor element. Wei et al.…”

“…In this strategy, distinct carbon‐ and gold‐ based nanomaterials are typically used as platforms for the efficient binding of antibodies. The interaction between antibodies and gold nanomaterials (mainly AuNPs) are usually achieved by chemisorption via thiol derivatives, involving a chemical adsorption process between the nanomaterial surface and the adsorbent surface, which causes the bond to be created , . As an example, Wang et al.…”

Towards cancer diagnostics – an α-feto protein electrochemical immunosensor on a manganese(iv) oxide/gold nanocomposite immobilisation layer

“…5 A pH of 7 was used as the optimum pH. [46][47][48] Fig. 4 (A) SWV of different fabricated immunosensors for the detection of 500 ng mL À1 AFP constructed from (a) GCE/antibody@BSA, (b) GCE/ MnO 2 NRs@antibody/BSA, (c) GCE/AuNPs@antibody/BSA and (d) GCE/ MnO 2 NRs @AuNPs@antibody/BSA (B) SWV of different concentrations of AFP from 0.005 to 500 ng mL À1 in 1 mM [Fe(CN) 6 ] 3À/4À in 0.1 M KCl at 25 Hz (C) EIS of different concentrations of AFP from 0.005 to 500 ng mL À1 using 1 mM [Fe(CN) 6 ] 3À/4À in 0.1 M KCl and the equivalent circuit employed to fit the experimental impedance data (inset).…”

Nanosensors-Assisted Quantitative Analysis of Biochemical Processes in Droplets

“…Currently, all-electric sensing techniques give a promise to represent a simplified setup, compared to its optical counterpart that requires integration of light sources and detectors. To name a few, impedimetric [15], magnetic [16], potentiometric, e.g., field-effect transistor-based (FET) [17], amperometric [18], and micromechanical [19]. One of the challenges was to broaden the range of sensitivity of the sensors, since the concentration of the target substance is often directly dependent on the stage of the disease's development.…”