A sandwich-like configuration with a signal amplification strategy using a methylene blue/aptamer complex on a heterojunction 2D MoSe2/2D WSe2 electrode: Toward a portable and sensitive electrochemical alpha-fetoprotein immunoassay

Abstract

Liver cancer is one of the most common global health problems that features a high mortality rate. Alpha-fetoprotein (AFP) is a potential liver cancer biomarker for the diagnosis of liver cancer. The quantitative detection of AFP at an ultratrace level has important medical significance. Using the reaction of the antibody–antigen pair in an immunosensor enables the sensitive and selective AFP assay. Finding a strategy in signal generation and amplification is challenging to fabricate new sensitive electrochemical immunosensors for AFP detection. This study demonstrates the construction of a simple, reliable, and label-free immunosensor for the detection of AFP on a smart phone. Exfoliated two-dimensional (2D) molybdenum diselenide (MoSe2) and 2D tungsten diselenide (WSe2) were employed to modify the disposable screen-printed carbon electrode (SPCE) to use as the electrochemical platform, which is affixed to a small potentiostat connected to a smart phone. The modified electrode offers antibody immobilization and allows detection of AFP via an immunocomplex forming a sandwich-like configuration with the AFP-corresponding aptamer. A heterojunction 2D MoSe2/2D WSe2 composite improves the SPCE’s reactivity and provides a large surface area and good adsorption capacity for the immobilizing antibodies. The signal generation for the immunosensor is from the electrochemical response of methylene blue (MB) intercalating into the aptamer bound on the electrode. The response for the proposed sandwich-like immunosensor is proportional to the AFP concentration (1.0–50,000 pg ml-1). The biosensor has potential for the development of a simple and robust point-of-care diagnostic platform for the clinical diagnosis of liver cancer, achieving a low limit of detection (0.85 pg ml-1), high sensitivity, high selectivity, good stability, and excellent reproducibility.

A new portable toluidine blue/aptamer complex-on-polyethyleneimine-coated gold nanoparticles-based sensor for label-free electrochemical detection of alpha-fetoprotein

“…For the sensor fabrication, the PEI-AuNPs-modified SPCE is incubated with the DNA aptamer and then BSA, to block the direct adsorption of the redox indicator (TB). Consequently, TB is expected to infiltrate only the DNA aptamer structure ( Chanarsa et al, 2022 ). According to the generation of the current response and the signal amplification, the adsorption amount of TB affects the measurement sensitivity and signal stability.…”

“…In recent years, AFP-specific aptamer has been introduced into the fabrication of biosensors for AFP analysis ( Yuan et al, 2021 ; Chanarsa et al, 2022 ). Aptamers are short nucleic acid that are single-stranded deoxyribonucleic acid (ssDNA) or ribonucleic acid (RNA) that can specifically bind to their targets ( Lerdsri et al, 2020 ; Li et al, 2020 ).…”

“…Disposable three-electrode screen-printed electrodes (SPEs) have been used in the field of device technology for making the electrochemical aptasensor due to their simplicity, ease of use, cost-effectiveness, and high reproducibility ( Upan et al, 2021 ). Especially, they can be implemented as portable aptasensors when applied with a portable potentiostat ( Chanarsa et al, 2022 ). Gold nanoparticles (AuNPs) have attracted great interest because of their unique physical and chemical properties, which exhibit the potential use for chemical and biological detection due to their nanoscale size, large surface area, and high conductivity ( Ding et al, 2019 ; Khan et al, 2019 ).…”

“…Disposable threeelectrode screen-printed electrodes (SPEs) have been used in the field of device technology for making the electrochemical aptasensor due to their simplicity, ease of use, costeffectiveness, and high reproducibility (Upan et al, 2021). Especially, they can be implemented as portable aptasensors when applied with a portable potentiostat (Chanarsa et al, 2022). Gold nanoparticles (AuNPs) have attracted great SCHEME 1 Illustration of the fabrication steps of proposed label-free electrochemical aptasensor for AFP detection.…”

Multi-Residue Detection of Eight Glucocorticoids by Nano-Au/Fluticasone Propionate Electrochemical Immunosensor

“…It exhibits the high sensitivity of electrochemical analysis as well as the high specificity of immune reactions, which also has the advantages of low detection equipment cost, simple and fast operation, and is not affected by sample color and turbidity [ 26 ]. The immunosensor can directly measure the concentration of the target and is widely used for qualitative and quantitative analysis of various substances in fields such as the environment, food, and clinical diagnosis [ 27 , 28 , 29 , 30 ]. Guo et al proposed an aptamer–antibody sandwich sensor modified by carbon nanotubes for detecting cortisol in human saliva [ 31 ].…”