A novel electrochemical aptamer–antibody sandwich assay for the detection of tau-381 in human serum

Abstract

Tau protein plays a crucial role in the pathogenesis of Alzheimer's disease (AD). However, the assay to detect low concentrations of tau protein is a great challenge for the early diagnosis of AD. We will outline a novel aptamer-antibody sandwich assay based on an electrochemical biosensor for the detection of tau-381 in human serum. To improve the detection sensitivity, the aptamer-antibody sandwich assay for the detection of tau-381 was developed by using a tau antibody (anti-tau) and an aptamer specific to tau-381 as the recognition element and cysteamine-stabilized gold nanoparticles (AuNPs) for signal amplification. Differential pulse voltammetry (DPV) was employed to record the signal response of tau-381 with different concentrations. The tau-381 concentration ranged from 0.5 pM to 100 pM. The responses of DPV measurements showed excellent results in this dynamic range. This simple, rapid, highly sensitive and specific assay gave a low limit of detection (LOD) of 0.42 pM for tau-381. The feasibility and reliability of the assay were verified by testing tau-381 in human serum from patients with AD. Thus, this method could prove valuable in diagnosing AD within the early stages of the disease.

Development of a Label-Free Electrochemical Aptasensor for the Detection of Tau381 and its Preliminary Application in AD and Non-AD Patients’ Sera

“…The dilution ratio was also optimized on the basis of preliminary work of our research group [20]. In Figure 4D, the current responses increased with the increasing dilution ratio of serum from 1:50 to 1:100, the amperometric responses that remained changed a few over 1:100.…”

“…The limit of detection (LOD), calculated at a signal/noise ratio of 3, was found to be 0.70 pM. The proposed label-free aptasensor showed a slightly higher detection limit compared to that of sandwich-based tau381 immunosensors [14,20].…”

Application of Electrochemical Aptasensors toward Clinical Diagnostics, Food, and Environmental Monitoring: Review

“…The practicability and consistency of the aptasensor were demonstrated by testing tau-381 protein in real patient samples suffering from AD. Authors have claimed that the developed method could possibly be utilized for early-stage screening of AD [70].…”

Nanomaterials towards Biosensing of Alzheimer’s Disease Biomarkers

“…Being very versatile, AuNPs have been applied with different and complementary functions, such as promotion of the conductivity and electrochemical activity of the transducer, immobilization of the biological recognition elements for direct/sandwich detection or conjugated with other nanomaterials. The most common applications of AuNPs were with self-assembled monolayers (SAM), either by being deposited on a SAM-modified platform or serving as the platform for promoting the chemical modification with different SAMs [75][76][77][78], and as amplifying agents modified with secondary antibodies and labels for sandwich immunoassays [46,[79][80][81][82]. Finally, AuNPs have also been applied in an isolated manner to transducer surfaces [83][84][85] or in conjugation with other materials such as polyethylene glycol (PEG) [86], MWCNTs [46], and ionic liquid [87].…”