Alzheimer’s disease (AD) is characterized by progressive memory loss and cognitive decline, significantly impacting the daily functioning of elderly individuals. The low abundance of AD-associated biomarkers in blood necessitates highly sensitive detection techniques. Tau protein, a critical biomarker of AD, plays a vital role in the early diagnosis and monitoring of disease progression. In this study, we developed an electrochemiluminescence (ECL) immunosensor based on the Ru(bpy)32+ luminophore and polyethyleneimine-carbon dots (PEI-NCD) as co-reactants for the detection of tau protein. The system employs a label-free format, where monoclonal Anti-tau antibodies are conjugated to PEI-NCDs, leveraging their abundant amino groups for efficient antibody attachment and co-reactant functionality. A two-electrode setup was established; upon the addition of tau antigen, the luminescence intensity decreased, producing a sensitive turn-off response. The immunosensor achieved a low detection limit of 6.103 pg/mL with high specificity and selectivity even in the presence of other biomarkers. Additionally, they demonstrated excellent recovery (93–104%) in spiked serum samples. Electrochemical characterization confirmed the stability and reliability of the sensor for tau detection. Overall, this Ru(II)-based immunosensor holds strong promise for the ultrasensitive and specific detection of tau protein, supporting early diagnosis and effective management of Alzheimer’s disease.
Kala et al. (Tue,) studied this question.