A facile and effective immunoassay for sensitive detection of phosphorylated tau: The role of flower-shaped TiO2 in specificity and signal amplification

Alzheimer’s disease (AD) is one of the most prevalent neurodegenerative disease. Plasma total phosphorylated tau (P-tau) with multi-phosphorylation sites is a potentially efficient biomarker for the diagnosis and prognosis of AD. Single phosphorylation site recognition methods lead to the false positive detection of P-tau and decrease the accuracy of AD analysis. In this work, a simple and precise electrochemical immunoassay was developed for the specific detection of P-tau. Calixarene derivative ProLinker was utilized to orient Anti-tau onto the surface of gold electrode. ProLinker provide abundant binding sites for immobilized antibodies via host-guest recognitions and ensure Anti-tau activity through non-covalent interactions. Flower-shaped TiO 2 (F-TiO 2 ) forming coordination bonds with the phosphate group of phosphorylated protein were utilized as signal amplification tags to construct a simple sandwich assay for multiple phosphorylated sites sensing of P-tau. The combination of F-TiO 2 and Anti-tau ensured the bispecific and precise recognition of P-tau with a wide detection range (1–200 ng/mL) and a low detection of limit (1.774 pg/mL). With large specific surface area, high electron hinder ability, and great stability, F-TiO 2 as an amplification molecule can improve the performance of the immunosensor and produce sensitive signal changes according to the concentration of P-tau in the clinical samples. Hence, this P-tau immunoassay paves the way for the development of efficient detection tools for clinical diagnosis and monitoring.