Ultrasensitive detection of blood-based p-tau217 for Alzheimer's disease integrated antibody-oligonucleotide conjugates and RCA/Cas12a system.

Tau phosphorylated at threonine 217 (p-tau217) is interesting increasingly as "star biomarker" in the field of Alzheimer's disease (AD) diagnosis due to the highest accuracy in detecting AD pathology and predicting future cognitive decline. Here, we developed an ultra-trace blood-based diagnostic platform for p-tau217, termed magnetic-particle-based Immunol Rolling-circle-amplification/Cas12a Assay (MPIRCA). In this approach, the operational process included two main stages: the preparation of All@MP (encompassing immobilization, capture, and binding) and the subsequent one-pot RCA/Cas12a reaction. Through the Ab-DNA, immunoassay was successfully converted into DNA-based molecular diagnostic technology (one-pot RCA/Cas12a reaction) to achieve ultra-high sensitivity with 1 fg/mL limitation of detection. The optimized assay exhibited excellent linearity across a range from 1 fg/mL to 1 ng/mL. The study presents a high feasible diagnostic strategy that combines one-pot operation, high sensitivity and selectivity, offering considerable potential for blood-based diagnosis and management of Alzheimer's disease (AD).