A dip-and-read optical aptasensor for detection of tau protein.

Neurodegeneration currently remains without a differential diagnosis or cure. Tau protein is one of the biomarkers of neurodegenerative diseases commonly known as tauopathies. Tau protein plays an integral role in stabilizing microtubules and cell structure; however, due to post-translational modifications, tau protein undergoes self-assembly into cytotoxic structures and is co-localized intra- and extracellularly. Hence, tau protein is a viable biomarker associated with protein pathogenesis and neurodegeneration. The novel optical biosensor for tau441 protein is based on the aptamer recognition probe and the biolayer interferometry (BLI) method for detection. The current biotin-aptasensor in combination with the streptavidin surface provides real-time monitoring of tau441 protein in the nanomolar range, with the limit of detection at 6.7 nM in vitro. The tau441 detection is achieved with high selectivity over other neurodegeneration biomarkers which include amyloid-β and α-synuclein. The aptasensor also allows for tau441 protein detection in a complex matrix such as fetal bovine serum, indicating its utility in other biological fluids for diagnostic applications. The optical method is simple, rapid and highly selective for point-of-care application which is critical for achieving the early and differential diagnosis of neurodegenerative diseases and identifying their treatments. Graphical abstract.