Gold nanoparticle-based immuno-PCR for detection of tau protein in cerebrospinal fluid.

Tau protein in cerebrospinal fluid (CSF) is an important biomarker of Alzheimer's disease and some other brain diseases. Enzyme-linked immunosorbent assays (ELISAs) have been mostly used for quantification of tau and other biomarkers in CSF. However, these assays do not have sufficient sensitivity and dynamic range. In this study we tested the suitability of gold nanoparticles functionalized with tau-specific monoclonal antibody and oligonucleotide template for immuno-polymerase chain reaction (Nano-iPCR) quantification of tau protein in human CSF samples and compared it with ELISA, either commercial or newly developed with tyramide signal amplification. Our data indicate that Nano-iPCR is superior in sensitivity and detection range to ELISA in tau protein detection.