Detection of Alzheimer's tau protein using localised surface plasmon resonance-based immunochip

In this study, we present the detection of tau protein, at room temperature, using a multi-spot localised surface plasmon resonance (LSPR)-based immunochip. To the best of our knowledge, this is the first report of an immunochip for tau protein. The detection method includes fabrication of a gold-capped nanoparticle LSPR chip, formation and functionalisation of a self-assembled monolayer (SAM), immobilisation of a suitable linker, effective blocking of non-specific adsorption, immobilisation of a monoclonal anti-tau antibody (tau-mAb), and finally, the optimum conditions for the immuno-reaction between tau-mAb and the antigen were determined. The method has a high performance, enables detection of tau at 10 pg/mL, lower than the cut-off value of 195 pg/mL (for AD) for tau protein in cerebral spinal fluid (CSF). Further, we demonstrated selectivity of the technique by showing that the introduction of bovine serum albumin (BSA), perhaps the most abundant protein component in serum and CSF, does not interfere with the detection of tau. This method also offers a potential platform for studying tau interactions with other proteins and/or potential drug candidates and could also be easily adapted for detecting phosphorylated tau and other AD biomarkers.