Multiplex signal amplification strategy-based early-stage diagnosis of Parkinson's disease on a SERS-enabled LoC system.

In this paper, a multiplex signal amplification strategy was developed for the determination of miR-214 and miR-221 on a surface-enhanced Raman scattering (SERS)-enabled lab-on-a-chip (LoC) system to realize the early-stage diagnosis of Parkinson's disease (PD). The gold nanobipyramids (GNBPs) with great monodispersity were functionalized with Raman reporter molecules and hairpin DNA 1, serving as the SERS nanotags. The presence of targets can initial the strand displacement amplification (SDA) reaction and the numerous short-stranded trigger DNA (tDNA) can be released under the action of polymerase and nicking enzyme. Then, the tDNA can trigger the catalytic hairpin assembly (CHA) event between the SERS nanotags and the capture nanoprobes (Magnetic beads (MBs) modified with hairpin DNA 2), resulting in the aggregation of GNBPs on the MBs surface. The multiplex signal amplification contributed by the SDA-CHA strategy and the magnet-induced aggregation effect can ultimately lead to the significant improvement of the detection sensitivity and the limit of detection (LOD) was low to aM level with reproducibility and specificity meanwhile. Furthermore, a MPTP-induced PD mice model was established to verify the practicability and the expression level of miR-214 and miR-221 at different stages analyzed with the LoC system was confirmed by qRT-PCR.