LoC-SERS Platform Integrated with the Signal Amplification Strategy toward Parkinson's Disease Diagnosis

Multiplexed detection of Parkinson's disease (PD) biomarkers is of great significance for early diagnosis and personalized treatment. In this study, we fabricated a robust surface-enhanced Raman scattering-enabled lab-on-a-chip (LoC-SERS) platform for simultaneous quantification of α-synuclein, phosphorylated tau protein 181, osteopontin, and osteocalcin. Herein, the antibody-DNA conjugate was designed to introduce the catalytic hairpin self-assembly (CHA) amplification into the protein detection. Au nano-stars (AuNSs) modified with Raman reporter molecules and hairpin-structure DNA 1 were applied as the SERS nanotags. Au-coated silicon nanocone array (Au/SiNCA) fabricated based on the maskless plasma etching-prepared high-density Si nanocone array (SiNCA) and surface ion sputtering was used as the capture substrate after the modification of hairpin-structure DNA 2. Benefitting from the antibody-DNA conjugate-induced CHA amplification, numerous AuNSs can be connected to the Au/SiNCA surface, which significantly amplify the plasmonic coupling effect for ultrasensitive SERS detection, and the limit of detection was less than the pg/mL level. The application of highly uniform Au/SiNCA and antibody-DNA conjugate endows the LoC-SERS platform excellent analytical performance, including superior reproducibility, satisfactory universality, and high sensitivity. In addition, a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice model was established, and satisfactory results were obtained in real sample analysis with the LoC-SERS platform, which may be enlightening for exploiting protein biomarkers in PD monitoring.