A SERS microfluidic chip for ultrasensitive and simultaneous detection of SCCA and CYFRA21-1 in serum based on Au nanobowl arrays and hybridization chain reaction

In this work, Au nanobowl (AuNB) arrays and the hybridization chain reaction (HCR) were utilized to develop a surface-enhanced Raman scattering (SERS) microfluidic chip for the ultrasensitive and simultaneous detection of squamous cell carcinoma antigen (SCCA) and cytokeratin 19 fragment antigen 21–1 (CYFRA21–1) in the serum of cervical cancer patients. Antibody-oligonucleotide conjugates were adopted as triggers, which initiated HCR by the hybridization between hairpin DNAs that were modified on Raman reporters-labeled Ag nanocubes, forming nicked double-stranded DNAs on AuNB arrays and leading to SERS signal amplification. Good linear response in the range of 10-12 – 10-6 g/mL, with an ultralow limit of detection for SCCA (0.08 pg/mL) and CYFRA21–1 (0.13 pg/mL), was achieved. Furthermore, the experiments demonstrated that the chip was feasible, time-efficient, and selective. The proposed chip was successfully applied to detect SCCA and CYFRA21–1 in clinical samples, and the results were consistent with those of enzyme-linked immunosorbent assay. Since most protein biomarkers in serum lack the corresponding aptamers, this method, which establishes antibody-oligonucleotide conjugates to trigger HCR, provides a general signal amplification technology for detecting protein biomarkers and exhibits good potential in clinical applications.