A vertical flow microarray chip is described that uses core-shell SERS nanotags as tags for ultrasensitive quantification of the tumor markers α-fetoprotein (AFP) and carcinoembryonic antigen (CEA) by detecting the intensity of the specific Raman bands at 592 cm-1. The nanotags warrant high sensitivity, and the use of porous nitrocellulose warrants a high surface-to-volume ratio. The linear dynamic ranges are 0.1 ng mL-1 - 10 μg mL-1 for both AFP and CEA, and the limits of detection) are 0.27 pg mL-1 and 0.96 pg mL-1, respectively. Quantification is rapid and can be performed without preconcentration. Graphical abstract Schematic representation of a vertical flow microarray chip using AuNBA@Ag SERS nanotags (where NBA stands for Nile blue A) as labels for rapid, ultrasensitive, and simultaneous detection of tumor biomarkers CEA and AFP.
Keywords: AFP; Broad linear dynamic range; CEA; Gold; Nile blue A; POCT; Portable Raman spectrometer; Silver; Tumor biomarkers.