SERS-based immunochromatographic assay with Au^DTNB@Ag nanoparticles for the detection of ancient silk residues

Silk fibroin (SF) is a key biomarker for ancient silk artifacts. The rapid and sensitive detection of SF is therefore essential for their compositional analysis and preservation. In this research, an anti-SF monoclonal antibody (anti-SF mAb) was conjugated with an Au^DTNB@Ag nanocore-shell structure to form a highly effective SERS immunoassay probe, and a surface-enhanced Raman scattering (SERS) assisted immunochromatographic assay (ICA) was developed for the detection of silk residues in artifacts. The visual limit of detection (vLOD) is 40 ng mL^-1 while the instrumental limit of detection (iLOD) is 3.96 ng/mL^-1 with a wide linear detection range (5-100 ng mL^-1) as determined through Raman spectroscopy. The assay exhibited high specificity against interfering proteins and demonstrated consistent inter-batch reproducibility. When detecting real cultural relic samples, the immunochromatographic strip assay showed high accuracy and reliability, which was validated by indirect enzyme-linked immunosorbent assay (ELISA). Considering its high sensitivity, rapid analysis, and portability, the SERS ICA may provide a technologically advanced strategy for the on-site screening of silk residues in archaeological and museological contexts.