Single functional magnetic-bead as universal biosensing platform for trace analyte detection using SERS-nanobioprobe.

SERS biosensor has demonstrated remarkable potential to analyze various bio/chemical targets with ultrahigh sensitivity. However, the development of universal SERS biosensing platforms with a uniform and reproducible structure that can quantitatively detect a broad range of trace analytes remains a significant challenge. The production of SERS nanotags with abundant Raman reporters and rational structure to conjugate with detection biomolecules is another key to design SERS-nanobioprobes. Here, we introduce a facile single magnetic-bead biosensing platform, formed by combining the captured antibodies/antigens conjugated magnetic-beads and the Au@Raman-Reporters@Ag sandwich-based nanorod tags labeled nanobioprobes. The advantage of the robust sandwich-structure-based nanotags is attributed not only to the high density Raman reporters contained inside, with high EF value because of enhanced electromagnetic field density, but also to the flexibility for bioconjugation of the detection biomolecules. The 3-D structure of the functional magnetic-bead provides a perfect platform to rapidly capture and enrich biomolecules. Ultrasensitive detection of two small molecules and a protein was achieved in samples, respectively.