Lateral flow immunoassay based on multimodal nanoprobes for gastric cancer marker detection

Nanomaterials are widely used in immunochromatography due to their excellent physical and chemical properties. However, traditional single-functional nanomaterials can only provide a single dimension of information, and cannot adapt to different scenarios and needs. In this work, gold-coated superparamagnetic nanocrystal clusters (SMNC@Au), a kind of multifunctional nanoprobe with magnetic and Surface-Enhance Raman Scattering (SERS) effects were synthesized and used as the tag of multimodal lateral flow immunoassay (LFIA) for simultaneous detection of pepsinogen I (PG I) and pepsinogen II (PG II). The SMNC@Au nanoprobe-based bioassay platform supports a qualitative colorimetric readout and two quantitative readouts of magnetic and Raman signals, which can be adapted to different detection scenarios and requirements. As a result, the visual limit of detections (LODs) of PG I and PG II were 10 ng/mL and 1 ng/mL, respectively, and the detection time was 15 minutes. The LODs of magnetic mode were 0.5 ng/mL and 0.1 ng/mL with a detection time of 20 minutes. Compared with the above two modes, the Raman detection has the better sensitivity with the LODs of 0.1 ng/mL and 0.05 ng/mL for PG I and PG II, respectively, and the detection process lasted for 3 hours. The above results show that the multimodal LFIA based on SMNC@Au can achieve multi-level signal detection and have huge development potential in the field of LFIA.