Engineered Core–Shell Multifunctional Nano‐Tracer in Raman‐Silent Region with Highly Retained Affinity to Enhance Lateral Flow Immunoassays
Sijie Liu, Xing Luo, Rui Shu, Yangjun Liao, Leina Dou, Tong Bu, Shaochi Wang, Yuechun Li, Jing Sun, Daohong Zhang, Ming-Qiang Zhu, Jianlong Wang
Abstract
Abstract Stimulated surface‐enhanced Raman scattering (SERS) in combination with engineered nano‐tracer offers extraordinary potential in lateral flow immunoassays (LFIAs). Nonetheless, the investigation execution of SERS‐LFIA is often compromised by the intricacy and overlap of the Raman fingerprint spectrum as well as the affinity‐interference of nano‐tracer to antibody. To circumvent these critical issues, an engineered core–shell multifunctional nano‐tracer (named APNPs) with precise control of the size of nano‐core (AuNPs) and coating of the nano‐shell (Prussian blue nanomaterials) is prepared for SERS‐LFIA via a modified enlarging particle size and coating modification strategy. Importantly, this nano‐tracer exhibits enhanced coupling efficiency, highly retained affinity, reinforced colloid stability, and unique SERS signal (2156 cm −1 ) in the silent region (1800–2800 cm −1 ) with high signal‐to‐background ratio simultaneously, all of which are beneficial to the enhancement of the analysis performance. With a proof‐of‐concept demonstration for detection of ractopamine (RAC), a dual‐pattern LFIA that synergizes both the enlarged particle size and coating modification supported colorimetric/biological silence Raman dual‐response (coined as the ECCRD assay) is demonstrated by integrating APNPs with the competitive‐type immunoreaction. This research may contribute to the rational design of multifunctional nano‐tracer, and the ECCRD assay can be expanded for a wide spectrum of applications in environmental monitoring and biomedical diagnosis.