measurements and have recently attracted considerable interest in food safety, medical diagnosis, and environmental monitoring. [1] Among the available diagnostic tools, lateral flow immunoassays (LFIAs) dominated POC field during the past decades due to they are arguably the simplest, cheapest, and user-friendly paper-based POC tests. [2] Thanks to the enhanced Raman scattering of reporters adsorbed on noble metal substrate, the fusion of LFIAs with surface-enhanced Raman scattering (SERS) allow the narrow bandwidth, satisfactory photostability, and signal-readout enormously amplified that permit ultrasensitive analysis. [3] Nevertheless, both conventional Raman reporters, biological species, and nitrocellulose (NC) membrane display multiple spectral bands in the fingerprint region (<1800 cm −1 ), which are generally overlapped and difficult to separate (particularly at weakly test-line), thus compromising the performance and increasing analysis difficulty. [4] To efficiently eliminate interference in the fingerprint region, several chemical groups including nitrile, deuterium, and alkyne have been synthesized as backgroundfree Raman reporters with distinctive signals in the biologically silent region (1800-2800 cm −1 , where neither conventional Raman reporters nor biomolecules do not possess any Raman signal). [5] However, the complicated chemosynthesis and 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-tobackground 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.

Engineered collaborative size regulation and shape engineering of multi‐functional nanomaterials (NPs) offer extraordinary opportunities for improving the analysis performance. It is anticipated to address the difficulty in distinguishing color changes caused by subtle variations in target concentrations, thereby facilitating the highly sensitive analysis of lateral flow immunoassays (LFIAs). Herein, tremella‐like gold‐manganese oxide (Au‐MnOx) nanoparticles with precise MnCl2 regulation are synthesized as immuno signal tracers via a facile one‐step redox reaction in alkaline condition at ambient temperature. Avail of the tunable elemental composition and anisotropy in morphology, black‐colored tremella‐like Au‐MnOx exhibits superb colorimetric signal brightness, enhanced antibody coupling efficiency, marvelous photothermal performance, and unrestricted immunological recognition affinity, all of which facilitate highly sensitive multi‐signal transduction patterns. In conjunction with the handheld thermal reader device, a bimodal‐type LFIA that combines size‐regulation‐ and shape‐engineering‐mediated colorimetric‐photothermal dual‐response assay (coined as the SSCPD assay) with a limit of detection of 0.012 ng mL−1 for ractopamine (RAC) monitoring is achieved by integrating Au‐MnOx with the competitive‐type immunoreaction. This work illustrates the effectiveness of this strategy for establishing high‐performance sensing, and the SSCPD assay may be extended to a wide spectrum of future point‐of‐care (POC) diagnostic applications.

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