Phase engineered amorphous-crystalline MIL-101(CuFe)@AuNPs with enhanced photothermal activity for sensitive immunochromatographic bimodal detection of streptomycin.

Phase engineering-assisted tuning of the plasma resonance properties of multifunctional nanocomposites provides an excellent opportunity to improve analytical performance. It is anticipated to break the dominating bottleneck of insufficient signal brightness in identifying imperceptible variation of the target concentration and further enhance the sensitive immunochromatographic assays (ICAs) analysis. Herein, by simply assembling isolated gold nanoparticles (AuNPs) on the surface of MIL-101(CuFe) (named MCF) with a tunable size and crystal phase, we synthesized amorphous-crystalline MCF@AuNPs nanocomposites as immuno signal tracers. For the first time, we utilized phase transformation to assist in realizing the effective regulation of the plasma resonance properties of MCF@AuNPs. It exhibits extraordinary colorimetric intensity, photothermal conversion efficiency (59.1%), stability, and dispersion, all of which facilitate the construction of sensitive and accurate bimodal complementary ICA. With a proof-of-concept for streptomycin, the MCF@AuNPs-ICA showed the limit of detection (LOD) at 0.14 ng mL with remarkable university in different samples. This work demonstrates the importance of the rational design of phase-transformation-assisted tuning plasma resonance properties to improve analytical performance with terrific potential for point-of-care (POC) diagnostic applications.