Galvanic replacement inspired signal amplification: Background-free and antibody-thrift in-situ growth immunochromatography

In-situ growth of metal materials for signal amplification was proposed alternative to enhance color intensity of nanomaterials thereby improving detective sensitivity. However, drawbacks, such as background interference, precipitation caused by premature self-nucleation, and low reproducibility, are hard to be eliminated owing to the use of requisite reducing agent. Herein, galvanic replacement (GR) inspiring in-situ growth of Au nanoparticles (Au NP) on CuS nanospheres (CuS-NS) is first applied into lateral flow immunoassay (LFIA) for the detection of salbutamol (SAL). It is established to escape the natural disadvantages above-mentioned rely on the force from redox potential difference rather than the assistance of reducing agent. Additionally, compared with the group of excess CuS that pursuits signal strength stubbornly, galvanic replacement-mediated CuS-NS signal amplification (GR-mediated CNSA) cuts down the consumption of antibodies and thus improves sensitivity. Obviously, the number of antibodies was reduced 2-fold and the sensitivity increased 5-fold compared with excess CuS on the premise that excess CuS obtained the same output signal as GR-mediated LFIA. This work explores the patterns of galvanic replacement inspired in-situ growth signal amplification, and broadens the range of potential applications in LFIA for rapid and accurate analysis of hazardous substances.