Strategic synthesis of trimetallic Au@Ag–Pt nanorattles for ultrasensitive colorimetric detection in lateral flow immunoassay

Achieving metal nanoparticles with high peroxidase activity and visible-light plasmonic property for lateral flow immunoassay has attracted extensive attention in the industry. However, the major challenge lies in establishing a general and robust preparation strategy. In this contribution, we developed a citrate-capped trimetallic Au@Ag-Pt nanorattle by employing seed-mediated growth and galvanic replacement reaction under a convenient condition, which can be translated directly to industrialized production. The rattle-like architecture empowers the Au@Ag-Pt NPs peroxidase-like activity while retaining the plasmonic property with intense color in the visible-light range. According to testing requirements, Au@Ag-Pt NPs-LFIA provides two colorimetric modes: low-sensitivity mode based on the color from their intrinsic plasmonic property and the high-sensitivity mode based on the nanozyme-triggered chromogenic reaction. Human cardiac troponin I (cTnI), one of the most specific markers for cardiac injury, was chosen as the detection model. Mainly, ultrasensitive colorimetric detection of human cTnI was successfully achieved as low as ∼20 pg mL-1. This strategy is robust to guarantee the stability and repeatability of the peroxidase activity without exact control, which can directly dock with the industrialized production of traditional LFIA strips and be readily adapted for on-demand clinical diagnosis.