Multivalent Pt/Ti₃C₂Tx Nanocomposite-Based Immunochromatographic Sensor for Colorimetric/Temperature/Pressure Trimodal Detection

Multimodal immunochromatographic sensors (ICSs) have acquired extensive attention since they not only provide reliable results by comparing the different output signals but also flexibly respond to various application environments. Herein, an ICS with triple signal outputs including colorimetry, temperature, and pressure was developed for sensitive detection of chlorothalonil. The multivalent Pt/Ti₃C₂Tx nanoparticles as signal tags were facilely synthesized by loading PtNPs onto single-layer Ti₃C₂Tx nanosheets with high surface area. The acquired Pt/Ti₃C₂TxNPs accelerated the rate-limiting step of the aerogenesis reaction of H₂O₂ for producing intensive pressure signals due to their significant catalase-mimic activity. Meanwhile, they showed desirable photothermal conversion efficiency in the near-infrared region for producing significant temperature signals. Furthermore, their deep color also allowed facile colorimetry by using the naked eye. Based on a competitive immunoassay, chlorothalonil was detected as a model analyte on this trimodal ICS platform. The detection limits for pressure, temperature, and colorimetric modes were 0.04, 0.09, and 5 ng mL^-1, respectively. The recoveries for detecting chlorothalonil supplemented in <i>Astragalus</i> and <i>Honeysuckle</i> with pressure mode were 84.0-110% and 108-114%, respectively. Therefore, the ICS presented a portable, sensitive, accurate, and flexible multimodal strategy suitable for point-of-care testing.