Multivalent Pt/Ti<sub>3</sub>C<sub>2</sub>Tx Nanocomposite-Based\nImmunochromatographic Sensor for Colorimetric/Temperature/Pressure\nTrimodal Detection

Multimodal immunochromatographic sensors (ICSs) have\nacquired extensive\nattention since they not only provide reliable results by comparing\nthe different output signals but also flexibly respond to various\napplication environments. Herein, an ICS with triple signal outputs\nincluding colorimetry, temperature, and pressure was developed for\nsensitive detection of chlorothalonil. The multivalent Pt/Ti<sub>3</sub>C<sub>2</sub>Tx nanoparticles as signal tags were facilely synthesized\nby loading PtNPs onto single-layer Ti<sub>3</sub>C<sub>2</sub>Tx nanosheets\nwith high surface area. The acquired Pt/Ti<sub>3</sub>C<sub>2</sub>TxNPs accelerated the rate-limiting step of the aerogenesis reaction\nof H<sub>2</sub>O<sub>2</sub> for producing intensive pressure signals\ndue to their significant catalase-mimic activity. Meanwhile, they\nshowed desirable photothermal conversion efficiency in the near-infrared\nregion for producing significant temperature signals. Furthermore,\ntheir deep color also allowed facile colorimetry by using the naked\neye. Based on a competitive immunoassay, chlorothalonil was detected\nas a model analyte on this trimodal ICS platform. The detection limits\nfor pressure, temperature, and colorimetric modes were 0.04, 0.09,\nand 5 ng mL<sup>–1</sup>, respectively. The recoveries for\ndetecting chlorothalonil supplemented in Astragalus and Honeysuckle with pressure mode\nwere 84.0–110% and 108–114%, respectively. Therefore,\nthe ICS presented a portable, sensitive, accurate, and flexible multimodal\nstrategy suitable for point-of-care testing.