Accurate immunochromatography with colorimetric/photothermal dual-readout to detect nitrofurazone metabolites

The single-signal colorimetric immunochromatography assay (ICA) is becoming increasing inadequate in dealing with current detection requirement, e.g., more flexible, accurate, and sensitive detection. Herein, by introducing tannic acid (TA) to exfoliate molybdenum disulfide (MoS2) nanosheets and selecting anisotropic gold nanorods (AuNRs) as the nanocarriers, a dual-signal nanocomposite of TA/MoS2 @AuNRs was steadily constructed. The nanocomposite possesses excellent signal transmission and photothermal properties because of the high NIR absorption cross-section and signal intensity of AuNRs as well as strong photothermal conversion efficiency of MoS2. The TA/MoS2 @AuNRs were used to prepare immunoprobes and then applied in the ICA. With 2-nitrobenzaldehyde semicarbazone (2-NPSEM) as the model analyte, the obtained competitive photothermal/colorimetric dual-signal readout ICA (PCICA) can monitor NPSEM colorimetrically and photothermally with a calculated sensitivity of 0.267 and 0.180 ng mL−1, respectively. Furthermore, the application feasibility of the immunoassay was further evaluated by measuring SEM in the honey sample with satisfactory recoveries ranging from 83.35% to 107.14% and coefficient of variation (CV) ranging from 0.12% to 7.63%. As a result, by introducing TA to exfoliate MoS2 nanosheet, this work has proposed a more stable photothermal/colorimetric platform and provide an invigorating pathway for the appliance of MoS2-related photothermal materials in point-of-care immunoassays.