A smartphone based photothermal-colorimetric immunochromatographic sensor for ultrasensitive and ultra-wide concentration range detection of deoxynivalenol

Immunochromatographic sensor (ICS) is one of the first choices for on-site detection of deoxynivalenol (DON), a common mycotoxin that contaminate food. However, it suffers from unsatisfactory sensitivity and narrow quantitative range. Herein, a photothermal-colorimetric dual mode ICS was established for visually fast screening or accurately quantifying DON. Black phosphorus-gold (BP-Au) nanocomposite with remarkable color and photothermal conversion efficiency up to 46.41% under 808 nm laser irradiation was developed as the dual mode signal probe instead of Au nanoparticles in traditional ICS. Both the photothermal and colorimetric signals could be collected by a smartphone with a commercial IR imaging adapter. The as-prepared BP-Au showed a great thermal contrast amplification (TCA) effect, exhibiting ultra-sensitive response to its amount arrested on test zone of ICS, which is correlated with the concentration of analyte in samples. The developed ICS for DON gave an ultra-sensitive LOD of 0.154 pg mL-1 and an ultra-wide quantitative range of 1-106 pg mL-1 in photothermal mode, which was much more improved than that in colorimetric mode or reported in literatures. It demonstrated good selectivity toward DON over other mycotoxins and recoveries of 95.38%-116.75% in diluted grain extracts. This ICS enables dynamic monitoring tiny variation of food contaminants in time and accurate assessment of the degree they exceeding limitation standards.