A high-sensitivity thermal analysis immunochromatographic sensor based on au nanoparticle-enhanced two-dimensional black phosphorus photothermal-sensing materials

For the first time, a quantitative photothermal-sensing immunochromatographic sensor (PT-ICS) is described using Au nanoparticle-enhanced two-dimensional black phosphorus (BP-Au) as signal component for the photothermal-sensing antibody probe. BP-Au has good photothermal properties at 808 nm, and the photothermal conversion efficiency of the BP-Au nanosheet increased by 12.9% over the black phosphorus nanosheet alone. In addition, the antibody was more easily coupled to this nanosheet due to the good physical adsorption capacity of Au nanoparticles. We used this PT-ICS to detect veterinary antibiotics enrofloxacin (ENR), the photothermal-sensing antibody probe was competitive captured by ENR target and antigen coating on test (T) lines of the sensor. This process was exothermic under an 808 nm laser, and the thermal energy decreased as the ENR in the sample increased. This thermal energy was recorded by an infrared thermal imager or an infrared thermometer, and the concentration of the ENR residues in animal-derived foods was obtained by analyzing the temperature changes in T-lines. Under optimal conditions, the PT-ICS exhibited sensitive and specific detection of ENR from 0.03 μg/L to 10 μg/L with detection limits of 0.023 μg/L. The results agreed well with a commercial enzyme-linked-immunosorbent assay kit. This PT-ICS provided a promising strategy for the detection of ENR residues in animal-derived foods and expected to be used for the detection of other highly sensitive biomacromolecules.