Photothermal-induced partial Leidenfrost superhydrophobic surface as ultrasensitive surface-enhanced Raman scattering platform for the detection of neonicotinoid insecticides

In view of the urgent demand to determine neonicotinoid insecticides in real samples, we first report a photothermal-induced partial Leidenfrost superhydrophobic (PIPLS) sensor using gold colloid and highly roughened SiO2/PDMS surface coupled with few-layered MXene (Ti3C2) nanosheets for the ultrasensitive surface-enhanced Raman scattering (SERS) detection of neonicotinoid insecticides. Under the remote control of near-infrared light, the temperature of the sensor can rise to 170 ℃ within 10 s due to the significant photothermal effect of MXene, resulting in the partial Leidenfrost evaporation phenomenon and effectively reducing the contact area between the droplet of gold colloid and the surface. Analyte concentration factors obtained from the PIPLS SERS sensor were 5.1-fold and 30.3-fold higher than those attainable by conventional superhydrophobic and hydrophobic surfaces, respectively. Due to the significant enrichment capability, the PIPLS SERS sensor detected analytes down to the fM level with a high enhancement factor (5.1 × 1011). Based on the principal component analysis method, the PIPLS SERS sensor effectively discriminated neonicotinoid insecticides (acetamiprid, clothianidin, imidacloprid, and thiamethoxam). The reliable detection of neonicotinoid insecticides in real samples, including apple, green tea, wheat, and corn, also demonstrates the applicability of the PIPLS SERS sensor for pesticide sensing in real-world settings.