A ratiometric fluorescence imprinted sensor based on N-CDs and metal–organic frameworks for visual smart detection of malathion.

• A novel ratiometric imprinted fluorescence sensor N -CDs@Eu-MOF@MIP was constructed. • Eu-MOF were introduced and enhanced the response sensitivity. • The dual emission strategy endowed sensors remarkable fluorescence color changes. • The fluorescence sensor selectively recognized malathion. • Smartphone-assisted platform offered a promising tool for visual inspection. Sensitive and rapid detection of pesticide residues in food is essential for human safety. A ratiometric imprinted fluorescence sensor N -CDs@Eu-MOF@MIP (BR@MIP) was constructed to sensitively detect malathion (Mal). Europium-based metal organic frameworks (Eu-MOF) were used as supporters to improve the sensitivity of the BR@MIP. N -doped carbon dots (N -CDs) were used as fluorescent source to produce fluorescent signal. A linear relationship between the concentration of Mal and the fluorescence response of the sensor was found in the Mal concentration range of 1–10 μM with a limit of detection (LOD) of 0.05 μM. Furthermore, the sensor was successfully applied for the detection of Mal in lettuce, tap water, and soil samples, with recoveries in the range of 93.0 % − 99.3 %. Additionally, smartphone-based sensors were used to detect Mal in simulated real samples. Thus, the construction of ratiometric imprinted fluorescence sensor has provided a good strategy for the detection of Mal. [ABSTRACT FROM AUTHOR]