Monodisperse core-shell-structured SiO 2 @Gd 2 O 3 :Eu 3+ @SiO 2 @MIP nanospheres for specific identification and fluorescent determination of carbaryl in green tea

Herein, rare-earth europium doped in Gd 2 O 3 @SiO 2 -based molecularly imprinted polymer (MIP) composite nanospheres with a multilayer core-shell structure was successfully prepared via a facile and versatile layer-by-layer assembly strategy of combination with sol-gel, hydrothermal, and surface imprinting procedure. The rare-earth Gd 2 O 3 :Eu 3+ was embedded into the inner portion of the imprinted polymer which was well-suited for fluorescent monitoring carbaryl selectively. Results showed that the recognition process of the nanosensor for carbaryl was fast and reached dynamic equilibrium at ca. 20 min. The fluorescence intensity ( F 0 / F ) is linearly related to the concentration of carbaryl [ Q ] within the range of 16–80 μg mL −1 , and the linear equation is F 0 / F = 0.8909 − 9.775 × 10 −4 [ Q ] ( R = 0.9963) with 10 μg mL −1 as the detection limit. Competition experiments showed that other analogues (methomyl, aldicarb, and isoprocarb) have nearly no interference in the detection of carbaryl. Moreover, this MIP nanosensor was successfully applied to detect carbaryl in green tea samples without pretreatment. The study afforded an efficient and desirable fluorescence sensor for carbaryl detection in a complicated matrix, which hopefully will be used for biomedical/chemical sensing recognition. Graphical abstract