A test strip constructed by molecular imprinting for ratiometric fluorescence with ultra-low limit of detection for selective monitoring of Sudan I in chili powder

• Published in: Mikrochimica acta (1966) Vol. 190; no. 7; p. 263
• Main Authors: Shi, Tian, Liu, Tong, Zhang, Jinyuan, Cai, Da, Zhang, Yueli
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2023; Springer; Springer Nature B.V
• Subjects: Additives; Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Fluorescence; Fluorescent indicators; Microengineering; Molecular imprinting; Nanochemistry; Nanotechnology; Original Paper; Strip; Upconversion; Sudan; Trace analysis; Chili powder; Sudan I; Monodisperse nuclear-satellite structure; Up-conversion fluorescence probe; Inner filter effect; Molecularly imprinted fluorescent test strip
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-023-05825-9

An up-conversion molecularly imprinted ratiometric fluorescent probe with a monodisperse nuclear-satellite structure and its test strip are designed which can avoid fluorescent background interference to detect Sudan I in chili powder highly selective and sensitive. The detection mechanism is based on the selective recognition of Sudan I by imprinted cavities on the surface of ratiometric fluorescent probe and the inner filter effect between Sudan I molecules and the emission of up-conversion materials (NaYF 4 :Yb,Tm). Under optimized experimental conditions, the response of fluorescent ratio signals (F 475 /F 645 ) of this test strip show a good linear relationship in the range 0.02–50 μM Sudan I. The limits of detection and quantitation are as low as 6 nM and 20 nM, respectively. Sudan I is selectively detected in the presence of fivefold higher concentrations of interfering substances (imprinting factor up to 4.4). Detection of Sudan I in chili powder samples show ultra-low LOD (44.7 ng/g), satisfactory recoveries (94.99–105.5%) and low relative standard deviation (≤ 2.0%). This research offers a reliable strategy and promising scheme for highly selective and sensitive detection of illegal additives in complex food matrix via an up-conversion molecularly imprinted ratiometric fluorescent test strip. Graphical abstract