Upconversion Nanoparticles-Based Fluorescence Immunoassay for the Sensitive Detection of 2-Amino-3-methylimidazo [4,5-f] Quinoline (IQ) in Heat Processed Meat

Abstract

A competitive fluorescence immunoassay for the quantitative detection of 2-amino-3-methylimidazo [4,5-f] quinoline (IQ) in pan-fried meat patties was developed, using magnetic nanoparticles coupled with coating antigen as the capture probe and anti-IQ antibody coupled with NaYF₄: Yb, Er upconversion nanoparticles as the signal probe. Under optimal conditionals, the wide detection range for IQ in phosphate buffer saline is from 0.01 to 100 μg·L^-1 (R² = 0.991) with a detection limit of 0.007 μg·L^-1. This proposed method has been applied to detect IQ in two different types of pan-fried meat patties at varying frying times, and the IQ content in chicken patties and fish patties are 2.11-3.47 μg·kg^-1 and 1.35-2.85 μg·kg^-1, respectively. These results are consistent with that of the ultraperformance liquid chromatography-tandem mass spectrometry. In summary, this method can serve as a sensitive and specific test tool for the determination of IQ in processed meat.

Keywords: 2-amino-3-methylimidazo [4,5-f] quinoline; fluorescence immunoassay; heat processed meat; magnetic separation; upconversion nanoparticles.

Figure 1

Names and molecular structures of common heterocyclic aromatic amines (HAAs).

Figure 2

Preparation of signal probe and principle of fluorescence immunoassay.

Figure 3

Characterization of the NaYF₄: Yb, Er UCNPs. (a,b): Transmission electron microscope (TEM) image of NaYF₄: Yb, Er UCNPs, (c,d): Size distribution of NaYF₄: Yb, Er UCNPs, (e): Fluorescence spectrums of NaYF₄: Yb, Er UCNPs (under 980 nm excitation), (f): Fourier transform infrared (FTIR) spectrums of NaYF₄: Yb, Er UCNPs.

Figure 4

Optimization of the working parameters. (a): Optimization of the anti-IQ antibody amount in signal probe, (b): Optimization of the coating antigen amount in capture probe, (c): Optimization of the added volume of the capture probe in test process with 25 μL of the signal probe, (d): Optimization of the incubation time of the signal probe, capture probe and sample solution. Each value is mean of three replicates.

Figure 5

Detection of 2-amino-3-methylimidazo [4,5-f] quinoline (IQ) with fluorescence immunoassay. (a): Fluorescence intensity of the immune complexes with varying concentrations of IQ, (b): Standard curve of the fluorescence immunoassay for IQ in the PBS buffer. Each value is mean of three replicates.

Figure 6

Specificity analysis of the fluorescence immunoassay. Each value is mean of three replicates. (2-amino-3-methylimidazo [4,5-f] quinoline, (IQ); 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ); 2-amino-3-methylimidazo [4,5-f] quinoxaline (IQx); 2-amino-3,8-dimethylimidazo [4,5-f] quinoxaline (MeIQx); 2-amino-3,4,8-trimethylimidazo [4,5-f] quinoxaline (4,8-DiMeIQx); 2-amino-3,7,8-trimethylimidazo [4,5-f] quinoxaline (7,8-DiMeIQx); 2-amino-3,4,7,8-tetraimethylimidazo [4,5-f] quinoxaline (4,7,8-TriMeIQx); 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP); 2-amino-1,6-dimethylimidazo [4,5-b] pyridine (1,6-DMIP); 2-amino-1,5,6-trimethylimidazo [4,5-b] pyridine (1,5,6-TMIP); 2-amino-9H-pyrido [2,3-b] indole (AαC); 2-amino-3-methyl-9H-pyrido [2,3-b] indole (MeAαC); 1-methyl-9H-pyrido [3,4-b] indole (Harman); 9H-pyrido [3,4-b] indole (Norharman); 3-amino-1,4-dimethyl-5H-pyrido [4,3-b] indole (Trp-P-1); 3-amino-1-methyl-5H-pyrido [4,3-b] indole (Trp-P-2); 2-amino-6-methyldipyrido [1,2-a:3′,2′-d] imidazole (Glu-P-1), 2-amino-dipyrido [1,2-a:3′,2′-d] imidazole (Glu-P-2)).