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Rapid Homogeneous Detection of Biological Assays Using Magnetic Modulation Biosensing System
Published on: June 13, 2010
Upconversion fluorescence immunoassay for imidaclothiz by magnetic nanoparticle separation
Xiude Hua1, Hongjie You1, Peiwen Luo1
1College of Plant Protection (State & Local Joint Engineering Research Center of Green Pesticide Invention and Application), Nanjing Agricultural University, Nanjing, 210095, China.
Insights
A novel fluorescence immunoassay detects imidaclothiz using magnetic nanoparticles (MNPs) and upconversion nanoparticles (UCNPs). This method offers sensitive and reliable detection of imidaclothiz in various samples, crucial for environmental and food safety monitoring.
Area of Science:
- Analytical Chemistry
- Biotechnology
- Environmental Science
Background:
- Imidaclothiz is a widely used insecticide requiring sensitive detection methods.
- Existing detection methods may lack the sensitivity or specificity needed for complex matrices.
- Nanoparticle-based assays offer advantages in sensitivity and signal amplification.
Purpose of the Study:
- To develop a sensitive fluorescence immunoassay for imidaclothiz detection.
- To utilize magnetic nanoparticles (MNPs) for concentration and upconversion nanoparticles (UCNPs) for signal labeling.
- To validate the assay's performance in various real-world samples.
Main Methods:
- Conjugating MNPs with imidaclothiz antigen and UCNPs with anti-imidaclothiz monoclonal antibody.
- Employing a competitive immunoassay format where imidaclothiz in the sample competes for antibody binding.
- Utilizing magnetic separation for MNPs and fluorescence detection of UCNPs.
- Validating the assay using High-Performance Liquid Chromatography (HPLC).
Main Results:
- The assay achieved a limit of detection (LOD) of 0.74 ng/mL.
- The linear assay range was 0.74-289.30 ng/mL with an IC50 of 14.59 ng/mL.
- High average recoveries (75.7-105.2%) and low relative standard deviations (<11.2%) were observed in diverse matrices.
- The immunoassay showed good correlation with HPLC results.
Conclusions:
- The developed upconversion fluorescence immunoassay is highly sensitive and specific for imidaclothiz detection.
- The assay is robust and suitable for analyzing imidaclothiz in environmental and food samples.
- This nanoparticle-based approach provides a valuable tool for pesticide residue monitoring.
Abstract:
A sensitive fluorescence immunoassay for the detection of imidaclothiz was established by using magnetic nanoparticles (MNPs) as concentration elements and upconversion nanoparticles (UCNPs) as signal labels. The NaYF4/Yb,Er UCNPs and MNPs were conjugated with imidaclothiz monoclonal antibody and imidaclothiz antigen, respectively. Imidaclothiz could compete with the antigen-conjugated MNPs for binding to the antibody-conjugated UCNPs and resulted in a decreased fluorescence signal when the MNPs were separated by an external magnet. Under the optimal conditions, the concentration of imidaclothiz producing 50% inhibition of the signal (IC50), limit of detection (LOD, IC10), and the linear assay range (IC10-IC90) were 14.59, 0.74, and 0.74-289.30 ng mL-1, respectively. The immunoassay exhibited no obvious cross-reactivity with analogues of imidaclothiz except for imidacloprid, with 89.2% cross-reactivity. The average recoveries measured in paddy water, pear, soil, peach, rice, tomato, wheat, and pakchoi were 75.7-105.2%, and the relative standard deviations (RSDs) were less than 11.2%. In addition, the results of the immunoassay correlated well with that of high-performance liquid chromatography (HPLC) for authentic samples. Graphical abstract Development of an upconversion fluorescence immunoassay for the detection of imidaclothiz by using antibody-modified upconversion nanoparticles (UCNPs) as the detection probe and antigen-modified magnetic nanoparticles (MNPs) as the capture probe.
