Aggregation-Induced Emission-Fluorescent-Microsphere-Based Lateral Flow Immunoassay for Highly Sensitive Detection of Capsaicinoids

TL;DR

A new immunoassay using fluorescent microspheres detects capsaicinoids in oil with high sensitivity and accuracy.

Contribution

A novel immunoassay using aggregation-induced emission fluorescent microspheres for capsaicinoid detection is developed.

Findings

The AIEFM-LFIA achieved a detection limit of 0.33 µg/kg for capsaicinoids in oil samples.

The assay showed high specificity with minimal cross-reactivity and strong correlation with mass spectrometry.

Recovery rates ranged from 75.0% to 106.0% with good precision.

Abstract

Capsaicinoids (CPCs) are regarded as a typical marker of waste oil, which has emerged as a serious food safety issue in developing countries, necessitating the development of rapid, sensitive, and specific detection methods. In this study, a novel hapten was synthesized to generate a high-affinity monoclonal antibody (mAb) targeting CPCs. Subsequently, aggregation-induced emission fluorescent microspheres (AIEFMs), known for their superior fluorescence intensity, were utilized as an enhanced probe to develop a lateral flow immunoassay (LFIA) based on mAb 8B4 for CPC detection. For comparison, a traditional gold nanoparticle (AuNP)-LFIA was also constructed using the corresponding mAb. The AIEFM-LFIA demonstrated a limit of detection (LOD) of 0.33 µg/kg for CPCs in edible oil samples, which is 4.21 times lower than the LOD of 1.39 µg/kg achieved by the AuNP-LFIA. And the assay effectively identified three additional CPCs, with LODs ranging from 0.26 to 0.99 µg/kg, while exhibiting minimal cross-reactivity with CPC analogs, indicating high specificity. The recovery rates of the AIEFM-LFIA in oil samples ranged from 75.0% to 106.0%, with coefficients of variation ≤ 8.3%, exhibiting excellent accuracy and precision. Furthermore, the results of the AIEFM-LFIA demonstrated a strong degree of correlation with liquid chromatography–tandem mass spectrometry, with a correlation coefficient (R2) of 0.978. Consequently, the developed AIEFM-LFIA shows significant promise as a rapid, sensitive, specific, and reliable method for detecting CPCs in oil samples.

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