# Boosting Sensitivity, Stability, and Speed: A Polydopamine-Engineered Silver Nanoparticle Lateral Flow Immunoassay for Aflatoxin B1 in Maize

## TL;DR

This paper introduces a new immunoassay using silver nanoparticles coated with polydopamine to detect aflatoxin B1 in maize with higher sensitivity and stability.

## Contribution

The novel use of polydopamine-functionalized silver nanoparticles improves sensitivity, stability, and speed in lateral flow immunoassays for aflatoxin detection.

## Key findings

- The developed assay achieved a detection limit of 0.23 ng/mL for aflatoxin B1 in buffer.
- The assay showed recoveries between 95.70% and 119.28% in spiked maize samples.
- The polydopamine coating enhanced nanoparticle stability and migration speed on test strips.

## Abstract

Conventional colorimetric lateral flow immunoassays (LFIAs) often suffer from insufficient sensitivity for detecting trace low-molecular-weight contaminants like mycotoxins. The development of colorimetric probes with a high molar extinction coefficient is therefore critical for enhancing detection performance. Although silver nanoparticles (AgNPs) exhibit an extremely high molar extinction coefficient, their practical application in LFIA is hindered by inherent chemical instability and suboptimal visual contrast. To address these limitations, we have engineered robust and high-performance polydopamine-functionalized AgNPs (Ag@PDA NPs) as advanced LFIA signal probes, which were successfully used for detecting aflatoxin B1 (AFB1) in maize. The multifunctional PDA nanoshell effectively shields the Ag core from oxidation and other destabilizing factors, ensuring superior long-term stability and significantly enhancing colorimetric contrast. Moreover, it improves the colloidal hydrophilicity, enabling faster and more uniform migration kinetics along the test strip. Leveraging these engineered properties, the developed assay achieved a limit of detection (LOD) of 0.23 ng mL−1 for AFB1 in buffer, representing a remarkable 2.17-fold sensitivity enhancement over conventional colloidal gold-based LFIAs. Validation in spiked maize samples confirmed high reliability, with recoveries ranging from 95.70% to 119.28% and precision (inter-/intra-assay CVs) below 13.03%.