# FGAN@PB NP Nanozyme-Based Colorimetric–Photothermal Dual-Mode Immunosensor for Malachite Green Detection

## TL;DR

A new dual-mode immunosensor using a Prussian blue nanozyme was developed to detect malachite green in aquatic products with high sensitivity and accuracy.

## Contribution

The FGAN@PB NP immunosensor offers a stable and sensitive alternative to traditional horseradish peroxidase for detecting malachite green.

## Key findings

- The colorimetric mode detected malachite green with an IC50 of 7.56 ng/mL and a linear range of 2.21–25.84 ng/mL.
- The photothermal mode had a detection limit of 0.31 ng/mL and a linear range of 0.262–25.6 ng/mL.
- The immunosensor's results correlated well with LC-MS/MS, showing promise for on-site screening in complex samples.

## Abstract

In this study, a colorimetric–photothermal dual-mode immunosensor based on Fe(Ⅲ)–gallic acid composite Prussian blue nanozyme (FGAN@PB NPs) was developed for the highly sensitive detection of malachite green (MG) in aquatic products. This strategy addresses the stability limitations associated with conventional horseradish peroxidase (HRP). In the colorimetric mode, the immunosensor exhibited an IC50 of 7.56 ng/mL with a linear detection range of 2.21–25.84 ng/mL. In the photothermal mode, the linear range was 0.262–25.6 ng/mL, with a detection limit (LOD) of 0.31 ng/mL. The results from the two detection modes were mutually corroborative. Moreover, the detection of the proposed immunosensor was strongly correlated with the LC-MS/MS, offering a promising approach for the rapid on-site screening of MG and improving its applicability in complex sample matrices.