Page 201 - 《水产学报》2025年第12期

陈赜，等 水产学报, 2025, 49(12): 129815

Detection of malachite green based on fluorescent polymer dots

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1,3*
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CHEN Ze , WANG Hao , DING Zhaoyang , XIE Jing 1,3*
1. College of Food Sciences and Technology, Shanghai Ocean University, Shanghai 201306, China;
2. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China;
3. Aquatic Product Storage Insurance Quality and Safety Risk Assessment Laboratory,
Ministry of Agriculture and Rural Affairs (Shanghai), Shanghai Ocean University, Shanghai 201306, China

Abstract: Malachite green (MG) is a synthetic compound with a green metallic sheen, widely applied to enhance production
and protect aquatic animals from various diseases. However, MG and its primary metabolite, leuco-malachite green, are toxic
inorganic contaminants hazardous to human and other organisms' health. Residual MG in aquaculture water has been identified
as a significant contributor to severe water pollution. Since 1981, MG has been designated as a Class II Health Hazard due to its
teratogenic, carcinogenic, and mutagenic impacts. Currently, numerous countries, including the European Union, the United
States, and China, have banned the use of MG in aquaculture practices. Nevertheless, its low cost and high effectiveness have
led many culturists, driven by economic interests, to continue its widespread use as a medication in fish farming, particularly in
some developing countries. In recent years, China has experienced outbreaks of MG residues exceeding acceptable levels in
aquaculture environments, prompting increased attention to the quality and safety of aquatic products. In 2002, the Ministry of
Agriculture of China listed MG among prohibited veterinary drugs. In this work, a fluorescence resonance energy transfer sys-
tem using poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] (PFBT) polymer dots as the energy
donor and MG as the acceptor was established to observe the fluorescence quenching phenomenon of PFBT polymer dots. The
PFBT-MG system maintained good stability in Britton-Robinson (BR) buffer solution at pH 5.0 to 9.0. Under optimized condi-
tions, the system's fluorescence showed a strong linear correlation with MG concentrations ranging from 0.04 to 0.59 mg/L.
The detection limit was as low as 1.38×10-4 mg/L, comparable to other methods. The correlation coefficient (R2) was 0.992 in
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our method. Simultaneously, common ions such as K , Ca , Na , Mg , Cu , Fe , and Cl in water showed minimal interfer-
ence with the fluorescence intensity of MG detected by PFBT. The method has been successfully applied to determine MG in
aquaculture freshwater, seawater, and transportation water, achieving a recovery rate of 96.6% to 103.1%. The relative stand-
ard deviation was less than 1.05%. Therefore, it could be concluded that PFBT polymer dots are a reliable and convenient
method for rapid detection of MG. This method provides a more accurate fluorescence technique for detecting MG. The syn-
thesis of PFBT polymer dots does not require abundant reagents for elution and avoids the costs of expensive equipment. The
entire process only requires imaging equipment, making it suitable for large-scale promotion economically. At the same time,
PFBT polymer dots significantly enhance detection efficiency, with the detection process not exceeding 30 minutes for ima-
ging and observation, thus enabling rapid on-site detection. Most importantly, PFBT polymer dots exhibit good sensitivity,
selectivity, and anti-interference capabilities in the MG detection process, providing an important reference for the future inclu-
sion of on-site MG detection.
Key words: malachite green (MG); polymer dots (Pdots); fluorescence quenching; fluorescent spectrometry method
Corresponding authors: DING Zhaoyang. E-mail: zyding@shou.edu.cn;
XIE Jing. E-mail: jxie@shou.edu.cn
Funding projects: Shanghai Agriculture Applied Technology Development Program (2022-02-08-00-12-F01155)

中国水产学会主办 sponsored by China Society of Fisheries https://www.china-fishery.cn
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