A Pt/au@MnO₂ Nanozyme-based colorimetric platform for discriminating and quantifying neonicotinoids in real samples

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Neonicotinoids (NEOs) present significant risks to environmental and food chain safety.
• Conventional nanozymes face limitations in simultaneously discriminating and quantifying pesticides with high sensitivity.
• Developing advanced nanomaterials is crucial for effective pesticide monitoring.

Purpose of the Study:

• To engineer a tunable platinum/gold@manganese dioxide (Pt/Au@MnO2) nanozyme for simultaneous discrimination and ultrasensitive quantification of NEOs.
• To develop a dual-mode nanozyme capable of switching between laccase-like (LAC) and peroxidase-like (POD) activities.
• To establish a practical platform for on-site NEO monitoring in food safety and agricultural applications.

Main Methods:

• Synthesized urchin-like Pt/Au nanoparticles using a two-step hydrothermal method.
• Developed Pt/Au@MnO2 nanozyme via electrostatic self-assembly onto MnO2 nanosheets.
• Utilized tunable Pt/Au to β-MnO2 ratio to switch nanozyme activity between LAC and POD modes for distinct analytical applications.

Main Results:

• The LAC mode enabled discriminative analysis of four NEOs using distinct colorimetric fingerprints analyzed by principal component analysis (PCA).
• The POD mode, amplified by glutathione (GSH), achieved ultrasensitive quantification of imidacloprid (detection limit: 4.42 × 10⁻⁹ M, linear range: 10⁻⁸–10⁻⁴ M).
• High accuracy was demonstrated in real samples, with recovery rates ranging from 96.2% to 104.0%.

Conclusions:

• The developed dual-mode Pt/Au@MnO2 nanozyme platform offers a robust and practical solution for NEO detection.
• This strategy overcomes limitations of conventional nanozymes, enabling both discrimination and ultrasensitive quantification.
• The platform holds significant potential for on-site neonicotinoid monitoring, enhancing food safety and agricultural control measures.