Ultrasensitive Fluorescence Sensing of Chlorpyrifos Using Core-Shell Au@Ag Nanoparticle-Enhanced Inner Filter Effect...

Area of Science:

• Materials Science
• Analytical Chemistry
• Environmental Science

Background:

• Organophosphorus pesticides (OPs) pose significant risks to human health and the environment.
• Accurate and sensitive detection methods for OPs are crucial for food safety and environmental surveillance.
• Existing detection techniques may lack the sensitivity, cost-effectiveness, or speed required for widespread monitoring.

Purpose of the Study:

• To develop a novel and ultrasensitive fluorescence sensing platform for the determination of organophosphorus pesticides (OPs).
• To utilize the inner filter effect (IFE) between graphitic carbon nitride (g-C3N4) nanosheets and silver-coated gold core-shell nanoparticles (Au@Ag NPs) for pesticide detection.
• To establish a rapid, cost-effective, and highly sensitive method for chlorpyrifos (CPF) residue analysis.

Main Methods:

• Synthesis and characterization of gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), and Au@Ag NPs.
• Evaluation of fluorescence quenching efficiencies of synthesized nanoparticles toward g-C3N4.
• Development of an acetylcholinesterase (AChE)-based assay where thiocholine induces Au@Ag NP aggregation, modulating the IFE and g-C3N4 fluorescence.
• Investigation of chlorpyrifos inhibition of AChE activity, preventing aggregation and restoring fluorescence.

Main Results:

• Au@Ag NPs demonstrated superior fluorescence quenching of g-C3N4 due to optimal spectral overlap, making them ideal quenchers.
• Thiocholine, generated from acetylthiocholine hydrolysis, induced Au@Ag NP aggregation, reducing IFE and restoring g-C3N4 fluorescence.
• Chlorpyrifos inhibited AChE, suppressing thiocholine generation and Au@Ag NP aggregation, leading to a measurable fluorescence signal proportional to CPF concentration.
• The developed sensor exhibited high sensitivity and a linear response to chlorpyrifos under optimal conditions.

Conclusions:

• A novel, ultrasensitive fluorescence sensing platform based on the IFE between g-C3N4 and Au@Ag NPs was successfully developed.
• The sensor effectively detects chlorpyrifos by monitoring the inhibition of AChE activity and subsequent modulation of nanoparticle aggregation and fluorescence.
• This approach offers a rapid, cost-effective, and highly sensitive method for CPF residue analysis, with significant potential for food safety monitoring and environmental surveillance.