Ionic Liquid-Modified Gold Nanoparticle-Based Colorimetric Sensor for Perchlorate Detection via Anion-π Interaction.

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Materials Science

Background:

• Ammonium perchlorate (AP) is a critical propellant oxidant requiring sensitive detection methods.
• Existing methods for AP detection can be time-consuming or lack sensitivity.
• Nanoparticle-based sensors offer potential for rapid and sensitive chemical analysis.

Purpose of the Study:

• To develop a rapid and convenient nanoparticle-based colorimetric sensor for ammonium perchlorate (AP) detection.
• To utilize functionalized gold nanoparticles (AuNPs) with an ionic liquid (IL) for enhanced sensing capabilities.
• To investigate the sensing mechanism based on nanoparticle aggregation induced by anion-π interactions.

Main Methods:

• Modification of gold nanoparticles (AuNPs) with a specific imidazolium-based ionic liquid (IL) functionalized with [(1-methyl-1H-imidazol-2-yl)sulfanyl]acetic acid.
• Stabilization of the resulting IL@AuNP nanosensor using polyvinylpyrrolidone.
• Colorimetric detection based on the red shift of the surface plasmon resonance (SPR) band of AuNPs due to aggregation, monitored by absorbance ratios.

Main Results:

• The IL@AuNP nanosensor exhibited a red shift in SPR from 540 nm to 700 nm upon aggregation, correlating to AP concentration.
• The sensor achieved a limit of detection (LOD) of 1.50 μM and a limit of quantification (LOQ) of 4.95 μM for AP.
• The sensor demonstrated acceptable recovery rates in the presence of potential interfering substances, including other energetic materials and common soil ions.

Conclusions:

• A novel and efficient colorimetric nanosensor for ammonium perchlorate (AP) detection has been successfully developed.
• The sensing mechanism leverages anion-π interactions between perchlorate and the IL@AuNP surface, leading to predictable nanoparticle aggregation.
• This work presents a promising platform for developing similar IL-functionalized nanoparticle sensors for various anionic analytes.