Deep eutectic solvent-assisted carbon quantum dots for nanomolar detection of 4-nitrophenol

Area of Science:

• Environmental Chemistry
• Materials Science
• Nanotechnology

Background:

• 4-Nitrophenol (4-NP) is a persistent, carcinogenic pollutant from industries, posing significant health risks.
• Existing detection methods for 4-NP face challenges in terms of eco-friendliness and sensitivity.
• There is a critical need for sustainable and efficient analytical tools for environmental monitoring.

Purpose of the Study:

• To develop a novel, eco-friendly nanosensor for the sensitive detection of 4-nitrophenol (4-NP).
• To synthesize and characterize nitrogen and chlorine co-functionalized carbon quantum dots (S-CQDs) for fluorescence-based sensing.
• To establish a cost-effective and rapid method for on-site detection of 4-NP in environmental water samples.

Main Methods:

• Synthesis of S-CQDs using a hydrothermal method with sucrose and a deep eutectic solvent (DES).
• Characterization of S-CQDs using HRTEM, FTIR, XPS, XRD, UV-vis, fluorescence spectroscopy, and TCSPC.
• Development of a fluorescence quenching-based sensing assay for 4-NP detection.

Main Results:

• Successfully synthesized spherical, monodispersed S-CQDs (average size 3.06 nm) with intrinsic nitrogen and chlorine functionalization.
• The S-CQDs exhibited strong green fluorescence, good water solubility, and photostability with a quantum yield of ~56%.
• The developed nanoprobe demonstrated high sensitivity and selectivity for 4-NP with a low detection limit of 10 nM, attributed to an inner filter effect.

Conclusions:

• The S-CQDs-based nanosensor provides a sensitive, selective, and green fluorescent platform for 4-NP detection.
• This approach offers a rapid, cost-effective, and environmentally friendly solution for on-site monitoring of 4-NP pollution.
• The developed method presents a promising tool for environmental water quality control and pollution management.