A Label-Free Fluorescent Sensor Based on Si,N-Codoped Carbon Quantum Dots with Enhanced Sensitivity for the Determination of Cr(VI).

Cai Jing,Jinyu Zhang,Binsong Wang

doi:10.3390/ma15051733

Abstract

A signal shut-off probe of Si, N-codoped carbon quantum dots (Si, N-CQDs) was exploited to detect Cr(VI) by fluorescence quenching without the aid of any biomolecules or labeling materials. The sensing system prepared the precursor of diacetone acrylamide and the silane coupling agent 3-aminopropyltriethoxysilane (KH-550) by a simple hydrothermal method, and the quantum yield is as high as 75% Si, N-CQDs. The fluorescence stability and microstructure of the Si, N-CQDs were studied. The Si, N-CQDs has a high sensitivity for detecting Cr(VI) with the linear range of 0–200 μM and the detection limit of 0.995 μM. The quenching mechanism of Si, N-CQDs is attributed to FRET.

Highlights

In recent decades, heavy metal pollution in natural water has become more and more serious due to the rapid development of modern industry, among which hexavalent chromium (Cr(VI)) is the most toxic pollutant in the water system [1]
There are many analytical techniques for Cr(VI), such as colorimetry [5], atomic absorption spectrometry (AAS) [6], inductively coupled plasma mass spectrometry (ICP-MS) [7], inductively coupled plasma atomic emission spectroscopy [8] and spectrophotometry [9], these methods have the advantages of accurate results and high detection sensitivity, while they have the disadvantages of complex detection process, cumbersome operation, expensive equipment, and large influence by the environment factors [10]
Two absorption bands are observed in the UV-vis spectra of Si,N-Carbon quantum dots (CQDs) aqueous solution (Figure 1a)

Summary

Introduction

Heavy metal pollution in natural water has become more and more serious due to the rapid development of modern industry, among which hexavalent chromium (Cr(VI)) is the most toxic pollutant in the water system [1]. There are many analytical techniques for Cr(VI), such as colorimetry [5], atomic absorption spectrometry (AAS) [6], inductively coupled plasma mass spectrometry (ICP-MS) [7], inductively coupled plasma atomic emission spectroscopy [8] and spectrophotometry [9], these methods have the advantages of accurate results and high detection sensitivity, while they have the disadvantages of complex detection process, cumbersome operation, expensive equipment, and large influence by the environment factors [10]. They require laboratory conditions during the testing process, so it is difficult to conduct quick and routine field tests [11]. There is an urgent need for efficient and sensitive identification of Cr(VI), which is not restricted by the site and does not require sample pretreatment

Methods

Results

Conclusion