Amino-functionalized MXene quantum dots for ultrasensitive detection of the recalcitrant nitroaromatic environmental pollutant

Abstract

Given the environmental recalcitrance and the explosive, toxic, and ecotoxic risks posed by 2,4,6-trinitrophenol (TNP), there is a pressing need to develop highly selective and sensitive analytical methods for its trace detection, in direct response to escalating public concerns over safety and health. This study presented a fluorescence sensing platform that utilized amino-functionalized MXene quantum dots (MQDs-NH₂) as fluorescent probe for TNP determination. The MQDs-NH₂ were synthesized via hydrothermal treatment of multilayer Ti₃C₂ MXene modified with N-(2-aminoethyl)-3-aminopropyl trimethoxysilane as the -NH₂ source. The resulting MQDs-NH₂ exhibited outstanding pH stability, thermal resistance, salt tolerance, photo-stability, storage durability, and biocompatibility, with a relative quantum yield of 8.8 %. The MQDs-NH₂ demonstrated excellent linearity and sensitivity toward TNP over a concentration range of 0.05-20 μM, with a limit of detection of 17 nM. While applied to detecting TNP in environmental water samples, the MQDs-NH₂ sensor attained satisfactory spike recovery values, confirming its potential as an effective tool for environmental applications. Additionally, the research on the response mechanism revealed that fluorescence quenching of TNP toward MQDs-NH₂ was mainly ascribed to the inner filter effect (35.7 %) and fluorescence resonance energy transfer (47.1 %). This study not only introduced an innovative strategy for functionalizing MXene QDs but also provided a robust analytical platform for monitoring TNP in environmental safety and public health.

Keywords: Fluorescence analysis; MXene quantum dots; Nanomaterials; TNP.