Meso-Au/BN Nanosensor for Trinitrotoluene Based on Fluorescence Resonance Energy Transfer and Surface-Enhanced Raman Spectroscopy Mechanisms

It is a considerable challenge to develop surface-enhanced Raman spectroscopy sensors with high sensitivity but a lack of selective recognition performance for target species in the applied field. Here, a strategy for fabricating a meso-Au/BN nanoparticle (NP) sensor through a synthesized mesoporous Au NPs’ surface modified by BN quantum dots (QDs) and 2-mercaptoethylamine (MEA) through electrostatic attraction and covalent bonding between a sulfur atom in the thiol group and an Au atom, respectively, was implemented to selectively recognize and sensitively detect 2,4,6-trinitrotoluene (TNT). TNT interacted with MEA on the meso-Au NP surface to form a TNT–MEA complex through the electrostatic affinity interaction between the electron-deficient nitro groups and the electron-rich amino group at the fluorescence-tagged sites, approaching the BN QDs on the meso-Au NPs’ surface at spatial proximity, leading to the suppression of the fluorescence intensity of BN QDs via the fluorescence resonance energy transfer mechanism, forming the selective recognition of TNT. Additionally, the meso-Au/BN NP sensor enhanced the Raman signal of TNT by the localized surface plasmon resonance hotspots of the meso-Au NP surface, achieving highly sensitive detection of TNT. The limit of detection for TNT was 10 –9 mol·L –1 . Comparing TNT, 2,4-dinitrotoluene, 2,4,6-trinitrophenol, and 2,4-dinitrophenol, the meso-Au/BN NP sensor exhibited much more selective recognition and sensitive detection of TNT than other aromatic compounds. The method can be widely applied in the selective recognition and trace detection of biological molecules, metal ions, and organic pollutants.