Electrochemiluminescence Detection of TNT by Resonance Energy Transfer through the Formation of a TNT–Amine Complex

Graphical An explosive situation : Methods for the electrochemiluminescence (ECL)-based detection of 2,4,6-trinitrotoluene (TNT) through the formation of a TNT–amine complex and through ECL resonance energy transfer have been developed (see figure). The determination of TNT concentration with 3-aminopropyltriethoxysilane (APTES)-modified [Ru(phen) 3 ] 2+ (phen=1,10-phenanthroline)-doped silica nanoparticles (RuSiNPs) down to 1 n M is achieved within 1 min. 2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive with significant detrimental effects on the environment and human health. Its detection is of great importance. In this study, both electrochemiluminescence (ECL)-based detection of TNT through the formation of a TNT–amine complex and the detection of TNT through electrochemiluminescence resonance energy transfer (ECRET) are developed for the first time. 3-Aminopropyltriethoxysilane (APTES)-modified [Ru(phen) 3 ] 2+ (phen=1,10-phenanthroline)-doped silica nanoparticles (RuSiNPs) with uniform sizes of (73±3) nm were synthesized. TNT can interact with APTES-modified RuSiNPs through charge transfer from electron-rich amines in the RuSiNPs to the electron-deficient aromatic ring of TNT to form a red TNT–amine complex. The absorption spectrum of this complex overlaps with the ECL spectrum of the APTES-modified RuSiNPs/triethylamine system. As a result, ECL signals of the APTES-modified RuSiNPs/triethylamine system are turned off in the presence of TNT owing to resonance energy transfer from electrochemically excited RuSiNPs to the TNT–amine complex. This ECRET method has been successfully applied for the sensitive determination of TNT with a linear range from 1×10 −9 to 1×10 −6 M with a fast response time within 1 min. The limit of detection is 0.3 n M . The method exhibits good selectivity towards 2,4-dinitrotoluene, p -nitrotoluene, nitrobenzene, phenol, p -quinone, 8-hydroxyquinoline, p -phenylenediamine, K 3 [Fe(CN) 6 ], Fe 3+ , NO 3 − , NO 2 − , Cr 3+ , Fe 2+ , Pb 2+ , SO 3 2− , formaldehyde, oxalate, proline, and glycine.