Highly Sensitive Ratiometric Fluorescent Sensor for Trinitrotoluene\nBased on the Inner Filter Effect between Gold Nanoparticles and Fluorescent\nNanoparticles

Abstract

In\nthis work, we developed a simple and sensitive ratiometric fluorescent\nassay for sensing trinitrotoluene (TNT) based on the inner filter\neffect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent\nnanoparticles (RFNs), which was designed by hybridizing green emissive\ncarbon dots (CDs) and red emissive quantum dots (QDs) into a silica\nsphere as a fluorophore pair. AuNPs in their dispersion state can\nbe a powerful absorber to quench CDs, while the aggregated AuNPs can\nquench QDs in the IFE-based fluorescent assays as a result of complementary\noverlap between the absorption spectrum of AuNPs and emission spectrum\nof RFNs. As a result of the fact that TNT can induce the aggregation\nof AuNPs, with the addition of TNT, the fluorescent of QDs can be\nquenched, while the fluorescent of CDs would be recovered. Then, ratiometric\nfluorescent detection of TNT is feasible. The present IFE-based ratiometric\nfluorescent sensor can detect TNT ranging from 0.1 to 270 nM, with\na detection limit of 0.029 nM. In addition, the developed method was\nsuccessfully applied to investigate TNT in water and soil samples\nwith satisfactory recoveries ranging from 95 to 103%, with precision\nbelow 4.5%. The simple sensing approach proposed here could improve\nthe sensitivity of colorimetric analysis by changing the ultraviolet\nanalysis to ratiometric fluorescent analysis and promote the development\nof a dual-mode detection system.