Surface Plasmon Resonance Enhanced Upconversion Luminescence In Aqueous Media For TNT Selective Detection

Surface plasmon resonance (SPR) enhanced luminescence has attracted growing interest for their applications in bioassays and solar cell devices in recent years. At the same time, upconversion materials have been widely used in biological imaging and detection for their superior luminescence properties such as high luminescence efficiency, small background interference, stability and long lifetime.This paper present a novel SPR enhanced upconversion luminescence strategy in aqueous media based on the properties of upconversion nanomaterials and gold nanoparticles. Through changing the modifying condition, we prepared two kinds of NaYF4nanomaterials, nanoflowers and nanospheres. And we prepared gold nanoparticles with different diameters. Series of experiments have proved that we succeed in devising SPR enhanced upconversion luminescence system. Compared to the similar results reported before which all exist in the form of a solid phase, this has greater research significance and application prospect. Moreover, this system also can be applied to the highly selective detection of2,4,6-trinitrotoluene (TNT), providing a new way for the qualitative and quantitative analysis of micro molecules.In chapter two, we devised SPR enhanced upconversion luminescence system and modulated the luminescence. We got NaYF4nanoflowers and nanospheres with negatively charged surfaces through modifying with polysuccinimide, which are stable in water and emitted bright green light under the980nm diode laser. Moreover, the amine-functionalized gold nanoparticles were prepared, whose diameters are50and5nm respectively, also dispersed well in water. Based on the electrostatic interactions, positively charged gold nanoparticles were attached onto the negatively charged NaYF4nanomaterials. Because of the plasmon resonance properties of gold, the luminescence enhanced greatly, however, similar results reported before all exist in the form of a solid phase. In this paper, when nanoflowers and gold nanoparticles with50nm were adapted, the luminescence enhanced greatest.In chapter three this system has been applied to the highly selective detection of TNT successfully. Because of the donor-acceptor interaction, TNT can make gold and nanoflowers closer and greatly enhanced the upconversion luminescence further because of the SPR property of gold nanoparticles. This method is very simple, which can be processed in the water. The recognition is fast and can keep stable for long time. What is more, this method has great selectivity for TNT, the upconversion luminescence was only proportional to the concentration of TNT and scarcely affected by other nitroaromatics such as2,4,6-trinitrophenol (TNP).