Preparation Of One-Dimensional Functional Nanomaterials And Its Application On The Sensors

With the rapid development of society, homeland security issues caused by explosives and environmental problems caused by pesticides have attracted more and more attentions. Detection of explosives and pesticides in real-time, fast, stable, in situ, ultrasensitive and selective has been of press societal concern. In this paper, we have fabricated two kinds of one-dimensional functional nanomaterials sensors, which ultrasensitive resonse to aforementioned analytes. One is the preparation of Ag nanotube array as surface-enhanced Raman scattering (SERS) substrates to achive ultrasensitive and highly selective detection of explorsive TNT using SERS technology. The other is the preparation of imprinted pesticide 2,4-D polypyrrole (PPy) nanonecklace as working electrode to achive sensitive and selective detection of non-electrochemially activity pesticide 2,4-D though electrochemical methods.In chapter 1, we review the development, synthetic methods and application of one-dimensional nanomaterials. In addition, we comprehensive introduce the mechanism, substrate preparation and application of SERS.In chapter 2, we report that trinitrotoluene (TNT) lighted up the ultrahigh Raman scattering of off-resonated p-aminobenzenethiol (PABT) through the formation of charge-transfer TNT-PABT complex on the top-closed flexible silver nanotube array. The temporal PABT-TNT-PABT bridges between self-approaching silver nanotubes cause the spectral resonance among the chromophore, the incident laser and localized surface plasmon, which enhances PABT Raman signals by a factor of 2×1013 that is comparable to those of resonant dyes such as rhodamine-6G. The enhancement effect is repeatedly renewable by the reconstruction of molecular bridge through the reversible self-approaching of silver nanotubes, and can selectively detect TNT with a limit of 1.5×10-17 M. The results of this report provide the novel understanding on surface enhanced Raman scattering and open the possibility of probing single molecule-level TNT explosives.In chapter 3, we report that molecularly imprinted polypyrrole (PPy) nanonecklaces were facilely synthesized through a surfactant-assisted two-step oxidative polymerization route for the detection of non-electrochemically active herbicide. It has been demonstrated that dissolved oxygen can preoxidize pyrrole to form PPy oligomer bundles, which further self-assemble into necklace-like micelles in the presence of cetyltrimethylammonium bromide (CTAB). Subsequently, these necklace-like microstructures were immediately gelled through quick polymerization of residual pyrrole monomers by the addition of ammonium persulfate (APS), leading to the formation of PPy nanonecklaces. Meanwhile, 2,4-dichlorophenoxyacetic acid (2,4-D) was synchronously locked into the formed PPy by the electrovalent and hydrogen bonds between 2,4-D and PPy backbone. After removal of 2,4-D molecules, highly-dense imprinted sites were generated in PPy nanonecklaces because the necklace-like structure with microgaps/pores provides the facile and complete removal of templates. The imprinted nanonecklaces exhibit the high capacity and fast kinetics to uptake 2,4-D molecules, and produce a imprinting factor of ~4.2. Importantly, the recognition and binding to 2,4-D significantly amplify the current response in amperometric measurements, providing a sensitive detection of 2,4-D with a detection limit down to 100 nM. The molecular imprinting strategy opens a novel avenue to the direct detection of non-electrochemically active species in a more convenient, simpler and cheaper way than the traditional competition-displacing approaches.