Preparation And Application Of Water-soluble Ammonium Pillar[5]arene Functionalized Au Nanostars

The detection and identification of environmental pollutants is of great significance to protect the environment and maintain the ecological health of the earth.Gold nanostars(Au NSs)have attracted much attention in the field of sensing and detection because of their asymmetric structure,rough surface,and high electromagnetic activity at the post-radiation tip,thus initiating unique optical properties.Meanwhile,since the detection systems constructed from gold nanomaterials do not require large,expensive and time-consuming detection methods such as transmission electron microscopy,X-ray photoelectron spectroscopy.UV-vis spectroscopy(UV-vis)analysis with simple operation and high sensitivity can be selected,which has advantages in analytical efficiency and cost savings.In recent years,pillararenes as the fifth generation supramolecular host have attracted the attention of scientists in host-guest recognition due to their highly symmetric skeleton structure and easy functionalization.The researchers found that pillararenes could be used to detect trace amounts of pollutants in water by constructing suitable host-guest recognition system in pure water phase.In this paper,firstly,we investigated the research progress of pillararenes and gold nanostar materials in recent years,and summarized the types of pillararenes,the properties of host and guest,and their applications in the field of nanomaterials that have been reported.At the same time,the preparation methods,related properties and application research progress of gold nanostars are summarized.We selected quaternary ammonium salt-functionalized pillar[5]arene to prepare water-soluble ammonium-based pillar[5]arene(AP5)functionalized gold nanostars(Au NSs)to explore the application of gold nanomaterials in surface-enhanced Raman analysis.At the same time,we studied the application of this nanocomposite in pollutant sensing by using UV-vis spectroscopy as an analytical method and the catalysis capability of p-nitroaniline reduction.The main research aspects of this paper are as follows:.First part,preparation of AP5 functionalized Au NSs:According to the literature method,we synthesized AP5 and then prepared the gold nanostars modified with AP5,AP5 as stabilizer and ascorbic acid(AA)as reducing agent.In the experiment,in order to ensure that after the reduction reaction,there are enough stabilizers adsorbed on the surface of the Au NSs material,we make the AP5 greatly excess than HAu Cl4.The excessive AP5 in the solution was washed by centrifugation for two times and we can obtain good dispersion and stability Au NSs.We tried to use the suitable AP5 modified Au NSs material for surface Raman enhancement studies,but the surface Raman enhancement effect was not significant.In the second part,the AP5 functionalized Au NSs are used for the sensing detection of naproxen-Na+:Naproxen-Na+ is a dose-dependent analgesic used in various types of arthritis pain,swelling.However,the abuse of naproxen-Na+ and all kinds of false treatments make it could infiltrate into the ground surface and enter into the groundwater source,which has an irreversible effect on the health of the people who live in the polluted water source for a long time.we further applied the prepared AP5-Au NSs to UV-vis sensing detection of naproxen-Na+ with a minimum detection concentration is 1×10-4 M.The third part,AP5 functionalized Au NSs for the catalytic reduction aromatic homologs--p-nitroaniline:p-Nitroaniline is widely used in the dye industry,by synthetic chemicals,as an intermediate of many kinds of printing,dyeing and pharmaceutical chemicals,it has an important position in production and life,but its toxicity is high,and eating by mistake will cause strong blood poisoning.Therefore,efficient reduction transformation methods are particularly important.We added AP5-Au NSs to the aqueous solution of p-nitroaniline to detect the UV-vis spectra of the mixed solution in real time.We found that with the addition of AP5-Au NSs,the characteristic absorption peak intensity of p-nitroaniline decreased gradually in the UV spectrum,and the characteristic absorption peak intensity of its reduction product--p-phenylenediamine increased gradually.And its reduction rate is linearly related to time.Experimental results show that,AP5-Au NSs can effectively catalyze the reduction of p-nitroaniline.