Research On Gold And Silver Bimetallic Nanomaterials For Solid-phase Microextraction Coupled With Surface-enhanced Raman Spectroscopy And Its Application

Solid phase microextraction(SPME)is characterized by rapid,sensitive and simple operation.It integrates sampling,analysis and injection procedures.It has been successfully combined with many analytical techniques,and has been quickly developed into a new sample pretreatment technology that can suit a broad range of application.Surface enhanced Raman spectroscopy(SERS)technology has high sensitivity,fast analysis and can provide fingerprint information of the measured molecular structure,and it is also a powerful tool for the analysis and detection of environmental pollutants.SPME coupled with SERS is a promising combination of fast sampling and detection,which combines the advantages of both fast,sensitive and easy to operate.A key point in the SERS detection application is the balance between the stability and the signal enhancement of the substrate.The stability of gold is strong,and its biocompatibility is good,but its enhancement effect is not satisfactory;the enhancement effect of silver is good,it can even reach single molecule detection level,but it is apt to be oxidized,resulting in the bad repeatment of the raman signal.In addition,an important constraint for SERS to be the conventional means of analysis is that the SERS effect is very sensitive to the surface nanostructures and local electromagnetic fields,and a little difference of the nanostructures the surface may cause the enhancement signal to change at several levels,quantitatively analysis is not so reliable.1.We synthesized a variety of gold and silver bimetallic materials,and load to the ZnO nanorod array modified stainless steel wire,to prepare a variety of extraction fibers.ZnO,an inorganic solid phase microextraction coating,has good uniformity and thermal stability,can be used as a good load matrix of gold and silver material.For the formation of gold and silver materials-zinc oxide composite nanostructure,on the one hand,it can provide gold and silver materials to enhance the electromagnetic field,on the other hand,there is the chemical enhancement effect of zinc oxide.At the same time,ZnO has a good extraction effect on some organic matter,especially sulfur-containing substances.We investigated the enhancement and stability of gold and silver materials with different compositions and different morphologies,and compared them with gold and silver nanomaterials of monocomponent.2.We have prepared the gold@4-ATP@silver nanoparticles which can provide the stable internal standard signal by the 4-ATP embedded and couple it to the surface of ZnO NRs modified stainless steel wire.Then we can get a new kind of SERS-active SPME extraction fiber.The as-prepared fiber has good stability,and the homogeneity of the substrate can be further enhanced by the method of normalization the raman signal with the internal standard.The quantitative ability of SERS was improved.This fiber provides a reliable method for the detection of water environment on-site.Using malachite green(MG)as a probe molecule,we demonstrated the feasibility of the theory.And the possibility of this strategy in practical application was confirmed by simulating the detection of MG and crystal violet(CV)in aquaculture water.