Fabrication Of Shape-controllable Nanoparticles With DNA Origami And Its Application As Sers Substrates In TCM Detection

The DNA origami structure is variable and nearly can be constructed to any shapes.However,comparing with nanoparticles with other materials,the stability of DNA origami is relatively poor,which limits its application to some extent.If DNA origami can be used as templates to build some new nanoparticles of other materials with the same shape and structure,we can combine with the advantage of variety in shapes of DNA origami and the stability of new materials,so the demand for nanoparticles of different shapes and materials is meet.In recent years,illegal coloring of traditional Chinese medicine happens from time to time.Among the methods that used to detect added pigments in traditional Chinese medicine,the Raman spectrometry is superior for non-damage to the sample,and very low,or even no requirements of pretreatment.Particularly,the surface-enhanced Raman scattering(SERS)technique is widely used for its high detection sensitivity.The enhancement effect of SERS is affected by the shape of SERS-active substrate.Therefore,it is necessary to investigate nanoparticles with variable controllable shapes and can be used as SERS-active substrate.The SERS can be greatly developed with the usage of DNA origami as SERS-active substrate.Based on the background stated above,the stability of DNA origami in different conditions is firstly investigates,in order to provide fundamental basis for its application in different fields.The results of the experiments show that the DNA origami is stable in buffer and can be stored for long time,while influenced more by the temperature and can only exist below its melting temperature.When DNA origami is fixed on the base and placed in the air,it is not stable and cannot be long-term stored,however,it has better tolerance of high temperature in this condition,and can suffer from temperature up to 200? approximately.In addition,the concentration of Mg2+ is a key factor to the stability of DNA origami,and the DNA origami has aggregative trend while the concentration of Mg2+ increases,within certain limit.Then,a method using DNA origami as templates to build nanoparticles of SiO2 is developed,while the DNA origami is stable.With the aid of a certain co-structure directing agent,a layer of SiO2 can be condensed on the surface of DNA origami to form SiO2 nanoparticles of the same shape and structure.The nanoparticles with controllable shape can be prepared by this method.Based on the stated method,orthogon,cylinder,star and tetrahedron frame structure shaped SiO2 nanoparticles are synthesized,and the property of these nanoparticles are investigated by using scanning electron microscope(SEM),transmission electron microscope(TEM),Energy Disperse Spectrometer(EDS),X-Ray Diffraction(XRD),small angle X-ray scattering(SAXS).The result shows that the obtained nanoparticles are core-shell structure,and the shell SiO2 is amorphous mesoporous structure.A layer of gold is sprayed on SiO2 nanoparticles with different shapes.These SiO2 nanoparticles are used in Raman detection as SERS-active substrate to detect lemon yellow and sunset yellow in traditional Chinese medicine.The result shows that the cylinder shaped nanoparticles have the strongest SERS effect;illegally added pigments in traditional Chinese medicine can be tested by using Raman detection with cylinder shaped nanoparticle as SERSactive substrate.