Gold-Coated Silicon Nanomaterials Based Test Strips Development For The Determination Of GMO Sequences

Lateral flow strip is widely used in food safety detection,clinical diagnosis,environmental monitoring and other fields because of its fast detection,simple operation and no need of expensive instruments.At present,the commercial label of test strip is colloidal gold,which is limited by its specific surface and capacity of detection probe.The sensitivity of strip detection is relatively low,and the problem of false negative in low concentration samples is to be solved.The core-shell structure of noble metal nanomaterials has some advantages over noble metals.In recent years,the research of adsorbing gold nanoparticles on the surface of SiO₂ nanospheres has attracted extensive attention.SiO₂ has good chemical stability and high specific surface area.SiO₂ layer can significantly improve the physical,chemical and mechanical stability of gold nanoparticles,and solve the problems of easy aggregation and insufficient detection limit of gold nanoparticle.Therefore,this paper constructs a SiO₂@Au labeled DNA biosensor,and uses the recognition principle of sandwich method to realize the high sensitivity and rapid detection of the transgenic Codon sequence.The main content of the paper are as follows:(1)Preparation of SiO₂@Au:Based on the Stober method,silica spheres were prepared.The size of silica spheres was adjusted by changing the amount of TEOS and ammonia.After optimization,it was found that adding 6mL of 98%TEOS and 6mL of 25%ammonia had the best effect,and the silica spheres with the size of 200nm were successfully prepared.In addition,different sizes of gold nanoparticles were prepared by reduction of sodium borohydride and trisodium citrate.The prepared gold nanoparticles,silica spheres and SiO₂@Au were characterized by transmission electron microscopy(TEM),ultraviolet spectrophotometer and nanoparticle size analyzer.The experimental results showed that when the diameter of the silicon spheres is 200nm and the gold nanoparticle is 5nm,the SiO₂@Au is uniform in size,has no aggregation,and a large number of gold nanoparticles are loaded on the surface of the silicon spheres.The SiO₂@Au can be used as the label material of lateral flow strip for subsequent experiments.(2)Strip test of genetically modified Codon sequence:SiO₂@Au labeled lateral flow strip was prepared and detected by sandwich principle.Under the optimal experimental conditions,there was a good linear relationship between the response signal and the concentration of Codon in the range of 5pM to 100pM,and the detection limit is 5pM.In order to further study the analytical performance of SiO₂@Au labeled nucleic acid sensor,we studied its stability,reproducibility and specificity.The results showed that the strip has good stability,reproducibility and specificity.The sensitivity of the SiO₂@Au labeled nucleic acid strip is 100 times higher than that of the traditional gold nanopaticle labeled.