Construction Of Au-Si Composite Nanoparticles And Visual Detection Of Carbonic Anhydrase

The qualitative and quantitative detection of protein is of great significance to the prevention and treatment of diseases.Homogeneous detection method has the advantages of no need for separation,simple operation,easy to realize automatic operation,etc.,and it has received more and more attention in recent years.In this paper,a homogeneous detection system based on Au-Si composite nanoparticles is designed for the visual detection of proteins.Au-Si composite nanoparticles were composed of gold nanoparticles(AuNPs)modified with polymer on the surface and mesoporous silica spheres(MSNs)loaded with color-developing molecules.AuNPs of small particle size were adsorbed on the surface of mesoporous channels of MSNs.The polymer could specifically recognize and bind to the protein,and competitively destroy the adsorption between Au-Si,causing the AuNPs to break away and release the chromogenic molecules,realizing the detection of proteins.1.Utilizing the strong reducibility of tannic acid(TA),by adjusting the addition ratio and concentration of tetrachloroauric acid(HAuCl4),AuNPs with suitable particle size were prepared.The prepared AuNPs had uniform particle size and unique light absorption characteristics;At the same time,adjusted the pH of the solution to form a TA shell structure on the surface of AuNPs to prepare AuNPs@TA.Experiments showed that AuNPs@TA has a negative charge on the surface,which can exist stably in water and can be redispersed after centrifugation.2.Polyethylene glycol(HS-PEG1000-SABA)with one end of sulfhydryl group and one end of arylsulfonamide(HS-PEG1000-SABA)was prepared.HS-PEG1000-SABA can be grafted to the surface of AuNPs through the function of Au-S bond to obtain polymer graft gold nanoparticles(AuNPs@TA-PEG1000-SABA).3.MSNs were prepared by organic-aqueous heterogeneous method,and modified by amination to prepare NH2-MSNs with positive charges on the surface.NH2-MSNs could effectively load a large number of chromogenic molecules Fe3+.NH2-MSNs loaded with Fe3+ and AuNPs@TA-PEG1000-SABA combined through electrostatic interaction to close the mesoporous channel of NH2-MSNs,and successfully constructed Au-Si composite nanoparticles.4.Experiments had proved that the constructed detection system can achieve high-sensitivity and high-specificity visual detection of CA II,with a detection limit as low as 50 nM.