Point-of-care Testing System Of Food Contaminants Based On SERS And Socket Communication

In recent years,frequent food safety issues have already aroused widespread concern in society,how to quickly detect the harmful contaminants in food is one of the hot spots at present.However,it is difficult to meet the demand of rapid detection of food contaminants due to complex pretreatment process,long detection cycle and lacking of corresponding portable equipment,such as gas chromatography,high performance liquid chromatography and enzyme inhibition.Therefore,it is of vital significance to develop a detection system for real-time and effective detection of food contaminants.In this dissertation,we propose a Point-of-care testing system for food contaminants based on surface-enhanced Raman scattering(SERS)and Socket communication technology,and it was applied to detection of melamine in milk powder and malachite green residues in aquatic products.The research mainly includes the following aspects:1.We demonstrate a real-time food contaminants detection system consists of SERS sensors,Raman data transmission system and a computer.In this system,the weak Raman spectrum signal of trace food contaminants can be collected by the hand-held Raman spectrometer due to the enhancement of SERS sensor.Then,Raman spectrum signal of food contaminants are transmitted to computer from hand-held Raman spectrometer by the data transmission system for data processing and analysis to complete the real-time detection of food contaminants.2.We have successfully prepared four kinds of SERS sensors,which are 3D biomimetic SERS sensor,3D hierarchical nanostructured SERS sensor with highly dense hot spots across a large scale,3D cloud-like aluminum hierarchical nanostructured SERS sensor and island-like silver nanostructured SERS sensor,and the sensitivity,reproducibility and stability of these SERS sensors were investigated.Furthermore,in order to explore the electromagnetic enhancement mechanism of these SERS sensors,the electromagnetic field distribution of the fourth SERS sensor was simulated using the software COMSOL Multiphysics,and the simulation shows that the nano-gap region between the silver nanoislands can produce a large number of electromagnetic hotspots.3.We propose a data transmission system based on Socket communication,which programming language is Java.According to requirement of the project,client/server(Client/Server)architecture and TCP/IP protocol is adopted in this system.It should be noted that the client is a self-developed client program installed in the handheld Raman spectrometer to transfer the data to the server.And the server is a file management program built on the computer,which is used to receive the data from the client and save it in the specified folder.4.The as-prepared food contaminants detection system equipped with island-like silver nanostructured SERS sensor was applied in detection of melamine in infant formula solution and malachite green in aquatic products,whose LOD are 10 mg/L and 10^-7M,respectively,such results indicate the system exhibits particularly good performances of detection.