Microfluidic Bacterial Enrichment And Flexible SERS Chip

Since the concept of"biological safety"was put forward,it has received extensive attention at home and abroad in terms of human health,resources and environment,and national defense security.The spread of bacteria and other microorganisms can cause various diseases,which not only affects human life,but also causes significant losses to economic development.Therefore,rapid detection of bacteria and other microorganisms is particularly important.However,the culture method requires a long pre-treatment time during the detection process,so it is easy to miss the best diagnosis and prevention time.The detection results of polymerase chain reaction and enzyme-linked immunosorbent assay are accurate and have a wide range of applications,but they require professional and expensive detection equipment,which cannot achieve rapid detection and real-time analysis.For the rapid detection of microorganisms,this thesis proposes a research plan that combines microfluidic enrichment technology with SERS detection technology,and carries out research on microbial enrichment chips and SERS detection chips.The key research in the thesis is the microbial enrichment chip based on the micro-nano adsorption effect,the gold-coated-silver core-shell nanoparticles and the flexible SERS chip with good biocompatibility.The main research work of the paper was:(1)Researched the domestic and foreign research progress and trends of the enrichment and detection methods of bacteria and other microorganisms,deeply analyzed the advantages and disadvantages of different methods,and clarified the research objectives and research content of this article;(2)Improved the synthesis method of gold-coated-silver core-shell nanoparticles,PVP was used as a protective agent and ascorbic acid was used as a reducing agent to complete the synthesis of gold-coated silver core-shell nanoparticles.Spectral absorption peak and TEM characterization were performed,and the results showed that the core-shell nanoparticles synthesized by this method had good uniformity,and the thickness of the shell layer was about 10 nm;(3)Proposed a micro-nano structure adsorption-based microbial enrichment method,simulated and analyzed the velocity distribution and particle tracking of the enrichment chip structure layer at different flow rates,completed the production of the chip,and optimized and analyzed the sampling time and sampling of the chip,the final three-level chip cascade enrichment efficiency could reach 99.7%;(4)Based on the synthesis of core-shell nanoparticles,the paper-based flexible SERS chip was prepared,and the enhancement factor and consistency of the core-shell SERS detection chip were characterized.The results showed that the enhancement factor of the gold-coated silver core-shell SERS chip was about1.12×10~6,and the relative standard deviation was about 4.00%;(5)The bacteria detection system was built,and the microfluidic enrichment chip and the gold-coated silver core shell-SERS detection chip were combined for the label-free rapid detection of S.aureus,and the detection of S.aureus at a concentration of10~4 cfu/m L was realized,indicating that the system could achieve bacterial enrichment and direct detection.