Design Guideline Of AuNPS-based Colorimetric Biosensor And Research On Detection Of Nucleic Acid And Bacteria

In scientific research,Au NPs(gold nanoparticles)have attained great interest due to their unique physical and optical properties.They are a kind of functional nanomaterials with great potential.Over the past few decades,Au NPs have been very commonly used in medical diagnostics and biosensor development.Au NPs-based detection methods have been extensively reviewed in the literature.Most of them are phased summary of the development of this field,such as the synthetic strategy of Au NPs,surface functionalization of Au NPs,detection for different target using Au NPs,or various Au NPs coupling methods.On the other hand,only rare literatures discussed and summarized the design strategies of Au NPs-based colorimetric assay.In order to make readers more easily understand the principles and the applications of the topic,this graduation thesis has mainly performed the following three aspects:(1)In Chapter 2,we reviewed nearly 30 years of research on Au NPs-based colorimetric sensing for nucleic acid detection and fully understood the development history of Au NPs-based colorimetric sensing methods.The surveyed sensing methods were summarized and classified.Through an in-depth analysis of existing research,at the end of this chapter we gave five potential research points in this field.This chapter aimed to provide a comprehensive reference outlining the general design strategies for constructing of Au NPs-based nucleic acid colorimetric biosensors.(2)The work in Chapter 3 is an innovative application of the Au NPs-based biosensor design guidelines outlined in Chapter 2.Chapter 2 introduced that low p H conditions can be used to prepare DNA-functionalized Au NPs.For the development of Au NPs-based colorimetric biosensors,we had successfully used low-p H conditions to provide a detection environment for the sensors,and modified the hybridization chain reaction with poly A blocks to successfully complete analysis of DNA targets.The results showed this method had a good linear relationship in the range of nucleic acid concentration from 0.05 to 0.80 n M,and the actual detection limit can reach 47.3 p M.(3)In order to apply the sensing method developed in Chapter 3 to more detection targets,in the work of Chapter 4,we designed an aptamer nucleic acid reaction.The aptamer can specifically bind to Salmonella Typhimurium,thus cleverly linking bacteria and nucleic acid reactions.By optimizing the parameters that affect the sensor,this work has achieved high sensitivity and specificity detection of Salmonella Typhimurium.The actual detection limit of this method can reach 2.42×10~2 CFU/m L,showing a good linear relationship in the range of 10~3 CFU/m L to 10~9 CFU/m L.By changing the nucleic acid sequence of aptamer,this method is expected to be used for the detection of other biological samples,such as heavy metals,cancer cells,and proteins.