Construction Of Biosensors Based On Gold Nanoparticles And Application In Detection Of Medicine And Disease Biomarkers

In this thesis,three optical biosensors based on gold nanoparticles were developed for the rapid,visual and highly sensitive detection of small molecule berberine,DNA and inflammatory biomarker C-reactive protein.The main contents include:?1?In the first chapter,we introduced the importance of drug and biomarker detection,and some traditional analytical methods were introduced.Then,the limitations of traditional analytical methods and the development trend of detection techniques were analyzed.On this basis,optical biosensors based on gold nanoparticles were proposed,and then the design principles and strategies of colorimetric biosensors and surface-enhanced Raman spectroscopy biosensors,as well as applications in the field of drug and biological analysis were introduced.Finally,research ideas of this thesis were proposed.?2?In the second chapter,a colorimetric biosensor for detection of berberine was developed based on electrostatic and coordination interaction of gold nanoparticles and berberine.Berberine can induce the aggregation of dispersed gold nanoparticles,leading to the color change from red to purple or blue.The reaction kinetics of gold nanoparticles in the presence of different concentrations of berberine and selectivity of this method were investigated.Finally,the proposed method was successfully applied to the visual detection of berberine in human plasma.The advantage of this method is that the test results are visible to naked eyes,and without the aid of an instrument.It's simple and fast,and the detection process takes only 10 min.?3?In the third chapter,a colorimetric biosensor for DNA detection was developed based on the aggregation of gold nanoparticles induced by palmatine and the molecular recognition of palmatine and DNA.This method does not require any modification or labeling of gold nanoparticles.Thus,solving the problem of complex modification and labeling process in conventional DNA colorimetric biosensors.After the optimization of detection conditions,DNA molecular logic gates were introduced to enable our colorimetric biosensor to have the potential to detect DNA online.The signal input and output results were investigated.And then,this biosensor was used for rapid visual detection of DNA with different concentrations.Finally,the DNA biosensor and molecular logic gates were combined with a microfluidic chip.Sample consumption was significantly reduced compared to conventional DNA biosensors based on gold nanoparticles.This method has the potential for miniaturization and automated analysis.?4?In the fourth chapter,a surface-enhanced Raman spectroscopy biosensor for ultrasensitive detection of protein biomarkers was developed.Firstly,high-enhanced and highly stable core-shell gold nanoparticles with nano-gap were synthesized as signal probes,and silver-coated Fe₃O₄ magnetic nanoparticles were used as magnetic capture substrates.C-reactive protein,an inflammatory biomarker was used as detecting target.Aptamers against the protein were modified on the surface of signal probes and magnetic capture substrates as specific recognition unit.This signal probe has strong and stable Raman signal,and the silver-coated Fe₃O₄ magnetic nanoparticles exhibits excellent Raman enhancement activity.The limit of detection of C-reactive protein was achieved at 10 fmol/L,and the sensitivity is higher than most reported methods.In addition,this method exhibits excellent selectivity and specificity for C-reactive protein under the interference of other proteins,and exhibits high accuracy in the detection of actual human serum samples.The method proposed in this chapter is expected to be further applied to the ultrasensitive detection of other disease biomarkers in human blood.?5?In the fifth chapter,we systematically summarized the research contents of this thesis,method advantages and application prospects.Besides,the shortcomings in current research and the focus of follow-up research were discussed.