Research On Fluorescence Biosensors For Novel Disease Markers Based On Nanomaterials

The development of disease markers detection and analysis can supply important scientific basis for the early diagnosis.Recently,with the development of molecular biotechnology,the development of simple,convenient,fast,sensitive,well practice biosensor for disease markers detection has become hot spot.The introductions of nanomaterials have further enhanced the performance of biosensors.In this thesis,we have synthesized some new nano-materials with good biocompatibility to construct fluorescence sensing platform for disease markers detection.This paper includes four chapters:In chapter 1,a general introduction of disease marker was made,including the definition,features,categories,clinical analytical methods and so on.Then,an overview of fabrication strategies and history of disease biosensors was made.Finally,the applications of nanomaterials in disease marker sensors were also introduced.The purpose and signification of this thesis were described.In chapter 2,enzyme-free fluorescent biosensor for miRNA-21 detection based on MnO2 nanosheets and catalytic hairpin assembly amplification.miRNA-21 is a breast cancer marker.In our experiment,In the absence of miRNA-21,MnO2 nanosheets can effectively quench the fluorescence of dye-labeled hairpin DNA.In the presence of target,catalytic hairpin assembly amplification can be triggered,resulting in the fluorescence recovery.Quantitative detection of miRNA-21 can be achieved by fluorescence recovery intensity.Results showed that the detection limit for miRNA-21 was 0.33 nM and the linearity range was from 1 to 50 nM.In chapter 3,CoOOH nanosheets suppressed fluorescence of coumarin:mechanistic study and application.ALP is a marker of primary liver cancer,osteocytopenia,obstructive jaundice,rickets.We systematically investigated the mechanism of CoOOH nanosheets suppressing fluorescence of coumarin The mechanism for the fluorescence suppression was attributed to a combination of inner filter effect and static quenching effect.In the presence of alkaline phosphatase,L-ascorbic acid diphosphate(AAP)can be catalyzed to produce ascorbic acid.CoOOH nanosheets can be reduced and decomposed by ascorbic acid,resulting in the fluorescence recovery.Results showed that the detection limit for ALP was 0.21 U/L and have good linearity range with 0.5 U/L?51.8 U/L.In chapter 4,polydopamine nanospheres-based nanoprobe for the sensitive fluorescence detection of T4 polynucleotide kinase activity and inhibition.Biocompatible polydopamine nanospheres were used as fluorescence quenching agents.In the presence of T4 polynucleotide kinase,dye-labeled dsDNA was phosphorylated and then cleaved by ? exonuclease to generate ssDNA,which could adsorb on the polydopamine nanospheres and whose fluorescence was quenched by polydopamine nanospheres.Results showed that the detection limit for ALP was 0.02 U/mL and have good linearity range with 0.05 U/mL?10 U/mL.