Photoeletric Sensor Based On Functionalized Nanomaterials And Its Application

Cancer is still a difficult problem for human beings in today's society.The prevention and inhibition of cancer is still of great significance for its treatment.However,the simple,rapid and sensitive detection of tumor markers are still difficult to achieve in medical diagnosis.It is urgent to develop signal amplification technology to achieve sensitive detection of tumor markers.In this study,Electrochemical analysis and photoelectrochemical analysis methods were used to achieve high sensitivity and high selectivity detection of T4PNK,DNA and telomerase,including cycle amplification and ratiometric biosensor.The main research content includes three aspects:(1)An electrochemical method is described for the sensitive detection of the activity of the enzyme T4 polynucleotide kinase(T4PNK)by using a DNA functionalized porphyrinic metal-organic framework(DNA/(Fe-P)n-MOF).In the presence of T4PNK,the hairpin oligonucleotide(HP1)becomes phosphorylated,and the trigger is released by lambda exonuclease(?exo).The trigger DNA hybridizes with hairpin probe(immobilized on the gold electrode)to form a nicking endonuclease cleavage site.Thus,a single strand capture probe is employed to hybridize with DNA/(Fe-P)n-MOF.The(Fe-P)n-MOF is a peroxidase mimicking material with high catalytic efficiency.By using this amplification strategy,an electrochemical signal is procured that allows for the determination of T4 PNK.The method is selective and can be used to screen for enzyme inhibitors.Conceivably,the(Fe-P)n-MOF can also be used to detect other analytes via its peroxidase mimicking activity.(2)A ratiometric electrochemical sensor was constructed for the detection of telomerase by using quantum dot composites.First,DNA1 is modified on magnetic beads and DNA2 is modified to the surface of quantum dots.Among them,DNA1 and DNA2 are hybridized with the telomerase primer strand O1 DNA portion,respectively.Therefore,under the action of the telomerase primer chain,the magnetic beads modified with DNA1 and the quantum dots modified with DNA2 are linked to each other.In the presence of telomerase,the telomeric repected sequence of(TTAGGG)_n extended at the 3'-end of O1 would hybridized with its complementary sequences at5'-ends.This led the telomerase extension product of O1 be folded to form a rigid hairpin structure.As the result,the CuS quantum dots were released into the solution,and the DNA 2 attached to the copper sulfide quantum dots is sheared off by the first cleavage enzyme to obtain pure copper sulfide quantum dots.On the other hand,the double-stranded DNA in which the ferrocene Fc and the methylene blue MB are simultaneously labeled,that is,the coenzyme structure of the copper ion,is self-assembled to the electrode surface through the Au-S bond,and the copper sulfide quantum dot can cut off the coenzyme structure.Fc changes from one end away from the electrode to the surface of the electrode,so that the positive current signal is enhanced.The DNA fragment of the methylene blue on the surface of the adjacent electrode is cut off,and the negative current signal changes from high to low,thus achieving telomere Detection of enzymes.The method can be used for actual sample detection,such as HeLa cells,and has potential application prospects.(3)A photoelectric sensor for sensitive detection of DNA was constructed based on the enhancement photoelectric signal with methylene blue.The chromium-selenide metal organic framework with photoelectric signal is modified on the ITO electrode,as a substrate to immobilize the hairpin DNA,and the configuration of the DNA is changed under the action of the target DNA to form a streptavidin aptamer structure.Methylene blue was embedded into the tetrahedral DNA dendrimer with biotin.Tetrahedral DNA dendrimers with methylene blue were connected to the surface of the metal organic framework.The target DNA was detected by the photoelectric signal.