Construction Of Functionalized Quantum Dot Fluorescence Aptasensor And Its Application In The Analysis And Detection Of Serum Tumor Markers

In recent years,with the increasing incidence and mortality of cancer,cancer has become a serious threat to human health and life.Serum tumor markers are one of the most ideal biomarkers in clinic,which are of great significance in tumor screening,diagnosis,determination of prognosis,monitoring treatment and detection of recurrence.How to detect serum tumor markers more sensitive,specific,simple,rapid,accurate,quanti tative and timely is a problem to be solved for clinical experimental diagnosis.Aptamer as a segment of oligonucleotides obtained by manual screening,it can specifically bind to proteins or other small molecular substances.However,the itself has a weak photoelectric signal,so it is often necessary to amplify the signal by appropriate methods in the construction of aptasensor.Quantum dot(QDs)is one of the most commonly used fluorescent probes.Because of its wide excitation,narrow emission and high quantum yield,QDs is widely used in the field of fluorescence sensors.In this paper is based on the effect of fluorescence resonance energy transfer(FRET),two kinds of QDs/WS₂/Fe₃O₄ fluorescence sensitized aptasensors were constructed to detect CA19-9 alone or AFP and CA19-9 simultaneously.The main contents of this paper are as follows:(1)Construction of GQDs/WS₂/Fe₃O₄fluorescent enhanced aptasensor and detection of CA19-9Carboxyl fossil graphene quantum dots(GQDs-COOH)and tungsten disulfide(WS₂)nanosheets were synthesized by hydrothermal method.In order to improve the fluorescence quantum efficiency of GQDs-COOH,the GQDs-PEG-Apt obtained by covalent coupling of polyethylene glycol(PEG),was used as the characteristic recognition and energy donor of CA19-9.Fe₃O₄/WS₂ nanocomposite is used as energy receptor,which is composed of ferric oxide(Fe₃O₄)nanoparticles and WS₂ nanoparticles.When there is no target CA19-9 in the sample,the FRET effect between the energy donor and the acceptor makes the fluorescence of GQDs-PEG-Apt can be quenched.When there is CA19-9 in the sample,GQDs-PEG-Apt binds to the target and breaks away from the Fe₃O₄/WS₂ nanocomplex,and the fluorescence of the system can be restored.After magnetic separation,the fluorescence intensity of the supernatant of the sensor system increased with the increase of the concentration of CA19-9.There was a good linear relationship between the relative fluorescence recovery rate of the system and the concentration of CA19-9 in the range of1.995?1000 U/m L,and the detection limit was 0.01 U/m L.The sensor has good specificity and can realize the quantitative detection of human serum tumor marker CA19-9.The RSD is 1.09?4.51%,and the recovery rate is 90.21?99.33%.(2)Construction of QDs/WS₂/Fe₃O₄ dual fluorescence enhanced aptasensor and simul-taneous Detection of AFP and CA19-9Using WS₂/Fe₃O₄ nanocomplex as a single energy acceptor,two kinds of blue fluorescent quantum dots(GQDs-PEG)and red fluorescent Cd Te quantum dots(RQDs)coupled GQDs-PEG-Apt1 and RQDs-Apt2 were used as specific recognition molecules of AFP and CA19-9 and dual energy donors,respectively.Due to the?-?stacking interaction between receptor and aptamer or FRET,the fluorescence of GQDs-PEG-Apt1 and RQDs-Apt2 were quenched simultaneously when the receptor WS₂/Fe₃O₄ nanocomplex was added to the system;when there were AFP and CA19-9 in the sample,the donor and receptor were separated,and the fluorescence intensity of the system was restored;after magnetic separation,the fluorescence intensity of the supernatant increased with the increase of the concentration of AFP and CA19-9.After optimizing the detection conditions,the relative fluorescence intensity of the system has a good linear relationship with the concentration of two serum tumor markers when the concentration of AFP is in the range of5?1000 ng/m L and the concentration of CA19-9 is in the range of 5?1000 U/m L.The detection limits are 0.5 pg/m L and 0.396 m U/m L,respectively.The sensor has good specificity and can be used for simultaneous quantitative detection of human serum tumor markers AFP and CA19-9,in which the RSD of CA19-9 is 2.72?6.24%,the recovery rate is95.13?100.89%RSD is 3.32?6.41%,and the recovery rate is 91.92?99.28%.The QDs/WS₂/Fe₃O₄ fluorescence-enhanced aptasensor constructed in this paper has the characteristics of wide linear range,high sensitivity,strong specificity and good stability,so it can be used in clinical experimental diagnosis and has the value of clinical application.By changing the aptamer sequence,the QDs/WS₂/Fe₃O₄ fluorescence-enhanced aptasensor can also be used for quantitative detection of other targets,which is of great significance for cancer diagnosis and accelerating the realization of healthy Chinese strategy.