| In this dissertation,graphene oxide as a carrier was used to prepare graphene-based magnetic composites?magnetic graphene oxide,chitosan cross-linked magnetic graphene oxide,magnetic mesoporous silica/graphene oxide,and magnetic?-cyclodextrin/graphene oxide?,and aptamers were modified on the surface of the composite material to obtain a graphene-based magnetic composite material with specific recognition ability for the target biomolecules.Combinated with the flow injection chemiluminescence technology,a series of novel chemiluminescent aptasensor were constructed to achieve sensitive,selective,accurate and rapid analysis of some disease-related biomolecules?hemin,thrombin,dopamine,adenosine?.In the first part,a novel chemiluminescent aptasensor was constructed to achieve highly sensitive and selective detection of thrombin,in which magnetic graphene oxide?MGO?was synthesized,then hemin aptamer?H-Apt?was functionalized on its surface to obtain MGO/H-Apt with specific recognition ability for hemin molecules and Cobalt porphyrin?Co-PP?was a catalyst for the luminol-hydrogen peroxide chemiluminescence system.Firstly,MGO with a large specific surface area and easy separation properties was synthesized and the composites were characterized by infrared spectroscopy,X-ray diffraction and scanning electron microscopy.Then,the immobilization and adsorption properties of the composites were researched.The immobilized amount of MGO to H-Apt was 4.8×10-10 mol/mg and the adsorption of MGO/H-Apt to Co-PP was 1.6×10-8 mol/mg.Finally,MGO/H-Apt/Co-PP was used for hemin detection with flow injection chemiluminescence technology and the novel chemiluminescent aptasensor was constructed.The detection range of the hemin sensor was8.0×10-11–4.8×10-8 mol/L while the detection limit was 3.9×10-12 mol/L?3??.The anti-interference ability of aptasensor and the reusability performance of MGO were researched.Finally,the aptasensor was used for the determination of hemin in serum samples and the results were satisfactory.In the second part,a chemiluminescent aptasensor for thrombin detection was constructed,in which chitosan cross-linked magnetic graphene oxide?CS@Fe3O4@GO?was synthesized,the thrombin aptamer?T-Apt?was immobilized on the surface to obtain CS@Fe3O4@GO/T-Apt with high specific recognition ability for thrombin molecules,and porphyrin Iron?HM?was introduced to as a catalyst.Firstly,GO with a large specific surface area and Fe3O4 with a uniform size were synthesized and CS@Fe3O4@GO was prepared by cross-linking with chitosan.The synthesized composites were characterized by infrared spectroscopy,X-ray diffraction,electron microscopy and so on.Then,the immobilization and adsorption properties of the composites were investigated.The immobilized amount of CS@Fe3O4@GO to T-Apt was 5.3×10-10 mol/mg,and the adsorption amount of CS@Fe3O4@GO/T-Apt to HM was 4.5.×10-1010 mol/mg.Finally,CS@Fe3O4@GO/T-Apt/HM was combined with flow injection chemiluminescence technology to construct a novel thrombin chemiluminescent aptasensor.The detection range was 5.0×10-15–2.5×10-10mol/L,and the detection limit was 1.5×10-15 mol/L?3??.The aptasensor was successfully used for thrombin detection in serum samples.In the third part,a novel chemiluminescent aptasensor for dopamine detection was constructed,in which magnetic mesoporous silica/graphene oxide?Fe3O4·mSiO2·nSiO2/GO?was synthesized and its surface was modified with dopamine aptamer?D-Apt?to obtain Fe3O4·mSiO2·nSiO2/GO/D-Apt with high specificity for dopamine molecules,and the complementary single-stranded DNA-modified gold nanoparticles?AuNPs@ssDNA?was regarded as catalyst.Therefore,the aptasensor showed highly sensitive,selective,accurate and rapid detection of dopamine.Firstly,Fe3O4·mSiO2·nSiO2 was synthesized,and Fe3O4·mSiO2·nSiO2/GO was obtained through the chemical bonding between Fe3O4·mSiO2·nSiO2 and GO.It showed many advantages,such as good biocompatibility,easy magnetic separation,large specific surface area and abundant recognition.Fe3O4·mSiO2·nSiO2/GO was characterized by infrared spectroscopy,X-ray powder diffraction,scanning electron microscopy and transmission electron microscopy,etc.The immobilization and adsorption properties of the composites were studied.The immobilized amount of Fe3O4·mSiO2·nSiO2/GO to D-Apt was 5.3×10-10 mol/mg.The adsorption amount of Fe3O4·mSiO2·nSiO2/GO/D-Apt to AuNPs@ssDNA was 4.5×10-10 mol/mg.Finally,Fe3O4·mSiO2·nSiO2/GO/D-Apt/AuNPs@ssDNA was used for the detection of dopamine with flow injection chemiluminescence teachnology and the novel chemiluminescent aptasensor was constructed.The detection range of the dopamine sensor was 2.5×10-13–2.0×10-9mol/L while detection limit was 3.9×10-14 mol/L?3??.The aptasensor showed strong anti-interference ability and was successfully used for dopamine determination in urine samples.In the fourth part,a novel chemiluminescent aptasensor for sensitive,selective,accurate and rapid adenosine detection was constructed,in which magnetic?-cyclodextrin/graphene oxide?Fe3O4@?-CD/GO?was synthesized,adenine aptamer?A-Apt?was immobilized on the surface to obtain Fe3O4@?-CD/GO/A-Apt with high specificity for molecules,and complementary single-stranded DNA modified carbon quantum dot?CQDs@ssDNA?was as a catalyst in chemiluminescent system.Firstly,Fe3O4@?-CD was synthesized and Fe3O4@?-CD/GO was prepared by the reaction between Fe3O4@?-CD and GO.The composites had advantages of good biocompatibility,easy separation,large specific surface area and so on,which provided rich immobilization sites to A-Apt.The synthesized composites were characterized by infrared spectroscopy,X-ray powder diffraction,scanning/transmission electron microscopy.The immobilization and adsorption properties of the composites were researched.The immobilized amount of Fe3O4@?-CD/GO to A-Apt was5.3×10-10 mol/mg and the adsorption amount of Fe3O4@?-CD/GO/A-Apt to CQDs@ssDNA was 4.5×10-10 mol/mg.Finally,Fe3O4@?-CD/GO/A-Apt/CQDs@ssDNA was used for flow injection chemiluminescence detection of adenosine and the chemiluminescent aptasensor was proposed.The detection range of the adenosine sensor was 5.0×10-13–5.0×10-9 mol/L and the detection limit was 2.1×10-13 mol/L?3??.The anti-jamming capability of the aptasensor was researched and it was used for adenosine determination in urine samples with satisfactory results. |
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