Fabrication Of Electrochemiluminescence Aptasensor By New Sulfide Composites And Its Application

Preparation, characterization and application of nanomaterials have been attracted many interests. In the field of life science, the analysis and detection of living matter, the diagnoses and treatment of disease, all these lie largely on the application of new, functional and modifiable materials. Aptamer is single-strain DNA or RNA which evolved by an iterative selection method called systematic evolution of ligands by exponential enrichment (SELEX). Owing to its many merits, such as high affinity and specificity, large extent of target binding, simple synthesis, good stability, aptamer have received considerable attention in recent years. Electrochemiluminescence (ECL) has been as an effect detecti-on method due to its advantages such as high sensitivity, wide linear range, high luminous efficiency and simplified setup and so on. Combines the high sensitivity of ECL, superior ECL performance of sulfide composites, high affinity of aptamer and good conductivity, biocompatibility of AuNPs the ECL aptasensors were fabricated for detection of proteins in this work. The aptasensors have been applied to detection of proteins in biosamples and satisfactory results were obtained. The main investigations are as follows:1. Based on the layered structure of molybdenum disulfide-graphene (MoS2-GR) nanocomposites and AuNPs, constructed a new label-free ECL aptasensor for the ultrasensitive detection of thrombin. First of all, MoS2-GR nanocomposites are assembled on the surface of glassy carbon electrode (GCE), MoS2-GR has good conductivity can promote the electron transfer and large surface area that can fixed a lot of luminescent reagents Ru(bpy)32+. Having good biocompatibility, AuNPs covered on the electrode can combined thrombin aptamer (Apt) through the Au-S bond, and further enlarge the ECL signal, thus formed the aptasensor. The results demonstrate that this aptasensor has excellent sensitivity, selectivity and stability. The aptasensor has been successfully applied in the determination of thrombin in human plasma samples. The recoveries of thrombin in human plasma samples are between88.6%and105.0%, and the RSD values are no more than3.7%. The protocol could serve as a new tool for protein detection in biochemical analysis. 2. A facile label-free ECL aptasensor, based on the ECL of cadmium sulfide-graphene (CdS-GR) nanocomposites through layer-by-layer was designed for the detection of carcinoembryonic antigen (CEA). The tripetalous structure CdS-GR nanocomposites were prepared via a simple one-step hydrothermal method and characterized using SEM, TEM, XRD and Raman. The prepared nanomaterials possess some excellent properties such as large specific surface area, high ECL intensity, and high stability. The large surface area can enhance the fixture of aptamer that in turn can improve the sensitivity of the aptasensor. The proposed aptasensor has been applied to the determination of CEA in real human serums samples. With advantages such as simple preparation, convenient operation, high sensitivity and good selectivity. The recoveries of CEA in the human serum samples were between85.0%and109.5%, and the RSD values were no more than3.4%. This work paves a novel way for the development of various ECL aptasensor.3. A novel ECL aptasensor based on CdS-MoS2nanocomposites was designed for detection of immunoglobulin E (IgE). The flowerlike CdS-MoS2composites were synthesized through a simple one-pot hydrothermal method. The CdS-MoS2composites were immobilized on glassy carbon electrode surface as ECL emitter attached a complementary DNA (NH2-ssDNA) of IgE. IgE aptamer (T-Apt) with DNAzyme-AuNPs can hybridize with NH2-ssDNA. The DNAzyme could electrocatalyze the reduction of H2O2, the coreactant of CdS-MoS2ECL emission, lead to an obvious ECL quenching. In the presence of IgE, IgE conjugated with DNAzyme-AuNPs-T-Apt and thereafter the conjugations released, which decreased the consumption of H2O2by DNAzyme-AuNPs, produced an increased ECL signal. CdS-MoS2has good ECL performance, and using of DNAzyme can improve sensitivity of the sensor. The prepared aptasensor has been applied to determination of IgE in human serum samples features high sensitivity, good selectivity and stability. The recoveries of IgE are between80.0%and101.8%with the RSD values no more than3.8%, suggesting the great potential applications in biochemical analysis.