An ultrasensitive chemiluminescence aptasensor for thrombin detection based on iron porphyrin catalyzing luminescence desorbed from chitosan modified magnetic oxide graphene composite

In this work, an ultrasensitive chemiluminescence (CL) aptasensor was prepared for thrombin detection based on iron porphyrin catalyzing luminol- hydrogen peroxide luminescence under alkaline conditions, and iron porphyrin was desorbed from chitosan modified magnetic oxide graphene composite (CS@Fe3O4@GO). Firstly, CS@Fe3O4@GO was prepared. CS@Fe3O4@GO has advantages of the good biocompatibility and positively charged on its surface of CS, the large specific surface area of GO and the easy separation characteristics of Fe3O4. GO, Fe3O4 and CS@Fe3O4@GO were confirmed by transmission electron microscopy (TEM), scanning electron microscope (SEM), fourier transform infrared (FTIR) and X-ray powder diffraction (XRD). Then, thrombin aptamer (T-Apt) and hemin (HM, an iron porphyrin) were sequentially modified on the surface of CS@Fe3O4@GO to form CS@Fe3O4@GO@T-Apt@HM. The immobilization properties of CS@Fe3O4@GO to T Apt and adsorption properties of CS@Fe3O4@GO@T-Apt to HM were sequentially researched through the curves of kinetics and the curves of thermodynamics. When thrombin existed in solutions, HM was desorbed from the surface of CS@Fe3O4@GO@T-Apt@HM owing to the strong specific recognition ability between thrombin and T-Apt, causing the changes of CL signal. Under optimized CL conditions, thrombin could be measured with the linear concentration range of 5.0 x10(-15)-2.5x10(-1) mol/L. The detection limit was 1.5x10(-15) mol/L (38) while the relative standard deviation (RSD) was 3.2%. Finally, the CS@Fe3O4@GO@TApt@HM-CL aptasensor was used for the determination of thrombin in practical serum samples and recoveries ranged from 95% to 103%. Those satisfactory results revealed potential application of the CS@Fe3O4@GO@TApt@HM-CL aptasensor for thrombin detection in monitoring and diagnosis of human blood diseases.