Thrombin aptasensor enabled by Pt nanoparticles-functionalized Co-based metal organic frameworks assisted electrochemical signal amplification

In this work, a Pt nanoparticles-functionalized Co-based metal organic frameworks (PtNPs@Co(II)MOFs@PtNPs) was synthesized and applied in electrochemical aptasensor for thrombin (TB) detection. First, the Co(II)MOFs@PtNPs were prepared via the mixed solvothermal method, which consists of inner Pt nanoparticles (PtNPs) encapsulated by aminofunctionalized Co(II)MOFs materials. Following that, additional PtNPs were adsorbed on the surface of Co(II)MOFs@PtNPs, resulting in the formation of PINPs@Co(II)MOFs@PtNPs nanocomposite. The PtNPs@Co(II)MOFs@PtNPs nanocomposites with a large surface area were implimented as nanocarriers to immobilize a mass of TBA II for the formation of the TBA II bioconjugates that could be captured onto the electrode surface by sandwich-type format. Moreover, the PtNPs@Co(II)MOFs@PtNPs nanocomposites could directly use as redox tags for charge-generating and electron-transporting with the electron transfer from Co(II) to Co(III). Furthermore, in the presence of H2O2, the PtNPs@Co(II)MOF@PtNPs could effectively catalyze H2O2 oxidation with improvement electron transfer of redox probe, resulting in electrochemical signal amplification. Based on the above superior advantages, TB was determined in the concentration range from 0.1 pM to 50 nM with a detection limit of 0.33 fM. Furthermore, the excellent sensitivity and selectivity can be easily established for quantitative analysis of other analytes.