A facile biosensor for Aβ

Amyloid β peptide oligomeFrs (AβOs) have been proved to be crucial biomarkers of Alzheimer's disease (AD). To explore an applicable method for the determination of AβOs is significant for the early AD diagnosis. Prussian blue nanoparticles (PBNPs), as one excellent nanomaterials, have the advantages of good stability, favorable biocompatibility, low cost, easy preparation and controllable shape. PBNPs was found to be of the fluorescence quenching ability to fluorophores, and the adsorption of DNA onto PBNPs surface occurred via the binding of phosphate skeleton in DNA to Fe2+/Fe3+ in PBNPs. On basis of this, carboxyl fluorescein (FAM) modified Aβ40O-targeting aptamer (FAM-AptAβ) was adsorbed onto PBNPs. And FAM-AptAβ@PBNPs-based fluorescent aptasensor for the determination of Aβ40O was developed. Upon incubating FAM-AptAβ@PBNPs with Aβ40O, the fluorescence intensity of the FAM-AptAβ@PBNPs obviously increased comparing to the initial fluorescence intensity of the FAM-AptAβ@PBNPs. The changes in the fluorescence intensity of the FAM-AptAβ@PBNPs were linear with the Aβ40O concentrations ranging from 1.00 nM to 100 nM. Moreover, AD patients and healthy persons can be distinguished using this method to determine Aβ40O concentrations in human cerebrospinal fluid samples from AD patients and healthy persons. It demonstrates that this PBNPs-based aptasensor is not only simple and cost-effective, but also sensitive, selective and more applicable. This fluorescent sensing strategy is promising for the development of aptasensor in clinical fields.