A label-free reusable aptasensor for Alzheimer’s disease

Abstract

To early effectively detect amyloid-beta (Aβ) oligomers, a label-free reusable aptasensor was designed. This aptasensor based on a luminescent nanoscale lanthanum-based metal-organic framework (L-MOF)-armored single-stranded DNA antibody (MOF-armored-anti-DNA antibody) as signal tags and aptamer bound to magnetic beads (Apt-MB) as capture probe. The reusable aptasensor combines signal tag and capture probe with antigen-antibody interaction. When the reusable aptasensor is formed, the strong fluorescence intensity of L-MOF will "turn off" by photo-induced electron transfer from excited states to an unfilled d shell of iron cations on the nanoparticle surface. Upon the presence of Aβ oligomersin serum samples, they can be especially distinguished with theAβ oligomers aptamer in capture probes and then signal tags are released into the solution for developing thefluorescence aptasensor under excitation/emission 365nm/430nm. Meanwhile, theaptamer was recovered from the complex of Aβ oligomers/Apt-MB by heat treatment. When the temperature returns to room temperature, therecovered aptamer in the capture probe can once again bound to the MOF-armored-anti-DNA antibody for reuse. The label-free reusable aptasensor system detection has high sensitivity and selectivity toward Aβ oligomers (LOD = 0.4pg/mL) and anexcellent linear range (0.001-100ng/mL). This strategy is a fruitful step for the development of reusable aptasensor and may turn on new avenues for the applications of Aβ oligomer detection in clinical diagnosis.Graphical abstract.