3D Blockage Mapping for Identifying Familial Point Mutations in Single Amyloid-β Peptides with a Nanopore.

Accurate discrimination of amyloid-β (Aβ) peptides containing familial point mutations would advance the knowledge of their roles in early-onset Alzheimer's disease. Herein, we simultaneously identified the mutant A21G, E22G, E22Q, and the wild-type (WT) Aβ 18-26 peptides with aerolysin nanopore using a 3D blockage mapping strategy. The standard deviation of current blockade fluctuations (σ b ) was proposed as a new supplement to current blockage (I b /I 0 ) and duration time (t D ) to profile the blockage characteristics of single molecules. Although the WT and A21G Aβ 18-26 are indistinguishable in a traditional I b /I 0 -t D 2D description, ∼87 % of the blockade events can be accurately classified with half reduction of false identification using a combination of I b /I 0 , t D, and σ b . This work offers an easy and reliable strategy to promote nanopore sensitivity of peptide mutants, leading to a more precise analysis of pathogenic mutations for developing effective diagnosis and treatment.