Nanopore based detection of Bacillus thuringiensis HD-73 spores using aptamers and versatile DNA hairpins

Abstract

A versatile nanopore sensing platform to detect any aptamer using nanopores by designing DNA hairpins that are complementary to the aptamer is described. This platform can detect the presence of aptamer binding targets regardless of their size, which has been a major hurdle for nanopore detection systems. Moreover, the signal-to-noise ratio is increased by eliminating most of the unwanted substances from the sample via simple sample preparation steps. To detect Bacillus thuringiensis HD-73 spores using this sensing platform, DNA hairpins complementary to the target-specific aptamers were designed, and the hairpins were characterized using alpha-hemolysin nanopores after the reaction of spores and aptamers and subsequent reaction with the complementary DNA hairpins. The platform exhibited a detection limit as low as 1.2 × 10¹ CFU mL⁻¹ and was compatible with a wide range of spore concentrations from 1.2 × 10¹ CFU mL⁻¹ to 1.2 × 10⁶ CFU mL⁻¹ while it is still expandable to higher spore concentrations.