Highly sensitive solid-state nanopore aptasensor based on target-induced strand displacement for okadaic acid detection from shellfish samples

Abstract

Okadaic acid (OA) is a marine toxin that is frequently found in a wide variety of shellfish and can cause major health complications. A sensitive and selective nanopore-based aptasensor for detecting OA in shellfish is presented. The nanosensor, which is based on target-induced strand displacement reactions, is primarily composed of an OA-specific biotinylated truncated aptamer immobilized onto streptavidin-coated magnetic beads and its predesigned complementary signaling probe (cDNA) to form a dsDNA duplex. The aptamer tends to form a more stable OA–aptamer complex in the presence of OA, resulting in the displacement of the signaling probe (cDNA) from the dsDNA duplex. Using the optimal conditions, the nanosensor displayed a broad detection range of 1.0 pg mL⁻¹ to 1.0 × 10² ng mL⁻¹ with a limit of detection of 3.0 × 10⁻² pg mL⁻¹, showing that this method has higher sensitivity than most reported methods in the literature for OA detection and exhibited good selectivity against interfering small molecules. More significantly, the proposed nanosensor showed tremendous potential for OA detection from real samples; it was effectively used on shellfish samples with recoveries ranging from 95.33% to 110.03%. Overall, our findings suggest that the proposed nanosensor can pave the way for the development of high-performance sensing methodologies for marine biotoxins.