Mismatched duplexed aptamer-isothermal amplification-based nucleic acid-nanoflower for fluorescent detection of okadaic acid

Food Chem. 2023 Oct 30:424:136374. doi: 10.1016/j.foodchem.2023.136374. Epub 2023 May 16.

Abstract

We developed a highly sensitive fluorescent assay to detect okadaic acid (OA), a prevalent aquatic toxin posing serious health risks. Our approach uses a mismatched duplexed aptamer (DA) immobilized on streptavidin-conjugated magnetic beads (SMBs) to create a DA@SMB complex. In the presence of OA, the cDNA unwinds, hybridizes with a G-rich segment pre-encoding circular template (CT), and undergoes rolling circle amplification (RCA) to produce G-quadruplexes, which are detected using the fluorescent dye thioflavine T (ThT). The method has a LOD of 3.1 × 10-3 ng/mL, a linear range of 0.1 ∼ 1.0 × 103 ng/mL, and was successfully applied to shellfish samples with spiked recoveries of 85.9% ∼ 102.2% and RSD less than 13%. Furthermore, instrumental analysis confirmed the accuracy and reliability of this rapid detection method. Overall, this work represents a significant advancement in the field of rapid aquatic toxin detection and has important implications for public health and safety.

Keywords: Fluorescent aptasensor; G-quadruplex; Marine toxin; Okadaic acid; Okadaic acid (PubChem CID446512); Rolling circle amplification; Thioflavine T (PubChem CID16953).

MeSH terms

  • Aptamers, Nucleotide* / genetics
  • Biosensing Techniques* / methods
  • Fluorescent Dyes
  • Limit of Detection
  • Nucleic Acid Amplification Techniques / methods
  • Nucleic Acids*
  • Okadaic Acid
  • Oligonucleotides
  • Reproducibility of Results

Substances

  • Nucleic Acids
  • Okadaic Acid
  • Oligonucleotides
  • Fluorescent Dyes
  • Aptamers, Nucleotide