Luxuriant Foliage: High-Sensitivity detection of saxitoxin using an enzyme-assisted double-cycling amplification SERS aptamer sensor.

BACKGROUND: Saxitoxin (STX), one of the most toxic marine toxins known, poses severe risks to marine ecosystems and human health through contaminated seafood. Effective monitoring of STX is critical for early red tide warnings, marine conservation, and food safety. However, existing detection methods often lack sufficient sensitivity or require complex protocols, limiting their practicality for rapid on-site analysis. Therefore, there is a pressing need for a reliable and user-friendly strategy to detect trace levels of STX in the marine environment and to improve the accuracy of these measurements.

RESULTS: This study designed an enzyme-assisted double-cycling amplification surface-enhanced Raman scattering (SERS) aptamer sensor for specific and sensitive detection of STX. With the introduction of Nb.BbvCI and Klenow fragment polymerase (KFP), both the target and its aptamer complementary strand achieved double cycling in the system. Meanwhile, the released DNA fragments triggered hybridization chain reaction (HCR), generating a dendritic network for Raman-enhanced detection of STX. All the results showed that the double-cycling amplification SERS aptamer sensor had good recovery rate and high accuracy through enzyme-assisted recycling of the target and its aptamer, and could be used for STX detection in real samples. It is worth noting that the limit of detection (LOD) was calculated to be 1.15 pM according to the 3σ rule, and it has good repeatability when detecting STX.

SIGNIFICANCE: The enzyme-assisted double-cycling amplification strategy is simple to operate and convenient to separate, improving the sensitivity and selectivity of STX detection, it holds great potential in the field of detecting red tide toxins. Additionally, the strategy's modular design could be adapted to detect other toxins, broadening its impact in environmental and food safety fields.