Sustainable and Sensitive Aptasensor for Detection of Cylindrospermopsin Using Conductive Polymer PEDOT:PSS

Abstract

Cyanotoxins, produced by cyanobacteria, pose serious genotoxic, hepatotoxic, nephrotoxic, and neurotoxic risks in aquatic ecosystems. Among these, cylindrospermopsin (CYN), known for its high water solubility and bioaccumulation potential, significantly threatens public health and environmental safety. Anthropogenic eutrophication and climate-induced environmental changes have significantly intensified the frequency and severity of cyanobacterial blooms, thereby underscoring the necessity for rapid and reliable detection strategies for CYN. Aptamer-based electrochemical biosensors offer selective and sensitive detection, with performance reliant on effective aptamer immobilization and electrode conductivity. Pencil graphite electrodes (PGEs) provide a novel, low-cost, conductive, and easily modifiable alternative to commonly used noble-metal-based platforms, such as gold nanoparticles. This study reports the fabrication of an electrochemical aptasensor by modifying PGE with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) to increase surface area and enable effective immobilization of the CYN-specific aptamer (cynApt). Electrochemical characterization of the PGE/PEDOT:PSS/cynApt biosensor platform was conducted using cyclic voltammetry (CV), while CYN detection was performed using differential pulse voltammetry (DPV). The developed PGE/PEDOT:PSS/cynApt sensor achieved a limit of detection of 0.154 ng mL⁻¹ in deionized water and 0.224 ng mL⁻¹ in lake water, with a linear response range of 0.25 to 2.5 ng mL⁻¹. The sensor also demonstrated high selectivity against other cyanotoxins, such as okadaic acid and saxitoxin (STX). These results highlight the potential of the proposed aptasensor for sensitive and selective cylindrospermopsin (CYN) detection in environmental monitoring applications.