Abstract
Ochratoxin A (OTA) represents a naturally occurring mycotoxin with a serious hazard to the health of individuals because of carcinogenic and teratogenic properties. To date, various analytical methods have been developed for the detection of OTA, among which aptamer-based electrochemical sensing has attracted significant attention due to its rapidity and high sensitivity. As a subtype of aptamer-based electrochemical sensing, ratiometric electrochemical methods further exhibit excellent anti-interference capability. However, their analytical performance remains limited by the labor-intensive and resource-consuming modification of electroactive signal molecules, as well as the restricted specific surface area of the electrodes. Here, we develop a ratiometric electrochemical aptasensor functionalized with Bidens pilosa-like DNA-gold structures and copper-based metal-organic frameworks (Cu-MOFs) for OTA detection. Cu-MOFs served as a substrate for electrode modification, performing two key roles: 1) providing a large surface area for aptamer immobilization, and 2) generating one current signal. Double-stranded DNA-gold nanoparticles (dsDNA-AuNPs) were assembled through Au-S bonding. The dsDNA-AuNPs conjugates, structurally resembling Bidens pilosa, could load more dsDNA and connect to Cu-MOFs via π-π stacking. When OTA was present, the aptamer-OTA complex was stripped from the aptasensor, reducing the amount of Fc-Apt, thus decreasing the corresponding Fc current (IFc). Simultaneously, the decreased interfacial resistance caused an increase in the Cu-MOF current (ICu), providing the decreased IFc/ICu ratio as a quantitative indicator. The aptasensor exhibited a linear detection range from 0.01ngmL-1 to 300ngmL-1, with a detection limit of 0.002ngmL-1 for OTA. The developed electrochemical ratiometric aptasensor demonstrated high reproducibility and stability, and it was successfully applied to maize sample analysis, underscoring its practical applicability. Moreover, it provides a promising strategy for the application of Cu-MOF-based electrochemical aptasensors. Furthermore, the modification procedures of the developed aptasensor were simplified by preparing dsDNA-AuNPs in solution rather than assembling them step-by-step on the electrode surface.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have