BACKGROUND

Lentinan medicament from Lentinus edodes has been considered as natural medicinal products with minimal side effects for cancer therapy, but Lentinus edodes are easily polluted by nonbiodegradable heavy metals, especially silver ion (Ag). Therefore, it is highly desirable to monitor Ag  pollution in Lentinus edodes considering their adverse impact on lentinan medicament. Electrochemical sensor isn't affected from the interference of matrix turbidity and color, and offers a powerful means for determination of variant analytes. As for electrochemical sensing toward Ag, there is a great need to design efficient signal probes for specific recognition and signal generation.

RESULTS

We present an appropriate electrochemical aptasensor for Ag  assay based on biomimetic catalysis of porphyrin-encapsulated MOF (PorMOF) and allosteric switch of C-rich DNA. Thanks to the excellent biocompatibility, PorMOFs as nanozyme are used to design signal probes by loading duplex-like DNA scaffold. Owing to the specific recognition of Ag toward cytosine (C) base-rich DNA, PorMOF at the distal end was close to the underlying electrode via C-Ag-C formation, leading to an enhanced current of catalytic hydroxylamine oxidation for signal generation. Using the positive correlation between current response and Ag level, the electrochemical system provides a promising means for on-line monitoring of Ag in Lentinus edodes with recoveries from 92.8% to 106.4% and relative standard deviation from 3.98% to 8.24%, verifying the applicability of the electrochemical aptasensor toward Ag in Lentinus edodes.

SIGNIFICANCE AND NOVELTY

With merits of portability, simple operation, and rapid response, the electrochemical pattern offers a useful solution for on-line monitoring of Ag in Lentinus edodes. By altering the DNA sequence, the proposed aptasensor provides a powerful way for monitoring other heavy metals, capable of protecting medicament production from heavy metal pollution.