Green nitrogen and sulfur co-doped carbon dots derived from eggshell as a high performance aptasensing interface for...

The concentration monitoring of the banned metronidazole (MTZ) drug as the alarmed carcinogenic agent in human biofluids is medically essential. The electrochemical aptasensors are good candidates to overcome some presence challenges in the detection process.

Herein, an electrochemical aptasensor based on nitrogen and sulfur co-doped carbon dots (NcS-CDs) has been developed for the high-sensitive detection of MTZ for the first time. The N-S-CDs have been synthesized from eggshell waste and the aptasensing interface has been fabricated by the attachment of the N-S-CDs to the glassy carbon electrode surface to fix the high-density aptamer (Apt) sequences via silver nanocubes (AgNCs). The electrochemical signal of the redox probe has changed by trapping the MTZ on the Apt's arm onto the aptasensing interface. The molecular dynamic simulation visually confirmed how the Apt binds to the MTZ. The resulting aptasensor measured MTZ in a wide linear range value from 1 fM to 901.4 nM with a limit of detection value of 333.3 aM and high selectivity regarding some possible interferences.

The results reveal that the novel aptasensor has high potential applicability for the non-invasive monitoring of MTZ in human saliva and urine, and also, the tap water analysis. Utilizing waste-derived nanomaterials for the aptasensor fabrication not only less the fabrication costs but also guarantees the greenness of the applied methodology according to sustainable chemistry principles as evaluated by two international index metrics.