Determination of aflatoxin M1 using an aptamer-based biosensor immobilized on the surface of dendritic fibrous nano-silica functionalized by amine groups.

Aflatoxins are potential food pollutants produced by fungi. Among them, aflatoxin M1 (AF M1) is the most toxic. A great deal of concern is associated with AF M1 toxicity. Aflatoxins are potential food pollutants produced by fungi. Among them, aflatoxin M1 (AF M1) is the most toxic. A great deal of concern is associated with AF M1 toxicity. In the present work, a novel aptamer-based bioassay was developed for monitoring aflatoxin M1 (AF M1) in real samples. A chitosan-modified graphene quantum dot (GQD-CS) nanocomposite was used as a biocompatible substrate coated with dendritic fibrous nanosilica functionalized by amine groups (KCC-1-NH-Tb). Accordingly, an innovative biocompatible polymeric matrix was prepared for aptamer immobilization. The unique oligonucleotide of AF M1 (5'-ATC CGT CAC ACC TGC TCT GAC GCT GGG GTC GAC CCG GAG AAA TGC ATT CCC CTG TGG TGT TGG CTC CCG TAT) labelled by toluidine blue was immobilized on the engineered interface. Hence, a novel aptamer-based bioassay was formed for the highly sensitive quantitation of AF M1 using cyclic voltammetry and differential pulse voltammetry techniques. The structure and morphology of GQDs-CS/KCC-1-NH-Tb was investigated by Fourier transform infrared spectroscopy, X-ray diffraction, atomic force and scanning electron microscopy and energy-dispersive X-ray spectroscopy. The toxicity tests, which were performed by MTT assays, revealed the biocompatible nature of KCC-1-NH-Tb. The engineered aptasensor demonstrated excellent behaviour toward the determination of AF M1, where the low limit of quantification was 10 fM. The proposed aptamer-based bioassay was successfully used for the monitoring of AF M1 in milk samples. This work provides a beneficial reference for the sensing of other toxins in food/pharmaceutical assays and veterinary medicine.