Eco-friendly synthesis of Carbon Quantum Dots (CQDs) from hazelnut husk for sensitive Aflatoxin B1 (AFB1) detection

In this study, green fluorescent carbon quantum dots (CQDs) with remarkable stability, water solubility, and biocompatibility were synthesized from hazelnut husk (HH) waste material using a novel approach by the pyrolysis method. The optical properties of the synthesized HH-CQDs were characterized by UV-Vis and fluorescence spectroscopy (PL), while their structural properties were characterized using various techniques, including transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). TEM images revealed that HH-CQDs had a spherical shape with diameters ranging from 2 to 10 nm. The fluorescence quantum yield of these CQDs was measured as 0.04. Furthermore, CQDs were very effective at finding aflatoxin B1 (AFB1) using a fluorescence resonance energy transfer (FRET) mechanism, with a clear fluorescence emission peak seen at 451 nm. The photoluminescent properties of CQDs were evaluated under various pH conditions, showing a blue shift and increased fluorescence intensity at pH 9–10, suggesting their potential use in pH-sensitive sensor applications. This study demonstrates the selective and sensitive detection of AFB1 using HH-CQDs, with a strong linear relationship (R² = 0.9936) between fluorescence intensity and AFB1 concentration in the range of 25–250 ppm, and high accuracy in real food samples, including 81.56 % in corn, 98.64 % in milk, and 95.73 % in peanuts. This eco-friendly and cost-effective synthesis method offers a promising alternative for AFB1 detection in food samples by utilizing waste material to create valuable analytical tools.