Trace Aflatoxins Extraction in Pistachio, Maize and Rice Based on β-Cyclodextrin-Doped Cu-Carboxylated Graphene Oxide Nanocomposite

Abstract

Aflatoxins remain among the most challenging food contaminants to monitor due to their structural diversity, low abundance, and the chemical complexity of cereal- and nut-based matrices. In this study, a multifunctional Cu/β-cyclodextrin@carboxylated graphene oxide (Cu/β-CD@CGO) nanocomposite was synthesized through a green, two-step procedure and employed as a high-affinity nanosorbent for trace extraction of AFB₁, AFB₂, AFG₁, and AFG₂. The architecture integrates three complementary components: β-cyclodextrin for inclusion-driven molecular recognition, copper nanoparticles that establish coordination interactions with lactone-bearing aflatoxins, and CGO nanosheets that supply extensive π-rich surfaces and abundant carboxyl functionalities. Comprehensive characterization (FTIR, Raman, XPS, SEM, EDX-mapping, and HRTEM) confirmed the formation of a uniform, porous hybrid network. Under optimized d-SPE conditions, the nanocomposite enabled quantitative recovery (92.0-108.5%) of aflatoxins from pistachio, maize, and rice extracts while achieving sub-ng kg^-1 detection limits and excellent reproducibility. The results demonstrate that the Cu/β-CD@CGO platform provides a robust, selective, and sustainable alternative to conventional immunoaffinity or polymeric sorbents, offering strong potential for routine surveillance of aflatoxins in complex food systems.