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Covalent organic framework-based aptananozyme (COF@NH2 apt-AFM1): A novel platform for colorimetric and fluorescent
Iram Naz1, Seham J F Alanazi2, Akhtar Hayat3
1Department of Chemistry, Govt. College Women University, Arfa Kareem Road, Faisalabad 38000, Pakistan; Interdisciplinary Research Center in Biomedical Materials (IRCBM), COMSATS University Islamabad, Lahore Campus, 1.5 Km Defense Road, off Raiwind Road, Lahore, Punjab 54000, Pakistan.
Abstract:
Nanozymes are valued for their cost-effectiveness and robustness but are often limited their lack of specificity. This study introduces a Covalent Organic Framework-based aptananozyme (COF@NH2 apt- AFM1) for label-free, dual-mode detection of Aflatoxin M1 (AFM1) in milk. The aptananozyme enables colorimetric detection by catalyzing the oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) and provides fluorescent signals for sensitive AFM1 identification. The dual-mode aptasensor achieves remarkable limits of detection (LOD) 7 pg/mL (colorimetric) and 5 pg/mL (fluorescent). Validation with High Performance Liquid Chromatography (HPLC) on milk samples showed recovery 97-99 % (colorimetric) and 96-101 % (fluorescent), confirming its stability and repeatability. Characterization of the COF and aptananozyme involved Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), UV-visible absorption spectroscopy, Fluorescence emission spectroscopy, Field emission scanning electron microscopy (FE-SEM), optical microscope images and Dynamic light scattering (DLS). This sensor demonstrates high sensitivity, accuracy and broader application potential.
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