From seeds to sensors: Bixa orellana derived carbon quantum dots for efficient dual way detection of Cu(II) ion and antioxidant efficacy

This study explores a green hydrothermal process for synthesizing carbon quantum dots (CQD) from Bixa orellana seeds, for the dual-mode detection of Cu(II) ions. The facile-prepared CQD was morphologically and optically characterized using various techniques. The CQD exhibited a quasi-spherical shape (3.50 nm) and excitationdependent photoluminescence with a quantum yield of 10.88 %. The amorphous structure was confirmed via XRD, with Raman spectrum showing weak graphitic features. Cu(II) detection was achieved through fluorescence quenching and electrochemical current enhancement in an extensive linear range, offering low detection limits of 12.82 nM and 6.35 nM, respectively. These findings highlight the potential of Bixa orellana seed derived CQD for sensitive environmental monitoring, while also demonstrating a sustainable approach to repurposing dry plant seeds by eco-friendly nanomaterial development. Additionally, the antioxidant properties of the CQD were also evaluated.