Fluorescent copper conjugated curcumin cysteine nanoprobe for selective determination of Fe³⁺ and G-quadruplex DNA

The synthesis of fluorescent copper-curcumin-cysteine (Cu-CC) as a sensing platform is reported. The synthesized probe has been confirmed by UV-visible spectroscopy, FT-IR, XRD, SEM, and TEM characterization techniques, respectively. The mechanistic aspects of selective sensing of Fe³⁺ and detection of different G-quadruplex DNA have been illustrated based on the "turn-off-on" concept of a regeneratable fluorescence sensing probe at λ_ex 450 nm. Interestingly, we have noticed a high selectivity to Fe³⁺ ion by the developed Cu-CC sensing probe in comparison with other metal ions. Furthermore, the restoration of fluorescence of the sensing probe in the presence of different DNA sequences is illustrating a cost-effective, convenient, and reliable detection methodology of DNA detection. It is highly sensitive for the determination of Pu27, promoter c-MYC quadruplex DNA in a wide linear range of 100-700 nM having a detection limit of 13.1 nM (RSD: 0.15%) and sensitivity of 37.2 cps/nM. Whereas, the Pu18 and H-telo telomeric DNA sequences are showing a narrow linear range, i.e., 10 nM-200 nM and 10 nM-180 nM, respectively. The real-world sample analysis performance of the regeneratable sensing probe for Pu27 DNA detection in fresh human blood serum samples is showing a satisfactory result.