High-efficiency fluorescent coordination polymer nanoparticles co-doped with Ce³⁺/Tb³⁺ ions for curcumin detection

Curcumin (Cur) possesses diverse biological and pharmacologic effects. It is widely used as a food additive and therapeutic medicine. A study to determine a sensitive detection method for Cur is necessary and meaningful. In this work, double rare earth ions co-doped fluorescent coordination polymer nanoparticles (CPNPs) were developed for the Cur detection. The CPNPs were synthesized by using adenosine monophosphate (AMP) as bridge ligands via coordination self-assembly with Ce³⁺ and Tb³⁺. The AMP-Ce/Tb CPNPs exhibited the characteristic green fluorescence of Tb³⁺ and had high luminescence efficiency. Under the optimal conditions, the fluorescence intensity of AMP-Ce/Tb CPNPs could be significantly quenched by Cur. The fluorescence quenching extent at λ_ex/λ_em of 300 nm/544 nm showed a good linear relationship with the Cur concentration in the range of 10 to 1000 nM. The detection limit was as low as 8.0 nM (S/N = 3). This method was successfully applied to the determination of Cur in real samples with satisfactory results. The luminescence mechanism of AMP-Ce/Tb CPNPs and the fluorescence quenching mechanism of the CPNPs by Cur were both examined.