Interaction of Curcumin Nanoparticles with Cu(II) Using Optical Spectroscopy

Abstract

In this study, a simple, sensitive, and cost-effective spectrophotometric method was developed for the determination of dopamine using curcumin nanoparticles (curcumin NPs) in the presence of copper(II) ions. Curcumin, a natural polyphenolic compound, exhibits notable optical properties that were exploited in this method to create a colored complex with copper(II). The addition of dopamine enhances the absorbance intensity of this complex due to specific interactions between dopamine molecules and the curcumin–Cu(II) system.

The experimental conditions were carefully optimized to achieve maximum sensitivity. The optimum conditions included a pH of 8.5, an ammonia buffer volume of 1.5 mL, a Cu(II) concentration of 20 mg·L⁻¹ with 2 mL volume, a reaction time of 40 minutes, and a curcumin NPs volume of 0.7 mL, in a final volume of 10 mL. Under these conditions, the calibration graph for dopamine was linear in the concentration range of 0.5–20 mg·L⁻¹, with a high correlation coefficient (r = 0.9994). The linear regression equation was ΔA = 0.0062 C + 0.0743, where ΔA is the difference in absorbance in the presence and absence of dopamine, and C is the dopamine concentration in mg·L⁻¹.

This method provides a promising approach for dopamine detection with good linearity, sensitivity, and reproducibility. It can potentially be applied in clinical or pharmaceutical settings for dopamine analysis in biological or synthetic samples.