Tuning energy transfer in Sugammadex-Tb³⁺ complex: Towards highly sensitive chemosensor for Sugammadex in pharmaceutical formulation

Sugammadex (SUG), a macrocyclic host molecule, has shown potential for chemosensing applications due to its interaction with the lanthanide ion Tb³⁺. This study aimed to explore the adaptability of this interaction in various environments (solvents and pH) to understand its sensing mechanism. Fluorescence intensity measurements revealed an energy transfer from SUG to Tb³⁺ in the complex upon ligand addition in acetonitrile at pH 6.5. This resulted in a linear increase in fluorescence intensity with increasing ligand concentration, ranging from 5 × 10⁻⁹ to 5 × 10⁻⁵ M. The detection limit was determined to be 4.35 × 10⁻¹² M with high correlation (0.98). This fluorescence enhancement is attributed to Förster resonance energy transfer (FRET) between SUG and Tb³⁺. Interestingly, the interaction displayed dependence on both solvent and pH, suggesting their influence on the formation, stability of the SUG-Tb³⁺ complex, and ligand binding affinity. These findings provide valuable insights for designing chemosensor based on SUG-lanthanide interactions. The observed solvent and pH dependence paves the way for further exploration of these interactions in various fields, highlighting their potential for diverse applications.