A physicochemical investigation of the complex formation by β-cyclodextrin with Triton X-100 and Triton X-114 and their aggregation behaviour in aqueous solution: an experimental approach

Abstract

The complexation behavior and binding affinity of Triton X-100 (TX-100) and Triton X-114 (TX-114) with β-cyclodextrin (β-CD) were extensively studied in an aqueous medium using a comprehensive suite of experimental techniques. These techniques allowed for the evaluation of key physicochemical parameters, including critical micelle concentration (cmc), aggregation number (N_agg), Stern–Volmer constant, and particle size distribution. These metrics were instrumental in understanding the underlying mechanism of the host–guest interaction between β-CD and Triton-X. Dynamic light scattering (DLS) data provided strong evidence for the formation of inclusion complexes, demonstrating significant hydrophobic interactions between the hydrophobic regions of Triton-X and the cavity of β-CD. The disruption of micellar structures, caused by β-CD encapsulating the hydrophobic moieties of the surfactants, was clearly observed. This process also resulted in an increased CMC, further underscoring the impact of β-CD on the aggregation behavior of the surfactants. To quantify the interaction, the Benesi–Hildebrand method was utilized to determine the stoichiometry and binding constants of the β-CD/Triton-X complexes. The results confirmed a well-defined 1 : 1 binding mode, indicating the precise incorporation of the surfactant's hydrophobic tails into the β-CD cavity while leaving the hydrophilic regions exposed to the aqueous environment. This selective binding mechanism alters the thermodynamics of micellization and disrupts the native micellar equilibrium of the surfactant systems. This systematic and comparative investigation is among the few studies that thoroughly examine the interactions between Triton-X surfactants and β-CD. Such research not only enhances our understanding of these complexes, but also reveals their significant potential for various applications. In drug delivery, for example, β-CD/Triton-X complexes can improve the solubility, stability, and bioavailability of hydrophobic drugs. In supramolecular chemistry, these complexes serve as model systems for studying host–guest interactions and self-assembly processes. Furthermore, their ability to modulate surfactant behaviour opens avenues for their use in material science, cosmetics, and industrial formulations, where precise control over micelle formation and aggregation is essential. This study underscores the versatility and utility of β-CD in interacting with non-ionic surfactants, offering insights that can be applied to other amphiphilic systems and paving the way for innovative applications in diverse fields.