Analysis of Phase Behavior and Rheological Properties of Supramolecular Systems Based on a Surfactant with “Yellow” Carbon Dots

Abstract Lyotropic liquid crystal matrices as universal carriers of hydrophilic and hydrophobic substrates are promising for biomedicine as a means of drug delivery. In recent years, intensive efforts have focused on their functionalization with various dopants, specifically carbon dots with luminescent properties, thereby enabling the creation of hybrid systems with biosensing capabilities for theranostics. For the targeted use of such systems as platforms for theranostics, information is needed on the conditions for controlling their phase states. This study presents phase diagrams of polyfunctional hybrid systems based on the nonionic surfactant tetraethylene glycol monododecyl ether, decanol, and an aqueous solution containing “yellow” carbon dots as a phosphor. The temperature and concentration parameters for controlling the supramolecular structure of the resulting hybrid media have been established. The viscosity and rheological properties of hybrid media in the regions of formation of lyomesophases and gels have been studied. Analysis of rheological curves has shown that the viscosity of lyotropic liquid crystalline phases in both types of systems—hybrids with “yellow” carbon dots and initial systems based on oligoethylene oxide—exceeds the viscosity of gel-like media. The behavior of hybrid systems C12EO4/(H2O+yCD)/dec has been analyzed within the framework of microrheological Newton, Bingham, Ostwald, Casson, and Herschel–Bulkley models. It has been revealed that the flow of hybrid lyotropic liquid crystals obeys the Casson model, and that of gel-like systems follows the Ostwald model. The work shows ways to regulate the composition and viscosity characteristics of such media, which opens opportunities for the development of effective nanosystems for drug delivery and their further use in bioimaging, theranostics, and targeting of various biosubstrates.