AIE-dots of amphiphilic oligostyrylbenzenes: Encapsulation and release monitored via FRET

Abstract

Aggregation-induced emission (AIE) is a phenomenon that has attracted interest in the field of fluorescent compounds in recent years which lies in the fact that compounds can emit light when aggregated or in the solid state. Although the initial interest in these compounds was centred on the development of OLEDs, recently, other fields of application such as biological and/or therapeutic are being considered. This requires the design of compounds that self-assemble and form fluorescent nanoparticles. These nanoparticles are called AIEdots, due to their similarity to other fluorescent nanoparticles such as Quatumdots or Carbondots. Here we present amphiphilic structures based on oligo-styrylbenzene and oligoethyleneoxide, capable of self-assembling to form micelles. In addition, the polar character of these chromophores has allowed us to extensively study the optical properties of the compounds in unusual solvents for fluorescence studies such as ethanol, cyclohexanol, or water. Then, their AIE properties have been evaluated when forming aggregates with solvent-non-solvent mixtures, and the self-assembly properties have been studied, described, and characterized. Finally, and taking advantage of the ability of micelles to encapsulate more polar compounds, we demonstrated with a reference compound such as Nile Red, that AIEdots can encapsulate molecules in their interior and that there is an energy transfer from the AIEdot to the encapsulated Nile Red. Also, due to the optical properties of both compounds, it is possible to establish a preliminary release profile of the AIEdots.