Non-ionic surfactants have raised a considerable interest for solubilization, encapsulation, permeabilization and controlled release of various compounds due to their unique physicochemical properties. Nevertheless, it is still challenging to create convenient self-assembled multifunctional materials with high solubilization and encapsulation capacities by preserving their advanced capabilities to protect loaded cargos without altering their characteristics. In this work, we present an extended concept of micellar clusters (MCs) formation based on partial entrapment and stabilization of chelate ligands by hydrophobic forces found on the non-ionic surfactant micelle interface of the Triton-X family (TX-100/TX-114), followed by subsequent complexation of the preformed structures either by metal ions or a supporting chelator. The formation aspects, inner structure and the role of external factors such as the addition of competitive ligands have been extensively studied. MCs loaded by hydrophobic fluorescent compounds with high encapsulation efficiency demonstrate an excellent optical response in aqueous media without crystallization as well as sufficient increase in solubility of toxic hydrophobic compounds such as bilirubin (>50 times compared to pure surfactants). Furthermore, Triton-X-based MCs provide a unique feature of selective permeability to hydrophilic ligand-switching proteins such as UnaG and BSA demonstrating bright "turn-on" fluorescence signal either inside the cluster or on its interface via complexation. The proposed strategies allowed us to successfully encapsulate and visualize a newly synthesized, highly hydrophobic anticancer PTR-58-CLB-CAMP peptide drug, while MCs loaded by the drug exhibit a considerable antitumor activity against HeLa cells.
Keywords: Anticancer drugs; Encapsulation; Fluorescence enhancement; Micellar clusters; Self-assembly; Surfactants; Triton-X.
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