Luminescent Nanoparticles of Chitosan–Carrageenan Polyelectrolyte Complex as Promising Multifunctional Vancomycin Delivery Systems

Nanoparticles of a chitosan–κ-carrageenan polyelectrolyte complex containing CdS/ZnS core–shell quantum dots have been obtained and characterized as models of biocompatible luminescent delivery systems for an antibiotic, vancomycin, with an encapsulation efficiency of 95–97%. The quantum dots have been obtained by the colloidal synthesis method and hydrophilized with mercaptopropionic acid. The effect of vancomycin encapsulated in the particles of the polyelectrolyte complex on the luminescent properties of CdS/ZnS quantum dots has been studied. It has been shown that the synthesized quantum dots can be employed as analytical nanosensors for determining vancomycin incorporation into and release from the developed carriers on the basis of quenching their luminescence. The binding of vancomycin to albumin as a model blood protein has been studied and the composition of the complex ([vancomycin] : [albumin] = 1.0 : 2.0) and its stability constant (β_c = 6.0 × 10⁴ M^–1) have been determined. The in vitro analysis of kinetic data on the release of vancomycin from the polymer carriers into albumin and tris-buffer solutions performed within the framework of the Korsmeyer–Peppas mathematical model has shown that the release of the antibiotic is controlled by both diffusion and relaxation of the polymer matrix.