Polyelectrolyte multilayer capsules with quantum dots for biomedical applications

The aim of this work was to encapsulate the CdTe quantum dots within the nanocapsules that were prepared by the layer-by-layer adsorption of polyelectrolytes. Two different polyelectrolyte pairs were used as components of the shell: synthetic polycation poly(allyamine hydrochloride) (PAH), together with anionic poly(sodium styrene sulfonate) (PSS), and biocompatible cationic poly-l-lysine hydrobromide in a pair with biocompatible anionic poly-d-glutamic acid sodium salt (PGA). The saturation method was used for formation of consecutive layers on the initial CdTe–polyelectrolyte complex. A growth of the polyelectrolyte shell was followed with the electrophoretic mobility and light scattering measurements, in order to determine the zeta potential and the size of capsules, respectively. The fluorescent spectra of the quantum dots, which are embedded within the capsules, were characterized with spectrofluorimeter. Later on, they were deposited on a negatively charged mica surface and studied by the means of atomic force microscopy (AFM). In order to estimate the cytotoxicity of capsules, their influence on the B-lymphoblastoid cell line proliferation and on unspecific binding to the P-blood mononuclear cells was examined using the flow cytometry.