ИСТИНА

DiI (1,1’-dioctadecyl-3,3,3’,3’-tetramethylindocarbocyanine perchlorate) is a carbocyanine dye widely used in cell biology due to its low toxicity and the tendency to give highly stable cell labeling. This dye labels cell membranes by inserting its two long (C18 carbon) hydrocarbon chains into the lipid bilayers. In the present study, DiI was used for fluorescent labeling of the poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs). The objective of the study was to evaluate the fluorescent properties of the PLGA nanoparticles with encapsulated DiI and to determine its optimal content. The PLGA NPs were prepared by a high pressure homogenization – solvent evaporation technique. The dye-topolymer ratios were in the range of 0.4 to 25 μg/mg. Bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) was added for better DiI encapsulation. Particle size and zeta potential were measured using a Zetasizer (Malvern Instruments, U.K.). The surface morphology and the size of the particles were confirmed by scanning electron microscopy (microscope JSM-6510 LV, Jeol Ltd., Peabody, MA). Amount of PLGA in the preparation was assessed using capillary electrophoresis (Kapel-105M, Lumex, RF); DiI assay was performed by spectrophotometry (UV-1800, SHIMADZU, Japan) and spectrofluorimetry (RF-6000, Shimadzu, Japan). Fluorescence brightness was calculated as: brightness  , where φ – quantum yield, ε – molar extinction coefficient, N – number of dye molecules per 1 nanoparticle.