Following the Fate of Dye-Containing Liposomes In Vitro

Abstract

<jats:p>The rather limited success of translation from basic research to clinical application has been highlighted as a major issue in the nanomedicine field. To identify the factors influencing the applicability of nanosystems as drug carriers and potential nanomedicine, we focused on following their fate through fluorescence-based assays, namely flow cytometry and imaging. These methods are often used to follow the nanocarrier internalization and targeting; however, the validity of the obtained results strictly depends on how much the nanosystem’s fate can be inferred from the fate of fluorescent dyes. To evaluate the parameters that affect the physicochemical and biological stability of the labeled nanosystems, we studied the versatility of two lipid dyes, TopFluor®-PC and Cy5-DSPE, in conventional liposomes utilizing well-defined in vitro assays. Our results suggest that the dye can affect the major characteristics of the system, such as vesicle size and zeta-potential. However, a nanocarrier can also affect the dye properties. Medium, temperature, time, fluorophore localization and its concentration, as well as their interplay, affect the outcome of tracing experiments. Therefore, an in-depth characterization of the labeled nanosystem should be fundamental to understand the conditions that validate the results within the screening process in optimization of nanocarrier.</jats:p>

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Therapeutic Liposomal Vaccines for Dendritic Cell Activation or Tolerance

“…Furthermore, hydrophilic cargo such as peptide or protein antigens, as well as other chemical components, such as fluorescent lipid dyes loaded onto the surface of liposomes tend to dissociate ( 189 ). Dependent on the nature of the cargo this could lead to undesired bystander effects, deleterious side effects such as anaphylaxis in case of allergen loading, and misinterpretation of molecular results, such as of cellular uptake and intracellular processing ( 189 ). The potential disadvantages carefully need to be assessed in the context of each specific disease setting.…”

Characterization of Liposomes Using Quantitative Phase Microscopy (QPM)

“…Liposomes were prepared following the film hydration method [ 15 ]. Low-pressure rotary evaporation of a methanol solution of SPC and fluorophore N (100:1) was performed using a Büchi rotary evaporator R-124 with vacuum pump V-700 (Büchi Labortechnik, Flawil, Switzerland).…”

“…Thereof, fluorescent-based techniques are powerful tools to directly establish physicochemical–behavioral relationships. However, the addition of an external component to nanosystems may affect the individual properties of both the nanosystem and the fluorophore [ 15 ]. For instance, fluorophores are known to alter nanosystems’ surface properties [ 16 ] and to detach from them [ 11 , 17 ].…”