Abstract
Polymeric drug-loaded nanoparticles have been extensively studied in the field of drug delivery for almost 30 years. Upon administration, particle biodistribution will be driven mainly by their physicochemical properties. As size is one of the easiest parameters to characterize particles, many reports have tried to correlate this parameter with in vitro or in vivo efficacy assays. The global message from literature is that small particles remain longer in the circulation and therefore have more chances to be distributed among the target sites. However, do we need to design smaller and smaller carriers? Are there no other parameters involved in the interaction with living organisms? Finally, is particle size correctly assessed? These are some of the questions that confront scientists trying to design the "ideal" drug colloidal carrier. The first part of the presentation will focus on understanding the relation between size and pathways of nanoparticles, after intravenous administration. The main techniques currently being used for particle size determination will be reviewed and the difficulty in interpreting the data of biodistribution studies without accurate particle size determination will be highlighted.
In a second part, data exploring the influence of different physicochemical parameters characterizing the particulate carriers such as size, charge or hydrophobicity on their interaction with a cellular model for intestinal cells, the Caco-2 model, will be presented.
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