An innovative microcarrier based on a carboxy-enriched and branched
polylactic acid derivative was developed to enhance the in vitro
phototoxicity of the
photosensitizer and
prodrug 5-aminolevulinic. Microparticles, prepared by double
emulsion technique and loaded with the
prodrug were carefully characterized and the effect of the
polymer structure on the chemical, physical and
biological properties of the final product was evaluated. Results showed that microparticles have a spherical shape and ability to allocate up to 30 μg of the
photosensitizer per mg of carrier despite their difference in solubility. Release studies performed in various simulated physiological conditions demonstrate the influence of the branched structure and the presence of the additional carboxylic groups on the release rate and the possibility to modulate it. In vitro assays conducted on human epithelial
adenocarcinoma cells proved the not cytotoxicity of the carriers in a wide range of concentrations. The hemocompatibility and
surface proteins adsorption were evaluated at different microparticles concentrations to evaluate the safety and estimate the possible microparticles residential time in the bloodstream. The advantages, of loading 5-aminolevulinic
acid in the prepared carrier has been deeply described in terms of enhanced
phototoxicity, compared to the free 5-aminolevulinic
acid formulation after irradiation with light at 635 nm. The obtained results demonstrate the advantages of the prepared derivative compared to the linear
polylactide for future application in
photodynamic therapy based on the
photosensitizer 5-aminolevulinic
acid.