Self-assembled chitosan-alginate polyplex nanoparticles containing temoporfin

The aim of this study was to develop biocompatible polyplex nanoparticles with physicochemical properties suitable for the delivery of photosensitizer temoporfin. We prepared, characterized, and compared the two types of polyplex nanoformulations consisting of sodium alginate in combination with chitosan polymer or chitosan oligomer lactate. We obtained the polyplex system by multiple electrostatic interactions between cationic chitosan and anionic alginate and identified key process parameters. Particle size distribution, dispersity, and zeta potential were determined by dynamic light scattering (DLS), and the diameter and the morphology of the individual particles were visualized by a transmission electron microscopy (TEM). It was found that size distribution of the polyplex nanoparticles depends on the concentrations of chitosan and alginate stock solutions and the order and ratio of addition of stock solutions as well as on the pH of the resulting mixture. It appears that the nanoparticles are homogeneous, although micrographs indicate some (vague, indistinct) core-shell structure. The nanoparticles are stable at pH 7.4 (pH of blood plasma) and show only very little drug leak in experiment modeling conditions of blood pool transport to target tissues.