Immobilization of Photoditazine on Vaterite Porous Particles and Analysis of the System Stability in Model Media

In this paper, we present the results on immobilization of Photoditazine, the photosensitizer of the second generation, on vaterite (metastable modification of calcium carbonate) porous particles of two different sizes. The adsorption efficiency is found to be 3.0 and 3.2 wt % Photoditazine on vaterite particles with average diameters of 5 and 0.5 μm, respectively. The curves of Photoditazine desorption from vaterite particles are determined depending on the composition of the dispersion medium (water and bovine serum albumin solution). It is found that vaterite particles in water are subjected to recrystallization in accordance with the dissolution–precipitation mechanism. The presence of albumin molecules at a physiological concentration allows stabilizing metastable vaterite particles of micron and submicron size for at least 17 days.