Polyelectrolytic gelatin nanoparticles as a drug delivery system for the promastigote form of Leishmania amazonensis treatment

In this study, phthalocianato[bis(dimethylaminoethanoxy)] silicon (NzPC) was loaded onto gelatin nanoparticles functionalized with polyelectrolytes (polystyrene sulfonate/polyallylamine hydrochlor- ide) by layer-by-layer (LbL) assembly for photodynamic therapy (PDT) application in promastigote form of Leishmania amazonensis treatment. The process yield, and encapsulation efficiency were 80.0% ± 1.8 and EE 1⁄4 87.0% ± 1.1, respectively. The polyelectro- lytic gelatin nanoparticles (PGN) had a mean diameter of 437.4±72.85nm, narrow distribution size with a polydispersity index of 0.086. The obvious switching of zeta potential indicates successful alternating deposition of the polyanion PSS and polyca- tion PAH directly on the gelatin nanoparticles. Photosensitizer photophysical properties were shown to be preserved after gel- atin nanoparticle encapsulation. The impact of the PDT in the via- bility and morphology of Leishmania amazonensis promastigote in culture medium was evaluated. The PGN-NzPc presented low tox- icity at the dark and the PDT was capable of decreasing the via- bility in more than 80% in 0.1mmol.L 1 concentration tested. The PDT also triggered significant morphological alterations in the Leishmania promastigotes. These results reinforce the idea that the use of PGN as photosensitizers carriers is useful for PDT of Leishmania promastigotes.