Preparation of PLGA Nanoparticles Loaded with the Anti-Infective Ctn[15-34] Peptide for Antifungal Application

Abstract This article aims to report the preparation and optimized formulation of Ctn[15-34], a designed anti-infective peptide, with poly(lactic acid-co-glycolic acid), PLGA, nanoparticles. Ctn[15-34] is a short peptide derived from crotalicidin, a cathelicidin-related antimicrobial peptide from the venom of the South American rattlesnake (Crotalus durissus terrificus), that has arisen as a promising antifungal and microbicide agent. The PLGA nanoparticles were prepared and loaded with carboxyfluorescein (CF)-Ctn[15-34] using the double emulsion/solvent evaporation method. After a preformulation study, which tested different formulation parameters, Poly (vinyl alcohol) 87-89% hydrolyzed and sonication with Sonifier® were choosen to prepare unloaded PLGA nanoparticles by that method, resulting in smaller particle size and Polydispersity Index (PDI) values and higher zeta potential values of nanoparticles. This better condition was used to prepare CF-Ctn[15-34]-loaded PLGA nanoparticles, resulting in homogeneous and spherical nanoparticles, with an average size of 213.2 ± 2.00 nm, PDI of 0.044 ± 0.04 and zeta potential of -16.03 ± 1.20 mV. An excellent encapsulation efficiency was obtained, corresponding to 93.3 ± 0.10 %. The drug-release profile showed a rapid initial release of the peptide, approximately 27 % in the first 24 hours, followed by a sustained release for at least 16 days. Another relevant aspect in the peptide formulation is that the CF-Ctn[15-34]-loaded nanoparticles potentiated the antifungal effect against the opportunistic pathogenic yeast Cryptococcus neoformans compared with the free, in solution Ctn[15-34], in equivalent volume dosage. A preparation method of CF-Ctn[15-34]-loaded PLGA nanoparticles was established and validated, representing a successful approach to deliver CF-Ctn[15-34] for pharmaceutical applications.