Chitosan nanoparticles for dermaseptin peptide delivery toward tumor cells in vitro.

The present study aimed to entrap and characterize the morphology and antitumor effects of a dermaseptin (DStomo01) peptide in chitosan nanoparticles, in vitro. DStomo01 nanoparticles showed moderate polydispersivity, excellent colloidal stability, and slow release. It was noted that free DStomo01 induced DNA fragmentation and mitochondrial hyperpolarization in HeLa cells. However, when entrapped in chitosan nanoparticles, DStomo01 was slightly more active against HeLa cells than the free peptide. In conclusion, the present sustained release system was efficient in entrapping the peptide and reducing tumor cell viability, which are promising steps for future studies involving specific targeting of nanoparticles and in-vivo treatments.

Partial characterization of a novel amphibian hemoglobin as a model for graduate student investigation on peptide chemistry, mass spectrometry, and atomic force microscopy.

Graduate students in chemistry, and in biological and biomedical fields must learn the fundamentals and practices of peptide and protein chemistry as early as possible. A project-oriented approach was conducted by first-year M.Sc and Ph.D students in biological sciences. A blind glass slide containing a cellular smear and an aqueous cellular extract were offered to the students. Qualitative and quantitative cell morphological parameters were analyzed by atomic force microscopy. The fractionation of the aqueous extract was conducted by reversed-phase chromatography followed by analysis of the isolated and partially purified proteins and peptides by mass spectrometry (MS). The proteins were treated by peptidases and the obtained peptide fragments were sequenced by de novo MS/MS, together with peptides already present in the extract. The most abundant protein fractions were identified as the alpha and beta chains of hemoglobin from an amphibian of the Leptodactylus genera. Two of the peptides sequenced by the students were synthesized by the solid-phase methodology, one of those being obtained by the split-and-pool library synthesis method. Thus, the students were able to learn some advanced principles and practices of protein chemistry and bionanotechnology in a 6-weeks project-oriented approach.