José R. Vega-Baudrit

Protein-loaded chitosan nanoparticles modulate uptake and antigen presentation of hen egg-white lysozyme by murine peritoneal macrophages

Chitosan binds to negatively charged tripolyphosphate (TPP) by an electrostatic interaction driven by its positively charged amino group. This interaction allows developing stable nanoparticles suitable as a carrier and controlled release system for drugs and vaccines. We study the effect of chitosan nanoparticles (CNp) on the uptake and antigen presentation of the model protein hen-egg white lysozyme (HEL) to peritoneal macrophages isolated from mice. Results showed that after four hours of pre-incubation with a T-cell hybridoma line cocultured with murine peritoneal macrophages, only trace amounts of IL-2 were detected in treatments with HEL alone, whereas cocultures treated with HEL-CNp had already reached maximum IL-2 expression. Confocal microscopy studies showed that CNp had a higher uptake rate of the fluorescently labelled protein than the protein itself after 30 min of incubation with the peritoneal macrophages. Our results suggest that CNp system is a potential candidate for an oral vaccine delivery system.

Polymer-liposome nanoparticles obtained by the electrostatic bio-adsorption of natural polymers onto soybean lecithin liposomes

This work is focused on the formulation of polymer-liposome nanoparticles based on the electrostatic bio-adsorption of natural polymers onto soybean lecithin liposomes, with potential as novel delivery system for macromolecules, such as proteins. The building up of the polymer-liposome nanoparticles was achieved through the alternating bio-adsorption of natural cationic (chitosan) and neutral (dextran) or anionic (dextran sulphate or alginate) polymer layers on a core composed by anionic nanosized soybean lecithin liposomes. The electrostatic bio-adsorption of natural polymers succeeded in building nanosized, spherical, monodisperse and stable polymer-liposome nanoparticles with cumulative sizes between 357.3 nm ± 25.3 nm and 498.2 nm ± 69.6 nm and surface charges (ζ-potential) between –30.66 mV ± 1.55 mV and –26.74 mV ± 1.04 mV for the liposomal systems composed by alternating layers of chitosan and dextran sulphate or alginate, respectively. Natural-polymer-liposome nanoparticles offer good properties for encapsulation on its liposomal aqueous core and sustained release of a model protein, BSA, in vitro.

Biogenic silica-based microparticles obtained as a sub-product of the nanocellulose extraction process from pineapple peels

Silica in plant tissues has been suggested as a component for enhancing mechanical properties, and as a physical barrier. Pineapples present in their shell and bracts rosette-like microparticles that could be associated to biogenic silica. In this study, we show for the first time that silica-based microparticles are co-purified during the extraction process of nanocellulose from pineapple (Ananas comosus). This shows that vegetable biomass could be an underappreciated source, not only for nanocellulose, but also for a highly valuable sub-product, like 10 µm biogenic rosette-like silica-based microparticles. The recovery yield obtained was 7.2 wt.%; based on the dried initial solid. Due to their size and morphology, the microparticles have potential applications as reinforcement in adhesives, polymer composites, in the biomedical field, and even as a source of silica for fertilizers.