Negatively charged chitosan nanoparticles prepared by ionotropic gelation for encapsulation of positively charged proteins.

The nanoprecipitation of hydrogel nanoparticles by complex coacervation is investigated through a systematic study of the popular chitosan-polyphosphate pair of polyelectrolytes with opposite charges at pH 4. Polyphosphates of varying molar masses and electrical charges are investigated as alternatives to the commonly used tripolyphosphate, so as to assess the influence of the strength of electrostatic interactions on the fabrication possibility, the size of hydrogel particles, and their overall charge. Sodium hexametaphosphate and sodium polyphosphate allow the manufacture of such nanoparticles with either a positive or a negative charge, depending on the chitosan/polyphosphate ratio and the order of mixing. The classical way of mixing by pouring the polyphosphate solution into the chitosan solution yields microparticles. Inverting the order of mixing by pouring the chitosan solution into the polyphosphate solution allows the precipitation of negatively charged nanoparticles with diameters in the range 100-200 nm. Such charge inversion of the chitosan into negative is not possible with the common TPP. It was achieved using sodium hexametaphosphate and sodium polyphosphate having a larger negative charge. Charge inversion of chitosan allows an efficient encapsulation of positively charged proteins with an improved encapsulation efficiency than in the usual TPP-based coacervate. The encapsulation of the bovine serum albumin at pH 4 is given as a case study of a positively charged protein.

Development and Evaluation of an Anti-aging Cosmetic Formulation Exploring Antioxidant Potential of Vitis vinifera L.

An important skin aging mechanism is oxidative stress. Reactive oxygen species in excess leads to skin integrity loss and visible changes. Antioxidants are able to prevent reactive oxygen species damage, making their supplementation important to slow down the aging process. We evaluated Vitis vinifera L. extract antioxidant potential to be applied for cosmetic purpose. The sample's thin-layer chromatography profile and antioxidant results indicated a good antioxidant activity. The extract was incorporated into different formulations, and a stability study was conducted with the emulsion chosen. Organoleptic and physicochemical parameters were evaluated, as well as the microbial count. The formulation was found to be in compliance with current standards and has the potential to be further studied and used as an anti-aging cosmetic.