Films based on neutralized chitosan citrate as innovative composition for cosmetic application.

In this work, citrate and acetate buffers, were investigated as neutralizers to chitosan salts in order to provide biocompatible and stable films. To choose the appropriate film composition for this study, neutralized chitosan citrate and acetate films, with and without the plasticizer glycerol, were prepared and characterized by thickness, moisture content, degree of swelling, total soluble matter in acid medium, simultaneous thermal analysis and differential scanning calorimetry. Chitosan films neutralized in citrate buffer showed greater physical integrity resulted from greater thicknesses, lower moisture absorbance, lower tendency to solubility in the acid medium, and better swelling capacities. According to thermal analyses, these films had higher interaction with water which is considered an important feature for cosmetic application. Since the composition prepared in citrate buffer without glycerol was considered to present better physical integrity, it was applied to investigate hyaluronic acid release in a skin model. Skins treated with those films, with or without hyaluronic acid, show stratum corneum desquamation and hydration within 10min. The results suggest that the neutralized chitosan citrate film prepared without glycerol promotes a cosmetic effect for skin exfoliation in the presence or absence of hyaluronic acid.

Effects of the composite nanovesicles on the physical properties and cellular adhesion of chitosan films.

Chitosan films were prepared by the casting of a chitosan gel in absence and presence of composite nanovesicles. The microscopy images showed the occurrence of agglomerates on the surface and internal pores when the nanovesicles were added to the films, differently from the smooth surface of the pure chitosan films. Despite the hydrophobic character that composite nanovesicles gave to the chitosan films, as showed by the reduction of the water permeation at prolonged times, there was a reduction on the contact angle values for these samples related to the roughness of the surface. The peak of water desorption observed on calorimetric analysis of chitosan was shifted to higher values when the nanovesicles were added to the films. Furthermore, the desappearance of Tg on the films containing nanovesicles denoted their plastifier effect in the chitosan film. The swelling results showed higher water diffusion at the first times for the films containing nanovesicles because of the pores observed by microscopy. However, at prolonged times, there was a reduction on the swelling because of the lipofilic composition of the nanovesicles. Furthermore, the presence of nanovesicles led to a reduction on the water content in the chitosan films. Due to the effect on the physical properties of the chitosan films, the addition of nanovesicles on discrete concentrations contributed to the cell adhesion.

Microparticles prepared with poly(hydroxybutyrate-co-hydroxyvalerate) and poly(epsilon-caprolactone) blends to control the release of a drug model.

The objective of this work was to verify the influence of the poly(epsilon-caprolactone) PCL concentration in poly(hydroxybutyrate-co-hydroxyvalerate) P(HBHV)/PCL microparticles, prepared by an emulsion/solvent evaporation process, on the release behavior of a drug. Differential Scanning Calorimetry analyses demonstrated that the preparation process increased the crystallite heterogeneity for the P(HBHV) in the particles. The drug caused an increase in the glass transition of the P(HBHV) in the microparticles. Dexamethasone acetate-loaded microparticles demonstrated drug sustained releases (up to 250 h), which profiles fit the biexponential model. The release of dexamethasone acetate caused an increase in the surface area of the microparticles. The kinetic constants of the sustained phase increased with the augmentation of the PCL content in the blend. The drug release mechanism was dependent on the presence of PCL in the microparticles. A Fickian release was determined for the microparticles prepared exclusively with P(HBHV), while non-Fickian release behaviors were found for the P(HBHV)/PCL microparticles.