Skin penetration and dermal tolerability of acrylic nanocapsules: Influence of the surface charge and a chitosan gel used as vehicle.

For an improved understanding of the relevant particle features for cutaneous use, we studied the effect of the surface charge of acrylic nanocapsules (around 150nm) and the effect of a chitosan gel vehicle on the particle penetration into normal and stripped human skin ex vivo as well as local tolerability (cytotoxicity and irritancy). Rhodamin-tagged nanocapsules penetrated and remained in the stratum corneum. Penetration of cationic nanocapsules exceeded the penetration of anionic nanocapsules. When applied on stripped skin, however, the fluorescence was also recorded in the viable epidermis and dermis. Cationic surface charge and embedding the particles into chitosan gel favored access to deeper skin. Keratinocytes took up the nanocapsules rapidly. Cytotoxicity (viability<80%), following exposure for ≥24h, appears to be due to the surfactant polysorbate 80, used for nanocapsules stabilization. Uptake by fibroblasts was low and no cytotoxicity was observed. No irritant reactions were detected in the HET-CAM test. In conclusion, the surface charge and chitosan vehicle, as well as the skin barrier integrity, influence the skin penetration of acrylic nanocapsules. Particle localization in the intact stratum corneum of normal skin and good tolerability make the nanocapsules candidates for topical use on the skin, provided that the polymer wall allows the release of the active encapsulated substance.

Repeated dose toxicity study of Vibrio cholerae-loaded gastro-resistant microparticles.

CONTEXT: Microencapsulation of antigens has been extensively studied over the last decades aiming at improving the immunogenicity of vaccine candidates. OBJECTIVE: Addressing microparticles (MPs) toxicity in rats. MATERIAL AND METHODS: Spray-dried Eudragit® L 30 D-55 MPs and Eudragit® L 30 D-55 alginate MPs were elaborated and characterized. MPs obtained were administered to rats, three groups were defined: G1, control group; G2, administered with Vibrio cholerae (VC)-loaded MPs; G3, receiving VC-loaded alginate MPs. Animals received three vaccine doses. Body weight, food and water intake were controlled during the study. Haematological parameters, vibriocidal titres, organ weight and histology in necropsy were also analyzed. RESULTS: All animals grew healthy. Body weight gain, food and water intake and haematological parameters remained within physiological values, showing no treatment-related differences. Moreover, organ weight changes were not detected and animals developed protective vibriocidal titres. CONCLUSION: VC-loaded MPs and VC-loaded alginate MPs have proved to be safe and effective in the assessed conditions.

Short-term in situ/ex vivo study of the anticariogenic potential of a resin-modified glass-ionomer cement associated with adhesive systems.

OBJECTIVE: As resin-modified glass-ionomer cement (RMGIC) is an adhesive material, its association to dentin bonding agents (DBAs) was previously proposed. This study investigated the adjunctive behavior of an RMGIC with etch-and-rinse bonding systems under in situ/ex vivo cariogenic challenge. METHOD AND MATERIALS: Bovine enamel blocks (3 3 3 3 2 mm) were randomly assigned to group VP, Vitremer + its own primer (3M ESPE); group VSB, Vitremer + Single Bond (3M ESPE); and group VPB, Vitremer + Prime and Bond 2.1 (Dentsply). Two blocks of each group were randomly placed in an acrylic palatal appliance, so each appliance included six blocks. Volunteers (n = 10) wore these appliances according to given instructions to promote a sucrose challenge eight times/day for 15 days. After this period, the blocks were removed from the devices and cleaned, and demineralization was assessed through longitudinal microhardness analysis (Knoop indenter, 25 g/5 s). Data were submitted to three-way ANOVA and Tukey test (P < .05). RESULTS: No treatment was able to completely avoid demineralization. All materials showed a statistically significant difference in mineral loss when the microhardness on the outer enamel was compared with deeper regions (P < .05). CONCLUSION: Association of the tested RMGICs with etch-and-rinse DBAs did not seem to be more beneficial against caries than the conventional treatment with RMGIC.