Effect of flexing and massage on in vivo human skin penetration and toxicity of zinc oxide nanoparticles.

AIM: We assessed the effects of flexing and massage on human skin penetration and toxicity of topically applied coated and uncoated zinc oxide nanoparticles (˜75 nm) in vivo. MATERIALS & METHODS: Noninvasive multiphoton tomography with fluorescence lifetime imaging was used to evaluate the penetration of nanoparticles through the skin barrier and cellular apoptosis in the viable epidermis. RESULTS: All nanoparticles applied to skin with flexing and massage were retained in the stratum corneum or skin furrows. No significant penetration into the viable epidermis was seen and no cellular toxicity was detected. CONCLUSION: Exposure of normal in vivo human skin to these nanoparticles under common in-use conditions of flexing or massage is not associated with significant adverse events.

Enhanced immune response against pertussis toxoid by IgA-loaded chitosan-dextran sulfate nanoparticles.

The objective of the present study was to evaluate immunological activities of chitosan-dextran sulfate (CS-DS) nanoparticle formulation of pertussis toxoid (PTXd) and its combination with a potential immunological adjuvant, immunoglobulin A (IgA). CS-DS nanoparticles were prepared using a complex coacervation (polyelectrolyte complexation) technique. CS-DS nanoparticle formulations with size and zeta potential in a range of 300-350 nm and +40-+55 mV, respectively, were obtained. An entrapment efficiency of more than 90% was obtained for pertussis toxin and IgA in CS-DS nanoparticles. All loaded nanoparticle formulations showed less than 20% of release within 24 h in in vitro release studies. The immunological evaluation of developed formulations in female Balb/c mice groups showed that the CS-DS nanoparticles formulations induced significantly higher serum IgG and IgG1 titers (p < 0.05) as compared with conventional alum-adjuvanted PTXd formulation administered by subcutaneous route. This study indicated the potential of CS-DS nanoparticles to be a simple and effective particulate delivery system with in-built immunological adjuvant property for acellular protein antigens. The study also revealed the potential important role of IgA-loaded CS-DS nanoparticles as a novel immunological adjuvant for vaccine delivery.

Influence of anatomical site and topical formulation on skin penetration of sunscreens.

Sunscreen products are widely used to protect the skin from sun-related damage. Previous studies have shown that some sunscreen chemicals are absorbed across the skin to the systemic circulation. The current study shows that absorption into the skin of sunscreen chemicals applied to the face is up to four times greater than that of the same product applied to the back. This has implications for the way sunscreen products are formulated and may allow the use of less potent products on the face compared with the rest of the body. The effect of formulation vehicles on the release and skin penetration of the common sunscreen agent benzophenone-3 (common name oxybenzone) was also assessed. Penetration of benzophenone-3 across excised human epidermis and high-density polyethylene (HDPE) membrane was measured using in vitro Franz-type diffusion cells. Penetration and epidermal retention was measured following application of infinite and finite (epidermis only) doses of benzophenone-3 in five vehicles: liquid paraffin, coconut oil, 50:50 ethanol:coconut oil, aqueous cream BP, and oily cream BP. Highest benzophenone-3 skin retention was observed for the ethanol:coconut oil combination. Maximal and minimal benzophenone-3 fluxes were observed from liquid paraffin and coconut oil, respectively. The alcohol-based vehicle exhibited low benzophenone-3 release from the vehicle but high skin penetration and retention.