Nanocosmetics and Nanomedicines

Nanotechnology can be used to modify the drug permeation/penetration of encapsulated substances, through the manipulation of many different factors, including direct contact with the skin surface and controlled release. In general, nanoparticles cannot cross the skin barrier, which can be explained by the cell cohesion and lipids of the stratum corneum, the outermost skin layer. The device most commonly used to study the transport of substances and nanoparticles across the skin is the Franz vertical diffusion cell, followed by the substance quantification in the receptor fluid or determination of the amount retained in the skin. Microscopy techniques have also been applied in skin penetration or permeation experiments. This chapter will present the fundamental considerations regarding the transport of encapsulated substances and/or nanoparticles across the skin, the experimental models applied in these studies and a review of the main studies reported in the literature in order to allow the reader to gain insight into the current knowledge available in this area.

A number of studies in the last 20 years describe the development of several techniques to produce a great variety of nanoparticles applied as drug delivery systems, among them, the nanoprecipitation. However, no study analyzing the profitability of such systems was found in the literature. Therefore, in this work it is analyzed the profitability of a polymeric nanoproduct produced by the method of nanoprecipitation: the bezophenone-3, a sunscreen agent. Based on the laboratory procedures, 3 alternatives were proposed for the industrial production, including a static mixer and a ceramic membrane pre-filtration step. The simplified profitability analysis was done based on a methodology called Bare Module Cost. Its results showed that lowest sale prices were achieved when the particles are produced through the most simplified process and dividing the production in more batches per day. The procedure presented in this chapter is general and can be widely applied to other type of nanoparticles and processes.

Nanotechnology represents an important complement to traditional chromophore-based UV filters. Nanosized metal oxides are widely used due to their broad protection spectrum and reduced skin irritation. These particles are already present in most commercial sunscreen lotions even though their photoreactivity has been highlighted as a potential cause of cytotoxic effects in human skin cells (e.g. fibroblasts, epithelial cells). However, this cytotoxicity is not likely to represent a significant health risk to consumers as several skin penetration assays have shown that the photoreactive particles penetrate at most to the stratum spinosum of the epidermis. Nanoencapsulation of traditional organic UV filters is a more recent approach to improve skin retention, photostability and the UV blocking ability of the free molecules. All of these improvements have been confirmed with different scientific assays for different particles, especially polymeric nanocapsules and solid lipid nanoparticles. These technological advantages offered by nanometric particles for sun protection formulations have made them commercially important. In inventories from non-governmental organizations there are approximately 30 commercial sunscreen products listed as containing nanoparticles.