**11. Influence of nanoparticulate formulations on biochemical processes of the skin**

Apart from environmental protection against radiation, functions of the skin include heat regulation, immune response, biochemical synthesis, sensory detection, regulation of absorp‐ tion/loss of water and electrolytes. The stratum corneum formed from nonviable corneocytes plays the major role.

A crucial question for the investigation of nanoparticulate drug delivery carriers is the site of drug release from the particles, i.e., does the release occur in suspension or on the skin surface leaving the carrier particles outside or do the particles penetrate the skin to release the drug within the tissue? Nanoparticles formulations for dermal delivery or transdermal delivery influenced some of the traditional functions of the skin. Once applied to the skin, enzymes activated by body heat led to the formation of an active ingredient (allyl isothiocynate). Transport of the active drug component took place by passive diffusion across the skin-the very basis of transdermal drug delivery [147,148]. The alcohol in ethosomes initiates the process of transdermal permeation and drug release by its permeation enhancing effect [149]. The major hindrance to TDDS is the stratum corneum layer that forms a strong barrier and limiting factor to skin penetration and permeation of many drugs.

The processes involved in drug delivery from ethosomes through the skin are illustrated in Fig. 8 [46]. The alcohol makes the vesicles to be packed loosely and the vesicle membranes to become softer and malleable [13]. It also causes reversible perturbations in the deeper layers of SC and penetrates intercellular lipid layers of skin cell membranes making them more fluid and less dense [150]. The vesicles then squeeze through the intercellular spaces into the deeper layers of skin. It has been shown that drug particles are concentrated more on the inside wall than in the core of vesicles [151]. In this position, release of the vesicular content is thermody‐ namically favored. Owing to the increased affinity, due to its lipid content, the vesicle fuses with the lipid contents of the skin layers and releases its content which then diffuses into deeper layers of the skin or membrane and into systemic circulation. Other mechanisms, such as the free drug diffusion, may be involved in penetration.

therapeutic opportunities and have been proposed for use in cosmetic products like

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853888/figure/F4/#108;93 A; http://www.ncbi.nlm.nih.gov/pmc/

**11. Influence of nanoparticulate formulations on biochemical processes of**

Apart from environmental protection against radiation, functions of the skin include heat regulation, immune response, biochemical synthesis, sensory detection, regulation of absorp‐ tion/loss of water and electrolytes. The stratum corneum formed from nonviable corneocytes

A crucial question for the investigation of nanoparticulate drug delivery carriers is the site of drug release from the particles, i.e., does the release occur in suspension or on the skin surface leaving the carrier particles outside or do the particles penetrate the skin to release the drug within the tissue? Nanoparticles formulations for dermal delivery or transdermal delivery influenced some of the traditional functions of the skin. Once applied to the skin, enzymes activated by body heat led to the formation of an active ingredient (allyl isothiocynate). Transport of the active drug component took place by passive diffusion across the skin-the very basis of transdermal drug delivery [147,148]. The alcohol in ethosomes initiates the process of transdermal permeation and drug release by its permeation enhancing effect [149]. The major hindrance to TDDS is the stratum corneum layer that forms a strong barrier and

The processes involved in drug delivery from ethosomes through the skin are illustrated in Fig. 8 [46]. The alcohol makes the vesicles to be packed loosely and the vesicle membranes to become softer and malleable [13]. It also causes reversible perturbations in the deeper layers of SC and penetrates intercellular lipid layers of skin cell membranes making them more fluid

limiting factor to skin penetration and permeation of many drugs.

sunscreens, moisturizers, long lasting makeup, etc.

218 Application of Nanotechnology in Drug Delivery

articles/PMC3853888/figure/F5/#117.75;90.75 B

**Figure 7.** Carbon nanotube (A) and fullerene (B)

**the skin**

plays the major role.

**Figure 8.** Mechanism of drug delivery from ethosomal vesicular carriers through the skin [46,115]. Note the initial flu‐ idization of the skin architecture.
