One of the mechanisms of improving skin vitality is by enhancing the oxygen levels of the skin. We know that oxygen is carried through the blood by erythrocytes that carry haemoglobin. Having adequate levels of haemoglobin in the blood is vital not only to the health of the body, but also to the skin, as blood also transports valuable nutrients that internally nourish it and give it a healthy glow.

Additionally, skin needs oxygen to assist in the production of collagen, elastin and other elements necessary for a healthy skin condition. As we age the circulation in our capillaries deteriorates, thus decreasing the level of oxygen and nutrients reaching our skin cells. This further leads to dehydration of the skin.

We know that skin normally renews itself approximately every 28 days. However, if oxygen and nutrients are diminished, the cell reproduction process is slowed down, and the new skin cells are not as healthy, resulting in premature ageing and the manifestation of fine lines, wrinkles and a dull or sallow complexion.

In aesthetics, procedures such as massage, which stimulate heat in the skin assist in improving circulation and drawing nutritious blood to the skin that may be hindered due to stress and other factors. On the other hand, gas phases in emulsions have generally been a nuisance for cosmetic formulators, in terms of accelerated destabilisation of micelles in creams. However, for many years, oxygen uptake in the skin has been an attractive cosmetic property. Increasing oxygen in the Stratum Corneum becomes equivalent to the search for the Holy Grail with its myth of Eternal Youth. Indeed, oxygen promotes metabolic processes within the dermis and viable cells to produce a higher state of activity. Oxygen enhances collagen formation in fibroblasts among many other actions within humans.

Perfluorodecalin, a perfluorocarbon, is one of the first cosmeceutical ingredients to be approved by the FDA in the US for use in cosmetic products. This can be explained, as perfluorodecalin is not a drug but a synthetic molecule able to store gases such as oxygen and carbon dioxide. In other words, this molecule acts as a replica of our body’s cellular breathing process. As such this unique substance may be described as a cosmeceutical, in that its function can be classified as being between a cosmetic and a pharmaceutical.

GENERAL CHARACTERISTICS
Perfluorodecalin is a totally inert, steady, colourless and odourless substance. Among its less known properties it is both hydrophobic and lipophobic, and as a consequence it is soluble only in materials with some fluor content. Liquid perfluorocarbons react in the same way as solid perfluor polymers such as PTFE.

WOUND HEALING MATERIAL
Perfluorodecalin is used as a wound-healing material in hyberbaric oxygen therapy. (ref. Roth and Weiss, Elsevier Science Inc., 1994). In hyberbaric oxygen therapy (HBOT) oxygen is administered in an environment where the ambient pressure has been increased. The ensuring hyperoxia and elevated pressure have a number of beneficial clinical effects, including the promotion of wound-healing. As an example in 1989 HBOT was approved for use in severely burnt patients. Much experimental and clinical data supporting the use of HBOT already has more than 10 years of information. With the use of HBOT oedema can be decreased, also marginally viable tissue can be preserved. HBOT promotes wound closure and enhances host defences. Based on the wound healing studies it can be concluded that with Perfluorodecalin acne skin and seborrheic scalp can be treated and positive results expected.

GAS CARRYING MECHANISM
The mechanism of natural gas carriers can be identified with the mechanism of erythrocytes, or red blood cells. They are very small cells, 33-10 microns, with generally no nucleus or internal membrane. Erythrocytes are mainly filled with the oxygen binding protein haemoglobin as mentioned earlier. The main functions of erythrocytes are to transport oxygen and carbon dioxide. They constitute 45 per cent of the volume of the 5-6 litres of blood that we carry. The oxygen molecules are bound by haemoglobin in a co-operative way.

The gas-carrying mechanism of perfluorocharbons is fully comparable to the function of respiratory gases in our body. The diffusion of respiratory gases, oxygen and carbon dioxide is directly related to the partial pressures of these gases.

PERFLUORODECALIN AS A COSMETIC INGREDIENT
Perfluorodecalin as a hydrophobic and lipophobic fluid is easily identifiable in emulsions as an interface micelle formation from oil or water networks. Such fluorinated materials depict traditionally third-phase elements in emulsions. The characteristics of carrying gas at a controlled level of volume allow the creation of a fourth active gaseous phase in emulsions. Perfluorodecalin is a unique gas carrier and as such allows cosmetic formulations to solve problems of carbon dioxide cleansing or oxygen enrichment of cells. The gas-carrying capacity of Perfluorodecalin is a physical phenomenon and totally reversible through gas diffusion.

OXYGEN AND THE SKIN
The issue of oxygen and the skin has received a great deal of media attention. It was demonstrated by Stanzl et al that the decrease in the oxygen partial pressure of the skin occurred with the increase of age and depended on risk behaviour such as smoking. In their study, Stanzl et al were able to point out a way of increasing the oxygen partial pressure of the skin by 100 per cent and of maintaining this increased status over a period of time. (28 days panel test).

Comparisons were also made of partial pressure of oxygen (PO2) in the skin after 28 days treatment with products containing 2, 4, 6, 8 and 10 per cent Perfluorocarbons. The calculation of the correlation coefficient (r=0.978) shows a linear correlation between the amount of oxygen applied and the increase of the partial pressure in the skin. An optimal state of oxygen supply results in greater build-up of collagen production according to the publication in Luber Stryer Biochemie, 1979. The oxygen supply to each cell of the body diffuses over a distance of approximately 0.05mm.

The uptake of oxygen in the cell is based on active transport mechanism between the cells and intercellular space. The increase of oxygen supply results in a stronger diffusion gradient, which allows the cells of the epidermis to take up the optimal quantity of oxygen for their metabolic processes.

MOISTURE CONTENT OF THE SKIN
The moisture content of the skin was tested using an emulsion, which contained 10 per cent Perfluorodecalin. Skin profile, change of depth of wrinkles and change of number of wrinkles after 14 days of application were tested using the emulsion twice a day and the same product with Perfluorocarbons was analysed. Twenty women, aged 25-55 years were tested.

The increase in skin moisture within the application period follows the same pattern as the increase in the oxygen partial pressure measured in the previous study. In contrast to known moisturisers, the effect remains at a higher level for several days.

Another test examined the time element of the skin moisture levels of 30 women, aged 35-40 years. The increase in moisture within the application period followed the same pattern as the increase in the oxygen partial pressure, which was measured in previous studies. Again, in contrast to known moisturises, the effect remains at a high level for several days.

COSMETIC PROPERTIES
Perfluorodecalin has specific surface characteristics. As mentioned previously, it is not hydrophilic or lipophilic, but homophilic, repelling other ingredients in the formulation and acting as a co-emulsifier. It creates instantly a third phase and stabilises the emulsion, increasing considerably the size of the micelle walls by up to 20 microns. The emulsion, before Perfluorocarbons addition and after Perfluorodecalin addition was studied by microscope. The addition of Perfluorocarbons changed the emulsion structure, reducing the amount of air bubbles.

The surface change of Perfluorocarbons was very negative, minus 7-100 mV at pH 5.5-7 and hence Perfluorocarbons is a very easy material to formulate with. It can be mixed into the final formulation at the end of the processing, like the fragrance. No special preparation is needed, except when it is used as a gas carrier. The gas-loaded product has to be incorporated at room temperature into the emulsions to avoid gas diffusion, which is accelerated by high temperatures. No incompatibility with any cosmetic ingredient is known, and as a very inert material, Perfluorocarbons are not sensitive to any chemical reactions.

Perfluorocarbons allow the skin to breathe to optimum levels and to self regulate better in polluted environments. It is an ideal detoxification agent, as it cleans the skin of carbon dioxide and enriches the oxygen levels of the skin. Perfluorodecalin does not interfere with the normal functions of the skin, like perspiration or the pH barrier, and doesn’t clog the pores. Perfluorocarbons provide an instant refreshing effect to the skin due to its very emollient characteristics, creating a thin-film application and in some cases providing even water-proofing properties. At relatively low concentrations it boosts SPF. Perfluorocarbons do not absorb UV-light, but with even a small addition of say 0.4 per cent they give a positive effect to a sunscreen. It has been concluded that Perfluorodecalin restructures the emulsion creating the third phase and improves the distribution of UV-filters. It also modifies the rheology and improves the application.

STATISTICS TO CONSIDER:

  • At age 30, the loss of oxygen levels in the skin drops by 25%
  • At age 40, the loss of oxygen levels in the skin drops by up to 50%
  • In highly polluted environments the oxygen loss to the skin can be even higher.

If you are interested in a skin care line using Perfluorodecalin view 2B’s Bio Serum 02 and Bio Oxygel in the product releases.

REFERENCES
Perfluorocarbon Nanoemulsions for Quantitative Molecular Imaging and Targeted Therapeutics. Kaneda MM, Caruthers S, Lanza GM, Wickline SA.

1. Flutec PP Fluorocarbon Liquids, ISC Chemicals Ltd, table E5-2/4

2. King, A. T., Mulligan, B. J., Lowe, K. C. Biotechnology, 7, 1989, p1037-1042.