No. 5Vol 42, No. 4, pp. 313–318, 2008A New Water-in-Powder Technology A Novel Structure for Creating Unique Cosmetic Products

A Water-in-Powder cosmetic is one encapsulating a large amount of water with powders. In this study we explain why the cosmetic is possible. First we focused on hydrophilic and hydrophobic balance of nano-sized powder surface. We looked into the surface state of powders with the gas adsorption test and discovered the functional powders that have the optimized balance of hydrorepellency due to fractal surface and hydrophilicity due to free hydroxyl groups. By using this material, we created a new powder technology that can encapsulate a large quantity of water stably. We also looked into how the powders encapsulated water by observation with wet-SEM and how the encapsulated water is stabilized by measuring water mobility with ¹7Q-M\IJR As a result, we developed a new technology with water and powder. By encapsulating a large amount of water, we achieved a cosmetic with many unique characteristics : the powder cosmetic can change into liquid by application of friction on skin, it gives us comfort in use and provides a watery, cool feel. It also provides excellent makeup function by spreading smoothly on skin to form a uniform makeup coating.
Keywords:  water-in-powder, hydrorepellency, hydrophilicity, fractal, encapsulate, technology     

Small proteoglycans in the skin: new targets in the fight against skin aging

IFSCC Magazine , 11 (2008) (1) 31–34
A water-in-powder cosmetic is one in which a large amount of water is encapsulated in a powder. In this study we describe the development of this type of cosmetic. We first focused on the hydrophilic/hydrophobic balance of the nano-sized powder surface. We looked at surface state of powders in the gas adsorption test and discovered functional powders that have an optimized balance of hydrorepellency and hydrophilicity due to fractal surface and free hydroxyl groups, respectively. Using this material we created a new powder technology that can encapsulate a large quantity of water in a stable structure. We also looked at how the powders encapsulated water by observing them with wet-SEM and how the encapsulated water is stabilized by measuring the water mobility with 17O-NMR. Based on these result, we developed a new technology with water and powder. By encapsulating a large amount of water, we achieved a cosmetic with many unique characteristics: The powder cosmetic can become a liquid by application of friction on skin, it is convenient to use and provides moist, cool feel. It also functions as an excellent makeup by spreading smoothly on skin to form a uniform makeup coating.     

Investigating hair properties relevant for hair 'handle'. Part I: hair diameter, bending and frictional properties

The expert working group 'Hair Care Products' of the DGK currently conducts a wide study to contribute to the understanding of how single hair fibre and hair collective properties contribute towards hair 'handle' and 'feel'. During the first stage of this study four hair types were selected from a large group of individual European hair braids, according to either similar or widely different panel ratings for handle. Against the background of the panel test and the state of the literature the working group readily identified the bending properties of single fibres interacting in the tress as a fibre collective and fibre friction as being of central relevance for hair 'handle' and 'feel'. Fibre diameters of the hair types were determined by Optical Fibre Diameter Analyzer and by weighing. From these data mean ellipticity and bending stiffness distributions were calculated. Single fibre friction was determined by the capstan method in the root, middle and tip regions. Significant differences were determined between the hair types in diameters, ellipticity, bending stiffness and friction. The results lead to conclude that 'handle' is perceived as inferior when the hair is thick and bending stiffness thus high. For such hair differences in handle rating are related to differences in friction, namely in the tip region. For thin and thus 'soft' hair fibre friction seems to play only a minor role.     

Relating rheological measurements to primary and secondary skin feeling when mineral‐based and Fischer–Tropsch wax‐based cosmetic emulsions and jellies are applied to the skin

Rheology measurements were correlated to skin sensations occurring when cream and petroleum jelly cosmetic products containing different amounts of synthetic Fischer–Tropsch wax were applied to the skin. A panel of 15 people with a background in cosmetic product development were asked to rate skin feelings when a range of petroleum jelly and cream samples are applied to the skin. Primary skin feel, or the spreadability of a cosmetic product, was correlated to the product's flow onset and maximum viscosity as measured by a Anton Paar rheometer, whereas secondary skin feel or the sensation occurring at the end of application when the product was completely rubbed into the skin was correlated to the product's viscosity measured at high shear rates. The cream samples prepared with a petroleum jelly containing 10% and 20% Fischer–Tropsch wax fell within the boundary of good primary skin feeling of cream products. Predominantly, synthetic petroleum jellies were given the best assessments in terms of primary skin feeling and were used with mineral‐based petroleum jellies to determine the boundary of good primary skin feeling for petroleum jelly products. The further away a product falls from this rheological boundary the poorer the skin feeling assessment appears to be by the panel. Products containing Fischer–Tropsch waxes were given the best assessment by the panel for secondary skin feeling. Comments from the panel include that these products feel silky and light on the skin. The higher the Fischer–Tropsch wax content, the lower viscosity was at high shear rate (? = 500 s^?1) and the higher the assessment by the panel. Rheological measurements can be used to objectively determine skin sensation when products are applied to the skin; this may shorten research and development times. A rheology boundary of certain product viscosity and shear stress applied is associated with good primary skin feeling for lotions, creams and petroleum jellies. Lower product viscosity at high shear rate seems to be associated with better secondary skin feeling. Products with higher Fischer–Tropsch wax content appear to be rated higher in terms of secondary skin feeling.     

Silicones: use of substantive properties on skin and hair

Silicones have been incorporated in personal care products since the 1950s. Initially used in skin care products, and more recently in hair care applications, silicones are recognized for their lubricating properties and for the characteristic soft smooth feel they impart. With recent advances in silicone technology, these fluids can also provide substantivity and durability.
Resinous silicones such as trimethylsiloxysilicate act as effective substantivity additives when combined with dimethyl silicone in skin care formulations. In tests evaluating the number of wash cycles required to penetrate a silicone barrier, resistance to removal increases markedly as the proportion of resinous silicone to dimethyl silicone is increased. This improvement is related directly to decreased solubility of the resin.     

New protein ingredients for skin detergency: native wheat protein–surfactant complexes

The cutaneous tolerability of detergent formulations can be improved by means of suitable additives. Exogenous proteins, for example, are able to reduce the skin irritation potential of surfactants according to a double mechanism: they complex the surfactant molecules lowering the concentration of their free monomeric species; they link to the skin keratin forming a protective colloidal layer that shields the denaturing attack of surfactants. Protein derivatives used as additives for detergency are usually prepared by partial hydrolysis of animal scleroproteins or plant reserve proteins. The main purpose of the hydrolytic cleavage is to make them water soluble and suitable for liquid products. Native, non hydrolysed wheat proteins have been recently introduced as active ingredients for detergents. Water solubility and stability are obtained by means of complexation with surfactants which also increases their actual hydrophobicity, an important parameter affecting cosmetic properties of proteins. The anti-irritant properties of these new derivatives of detergents have been evaluated by in vitro predictive tests (swelling response of collagen membranes), by acute irritancy in vivo methods (occlusive patch tests) and by use tests (forearm washing test). Transepidermal water loss and electric capacitance have been adopted as investigation techniques to evaluate the skin integrity/damage after the in vivo tests. The performance of native wheat protein-surfactant complexes has been compared with traditional protein hydrolysates and to amphoteric surfactants as detergent additives. The results show a noticeable reduction of skin irritation in surfactant formulations with addition of native wheat proteins.     

Dispersions of lamellar phases of non-ionic lipids in cosmetic products

Although aqueous dispersions of lipids in the form of particles having a lamellar structure (liposomes) are already known as excellent vehicles for pharmaceutical substances, their usefulness in cosmetic formulations has not been demonstrated. The present work shows the advantages obtained by application of such systems to the skin, and in particular the use of non-ionic lipids in aqueous dispersions. Thus, in comparison with classical formulations such as emulsions, these systems exhibit lower toxicity and permit closer control of the availability of active substances at the stratum corneum. As examples, compositions suitable for skin moisturising and for tanning products are presented. Dispersions de phases lamellaires de lipides non-ioniques en cosmétique     

Transdermal delivery of two antioxidants from different cosmetic formulations

The efficacy of any cosmetic product containing a functional ingredient is determined by the skin delivery of the active molecule, which is influenced by the type of the vehicle and the molecule itself. This study was designed to compare the percutaneous absorption habits of the antioxidants carcinine and lipoic acid out of various formulations by means of the porcine skin model. Initial evaluation of the in vitro porcine skin model has demonstrated its feasibility for various substances and formulations [1, 2]. Increasing legal requirements for risk assessment in the cosmetic industry have led to the development of this alternative test method. The penetration properties are determined by the OECD Guideline TG 428: Skin Absorption: in vitro Method [3, 4], which allows the use of porcine skin for penetration studies. Porcine skin is used because of its similarity to human skin in terms of its morphology and the essential permeation characteristics [5]. The mass balances for each tested formulation type of the antioxidants show individual penetration behaviours with significant differences. The presented data plainly demonstrate that the lipophilic lipoic acid has a distinct higher penetration potential than the hydrophilic carcinine. The chosen vehicle can enhance or reduce the transdermal delivery of both tested antioxidants. Modern effective cosmetic formulations will work only, if the active ingredients penetrate into the epidermis. In conclusion, the correct selection of a suitable formulation plays an important role during product development.     

Cream or foam in pedal skin care: towards the ideal vehicle for urea used against dry skin

The aim of this study was to evaluate different urea‐containing cosmetic preparations designed for foot care regarding skin occlusion. The primary aim was therefore to screen the short‐term transepidermal water loss (TEWL) as a parameter for skin barrier function and skin occlusion and to characterize the relative role of the vehicle, i.e. cream or foam in the context of cosmetics containing urea in the 2–10% range addressing the cosmetic products urea 2% cream (GEHWOL FUSSKRAFT blau), petrolatum containing cream (GEHWOL med Schrundensalbe), urea 10% cream (GEHWOL med Lipidro‐Crème), urea 10% foam (Allpresan Fuss Schaum) and vaseline (positive control) compared with an untreated area on the volar forearms of volunteers. Moreover, the short time (24 h) kinetics regarding the moisturizing effect of cream and foam formulations in diabetic patients were compared. The efficacy of a cream on reduction of skin thickness of hyperkeratotic skin in the heel region before and after a period of product application was also evaluated. In some of the trials, healthy individuals and in others, diabetic patients (type I and II) were enrolled. TEWL was determined before product application, as well as at given points of time thereafter. In this study, no excessive occlusion effects comparable with a blockage of the skin’s natural water evaporation could be observed for any of the test products. To the extent to be expected, this was found neither for the cream products nor for the foam product. Slightly lowered TEWL values after application of the 10% urea cream can be interpreted as a beneficial effect in terms of an improved barrier function. Regarding skin moisture, the urea‐containing cream formulation appeared equal or slightly superior to the foam formulation. The thickness of the horny layer was found reduced after application of 10 % urea‐containing cream. At present it looks as if cream vehicles would still be vehicles of choice in general, when it comes to the formulation of skin care preparations for not only dry skin but also in the context of pedal skin care.     

Absorption of materials by or through the living skin

The skin comes into contact with a large range of materials either deliberately or inadvertently. It should be possible to predict the exact transport rates of these materials through the skin as a function of the physicochemical properties of the different compounds. With this sort of knowledge it is possible to predict the exact disposition of compounds and use this in the formulation of new products both in the pharmaceutical and cosmetic field. The information will also be useful from the standpoint of skin toxicology and environmental health. In order to be able to predict this complex process it is necessary to split the overall transport into different component parts. This article will identify these components and provide illustrations. The major areas discussed will be barrier function of the skin, the release properties of different topical formulations and how these may be monitored. Novel means of enhancing the penetration of drugs will be discussed and how some additives that are incorporated into formulations will perhaps alter the barrier function of skin. A mathematical model describing skin penetration has been developed and its use in predicting blood levels will be described. This model has been tested both in animal experiments and in limited human studies and its relevance to these situations will be highlighted.
Absorption cutanée et transcutanée in vivo     

Role of proteins in cosmetics

The review critically evaluates the safety and effectiveness of proteins or peptides in cosmetic formulations designed for skin and hair care. Special attention is paid to soluble collagen and the use of this fibrillar protein in combination with detergents.
The authors indicate various misconceptions on the mechanism of the effect of collagen and possible risks if the formulations containing collagen are not used on intact skin. Besides the moisturizing effect of collagen on the stratum corneum, the formation of a protective layer on the surface of the skin or hair, and the formation of complexes with detergents and the mechanisms of the effectiveness of this protein are considered.
Le role des proteines dans les cosmetiques     

The preparation of visible emulsions and its applications to cosmetics

We developed a preparation method for visible emulsion droplets (0.05–3 mm) consisting of a solid type oil and a liquid type oil. It was found that (1) using amphiphiles as the solid oil gave a spherical and visible sized particle and (2) behenyl alcohol was the most preferable amphiphile to make a large sized particle. DSC measurement and microscopic observation of the particle showed that the amphiphilic solid oil built a shell on the outer side of the particle and the shell protected the emulsion against aggregation and coalescence. It was found that the preparation of an extremely large emulsion could create innovative functions in the cosmetic field. The visible sized emulsion could provide a freshening feel in the early stages of the application and an emollient feel after rubbing into the skin. Furthermore, since this emulsion could protect an unstable lipophilic material from hydrolysis, it offers a suitable storage for useful cosmetic ingredients such as lipophilic drugs and hydrophobic powders.     

Development of an in vitro efficacy test for self-tanning formulations

In the last few years, the desire to acquire a tan without sunbathing has grown. In response, many cosmetic companies have produced self-tanning preparations. However, to optimize these formulations, a suitable model to assess the colour induced on the skin remains to be developed. We have developed an in vitro method using a synthetic skin in order to study the efficacy of self-tanning formulations. The in vitro test was then used to study the influence of cosmetic ingredients upon the colour induced by erythrulose- or dihydroxyacetone-containing formulations. Finally, an in vivo study allowed us to relate the results obtained in vitro with those found on human skin. The results show that this in vitro test system is a reliable tool to predict the efficacy of self-tanning products.     

Skin moisturization by hydrogenated polyisobutene—Quantitative and visual evaluation

Hydrogenated polyisobutene (HP) is used in topically applied cosmetic/personal care formulations as an emollient that leaves a pleasing skin feel when applied, and rubbed in after application. This effect, although distinguishable to the user, is difficult to define and quantify. Recognizing that some of the physical properties of HP such as film formation and wear resistance may contribute, in certain mechanisms, to skin moisturization, we designed a short-term pilot study to follow changes in skin moisturization. HP's incorporation into an o/w emulsion at 8% yielded increased viscosity and reduced emulsion droplet size as compared to the emollient ester CCT (capric/caprylic triglyceride) or a control formulation. Quantitative data indicate that application of the o/w emulsion formulation containing either HP or CCT significantly elevated skin moisture content and thus reduced transepidermal water loss (TEWL) by a maximal ∼33% against the control formulation within 3 h and maintained this up to 6 h. Visual observation of skin treated with the HP-containing formulation showed fine texture and clear contrast as compared to the control or the CCT formulation, confirming this effect. As a result of increased hydration, skin conductivity, as measured in terms of corneometer values, was also elevated significantly by about tenfold as early as 20 min after HP or CCT application and was maintained throughout the test period. Throughout the test period the HP formulation was 5–10% more effective than the CCT formulation both in reduction of TEWL as well as in increased skin conductivity. Thus, compared to the emollient ester (CCT), HP showed a unique capability for long-lasting effect in retaining moisture and improving skin texture.     

Renewable sources: applications in personal care formulations

A global tendency for products considered environmentally sustainable, and ecologically obtained led the industry related to personal care formulations to fund the research and the development of personal care/cosmetics containing ingredients from natural resources. Furthermore, consumers are aware of environmental and sustainability issueans, thus not harming the environment represents a key consideration when developing a new cosmetic ingredient. In this study we review some examples of active ingredients or raw materials used in cosmetics/personal care/biomedical products that are coming from either through biotechnological systems, or as byproducts of several industries. A skin formulation containing biosynthetic actives, prepared by us and the study regarding its dermocosmetic properties are also described. The need for the standardization processes, the safety assessment tools, the improvement of the exploitation methods of these renewable sources in order the production to be ecologically and economically better are also discussed.     

Kinetics of moisturizing and firming effects of cosmetic formulations

The assessment of cosmetic efficacy is rarely performed in studies comparing different concentrations of active compounds. The aim of the present study was to determine the skin hydrating and the skin firming dose-response effects of cosmetic formulations enriched in compounds derived from algae and fish collagen. A series of factors were studied including the type of formulation (cream or serum), the concentration in active ingredients, the effect of repetitive applications, as well as any residual effect of the formulations after stopping their applications. The serum enriched in marine compounds showed a better moisturizing effect in short term. The cream appeared more active later, particularly following repeat applications. A sustained tensor (firming) effect was observed during treatment with both the lotion and the cream. However, no remnant firming effect was perceived after stopping treatment.     

A comparison of females and males for anti-perspirant efficacy and sweat output

For human skin, high water content and low sebum secretion are considered to be main features of fair skin. To explore the proper personal care regimen for facial skin, we investigated the change of skin physiologic parameters after cosmetic application by measuring the skin water content, transepidermal water loss, and skin sebum secretion on facial skin before and after the cosmetic application using the Corneometer, Tewameter, and Sebumeter, respectively. The results indicated that the cosmetics application kept a higher water content and a lower transepidermal water loss, and at the same time, a lower sebum secretion 4 h and 8 h after the cosmetic application, compared with those before it. The situation was maintained in the succeeding three week continuous use of the cosmetics. It could be concluded that the cosmetic application on human facial skin might provide some moisturizing effect and at the same time an anti-sebum effect, which favors the maintenance of good skin physiological function after applying skin care products. Our results might provide a scientific personal care regimen for human facial skin to prompt the balance for the hydrolipid film on skin.     

In vitro skin permeation evaluation: the only realistic option

Increasing requirements for cruelty-free risk assessment in the cosmetic industry have led to the development of several alternative experimental evaluation strategies. Quantification of the potential dermal absorption of ingredients of cosmetic and other formulations by determination of human skin permeation rates in vitro is particularly relevant. Using modifications of standard in vitro protocols the human skin permeation rates of several cosmetic ingredients and potential contaminants have been determined under conditions designed to mimic consumer use. Skin penetration and permeation of octyl salicylate (a sunscreen), nonylphenol ethoxylates (surfactants) and three nitrosamines (potential contaminants) is discussed. The data demonstrate the usefulness of this technique as a tool in the overall risk assessment of cosmetic formulations.     

Infant skin physiology and development during the first years of life: a review of recent findings based on in vivo studies

Infant skin is often presented as the cosmetic ideal for adults. However, compared to adult skin it seems to be more prone to develop certain pathological conditions, such as atopic dermatitis and irritant contact dermatitis. Therefore, understanding the physiology of healthy infant skin as a point of reference is of interest both from the cosmetic as well as from the clinical point of view. Clinical research on healthy infants is, however, limited because of ethical considerations of using invasive methods and therefore until recently data has been scarce. Technical innovations and the availability of non‐invasive in vivo techniques, such as evaporimetry, electrical impedance measurement, in vivo video and confocal microscopy, and in vivo fibre‐optic based spectroscopy, opened up the field of in vivo infant skin physiology research. Studies incorporating such methods have demonstrated that compared to adult, infant skin continues to develop during the first years of life. Specifically, infant skin appears to have thinner epidermis and stratum corneum (SC) as well as smaller corneocytes at least until the second year of life. The water‐handling properties are not fully developed before the end of the first year and infant SC contains more water and less amounts of natural moisturizing factors. Such findings re‐evaluate the old notions that skin is fully matured at birth. Armed with this knowledge, we are in a position not only to better understand infant dermatological conditions but also to design better skin care products respecting the distinct qualities of infant skin.     

Main features and applications of organogels in cosmetics

Cosmetic treatments aim at improving skin appearance through vehicles of good sensory properties. Those vehicles are mainly emulsions and gels designed to deliver safe and effective compounds to skin. Creams and serums are widely used to achieve these goals, but recently a new type of formulation known as organogels triggered scientific attention, particularly in the design of both topical and cosmetic formulations. It has been established that the lipophilic nature of organogels makes it an excellent candidate for the delivery of cosmetic molecules through skin. In this review, we discuss the properties and characteristics of organogels and present the advantages of the application of these systems in cosmetics.