Spontaneously Self-Assembled Microgel Film as Co-Delivery System for Skincare Applications.

Nowadays, the design of innovative delivery systems is driving new product developments in the field of skincare. In this regard, serving as potential candidates for on-demand drug delivery and fulfilling advanced mechanical and optical properties together with surface protection, spontaneously self-assembled microgel films can be proposed as ideal smart skincare systems. Currently, the high encapsulation of more than one drug simultaneously in a film is a very challenging task. Herein, different ratios (1:1, 3:1, 9:1) of different mixtures of hydrophilic/hydrophobic UVA/UVB-absorbers working together in synergy and used for skin protection were encapsulated efficiently into spontaneously self-assembled microgel films. In addition, in vitro release profiles show a controlled release of the different active molecules regulated by the pH and temperature of the medium. The analysis of the release mechanisms by the Peppas-Sahlin model indicated a superposition of diffusion-controlled and swelling-controlled releases. Finally, the distribution of active molecule mixtures into the film was studied by confocal Raman microscopy imaging corroborating the release profiles obtained.

Influence of cosmetic formulations on the skin's circadian clock.

OBJECTIVE: The circadian rhythm was set into focus by awarding the Nobel Price of Physiology/Medicine to Jeffrey Hall, Michael Rosbash and Michael Young in late 2017. Numerous publications elucidated the molecular mechanisms driving the circadian biorhythms of our body, peripheral organs and each single cell. However, there is minor knowledge on the circadian rhythm of the skin, which has its own peripheral circadian clock in contact with cosmetic formulations. The skin's epidermal clock is excessively influenced by environmental factors like UV radiation or modern lifestyle, which may induce epidermal jetlag. Here, we give an overview on the current knowledge about the epidermal circadian clock and provide a cosmetic solution to protect and preserve the biorhythm of the skin. METHODS: Quantitative RT-PCR to analyse the gene expression of circadian clock genes and the downstream DNA repair gene OGG1 in keratinocytes irradiated with UV-B. In vivo study to determine skin parameters dependent on the circadian cycle and interference of cosmetic formulations to them by assessment of morning and evening values at each measurement day after 28, 56 and 84 days of the study. RESULTS: UV-B irradiation leads to a pronounced delay in circadian clock and downstream gene expression which interferes in the proper function of epidermal stem cells and as thus skin function. The use of a cosmetic active ingredient prevents cyclobutane pyrimidine dimer formation, protects epidermal stem cells and resets the circadian gene expression. It preserves the circadian changes in skin hydration, reduces daily fluctuations of skin redness and strengthens the skin barrier. CONCLUSION: The skin has its own circadian biorhythm to gain full functionality. Interruption of this oscillation will lead to functional impairments. Here we show a cosmetic solution to protect and preserve the skin's circadian rhythm. DNA protection, ROS elimination and stimulation of circadian gene expression seem to be crucial to keep the skin in balance.

OBJECTIF: Le rythme circadien a été mis en lumière par l'attribution du prix Nobel de physiologie/médecine à Jeffrey Hall, Michael Rosbash et Michael Young fin 2017. De nombreuses publications ont élucidé les mécanismes moléculaires qui régissent les biorythmes circadiens de notre corps, des organes périphériques et de chaque cellule. Cependant, il existe peu de connaissances sur le rythme circadien de la peau, qui possède sa propre horloge circadienne périphérique, avec les formules cosmétiques. L'horloge épidermique de la peau est excessivement influencée par des facteurs environnementaux comme les rayons UV ou le mode de vie moderne, qui peuvent induire un "décalage horaire de l'épiderme". Nous donnons ici un aperçu des connaissances actuelles sur l'horloge circadienne épidermique et proposons une solution cosmétique pour protéger et préserver le biorythme de la peau. MÉTHODES: Test RT-PCR quantitatif pour analyser l'expression des gènes de l'horloge circadienne et du gène de réparation de l'ADN OGG1 en aval dans des kératinocytes irradiés aux UV-B. Étude in vivo pour determiner les paramètres cutanés dépendant du cycle circadien et l'interférence des formules cosmétiques sur ces paramètres par évaluation des résultats du matin et du soir à chaque jour de mesure après à 28, 56 et 84 jours d'étude. RÉSULTATS: L'irradiation aux UV-B entraîne un retard prononcé de l'horloge circadienne et de l'expression des gènes en aval, ce qui interfère avec le bon fonctionnement des cellules souches épidermiques et donc en conséquence avec la fonction de la peau. L'utilisation d'un principe actif cosmétique empêche la formation de dimère de cyclobutane pyrimidine, protège les cellules souches épidermiques et rétablit l'expression génique circadienne. Il préserve les changements circadiens dans l'hydratation de la peau, réduit les fluctuations quotidiennes des rougeurs cutanées et renforce la barrière cutanée. CONCLUSION: La peau a son propre biorythme circadien pour acquérir une assurer une parfaite fonctionnalité. L'interruption de cette oscillation entraînera des troubles fonctionnels. Nous présentons ici une solution cosmétique pour protéger et préserver le rythme circadien de la peau. La protection de l'ADN, l'élimination des ROS et la stimulation de l'expression des gènes circadiens semblent être cruciales pour maintenir l'équilibre de la peau.

Urea incorporated into ordered mesoporous silica for potential cosmetic application

Urea's thermal instability and burning on sensitive skin can cause problems for cosmetic formulations. To overcome these drawbacks, urea was incorporated into ordered mesoporous silica (SBA-15). SBA-15 was synthesized using tetraethyl orthosilicate and Pluronic® P123 in an acid medium. Urea (20 wt.%) was incorporated into calcined SBA-15 by the incipient wetness impregnation method. Several techniques were used to characterize the samples. Skin hydration and transepidermal water loss were measured using Corneometer® CM 825 PC and Tewameter® 300 TM. Results showed that the structural properties of SBA-15Urea were similar to pure SBA-15, indicating that SBA-15 remained structured even after urea incorporation. Nitrogen physisorption data showed the volume and surface area of the pores in SBA-15Urea were much lower than those in SBA-15, demonstrating that urea was deposited inside the mesopores. In vivo moisturization studies revealed that SBA-15Urea was not able to reduce transepidermal water loss compared to the other products and control, while forming a non-occlusive surface film on the skin. We conclude that incorporation of urea in the pores of the inorganic SBA-15 matrix is a promising approach to enhancing its stability and providing a prolonged moisturizing effect.

Versatile oligo(ethylene glycol)-based biocompatible microgels for loading/release of active bio(macro)molecules.

The present study aims in the understanding of the effect of oligo(ethylene glycol)-based biocompatible microgels inner structure on the encapsulation/release mechanisms of different types of cosmetic active molecules. For that, multi-responsive microgels were synthesized using three types of cross-linkers: ethylene glycol dimethacrylate (EGDMA), oligo(ethylene glycol) diacrylate (OEGDA) and N,N-methylenebisacrylamide (MBA). The inner morphology of the microgels synthesized was studied by 1H-nuclear magnetic resonance (1H NMR) and small-angle neutron scattering (SANS) techniques and no effect of cross-linker type on microgel microstructure was observed in the case of analysing purified microgel dispersions. Moreover, all the microgels synthesized presented conventional swelling/de-swelling behavior as a function of temperature and pH. Two hydrophobic, one hydrophilic, and one macromolecule as cosmetic active molecules were effectively loaded into different microgel particles via hydrophobic interactions and hydrogen-bonding interactions between -OH groups of active molecules and ether oxygens of different microgel particles. Their release profiles as a function of cross-linker type used and encapsulated amounts were studied by Peppas-Sahlin model. No effect of the cross-linker type was observed due to the similar inner structure of all the microgels synthesized.

The promise of marine molecules as cosmetic active ingredients.

The marine environment represents an underexploited resource for the discovery of novel products, despite its high level of biological and chemical diversity. With increasing awareness of the harmful effects of chronic ultraviolet exposure, and a universal desire to improve cosmetic appearance, the market for new cosmetic ingredients is growing, and current trends have generated a greater demand for products sourced from the environment. A growing number of novel molecules from marine flora and fauna exhibit potent and effective dermatological activities. Secondary metabolites isolated from macroalgae, including carotenoids and polyphenols, have demonstrated antioxidant, anti-ageing and anti-inflammatory activities. In addition, marine extremophilic bacteria have recently been shown to produce bioactive exopolymeric molecules, some of which have been commercialized. Available data on their activities show significant antioxidant, moisturizing and anti-ageing activities, but a more focussed investigation into their mechanisms and applications is required. This review surveys the reported biological activities of an emerging and growing portfolio of marine molecules that show promise in the treatment of cosmetic skin problems including ultraviolet damage, ageing and cutaneous dryness.