What’s the biggest challenge of all skincare products and active ingredients? The correct answer is penetration.
The skin is the largest human organ and consists of three functional layers: epidermis, dermis, and subcutis. It has a wide variety of functions. One major task of the skin is to protect the organism from water loss and mechanical, chemical, microbial, and physical influences. The protective properties are provided by the outermost layer of the skin, the epidermis. Although its thickness measures on average only 0.1 mm (from 0.02 mm on the face up to 5 mm on the soles of the feet) it is specially structured to fulfil this challenging task. Out of the five layers of the epidermis, it is mainly the uppermost layer (horny layer; stratum corneum) which forms the permeability barrier.
Dermatological and cosmetic preparations frequently contain active principles which can only act when they penetrate at least the outermost layer of the skin. However, the efficacy of topically applied actives is often suboptimal because the transport into the skin is slow due to the resistance of the outermost layer of the skin, the stratum corneum. Most small water-soluble nonelectrolytes, therefore, diffuse into the systemic circulation a thousand times more rapidly when the horny layer is absent. Thus, a variety of means have been studied in attempts to overcome this barrier. And microneedles are one of the most promising ones.
Using the microneedle array, significant enhancement in the skin permeability of niacinamide and the antioxidant activity of ascorbic acid after crossing the skin was observed.
Generally, microneedles can be divided into two types, a solid type consisting of silicon or stainless material, and a self-dissolving type made mainly from biodegradable materials, such as hyaluronic acid or saccharides.
A special category of self-dissolving microneedles is bio needles, extracted from the freshwater Spongilla sponge. These needles are so tiny, you won’t be able to see them with your naked eyes. Due to the small size, they are completely painless and could be used both in patches and mixed with skincare products: creams, serums and even peeling gels.
Facial wrinkles are representative of skin ageing caused by the reduction of skin elasticity and degradation of the extracellular matrix. Raphas (South Korean company specializing in the production of dissolving microstructures) has commercialised various wrinkle treatment microneedle patch products. The matrix material of this microneedle is hyaluronic acid, which has been used as a moisturising and filling agent for many cosmetic products. This hyaluronic acid-based microneedle has wrinkle treatment efficacy by itself. Additionally, this product could be combined with a cream or essence type product for better wrinkle treatment efficacy. Epidermal growth factor (EGF) loaded microneedles showed significant wrinkle treatment efficacy after applying every day for 10 days.
Shiseido successfully developed an eye patch showing effective improvement of wrinkles, which was used self-dissolving microneedle technology. Successive administration of this patch preparation to the eye corner resulted in significant improvements of wrinkles, with increases of water content in the stratum corneum and viscoelasticity, which is an index of resilience.
Raphas also developed Trouble Cure, the product designed for restoring acne affected skin quickly without leaving scars. This product can help people manage acne efficiently and hygienically. The microneedle contains antimicrobial and anti-inflammatory ingredients within the hyaluronic acid backbone structure. The length of the microstructure is around 500 µm so that the active ingredient can be directly transferred to the hair follicle region where the bacterium causes the acne. After application, an anti-inflammatory ingredient is delivered into the skin to suppress the inflammation of the acne, and an added antimicrobial ingredient helps to inhibit the activity of inflammation-causing bacteria. The antimicrobial ingredient is a peptide that is effective against antibiotic-resistant strains.
Trouble Cure can deliver the antimicrobial peptide directly into the target region via the microneedle patch without loss of activity. Clinical trial results showed that more than 90% of subjects had improved skin condition after four days from the first application of the product, which proved to be safe, without adverse skin reactions during the test.
Raphas has developed a novel concept for a topical whitening product by the name of Spot Eraser. This product can treat topical hyperpigmented spots by inhibiting the multi-pathway of hyperpigmentation using tranexamic acid, niacinamide, ascorbic acid and arbutin. Tranexamic acid can inhibit melanogenesis through the activation of autophagy in a melanoma cell line. Niacinamide reduces cutaneous pigmentation by inhibiting melanosome transfer. Ascorbic acid is a strong antioxidant that can inhibit melanin oxidation to keep the melanin in a relatively brighter colour form. Arbutin is a glycosylated hydroquinone which can inhibit tyrosinase activity. Clinical results for Spot Eraser showed significant efficacy in terms of postinflammatory hyperpigmentation after a single application every two days for four weeks, and observing for an additional two weeks without further applications. Clinical results also showed a significant decrease in melasma area and severity index. These results indicate the Spot Eraser could be a good solution for the topical treatment of hyperpigmentation.
Unfortunately, self-dissolving microneedles are still very new to skincare. And while the Korean company, mentioned above, Raphas already sells patches with microneedles under their trade name Acropass and also manufactures these products for other companies, there're still no affordable and easily accessible skincare products with microneedles on the market.
There's no doubt, that these will be introduced by popular Korean brands very soon though. Until then, we have to wait patiently.
- Korean Kiwi Beauty