Epidermis
The epidermis consists of five layers: the Stratum Corneum (outermost layer), Stratum Lucidum (transparent layer), Stratum Granulosum (granular layer), Stratum
Spinosum (spiny layer), and Stratum Basale (new cell layer). Directly beneath the epidermis is the dermis, which contains essential components such as hyaluronic acid, elastin, collagen, fibroblasts, growth factors, sebaceous glands, and sudoriferous glands. Beneath the dermis is the hypodermis, which consists of adipose tissue or fat, providing shape and form to our skin.
Skin Barrier
The skin barrier is a critical component of our body's defense system, located on the outermost layer of the skin, known as the stratum corneum. This barrier plays a crucial role in protecting the skin from various harmful elements such as bacteria, viruses, free radicals, and the sun's damaging rays, while also helping to retain moisture and keep the skin well-hydrated. The skin barrier, or acid mantle, must remain intact to function properly. Continuously stripping off the barrier will impair its ability to do its job, underscoring the importance of choosing the right cleanser and skincare products. The skin barrier can be replenished with the correct skincare finishing products, which I will be discussing in my next blog.
Absorption Pathways
Skincare products are absorbed into our skin through intercellular, transcellular, and transappendageal pathways. Intercellular movement happens between skin cells, transcellular penetration requires passing through cell membranes, and the transappendageal pathway involves traveling through sweat glands or hair follicles. Understanding these pathways is crucial for formulators aiming to improve absorption and target specific skin layers.
Molecular Weights
Skincare products are like a carefully orchestrated symphony, with ingredients of varying molecular weights playing different roles. These weights range from large to standard, small, or even nano-sized molecules. The molecular weight of these ingredients is a key player in determining their ability to penetrate the skin. Larger molecules tend to stay on the skin's surface, providing hydration and creating a protective barrier.
Smaller molecules can penetrate deeper into the skin layers, delivering active ingredients to where they are most effective.
Nano-sized molecules, due to their tiny size, can penetrate even further, reaching the deepest layers of the skin. This precise manipulation of molecular weights empowers skincare formulators to create products that offer optimal benefits at specific depths within the skin. As a result, the science of skincare involves a sophisticated interplay of molecular weights and skin penetration pathways.
Hyaluronic Acid
Let's take a look at the molecular weights of Hyaluronic acid (HA), a common ingredient in many skincare products. The size, or "molecular weight," of HA is crucial for its effectiveness and is measured in daltons or kDa. HA comes in different sizes, but those around 130 kDa are considered most beneficial for the skin based on recent research.
The size of HA in skincare products can significantly influence its effects. For instance, smaller HA (known as low molecular weight HA or LMWHA), typically ranging from 20-300 kDa, can penetrate the top layer of the skin more easily than larger HA (known as high molecular weight HA or HMWHA). This allows LMWHA to enhance skin moisture and elasticity and reduce the depth of wrinkles.
On the other hand, larger HA tends to remain on the skin's surface, creating a moisturizing barrier and delivering an immediate plumping effect. By incorporating different sizes of HA in skincare products, we can target specific benefits, ultimately improving the appearance of the skin's surface as well as its overall health.
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