Hair is basically composed of proteins, water, lipids and pigments. The amino acids in the cuticle and hair cortex are similar and more often than not neutral (>70%), while in general hair has a negative charge, a result of the amino acids’ side-chains. Chemically speaking, 80% of human hair is made of keratin.
Keratin is a water-insoluble fibrous protein found in hair, skin and nails and formed of helix-shaped polypeptide chains. It maintains its structure and characteristics thanks to the bonds formed in the polypeptide chains, which could be Van der Waals force (very fragile, bringing molecular stability and making keratin folding possible), hydrogen bonds (fragile bonds between amino acids), ionic bonds (between acid and basic side-chains) or disulfide bonds (bonds between the cysteines).
Keratins are grouped into two families, α- and β-keratin, with the majority of hair α-keratin. Its polypeptide chain forms an α helix and several of these make up protofibrils. Protofibrils combine and form microfibrils, which, in turn, form macrofibrils. Hair fiber is made up of accumulated macrofibrils, which gives hair optimum resistance.
β-keratin is different in that it has no cysteine, is less stable and last less time, but it is flexible, owing to its beta configuration. Both α- and β-keratin are shown in Image I below:
Image I – Structure of α- (above) and β-keratin (below)
Hydrolyzed Wheat Gluten (and) Hydrolyzed Corn Protein (and) Hydrolyzed Rice Protein (and) Zea Mays Starch is a cereal hydrolisate obtained from controlled enzymatic hydrolysis of rice, wheat and corn protein, located in a controlled-release cationic matrix.
As an active cosmetic ingredient must be left on the hair surface long enough to bring about a cosmetic benefit and achieve the maximum effect on hair and its keratin, a mechanism of application which allows this is needed. The controlled-release cationic matrix is responsible for this.
This matrix is formed of amilopectin, of a cationic derivative of guar gum and poliquaternium -7, elements selected and combined to act selectively on hair fiber. This combination of non-ionic, cationic, film-forming components gives rise to Matriz Plus, a sequential and controlled-release system of active hair ingredients. This matrix adheres to the hair fiber and increases the contact time with the active ingredients released, which act on the hair cuticle and cortex.
Amilopectin is a non-ionic water-soluble biopolymer obtained from corn and made up of glucose units bound linearly by α bonds. Its branch structure, as shown in Image II below, gives it a configuration able to hold 100,000-200,000 glucose molecules and allows the product to remain on the hair surface but doesn’t allow it to accumulate in excess, unlike that which occurs in linear polymers.
Cationic guar gum is a cationic polymer and as such integrates with the negative charges on the hair surface and deposits itself over the keratin, making it easier to brush wet hair and increasing hair substantivity. The third component is poliquaternium-7, a polymer which doesn’t allow the build-up of static electricity and improves the film-forming properties of the matrix components.
In addition to this, the active ingredient forms a protective film, facilitating tissue repair, protecting the fiber against external aggressions and improving hair’s elasticity. Further, it forms bonds with the keratin negative charge amino acids and contributes to the stabilization of the fibers’ peptide chains.