Retinol derivative as bioinitiator in the synthesis of hydroxyl-functionalized polymethacrylates for micellar delivery systems
eXPRESS Polymer Letters
Introduction Retinol (RET, also known as vitamin A), which is the popular component of cosmetic products, belongs to the group of fat-soluble hydrophobic vitamins indicating good penetration into the epidermis and recovery effect, especially with regard to skin disorders like wrinkles, acne and hyperpigmentation  . RET improves elasticity of the skin because it stimulates collagen and glycosaminoglycans synthesis. The anti-aging properties are the consequence of the prevented oxidation
... ted oxidation stress and the delayed/inhibited matrix degradation by blocking the enzymes which decompose collagen  . In addition, RET eliminates sun and hormonal skin discolorations by reducing the size of melanocytes and the amount of melamine. RET as terpene alcohol has already been applied as the initiator of the ring-opening polymerization (ROP) of ethylene oxide  or lactide  resulting in welldefined biohybrid polymers with potential applications as liquid crystalline materials, amphiphilies, or conjugate systems targeted to stellate liver cells. However, according to the literature the delivery of RET is supported by encapsulation strategy, mostly into chitozan    , and polyester (polyadipates, polycaprolactone)  nanoparticles. Moreover, spherical inorganic particles containing RET have been fabricated using silica in combination with surfactants and hydroxypropyl cellulose , tetraethyl orthosilicate sol-gel systems , or polyphosphates with calcium ions  . The alternative systems entrapping RET are represented by solid lipid nanoparticles based on glyceryl behenate [12, 13] . Abstract. Amphiphilic copolymers containing 2-hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) units were synthesized by controlled atom transfer radical polymerization (ATRP) applying bromoester modified retinol (RETBr) as a novel initiator. Analogous series of copolymers with adjustable hydrophilic-hydrophobic balance was obtained with the use of a standard initiator, i.e. ethyl α-bromoisobutyrate (EBriB). The self-assembling particles, prepared by the solvent evaporation, were loaded with vitamin C (VitC) or ferulic acid (FA). The hydrophilic/hydrophobic ratio in the copolymer was indicated as a crucial factor to regulate efficiencies of encapsulation processes in the range of 53-98%. In vitro release of bioactive substance was carried out in phosphate buffer solution (PBS) at pH 7.4 with the maximum amount of VitC after 1h (27-62%) or FA within 2 h (71-97%). The polymeric systems with satisfactory encapsulation characteristics and release profiles are attractive micellar carriers of antioxidants, which, due to their activities could be also delivered using the popular approaches in cosmetology like masks, under-eye patches, or wraps.