Preparation of hybrid organic/inorganic composite materials with antioxidant and antimicrobial properties for cosmetics and personal care applications

Abstract

ABSTRACT TiO2, a transition metal oxide that existed abundantly on earth has attracted many research interest due to its outstanding physical and chemical properties such as high refractive index, high thermal stability, nontoxicity and low cost. Over the centuries, TiO2 has been widely applied as a pigment in paints, enamels, plastics, paper, food, cosmetics and toothpastes. Recently, more research attention has been given to the functionalization of TiO2 leading to more promising applications, ranging from antimicrobial, photocatalysts for water treatment and functional cosmetics In this study, we focused on the applications of TiO2 in cosmetics and personal care products. Firstly, in order to ensure safety uses of TiO2 as a topical sunscreen and to enhance its properties, morphological control, surface modification and functionalization of TiO2 using organic topical skin lightening materials with antioxidant properties has been performed. To avoid skin penetration of ROS species, the TiO2 microspheres in amorphous phase were prepared by using Hexadecylamine as a structure controlling agent during the formation of microspheres. Prior to functionalization, the TiO2 particles were surface modified with monochloroacetic acid to introduce carboxyl groups as a chemical binder on the surface of TiO2 microspheres. To further suppress the photocatalytic properties and enhance properties of TiO2 in topical cosmetics and personal care applications, multifunctional hybrid. The core shell type organic/inorganic skin lightening materials-TiO2 were synthesized with carboxyl groups as a chemical binder under reflux method. The photocatalytic properties of TiO2 could be suppressed by coating an antioxidant on the surface of TiO2 that can trap ROS species. Also, antioxidant properties and enhanced UV absorption could also be achieved through the synergistic effect of alpha-bisabolol and phenylethyl resorcinol/TiO2 composites. Second, niacinamide (vitamin B3) which has been proven to have significant effects on skin treatment such as reductions in wrinkles and hyperpigmentation. However, naturing occurring topical skin lightening agents have very low thermal stability and insufficient skin penetration efficiency. To overcome these problems, Niacinamide-TiO2 has been synthesized. Hydroxylation treatment was carried out to introduce hydroxyl chemical binders for esterification reaction between Niacinamide and TiO2. As a result of the hybridization, Niaciamide-TiO2 composites demonstrated enhanced thermal stability and antimicrobial properties, which made it a suitable candidate for applications in cosmetics and personal care products. Besides that, in order to apply as the raw ingredients for acne treatment, azelaic acid, a skin lightening material with anti-inflammatory and antimicrobial properties has been employed to functionalize TiO2 microspheres. Prior to the functionalization process, the TiO2 microspheres were surface modified with NaOH to introduce hydroxyl groups on the surface of TiO2 as a chemical binders. Decoration of azelaic acid could be carried out by a condensation reaction between hydroxyl groups that existed on the surface of TiO2 and the hydroxyl groups of azelaic acid. The influence of NaOH concentration on the functionalization of azelaic acid was studied through the morphological and chemical states changes. The effect of hydroxylation treatment also has been investigated. The result obtained showed that higher degree of hydroxylation resulted in higher amount of deposited azelaic acid on the surface of TiO2. The synthesized hybrid azelaic acid-TiO2 showed high antimicrobial activities towards both Gram positive and negative bacterial strains, which is S.Aureus and E.coli. This research provides a new strategy to tune the properties of inorganic materials through morphological control, surface mordification and deposition of functional organic materials.