Solid SiO₂-Sealed Mesoporous Silica for Synergistically Combined Use of Inorganic and Organic Filters to Achieve Safe and Effective Skin Protection from All-Band UV Radiation

Abstract

To effectively shield the full band of ultraviolet (UV) radiation and provide desirable protection, the combination of inorganic and organic filters was often used to protect human skin from the serious harm of UV exposure. However, the incompatibility of different filters and their mutual negative effect limit the production of multifilter sunscreen. In addition, the hazard of reactive oxygen species (ROS) produced by inorganic filters after UV exposure and the skin permeability of organic filters remain unresolved problems. In this study, titanium dioxide (TiO2) and diethylamino hydroxybenzoyl hexyl benzoate (DHHB), two kinds of common filters with complementary UV shielding range, were first encapsulated into large mesoporous silica nanoparticles (MSN, ∼300 nm) to obtain MSN-TiO2 and MSN-DHHB. Also, a SiO2 coating was then made to seal and stabilize the MSN-TiO2 and MSN-DHHB. The structure, UV screen function, and safety of the SiO2-coated filters, MSN-TiO2@SiO2 and MSN-DHHB@SiO2, were evaluated. The good mechanical stability exhibited by the solid SiO2 layer prevented the release and skin penetration of the sealed DHHB and the photocatalysis of TiO2. Furthermore, the combination of MSN-TiO2@SiO2 and MSN-DHHB@SiO2 in sunscreen cream showed excellent UV shielding performance on covering the whole UV radiation range without mutual interference. Therefore, coating SiO2 over MSN is a feasible strategy for entrapping various filters to improve their photostability, preventing skin penetration and ROS generation, and enhancing their compatibility with different sunscreen formulations.

Human-Hair-Derived Natural Particles as Multifunctional Sunscreen for Effective UV Protection

“…For example, UV-absorbing molecules are encapsulated into biocompatible polymers or nanoparticles (liposome nanoparticles, polylactic acid nanoparticles, silica nanoparticles, etc.) to reduce their toxicity. − In addition, coating biocompatible materials such as cyclodextrins and polymers on inorganic particles was also an effective way to reduce the risk of sunscreens. , Surprisingly, several nanomaterials have been found to be directly used as sunscreens and achieve a certain UV protection effect. − These studies showed only a slight improvement in minimizing the negative effects of traditional sunscreens, while the fundamental problems have not been solved yet, and the side effects caused by such products still pose a threat to human health.…”

Advancing Evidence-Based Data Interpretation in UV–Vis and Fluorescence Analysis for Nanomaterials: An Analytical Chemistry Perspective

“…Reliable quantification of nanoparticles absorption, scattering, and emission activities is essential for rational materials characterization, design, and applications as these optical processes differ significantly in their causes, effects, and applications. As examples, metal oxide nanoparticles with strong scattering activities in the UV ranges has been used extensively as sun block, while plasmonic nanoparticles find utilities in biosensing due to their strong scattering in the visible to infrared wavelength range. − The applications of photoactive nanoparticles, referring to chromogenic and fluorogenic nanomaterials, are even more diverse, ranging from photocatalysis, − photoluminescence, − photodynamic therapy, − photoelectronics, − and photothermal energy harvesting, − just to name a few. For these applications, it is the absorbed photons, not the scattered photons, that are directly responsible for chemical reactions in photocatalysis, light emission in photoluminescence, and singlet oxygen generation in photodynamic therapy.…”

Application of Bimetallic Heterojunction Nanoparticle-Based Multishelled Porous Hollow Microspheres as a Two-in-One Inorganic UV Filter

“…7 Due to their capacity to penetrate past the epidermis of the skin, TiO 2 and ZnO NPs are incorporated into the stratum corneum, altered transcriptional patterns, and substantially enriched genes and pathways that control cell communication, apoptosis, cell proliferation/differentiation, and RNA production. 19 Coating the particles 20 cannot totally avoid photocatalytic effects, which are most prominent for anatase TiO 2 . 7 A potential solution is to use a nanofree UV filter through controlled synthesis of two-in-one porous hollow micro-UV filters.…”