Confined‐Synthesis of Ceria in Tubular Nanoclays for UV Protection and Anti‐Biofilm Application

Abstract

UV radiation is the main cause of skin aging and cancers. Commercial sunscreens suffer from low efficacy and poor safety, while ceria nanocrystals are promising inorganic UV filters. Herein, the lumen of natural halloysite clay nanotubes (HNTs) is employed for the confined growth of ceria nanocrystals, which can effectively tailor the particle size, morphology, distribution, and oxygen vacancies of the ceria. The ceria in HNTs lumen exhibits increased UV protection and catalytic activity, while the outer surfaces of HNTs can be retained for additional modification. Ceria‐loaded HNTs (named CeOx@HNTs) can act as oil–water interfacial stabilizers to develop skin‐friendly Pickering emulsion sunscreens. Attributed to the Pickering emulsion interfacial catalytic effect of CeOx@HNTs, the UV absorption performance of the sunscreens is enhanced by 3.1 times after emulsification, achieving a sun protection factor of 58.5. In vitro and in vivo studies confirm the effectiveness of the prepared sunscreen in mitigating DNA damage, apoptosis, and malignant transformation. In addition, the sunscreen inhibits biofilm formation by disturbing membrane homeostasis through oxidative stress. This work develops a confined‐growth method of rare earth oxides within tubular nanoclays, which shows promising applications in many fields, such as aging resistance, photoluminescence, and chemical catalysis.

Nitric Acid-Pretreated Natural Halloysite Nanotubes as Ni Nanoparticle Catalyst Supports for CO2 Methanation

“…The micromorphology of the reduced catalysts was examined by TEM characterization (Figure ). It can be seen that most Ni particles are dispersed on the outer surface of HNTs, and a small fraction of Ni particles may enter into the lumen of HNTs (Figure S3) due to the vacuum operation. , The average Ni particle size of Ni(17%)/HNTs- x AC is smaller than that of Ni(17%)/HNTs (Table ), suggesting that HNTs pretreated with HNO 3 can improve the dispersion of metal particles. It is worth noting that the size of Ni nanoparticles grows when the concentration of HNO 3 solution increases from 8 to 10 mol/L.…”

Synergistic Catalytic Removal of NOx and n-Butylamine via Spatially Separated Cooperative Sites

“…For example, Tao et al found that the introduction of molybdenum oxide promoted the dispersion of vanadium oxide species on TiO 2 support. , As the literature reported, the ionic radius of Cu 2+ (72.0 pm) was smaller than that of Ce 3+ (101.3 pm). When Cu 2+ and Ce 3+ coexisted in aqueous solution, Cu 2+ ions could more easily penetrate the tube of TiO 2 NTs than Ce 3+ . , To maintain the potential balance of the solution, Ce 3+ ions were mainly focused on the outer surface of the tube. After calcination, most of the CuO x species were inclined to enter the TiO 2 NTs, while most of the CeO x species were mainly anchored on the outer surface .…”

A Solid-System Strategy for Controlled Hydrolytic Release of Hydrogen by Encapsulation of Ammonia Borane in Cobalt Decorated Halloysite Aerogel

“…It has been widely used in various fields, 27,28,31−35 including pollutants removal, catalysis, energy storage, polymer filler, drug delivery, etc., attributing to its hollow tubular structure, high specific surface area, and opposite surface charges. 35−37 Especially, HNT is supposed to be a potential carrier for supporting nanocatalysts [31][32][33]38 and trapping AB into its channels or coating AB on its surface in view of its distinct microstructure and the abundance of Al/Si-OH groups on inner/outer surfaces. 34,39,40 Assembling HNT into hierarchical porous aerogel can further increase the porous volume for supporting and trapping more matrix and inhibiting their aggregation 41−44 because aerogels have more complex porosity, lower density, and higher surface area.…”

“…It usually has a tubular shape with an inner diameter of 5–20 nm and a length of 0.5–2 μm. − Halloysite nanotubes (HNT) are composed of silyl groups (Si-O-Si) on their outer surfaces and aluminum trihydrate octahedral groups (Al-OH) on their inner surface. It has been widely used in various fields, ,,− including pollutants removal, catalysis, energy storage, polymer filler, drug delivery, etc., attributing to its hollow tubular structure, high specific surface area, and opposite surface charges. − Especially, HNT is supposed to be a potential carrier for supporting nanocatalysts − , and trapping AB into its channels or coating AB on its surface in view of its distinct microstructure and the abundance of Al/Si-OH groups on inner/outer surfaces. ,, Assembling HNT into hierarchical porous aerogel can further increase the porous volume for supporting and trapping more matrix and inhibiting their aggregation − because aerogels have more complex porosity, lower density, and higher surface area. − For example, Ma et al in our group have encapsulated phase change material lauric acid into HNT aerogel, which can significantly improve the loading capacity of lauric acid …”