Exploiting Confined Interior of Clay Nanotubes: Architectonic Design and Enhanced Mesocatalysts

Dr. Yuri M. Lvov
Professor of Chemistry
Louisiana Tech University

We developed self-assembly of halloysite clay nanotubes for organized organic / inorganic heterostructures. These 50-nm diameter and 1 mkm length aluminosilicate tubes allow for 10-20 wt. % loading with proteins, drugs metals, or other chemicals and templating mesosilica; these nanotubes may be also assembled in ordered arrays at interfaces and surfaces. Halloysite is safe, available in thousand tons natural material, which is not harmful for environment and allows for “green” water-based chemical processing. 1) Nanoconfined catalysis [1,2]: 2-5 nm metal particles (Au, Ag, Co, Ru, Fe2O3, ZrO2, Cu-Ni and CdS) inside / outside of these aluminosilicate nanotubes were also produced as mesocatalytic systems. We also focused on enzymatic catalysis and study bio-inhibiting effects in the confined interior of the nanotubes. Halloysite nanotubes are rolled kaolin sheets with different inside/outside surface chemistry (Al2O3/SiO2) allowing for selective and spatially separated treatments toward enzymatic catalysis. We demonstrated the tubes’ enzyme loading selectively inside or outside of the tubes. We performed halloysite-mediated enclosure and stabilization; our first choice is glucose oxidase (GOx) and fluorescently labeled GOx and the next enzyme of interest is pepsin. We will explore the influence of the specific conditions in the nanoconfined interior on behavior of the enclosed bio macromolecules. We will analyze glucose oxidase, urease, peroxidase and laccase encapsulation, will visualize the proteins’ load and optimize it by varying the lumens’ diameter, length, formation of the tube-end stoppers, developing pH gradient inside the tubes, and providing water enclosure necessary for enzyme functionality in oil media. Study of synergy for the nanoclay having an enzymatic core, and ceramic shell decorated with not harmful NiO nanoparticles for catalytic waste polymer decomposition will be exploited. 2) Biocoating [3]: Halloysite self-assembly on hair and textile fibers allows for stable 3-4 mkm clay coating. Encasing of dye or drugs into these nanotubes applied to hair from aqueous dispersions provides stable coloring and antilacing effect. Clay nanotubes were also processed in oriented arrays with brush assistant shear force deposition or using “coffee ring” ensemble formation mechanisms. These nanoclay patterns supported the stem cell proliferation with alignment and promoted osteogenesis differentiation without growth factor. 1. Y. Lvov, W. Wang, R. Fakhrullin, Advanced Mater., v.28, 1227, 2016, “Halloysite Clay Nanotubes for Loading and Sustained Release of Functional Compounds,” A. Glotov, A. Vutolkina, Y. Lvov, Chem. Soc. Rev, v.50, 9240, 2021, “Clay nanotube-metal core/shell catalysts.” A. Stavitskaya, Y. Lvov, et al, Nanoscale Adv., v.4, 2823-2835, 2022, "Architectural design of core-shell nanotube systems based on aluminosilicates." 2. J. Tully, Y. Lvov, Biomacromolecules, v.17, 615, 2016, "Enzyme Stabilization by Immobilization Into Clay Nanotubes." 3. A. Panchal, G. Fakhrullin, Y. Lvov, Nanoscale, v.10, 18205, 2018, "Clay nanotube hair coating for coloring and drug delivery,” and X. Zhao, M. Liu, Y. Lvov, et al, Small, v.15, 1900357, 2019, “Clay nanotube aligned with shear forces for stem cells patterning.”