Structure and Properties of Hybrid Film Fabricated by Spin-Assisted Layer-by-Layer Assembly of Sacran and Imogolite Nanotubes

Abstract

A free-standing (biomacomolecule/synthetic inorganic nanotubes) hybrid film was fabricated through an alternative layer-by-layer (LBL) assembly of sacran and imogolite nanotubes. Sacran is a natural polysaccharide extracted from the cyanobacterium Aphanothece sacrum, while imogolite is a natural tubular aluminosilicate clay found in volcano ash. The hybrid film thickness increased linearly with the number of the bilayers, because of the interaction between the negatively charged surface of sacran and the positively charged surface of imogolite. UV–vis spectroscopy indicated that the LBL film exhibited good transparency. The surface morphology of the LBL film was smooth in the micrometer scale; many imogolite nanotubes were adsorbed onto the sacran layer, while no imogolite clusters were observed. Furthermore, the structure, stability, gas permeability, and mechanical properties of the LBL films were investigated.

Effect of Multilayer Termination on Nonspecific Protein Adsorption and Antifouling Activity of Alginate-Based Layer-by-Layer Coatings

“…Marine biofouling, the accumulation and growth of animals, plants, and microorganisms on surfaces which are in contact with aqueous environments, causes severe economic and ecological issues such as high fuel consumption, high operational and maintenance costs, an increased greenhouse effect, biocorrosion, and the translocation of nonindigenous species. − Since numerous commonly used antifouling coatings are toxic and environmentally harmful, nontoxic alternatives are investigated and developed to control and prevent marine biofouling without polluting the environment. − To identify new chemistries that are worth exploring for polymer formulations, monolayer systems or grafted macromolecules are frequently used. − Another facile method to directly apply charged biomacromolecules to surfaces is layer-by-layer (LbL) deposition in which oppositely charged macromolecules are alternately assembled on surfaces. − The resulting coatings provide functional materials with defined compositions, structures, and surface properties and are well suited for studies exploring interactions with cells, bacteria, or fouling organisms. − Besides electrostatic interactions, hydrophobic interactions, charge-transfer interactions, host–guest interactions, coordinative interactions, hydrogen bonding, or covalent bonding can also be exploited as a driving force for the formation of LbL coatings. − Fine tuning of the properties of the coatings can be achieved by tailoring the charge density, addition of salts, and choice of solvents. − Depending on the choice of macromolecules, LbL coatings can respond to water, ions, pH, and temperature by swelling, morphological reorganization, changes in mechanical properties, or an alteration of their permeability. ,,− Polyelectrolyte multilayers (PEMs) are applied in different fields where resistance against the nonspecific adsorption (NSA) of proteins and antibacterial properties is required, especially in biomedical applications. ,,−…”

The Use of Megamolecular Polysaccharide Sacran in Food and Biomedical Applications

“…In solution, sacran is a polyelectrolyte, and because of its electric charge, the conformation of the sacran chain changes depending on its concentration. For instance, a helix transition concentration occurs when a chain of sacran changes from a random coil into a double helix at 0.09%, and gelation concentration occurs when sacran transitions from liquid to gel at 0.25% [ 28 , 29 ]. With increasing concentration, the sacran chain changes into a rigid rod form, showing liquid crystalline (LC) properties [ 30 , 31 ].…”

Effect of Polymer Length on the Adsorption onto Aluminogermanate Imogolite Nanotubes

“…Within this, imogolite was successfully employed with various polymers as a reinforced filler for functional nanocomposites with enhanced mechanical, optical, or electrical properties, including self-healing capability. [27][28][29][30][31][32][33][34] An interesting advantage of INTs is the high density of hydroxyl groups on the outer surface (~ 18 OH/nm²). It should promote different possibilities of polymer adsorption, 35 or change in conformation as shown recently by nuclear magnetic resonance.…”

“…Consequently, INTs represent as interesting alternatives of the CNTs in numerous applications including the fabrication of polymer/filler nanocomposites with multifunctional characteristics. Within this, imogolite was successfully employed with various polymers as a reinforced filler for functional nanocomposites with enhanced mechanical, optical, or electrical properties, including self-healing capability. − An interesting advantage of INTs is the high density of hydroxyl groups on the outer surface (∼18 OH/nm 2 ). It should promote different possibilities of polymer adsorption or change in conformation as shown recently by nuclear magnetic resonance. , To date, however, the underlying mechanisms remain largely unexplored.…”