Universal remote control of wetting behavior enabling the transition from a superomniphobic to an omniphilic wetting state in an external magnetic field via the alternation of reentrant curvature of a microstructured surface is demonstrated. This reconfigurable microtexture made of Ni micronails repels water, water-surfactant solutions, and practically all organic liquids, whereas it gets wetted by all of these liquids after a magnetic field pulse is applied.
The objective of this study is to provide a novel synthetic approach for the manufacture of wound-healing materials using covalently cross-linked alginate fi bers loaded with silver nanoparticles. Alginate fi bers are prepared by wet-spinning in a CaCl 2 precipitation bath. Using this same approach, calcium cross-links in alginate fi bers are replaced by chemical cross-links that involve hydroxyl groups for subsequent cross-linking by glutaraldehyde. The cross-linked fi bers become highly swollen in aqueous solution due to the presence of carboxyl functional groups, and retain their mechanical stability in physiological fl uids owing to the stabilized network of covalent bonds. Alginate fi bers can then be loaded with silver ions via the ion-exchange reaction. Silver ions are reduced to yield 11 nm silver nanoparticles incorporated in the polymer gel. This method provides a convenient platform to incorporate silver nanoparticles into alginate fi bers in controlled concentrations while retaining the mechanical and swelling properties of the alginate fi bers. Our study suggests that the silver nanoparticles loaded fi bers may be easily applied in a wound healing paradigm and promote the repair process though the promotion of fi broblast migration to the wound area, reduction of the infl ammatory phase, and the increased epidermal thickness in the repaired wound area, thereby improving the overall quality and speed of healing.
Wet-spun stimuli-responsive composite fi bers made of covalently crosslinked alginate with a high concentration of single-walled carbon nanotubes (SWCNTs) are electroconductive and sensitive to humidity, pH, and ionic strength, due to pH-tunable water absorbing properties of the covalently crosslinked alginate. The conductivity depends on the material swelling in humid atmosphere and aqueous solutions: the greater the swelling, the smaller is the electrical conductivity. The covalently crosslinked fi bers reversibly deform during the swelling/shrinking. In the swollen state, the fi bers are less conductive, while they return to the same level of conductivity after shrinking. This unique reversible change of electroconductivity of the SWCNT-alginate fi bers is due to the elastic deformation of the alginate network in the area of electrical contacts between SWCNT bundles arrested in the alginate matrix. Fibers of this kind can be used as a simple, robust, disposable, and biocompatible platform for electrotextiles, biosensors, and fl exible electronics in biomedical and biotechnological applications.
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