From highly ramified, large scale dendrite patterns of drying “alginate/Au NPs” solutions to capillary fabrication of lab-scale composite hydrogel microfibers

Abstract

The processes of complexation, aggregation and self-assembly involving natural polymers are not only ubiquitous in biological systems (proteins), but they are also crucial for environmental and technological applications (humic acids, polysaccharide-based hydrogels). In this paper, we address these issues through a model study of the drying structures of bi-component solutions of oppositely charged alginate polysaccharide and gold nanoparticles. Unlike single component alginate and nanoparticle solutions, we show that the sessile drops of the bicomponent mixtures lead, upon drying, to fibrillar dendrite patterns of rather unusual size and ramification density. We discuss the key parameters and the mechanisms which drive the formation of these highly ramified dendrite structures. These involve, on the one hand the composition (residual salt content), the drying mode and nanoparticle size, and on the other hand, the shear-drainage and concentration, the counterion condensation, and the co-assembly and co-crystallization of the polymer, the nanoparticles and the residual salts. Finally, inspired by these fibril-like drying patterns and the gel forming property of alginate, we have developed a microfabrication process of composite hydrogel microfibers, which we showed to be an effective and flexible tool for a lab-scale production, characterization and functional optimization of such nanomaterials, before large production.

Precipitation dynamics of surrogate respiratory sessile droplets leading to possible fomites

“…The bio-fluid compounds usually contain dissolved salt in them, and the deposition patterns of these salt-protein biofluid droplets were reported [52,53,54] . The formation of dendritic patterns was shown by Darwich et al [55] for a bi-component solution of oppositely charged alginate polysaccharides and gold nanoparticles. The dendritic structure formation was dependent on the salt concentration, drying mode, and particle size.…”

Universal scaling of polygonal desiccation crack patterns

“…This complexity is enhanced by the multi-phase nature of the material: liquid menisci between particles generate heterogeneous shrinkage through capillary pressure, and excess liquid-vapor surface area in the bulk of the material [32][33][34][35][36]. As a consequence, in addition to polygonal cracks, a large variety of cracks patterns have been reported in dried suspensions [8,30,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. The variability in observed patterns depends on numerous factors such as film geometry [40,53], particle mechanics [54], liquid additives [55,56], preparation history [57,58], solvent volatility [59,60], and external fields [61,62].…”

Nanopost-Guided Self-Organization of Dendritic Inorganic Salt Structures

“…Hierarchical architectures self-organized from artificial nanoscale building blocks have attracted much attention due to their fascinating optical, electronic, sensing, and catalytic properties. − Hierarchical architectures of metals, oxides, sulfides, carbonates, biomolecules, or organic–inorganic hybrid materials have been realized and are generally formed in specifically tailored chemical or electrochemical systems. − However, it remains a challenge to develop a simple synthetic approach to create morphology-controlled hierarchical architectures of various systems. Hierarchical architectures can also be formed in aqueous solutions or in gels under appropriate physical conditions, including the evaporation rate, temperature, pressure, viscosity, and concentration. − It has been demonstrated that polymers, semicrystalline polymers, and biomolecules, such as silk proteins, alginate polysaccharides, and actin filaments, can themselves, or in interaction with other components such as gold nanoparticles, form hierarchical structures. − Nonetheless, the degree of branching and angles between branches are often arbitrary and of little control due to random aggregation, making pattern prediction difficult and, hence, limiting certain applications of such structures. In addition, biomaterials are not easily applied to conventional fabrication processes due to their easy degradation in nonaqueous environments.…”