Hydrogel can cause self-repairing behavior of crystalline materials

【introduction】

As the degree of interaction between atoms or molecular components increases, the materials generally become more ordered. However, high levels of structural order and flexibility are not necessarily mutually exclusive; there are many biological and synthetic assemblies that can perform considerable structural transformations without losing their crystallization order and with significant mechanical properties. These mechanical properties can be used in a variety of applications such as selective adsorption, separation, sensing and mechanical actuation. However, the degree of structural change and the flexibility of such flexible crystals are limited by maintaining a network of connections between the lattice components. Therefore, even the most dynamic porous material tends to be brittle and separated into microcrystalline powder, and flexible organic or inorganic molecular crystals cannot expand without breaking. Due to their rigidity, crystalline materials rarely exhibit self-healing behavior.

[Introduction]

The latest issue of Nature, University of California, F. Akif Tezcan (corresponding author) team published an article entitled "Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks", which found that macromolecular ferritin crystals with hydrogel polymers can be isotropically expanded to their original 180% of the size and more than 500% of its original volume while maintaining periodic ordering and multi-faceted Wulff form. Even if the adjacent ferritin molecules are separated by 50 angstroms when the lattice is expanded, the specific molecular contact between them can be reformed when the lattice shrinks, achieving the atomic-level periodicity and the highest resolution ferritin structure reported so far. Recovery. The dynamic binding interaction between the hydrogel network and the ferritin molecules gives the crystals the ability to resist fragmentation and self-healing, while the chemical adjustment of ferritin molecules can produce chemically and mechanically differentiated domains within a single crystal. At the age of 16 years, Tezcan also published a book on protein crystals at the University of California, San Diego. This material has an attribute that violates our normal perception: when we stretch it in one direction, In the direction perpendicular to the stretching direction, the material is not thinned but becomes thicker. Similarly, when we squeeze it in one direction, it shrinks in the direction perpendicular to it rather than expanding, and the density becomes larger during this process. The "adaptive protein crystal", an anomalous property of "just-in-time", has many potential applications. For example, the sole used for running shoes, when the sole collides with the road surface, it will automatically thicken to have better shock absorption; for bulletproof clothing, when it is shot by bullets, it will use its own adaptive action. More tougher.

[Graphic introduction]

Figure 1. Expansion-contraction of ferritin crystals after injection of a hydrogel network

Figure 2 Ferritin crystals - Characterization of swelling and shrinkage behavior of hydrogel hybrids

Figure 3 Atomic structural characterization of ferritin crystal-hydrogel hybrids by XRD

Figure 4 Self-healing behavior and functionalization of ferritin crystal-hydrogel hybrids

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