[Reproduced] This group made another breakthrough in Nature after two years:Adding hydrogel can take temporary setbacks
    In the latest issue of Nature's report, F. akif Tezcan (corresponding author) team from the University of California published a report entitled “Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks”. It is found that the macromolecular ferritin crystals with hydrogel polymers can expand to 180% of their original size in an isotropic manner, and exceed 500% of their original volume, while maintaining periodic ordering and multiplanar Wulff morphology. Even if the neighboring ferritin molecules are separated by 50 angstroms during lattice expansion, the specific molecular contact between them can be re-formed during lattice contraction, which achieves the atomic level periodic and highest resolution recovery of ferritin structure reported so far. The dynamic binding interaction between the hydrogel network and the ferritin molecules gives the crystal the ability to effectively resist fragmentation and self-healing, while the chemical adjustment of ferritin molecules can produce chemical and mechanically differentiated domains in the single crystal. When Tezcan was still at the University of California, San Diego, in 16 years, he published a paper on the material adapting to protein crystals. This material has an attribute that goes against our normal cognition: when we stretch it in one direction, in the direction perpendicular to the stretching direction, instead of thinning, the material becomes thicker. Similarly, when we squeeze it in one direction, it shrinks rather than expands in the perpendicular direction, and the density increases in the process. The abnormal property of "adaptive protein crystal", which is "hard when it comes to hard", makes it have many potential applications. For example, when the sole of running shoes collides with the road, it will automatically thicken, so it has better shock absorption effect; when bullet shooting, it will make use of its own adaptive effect to become stronger.

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

Fig. 2 Characterization of swelling and shrinkage behavior of ferritin Crystal Hydrogel hybrid

Fig. 3 Atomic structure characterization of ferritin crystal-hydrogel complexes by XRD

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

Literature link:Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks(Nature,2018,DOI:10.1038/s41586-018-0057-7)