Huazhong University of Science and Technology has made important progress in the preparation technology of biomimetic underwater viscose for mussels

On October 12, 2022, Professor Yan Yunjun's team from the School of Life Science and Technology of Huazhong University of Science and Technology published a paper entitled "Mussel foot inspired bionic adhesive material enhanced by a reconstructed in vitro" in the international authoritative journal Chemical Engineering Journal System for Interfacial Adhesion"
.

Wet adhesion plays an important role in medical and economic applications and is also the most challenging subject
.
Mussel mycin is a natural protein with strong underwater adhesion ability, which can be used in surface chemistry, biomedicine, marine engineering, daily chemical products and many other fields, such as surgical suture bonding in medicine, promoting cell adhesion wall crawling, promoting wound healing and inhibiting itching, forming a water-resistant protective film, etc
。 The super interfacial adhesion ability of mussel mycin in a wet environment depends on its own complex curing and regulation process, including post-translational modification reaction of mucin catalyzed by tyrosinase in glandular cells, protein storage after the end of the reaction, antioxidant protection of dopa, the key functional group of maturing proteins in vesicles, delayed oxidation at the adhesion interface after protein secretion, and pH transition in aquatic environment
.
The research and in vitro simulation of these reaction mechanisms can help people to understand the curing and regulation process of mussel viscose protein, and realize the functional perfection of
biomimetic mussel viscose protein materials.

In this study, the biomimetic mussel biomimetic mucin precursor, named PGA-Tyr-Arg, was prepared by EDC/NHS grafting method as a substrate for post-translational modification in vitro (Figure 1c), which broke through the limitations of
low effective functional group content and weak interfacial adhesion ability in wet environment of traditional biomimetic mussel adhesion materials 。 Secondly, during the in vitro post-translational modification reaction catalyzed by tyrosinase, different reducing agents were compared, and it was found that tannic acid had the smallest inhibitory effect on tyrosinase enzyme activity during the reaction and had a good antioxidant effect, which was suitable as a reducing agent in the process of enzyme-catalyzed reaction (Figure 1a), and mussel biomimetic mucorder protein Mfp6 (PGA-Cys) had stronger tyrosinase enzyme activity inhibition and antioxidant effect, and was suitable as a reducing agent in the protein storage stage and the initial stage of interfacial adhesion (Figure 1d).
It was revealed that different stages of post-translational modification and storage of mussel mycin before secretion also require complex redox protection
.
Finally, an immobilized enzyme using affinity adsorption method, IEAMNP-Cu2+-Tyrosinase (Figure 1b), was designed and prepared, which is suitable for catalyzing the reaction of macromolecular substrates, and the enzyme activity is increased by 1.
5 to 3 times compared with the free tyrosinase catalyst (Figure 2e), achieving a high conversion rate of tyrosine to dopa in the post-in vitro modification reaction (Figure 2c), breaking through the limitation
of the low catalytic activity of traditional free enzymes in an in vitro environment 。 The mucin prepared under these conditions can achieve shear adhesion up to 9.
5 MPa (Figure 2f) in wet environments and is expected to be further improved, allowing biomimetic mussel adhesion materials to further improve interfacial adhesion while retaining their strong resistance to water environments to meet more challenging application needs
.

Professor Yan Yunjun's team is committed to the research and development of new bio-based underwater adhesion materials, and has made a series of important progress, and this study has successfully constructed an extracellular functionalization system for mussel mycin (Li et al.
, CHEM.
ENG.
J.
452 (2023) 139580）
。

Fig.
1 (a) the technical route of this study, (b) the synthesis method of the catalyst IEAMNP-Cu²⁺-Tyrosinase, (c) the preparation process of Mfp35 biomimetic protein precursor (PGA-Tyr-Arg), (d) the synthesis
of Mfp6 biomimetic protein (PGA-Cys).

Fig.
2 Comparison of free enzymes and immobilized enzymes under different treatment conditions (a-f) and reusability of immobilized enzyme IEAMNP-Cu²⁺-Tyrosinase (g-j).

Professor Yan Yunjun from the School of Life Science and Technology of Huazhong University of Science and Technology is the corresponding author of the paper, and postdoctoral fellow Li Kai is the first author
of the paper.
This research was supported
by the National Natural Science Foundation of China and the Independent Innovation Fund of Huazhong University of Science and Technology.

Article link: https://doi.
org/10.
1016/j.
cej.
2022.
139580