Chitin Hydrogel Shows Potential in Biomedical Applications

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For several biomedical applications, chitin hydrogel is known as a promising material. It is beneficial for tissue repair, artificial organs and wound healing because of its biocompatibility and biodegradability. However, producing chitin hydrogels remains a difficult task for scientists. A group of researchers have created a scalable, environmentally friendly and effective method for making chitin hydrogels.

This scheme shows the preparation of chitin hydrogels via solvent exchange-assisted acetylation of chitosan hydrogels. Image Credit: Nano Research, Tsinghua University Press

The team’s research offers a logical method for making chitin hydrogels and paves the way for their practical use as excellent biomedical materials.

Their study was published on July 1^st2023, in the journal Nano Research.

The exoskeletons of insects, shrimp and crabs contain chitin, the second most common natural polymer. Chitin is inexpensive, biocompatible, renewable and degradable. Due to these characteristics, it is the preferred choice for various biomedical applications.

Chitin hydrogel, which has much in common with the extracellular matrix, is an ideal material for tissue engineering and regenerative medicine. However, it is a challenge to dissolve chitin in an aqueous solution to produce hydrogel materials. Therefore, it is very important to develop a rational fabrication strategy.

Li-Bo Mao, Professor, University of Science and Technology

Chitin hydrogels must be biosafe, possess the necessary mechanical strength, and chemically stable to be effective in biomedical applications. It must be able to fend off biofouling, which can trigger an immunological reaction or inflammatory response in the human body. Chitin hydrogels also needed to be affordable and scalable for commercial use.

Since chitin is insoluble in many solvents and has shorter chain lengths when formed from solution, this creates difficulties in preparing strong chitin hydrogels. Biopolymer dissolution and subsequent gelation are the two steps commonly used to prepare biopolymer hydrogels.

However, due to the strong intra- and intermolecular hydrogen bonds that exist between the polymer chains, chitin is insoluble in water or other common solvents. The group tackled this problem by chemically converting chitosan, a water-soluble deacetylated chitin derivative, into a chitin hydrogel with a biomimetic structure.

Chitosan easily dissolves in water when acid is present. Different microstructures can be added to these chitosan hydrogels. However, they are not chemically or mechanically stable. Concerns about biosafety have been highlighted in efforts to use crosslinking agents to improve this.

The team succeeded in creating an acetylated chitin-based hydrogel that is chemically stable and anti-fouling. The chitin hydrogel that the researchers created through the acetylation procedure exhibited outstanding resistance to swelling, degradation, high temperature and pH conditions, as well as organic solvents.

The researchers also found that by coating chitosan precursors with ice crystals, they were able to create chitin hydrogels with various biomimetic forms. Depending on the freezing process used with the chitosan precursor, this structure can be either nacre-like or wood-like.

The team’s chitin hydrogel exhibits superior mechanical characteristics while maintaining a high water content. In addition, it exhibits outstanding antifouling performance by thwarting the adherence of blood, cells, proteins and bacteria.

Mao added, “In addition to the many advantages that are characteristic of chitin, the hydrogel material we have obtained is mechanically strong and robust. In addition, hydrogels can be feasibly processed into various shapes and structures. This ensures the practical application of chitin hydrogels.”

The team’s next task is to improve the mechanical properties of chitin hydrogel and investigate its potential use in biomedical uses life test.

Mao further stated, “We anticipate a variety of chitin-based hydrogel materials could be prepared via this strategy and used for different clinical applications, such as cartilage replacement, bone replacement, wound dressing and even artificial organs.”

The research team consisted of Rui-Rui Liu, Yu-Feng Meng, Li-Bo Mao, and Shu-Hong Yu from the University of Science and Technology of China; and Qian-Qian Shi and Yong Zhou from Anhui Provincial Medical University.

The China National Natural Science Foundation, the Main Scientific Research Foundation of the Anhui Province Ministry of Education, and the China National Major Research and Development Program provided funding for the research.