A Blueprint for Self-Sharpening: Optimized Geometric Design Coupled With Multiscale Architecture in Northern Snakehead Teeth

Sat, 21 Mar 2026 12:00:00 +0800

On March 21, 2026, the research team led by Researcher Zhaoyong Zou from Academician Zhengyi Fu’s group at the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, published their findings entitled “A Blueprint for Self-Sharpening: Optimized Geometric Design Coupled With Multiscale Architecture in Northern Snakehead Teeth” in Advanced Functional Materials.

1. Research Background

In nature, biological minerals (such as bones, teeth, and scales) exhibit exquisite micro-/macro-scale structures. These structures typically form under ambient conditions yet possess remarkable mechanical properties (including strength, toughness, and wear resistance), often outperforming synthetic materials. As the most highly mineralized biological tissue in vertebrates, teeth combine high fracture toughness, high compressive strength, and excellent wear resistance, serving as a paradigm for bio-inspired structural material design.

Compared with mammals, fish—especially carnivorous fish—exhibit pronounced functional specialization in their dentition. For example, the molar-like pharyngeal teeth of black drum are specialized for crushing hard-shelled organisms, while the serrated teeth of piranhas are adapted for cracking nuts. This diversity provides a rich library of design principles for developing novel high-performance materials and bio-inspired processing technologies. For piercing-type predators, sharp teeth are essential for concentrating stress and penetrating prey. However, this sharpness itself presents a mechanical paradox: reducing the contact area to increase stress simultaneously makes teeth more susceptible to fracture and wear. To resolve this contradiction, carnivorous fish have evolved complex biomineralization strategies, including mineral phase selection, crystal orientation control, and organic-inorganic interface optimization.

The northern snakehead (Channa argus) is an apex ambush predator in East Asian freshwater ecosystems. Its remarkable environmental adaptability (e.g., hypoxia tolerance) and voracious predatory behavior (preying on fish, crustaceans, amphibians, etc.) make it an important subject for ecological and evolutionary studies. The successful predation of the northern snakehead heavily relies on two highly specialized dentitions in its oral cavity: sharp oral teeth for piercing, hooking, and firmly anchoring struggling prey, and pharyngeal teeth for further tearing prey to facilitate swallowing. This efficient predation process imposes stringent demands on the morphology, microstructure, and mechanical properties of the snakehead teeth. However, despite extensive documentation of the ecology and aquaculture of the northern snakehead, multiscale analysis of the structure–property relationships of its teeth remains completely unexplored.

2. Research Content

The team systematically revealed the multiscale design principles of northern snakehead teeth through multiscale characterization techniques (including micro-CT, Raman spectroscopy, energy-dispersive spectroscopy, and scanning electron microscopy) combined with advanced mechanical testing (nanoindentation, in-situ compressive CT) and finite element simulations.

Gradient-Mineralized Enamel Structure

The study found that only a ~200 μm thick cap enameloid exists at the tip of the snakehead tooth, exhibiting a self-sharpening characteristic (Fig. 1). Multiscale characterization results (CT, Raman, EDS, SEM, and nanoindentation) revealed that the enameloid presents a functionally graded structure (Figs. 2, 3, 5): the outer layer consists of highly aligned fluorapatite (FAP) nanorod bundles with their long axes parallel to the tooth tip direction, achieving excellent hardness (5–6 GPa) and wear resistance; the inner layer exhibits an interwoven, disordered structure that effectively enhances toughness through crack deflection. This gradient design enables the relatively thin enameloid layer to achieve efficient piercing, wear resistance, and self-sharpening, providing inspiration for the design of coatings, drill bits, and related tools.

Dentin-Enameloid Junction (DEJ) and Hierarchical Dentin Structure

The cap enameloid is supported by underlying dentin, with the enameloid and dentin tightly connected through the DEJ. The DEJ of the snakehead tooth presents a “mountain-shaped” geometric structure. Finite element simulations indicate that this design effectively redistributes interfacial shear stress and reduces stress concentration in the dentin, thereby preventing catastrophic fracture (Supporting Fig. 19). The dentin is composed of highly ordered mineralized collagen fibers arranged along the long axis of the tooth. Dentinal tubules radiate outward from the central pulp cavity, forming a hierarchical canal network (Fig. 4). This hierarchical canal system, together with the mineralized collagen fibers aligned along the tooth long axis, enables the dentin to efficiently absorb energy during the biting process.

Self-Sharpening Mechanism

In-situ compressive CT studies revealed that during the wear process, crack deflection and localized flake-like spalling occur at the tip enameloid without catastrophic fracture, forming a new sharp tip. This behavior is closely related to the gradient structure of the enameloid. Once the enameloid is completely damaged, the dentin undergoes significant failure under compression, leading to loss of tooth function (Fig. 6). Throughout the fish’s life, new teeth can be continuously replaced to maintain feeding function. Finite element simulations revealed that the physiological curvature of the snakehead tooth (~26°) causes stress to concentrate more readily on the concave surface during biting and tearing of prey, leading to preferential brittle fracture and spalling of the enameloid on the concave side (Fig. 7). This process continuously regenerates sharp cutting points during tooth use, explaining how the teeth maintain their sharpness throughout their service life.

3. Summary and Outlook

In this work, the team investigated the multiscale design principles of northern snakehead teeth, revealing how the synergistic integration of gradient enameloid, stress-dissipating “mountain-shaped” interfaces, tough dentin, and macroscopic curvature enables efficient piercing function and maintains self-sharpening during use. This study provides a fundamental blueprint for the biomimetic design of next-generation lightweight, self-sharpening tools.

This work was supported by the National Key R&D Program of China “Transformational Technologies Key Scientific Problems” project “Key Scientific Problems of Room-Temperature Ceramic Preparation Inspired by Biological Processes” (2021YFA0715700), the National Natural Science Foundation of China (52172287, 12522204), and the Hubei Provincial Innovation Group Project (2024AFA002). The authors thank Huakong (Suzhou) Intelligent Equipment Co., Ltd. for providing the in-situ mechanical loading device and in-situ CT characterization.

Junyan Guo, a Ph.D. candidate at Wuhan University of Technology (Class of 2023), is the first author of this paper. Researcher Zhaoyong Zou and Professor Zhengyi Fu from Wuhan University of Technology are the corresponding authors.

4. Publication Information

Junyan Guo, Ping Yuan, Xiangyin Pan, Zhuanfei Liu, Zeyao Fu, Yinbo Zhu, Zhengyi Fu and Zhaoyong Zou, A Blueprint for Self-Sharpening: Optimized Geometric Design Coupled with Multiscale Architecture in Northern Snakehead Teeth. Advanced Functional Materials, 2026, 0: e32022.

https://doi.org/10.1002/adfm.202532022

Bio-Inspired Design | Bioprocess Inspired Fabrication