Waste-to-health: eggshell for precision bone regeneration

An interdisciplinary research team lead by Harbin Institute of Technology has developed a multifunctional biphasic bone scaffold featuring a "steel-cement" structure using eggshells waste. This scaffold integrates a rigid lattice (biosteel) with a bioactive hydrogel (biocement) loaded with composite drug-releasing particles, facilitating anti-infective and osteogenic functions. With adjustable mechanical properties, biodegradability, and intelligent responsiveness, this scaffold demonstrates significant potential for precise, sustainable, and dynamic bone regeneration.

This study not only demonstrates the high-value transformation of waste biological resources but also provides new ideas for advancing bone regeneration toward intelligent and personalized therapeutic paradigms.

Bone tissue engineering has advanced considerably over the past decades, focusing on scaffolds that emulate natural bone architecture, support cell growth, and promote regeneration. Particularly for critical-sized bone defects that cannot heal spontaneously through endogenous regeneration mechanisms. These defects often demand the implantation of bone-regenerative materials to accelerate tissue regeneration. On the other hand, traditional bone grafting is limited by donor shortages, immune rejection, and the trauma of secondary surgeries. Metal implants have drawbacks such as stress shielding, mechanical property mismatch, and the induction of long-term inflammatory responses. Synthetic polymers are widely used in bone tissue engineering due to their degradability and processability. Despite this, their  biologic inertness and single-component nature limit the osteoinductive capacity and biological functionality. Furthermore, conventional bone scaffolds are static in structure and exhibit limited adaptability to complex and irregular defects. Therefore, the development of new bone-regenerative materials that combine mechanical adaptability and biological activity is of great significance.

Addressing these limitations, researchers have developed a multifunctional biphasic bone scaffold with a "steel-cement" structure, achieving the coordinated integration of biological activity, mechanical adaptability, and intelligent response performance. By utilizing the porous structure and biomineralization potential of discarded eggshells, composite particles with sequential drug release behavior were constructed, facilitating

early-stage antibacterial activity and late-stage osteogenesis. These particles were subsequently embedded into a dual-network hydrogel phase to mimic the soft matrix of natural cancellous bone, thereby significantly improving hydrophilicity, cellular compatibility, and sustained drug release capability. The rigid lattice metamaterial framework was fabricated of radiopaque intelligent materials, simulating the cortical bone to provide essential mechanical support. The mechanical properties and porosity of the scaffold can be rendered broadly tunable by precisely adjusting the geometric parameters of ligaments and nodes, while imparting shape memory and radiopacity characteristics, thus enabling minimally invasive implantation, dynamic self-adaptation, and precise positioning. This design integrates mechanical support, morphological adaptability, antibacterial and osteoregenerative functions, offering critical technological support for the regenerative repair of bone defects and presenting a novel strategy for the high-value utilization of waste biological resources.

This study presents a biomimetic 4D-printed biphasic bone scaffold derived from discarded eggshells, designed to mimic the "steel-cement" architectural structure, achieving excellent mechanical support and biological activity. This strategy not only enables the high-value utilization of biological waste but also offers an innovative solution for intelligent bone regeneration. Future studies will further validate the clinical translational potential through long-term animal experiments and continuously explore the feasibility of applying other biological waste resources (e.g., shells, shrimp and crab shells) in functional bone repair materials, providing new ideas for the green biomanufacturing of bone tissue engineering scaffolds and the development of the circular economy.

The research has been recently published in the online edition of Materials Futures, a new international journal in the field of interdisciplinary materials science research.

Reference: Zhichen Zou, Chunli Yang, Mengjiao Yang, Yan Zhu, Xiaozhou Xin, Mingli Huang, Yixiu Liu, Zhongmin Wang, Shifeng Yang, Peng Li, Cheng Lin. Waste-to-healthcare: eggshell-derived 4D-printed biphasic scaffolds for precision bone regeneration[J]. Materials Futures. DOI: 10.1088/2752-5724/ae1e1a