image: Figure 1 | Rapid formation of avian eggshells and the role of the eggshell membrane as a mineralization interface.
Credit: ©Science China Press
Avian eggshells are a typical example of rapid biomineralization in nature. The eggshell of a chicken egg can complete mineral deposition in less than one day, and different avian species generally exhibit an efficient capacity for eggshell formation. In this complex physiological process, the eggshell membrane (ESM) is an important initial interface for mineral deposition. How, then, does the eggshell membrane promote rapid mineralization? Is this role widely present across different avian species?
Recently, Professor Meng Li of Chongqing University, together with the research team of Professor Zuankai Wang of The Hong Kong Polytechnic University, published a research paper entitled “Membrane-induced eggshell biomineralization towards controllable crystallization” in National Science Review (NSR). The study revealed the common interfacial features through which eggshell membranes of different avian species promote mineralization and, inspired by these features, achieved biomimetic control of rapid crystallization and conducted application demonstrations.
Eggshell Membranes from 33 Avian Species: A Common Mineralization Capacity beneath Diverse Appearances
From large-bodied ostriches to small songbirds, avian eggshells differ markedly in size, yet the eggshell membranes within them exhibit a similar capacity to promote crystallization. The research team compared eggshell membranes from 33 avian species under standardized low-supersaturation conditions and found that all tested samples promoted calcium carbonate deposition; the best-performing sample had a deposition rate approximately 20 times that of the control material. Further investigation showed that these eggshell membranes possess similar interwoven fibrous networks, amino acid compositions, and negatively charged surfaces, which facilitate calcium ion enrichment at the solid–liquid interface and reduce the crystal nucleation energy barrier, jointly creating a solid–liquid interfacial environment conducive to rapid mineralization.
Learning from Nature: Enabling Rapid Crystallization of Minerals at Designated Interfaces
Inspired by natural eggshell membranes, the research team prepared a biomimetic fibrous membrane (b-FM) through fiber formation and surface chemical modification, achieving synergistic regulation of interfacial ion migration, crystal nucleation, and crystal polymorph evolution. Under identical experimental conditions, its crystallization-inducing capacity exceeded that of the best-performing natural eggshell membrane.
This strategy also provides a new approach for scaling prevention and control in energy and power systems. Calcium carbonate scale in circulating cooling water readily increases the heat transfer resistance of heat exchange equipment and the flow resistance of pipelines. The research team sought to shift from passive scale inhibition to active crystallization regulation, guiding minerals to preferentially deposit on the biomimetic membrane surface, thereby achieving near-zero-energy water softening and pipeline scaling inhibition. In a continuous 30-day circulation experiment, the treatment system effectively reduced water hardness and kept the loss of effective flow cross-sectional area of different metal pipelines within 2%.
Research Highlights: From Understanding Natural Interfaces to Designing Artificial Interfaces
The study revealed, through cross-species comparison of avian species, the common principles by which eggshell membranes promote mineralization, and translated this natural strategy into an interfacial design method for artificial biomimetic materials. It established a link between biomineralization and mass transfer and crystallization regulation in energy and chemical engineering, offering new ideas for low-energy water treatment, scaling prevention and control in heat exchange systems, and engineering applications of biomineralization mechanisms.
Zhaoyu Chen, a doctoral student at Chongqing University, is the first author of the paper. Professor Meng Li of Chongqing University and Professor Zuankai Wang of The Hong Kong Polytechnic University are the corresponding authors. The collaborators of this paper include Professor Qiang Liao, Professor Yang Xiao, and Professor Yang Lu of Chongqing University; Academician John Wang of the National University of Singapore; Professor Jing Wang of Shanghai Jiao Tong University; Professor Chaoyong Zou of Wuhan University of Technology; Professor Ting Yang of Wuhan University; and Senior Engineer Kuang Gaoxiang of Chongqing Zoo, among others. The research team especially thanks Chongqing Zoo for its support and assistance in the collection and acquisition of avian eggshell samples, which provided important support for the smooth conduct of this study.