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Eggshells are transformed into products with high added value 

In the project of the Baltic Research Programme, researchers of Riga Technical University, in cooperation with partners from Estonia, Iceland and Norway, are studying the possibilities of using eggshells. 

Every year tens of millions of tons of eggs are produced, several million tons of which are eggshells. Although eggshells are considered useless and mostly discarded as waste, they can serve as a raw material to produce high-value-added products. The European Economic Area and Norway Grants (EEA/N) programme “Research and Education” funded project “Waste-to-resource: eggshells as a source for next generation biomaterials for bone regeneration” has brought together scientists from Latvia, Estonia, Iceland, and Norway, to develop a new concept for the conversion of eggshells into biomaterials. Within the project, chicken eggshells are being used as a source of calcium for the synthesis of amorphous calcium phosphate. Later, porous, natural bone-like ceramic scaffolds are produced from the synthesized material that could be used for bone regeneration applications. Amorphous calcium phosphate has excellent biological properties, but due to its metastability, it is particularly challenging to produce it in a bulk ceramic form. Within the scope of the project, proteins possessing high bioactivity and antibacterial properties are being extracted from eggshell membranes to fully optimize the utilization of eggshells, and subsequently, these proteins undergo characterization. The obtained proteins are intended for coating the developed amorphous calcium phosphate ceramic scaffolds, thus imparting them with unique properties. 

After optimization of the synthesis process, the project team has successfully obtained amorphous calcium phosphate (utilizing eggshells as a source of calcium) and also scaled up the synthesis to obtain it in large volumes. The synthesized amorphous calcium phosphate has excellent bioactivity under in-vitro conditions. Dense and porous ceramic scaffolds were obtained from the synthesized material and are currently being studied under in-vitro and in-vivo conditions. Project partners have published multiple peer-reviewed papers on the results obtained during the project and have also prepared several joint project proposals to continue the study. 

During the implementation of the project, the project team encountered several challenges that required innovative solutions. One of the challenges was related to the scale-up of the amorphous calcium phosphate synthesis to produce material in large volumes. After careful optimization of the synthesis parameters, it was possible to obtain amorphous calcium phosphate in quantities exceeding several tens of grams. Additionally, the initially chosen method for densification of the amorphous calcium phosphate could not be used to obtain ceramic with the required properties. Through collaboration among the project partners, an alternative densification approach was developed, and dense and porous amorphous calcium ceramic scaffolds were successfully obtained.  

The project results demonstrate that waste material – eggshells – can be used to produce high-value-added products. The implementation of the project allowed the project partners to expand their knowledge and acquire new skills, which will be useful in developing new research directions and forming new collaborations. It is expected that the project results will generate interest among companies specializing in biomaterials development. The developed materials could promote faster bone regeneration, thereby potentially improving patient treatment outcomes and quality of life.