Chitosan and carboxymethyl chitosan mimic biomineralization and promote microbially induced calcium precipitation

This research aimed to evaluate chitosan (CTS) and carboxymethyl chitosan (CMCS) as polysaccharides that could mimic the role of bacterial extracellular polymeric substance (EPS) in the biomineralization process through bionic experiments. The introduction of -COOH resulted in higher calcium precipitation efficiency of CMCS (65.07%) than CTS (55.66%). CaCO3 nucleation on the surface of CTS and CMCS was triggered through the binding of Ca2+ to -NH2, -OH, -COOH and -NHCOCH3 groups. Moreover, the experiment of poly-saccharides mediated biomineralization was conducted. The maximum calcium precipitation efficiency reached 96.07% with the addition of 0.15% CMCS. Combining the characterization results, the synergetic mineralization mechanisms between polysaccharides and bacteria were proposed. Among them, bacterial metabolic by-products (alkalinity), active groups and adhesion of polysaccharides played a significant role. This work provides a reference for further understanding of the biomineralization mechanism, and gives a new insight into the intensified strategies of MICP technology.

Automated summary

This research evaluates chitosan and carboxymethyl chitosan as polysaccharides that mimic the role of bacterial extracellular polymeric substance in biomineralization. Carboxymethyl chitosan demonstrated higher calcium precipitation efficiency and the nucleation of calcium carbonate was triggered by the binding of different functional groups on the polysaccharides. The study also conducted experiments on polysaccharide-mediated biomineralization, showing improved calcium precipitation efficiency with the addition of carboxymethyl chitosan. The findings provide insights into the biomineralization mechanism and strategies for enhancing MICP technology.