Protein-Assisted Synthesis of Double-Shelled CaCO3 Microcapsules and Their Mineralization with Heavy Metal Ions

Authors

  • Xuan Qi Li,

    1. NUS Graduate School for Integrative Sciences and Engineering, Department of Chemical and Biomolecular Engineering and KAUST-NUS GCR Program, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)
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  • Prof. Zhiwei Feng,

    1. School of Biological Sciences, College of Science, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore)
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  • Yinyan Xia,

    1. School of Biological Sciences, College of Science, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551 (Singapore)
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  • Prof. Hua Chun Zeng

    Corresponding author
    1. NUS Graduate School for Integrative Sciences and Engineering, Department of Chemical and Biomolecular Engineering and KAUST-NUS GCR Program, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)
    • NUS Graduate School for Integrative Sciences and Engineering, Department of Chemical and Biomolecular Engineering and KAUST-NUS GCR Program, Faculty of Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)
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Abstract

Calcium carbonate (CaCO3) is one of the most abundant and important biominerals in nature. Due to its biocompatibility, biodegradability and nontoxicity, CaCO3 has been investigated extensively in recent years for various fundamental properties and technological applications. Inspired by basic wall structures of cells, we report a protein-assisted approach to synthesize CaCO3 into a double-shelled structural configuration. Due to varying reactivities of outer and inner shells, the CaCO3 microcapsules exhibit different sorption capacities and various resultant structures toward different kinds of heavy metal ions, analogical to biologically controlled mineralization (BCM) processes. Surprisingly, three mineralization modes resembling those found in BCM were found with these bacterium-like “CaCO3 cells”. Our investigation of the cytotoxicity (MTT assay protocol) also indicates that the CaCO3 microcapsules have almost no cytotoxicity against HepG2 cells, and they might be useful for future application of detoxifying heavy metal ions after further study.

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