title: Protein-assisted synthesis of double-shelled CaCO3 microcapsules and their mineralization with heavy metal ions.
abstract: Calcium carbonate (CaCO(3)) is one of the most abundant and important biominerals in nature. Due to its biocompatibility, biodegradability and nontoxicity, CaCO(3) 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 CaCO(3) into a double-shelled structural configuration. Due to varying reactivities of outer and inner shells, the CaCO(3) 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 "CaCO(3) cells". Our investigation of the cytotoxicity (MTT assay protocol) also indicates that the CaCO(3) microcapsules have almost no cytotoxicity against HepG2 cells, and they might be useful for future application of detoxifying heavy metal ions after further study.
authors.affiliation: 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.
authors.forename: Xuan Qi
authors.initials: XQ
authors.lastname: Li
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Feng
authors.forename: Yinyan
authors.initials: Y
authors.lastname: Xia
authors.forename: Hua Chun
authors.initials: HC
authors.lastname: Zeng
mesh_terms: D000818:Animals; D002104:Cadmium / Q000032:analysis; D002119:Calcium Carbonate / Q000138:chemical synthesis* / Q000737:chemistry; D002214:Capsules / Q000138:chemical synthesis* / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D007477:Ions; D007854:Lead / Q000032:analysis; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy; D008628:Mercury / Q000032:analysis; D019216:Metals, Heavy / Q000737:chemistry*; D008954:Models, Biological; D011506:Proteins / Q000737:chemistry*
chemical_list: D002214:Capsules; D007477:Ions; D019216:Metals, Heavy; D011506:Proteins; D002104:Cadmium; D007854:Lead; D008628:Mercury; D002119:Calcium Carbonate