title: Controlling the Vaterite CaCO3 Crystal Pores. Design of Tailor-Made Polymer Based Microcapsules by Hard Templating.
abstract: The spherical vaterite CaCO3 microcrystals are nowadays widely used as sacrificial templates for fabrication of various microcarriers made of biopolymers (e.g., proteins, nucleic acids, enzymes) due to porous structure and mild template elimination conditions. Here, we demonstrated for the first time that polymer microcarriers with tuned internal nanoarchitecture can be designed by employing the CaCO3 crystals of controlled porosity. The layer-by-layer deposition has been utilized to assemble shell-like (hollow) and matrix-like (filled) polymer capsules due to restricted and free polymer diffusion through the crystal pores, respectively. The crystal pore size in the range of few tens of nanometers can be adjusted without any additives by variation of the crystal preparation temperature in the range 7-45 °C. The temperature-mediated growth mechanism is explained by the Ostwald ripening of nanocrystallites forming the crystal secondary structure. Various techniques including SEM, AFM, CLSM, Raman microscopy, nitrogen adsorption-desorption, and XRD have been employed for crystal and microcapsule analysis. A three-dimensional model is introduced to describe the crystal internal structure and predict the pore cutoff and available surface for the pore diffusing molecules. Inherent biocompatibility of CaCO3 and a possibility to scale the porosity in the size range of typical biomacromolecules make the CaCO3 crystals extremely attractive tools for template assisted designing tailor-made biopolymer-based architectures in 2D to 3D targeted at drug delivery and other bioapplications.
authors.affiliation: Branch Bioanalytics and Bioprocesses (Fraunhofer IZI-BB), Fraunhofer Institute for Cell Therapy and Immunology , Am Muehlenberg 13, 14476 Potsdam-Golm, Germany.|Department of Chemistry, Lomonosov Moscow State University , Leninskiye gory 1-3, 119991 Moscow, Russia.
authors.forename: Natalia
authors.initials: N
authors.lastname: Feoktistova
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam , Karl-Liebknecht-Str. 24-25, 14476 Potsdam-Golm, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Rose
authors.affiliation: Branch Bioanalytics and Bioprocesses (Fraunhofer IZI-BB), Fraunhofer Institute for Cell Therapy and Immunology , Am Muehlenberg 13, 14476 Potsdam-Golm, Germany.
authors.forename: Vladimir Z
authors.initials: VZ
authors.lastname: Prokopović
authors.affiliation: Branch Bioanalytics and Bioprocesses (Fraunhofer IZI-BB), Fraunhofer Institute for Cell Therapy and Immunology , Am Muehlenberg 13, 14476 Potsdam-Golm, Germany.|School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Vikulina
authors.affiliation: Department of Molecular Biotechnology & NB-Photonics, University of Ghent , Coupure Links 653, 9000 Gent, Belgium.
authors.forename: Andre
authors.initials: A
authors.lastname: Skirtach
authors.affiliation: Branch Bioanalytics and Bioprocesses (Fraunhofer IZI-BB), Fraunhofer Institute for Cell Therapy and Immunology , Am Muehlenberg 13, 14476 Potsdam-Golm, Germany.|Department of Chemistry, Lomonosov Moscow State University , Leninskiye gory 1-3, 119991 Moscow, Russia.|School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG11 8NS, United Kingdom.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Volodkin