@article{RadziukSkirtachGessneretal.2011,
  author    = {Radziuk, Darya and Skirtach, Andre and Gessner, Andre and Kumke, Michael Uwe and Zhang, Wei and M{\"o}hwald, Helmuth and Shchukin, Dmitry},
  title     = {Ultrasonic Approach for Formation of Erbium Oxide Nanoparticles with Variable Geometries},
  series = {Langmuir},
  volume    = {27},
  journal   = {Langmuir},
  number    = {23},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/la203622u},
  pages     = {14472 -- 14480},
  year      = {2011},
  abstract  = {Ultrasound (20 kHz, 29 W. cm(-2)) is employed to form three types of erbium oxide nanoparticles in the presence of multiwalled carbon nanotubes as a template material in water. The nanoparticles are (i) erbium carboxioxide nanoparticles deposited on the external walls of multiwalled carbon nanotubes and Er(2)O(3) in the bulk with (ii) hexagonal and (iii) spherical geometries. Each type of ultrasonically formed nanoparticle reveals Er(3+) photoluminescence from crystal lattice. The main advantage of the erbium carboxioxide nanoparticles on the carbon nanotubes is the electromagnetic emission in the visible region, which is new and not examined up to the present date. On the other hand, the photoluminescence of hexagonal erbium oxide nanoparticles is long-lived (mu s) and enables the higher energy transition ((4)S(3/2)-(4)I(15/2)), which is not observed for spherical nanoparticles. Our work is unique because it combines for the first time spectroscopy of Er(3+) electronic transitions in the host crystal lattices of nanoparticles with the geometry established by ultrasound in aqueous solution of carbon nanotubes employed as a template material. The work can be of great interest for "green" chemistry synthesis of photoluminescent nanoparticles in water.},
  language  = {en}
}
@article{FeoktistovaRoseProkopovicetal.2016,
  author    = {Feoktistova, Natalia and Rose, J{\"u}rgen and Prokopovic, Vladimir Z. and Vikulina, Anna S. and Skirtach, Andre and Volodkin, Dmitry},
  title     = {Controlling the Vaterite CaCO3 Crystal Pores. Design of Tailor-Made Polymer Based Microcapsules by Hard Templating},
  series = {Langmuir},
  volume    = {32},
  journal   = {Langmuir},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0743-7463},
  doi       = {10.1021/acs.langmuir.6b00717},
  pages     = {4229 -- 4238},
  year      = {2016},
  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 745 degrees 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 adsorptiondesorption, 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.},
  language  = {en}
}