TY  - JOUR
A1  - Radziuk, Darya
A1  - Skirtach, Andre
A1  - Gessner, Andre
A1  - Kumke, Michael Uwe
A1  - Zhang, Wei
A1  - Möhwald, Helmuth
A1  - Shchukin, Dmitry
T1  - Ultrasonic Approach for Formation of Erbium Oxide Nanoparticles with Variable Geometries
JF  - Langmuir
N2  - 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.
Y1  - 2011
U6  - https://doi.org/10.1021/la203622u
SN  - 0743-7463
VL  - 27
IS  - 23
SP  - 14472
EP  - 14480
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kiel, Mareike
A1  - Möhwald, Helmuth
A1  - Bargheer, Matias
T1  - Broadband measurements of the transient optical complex dielectric function of a nanoparticle/polymer composite upon ultrafast excitation
JF  - Physical review : B, Condensed matter and materials physics
N2  - We determined experimentally the complex transient optical dielectric function of a well-characterized polyelectrolyte/gold-nanoparticle composite system over a broad spectral range upon short pulse laser excitation by simultaneously measuring the time-dependent reflectance and transmittance of white light pulses with femtosecond pump-probe spectroscopy. We extracted directly the ultrafast changes in the real and imaginary parts of the effective dielectric function, epsilon(eff)(r) (omega,t)and epsilon(eff)(i) (omega,t), from the experiment. This complete experimental set of information on the time-dependent complex dielectric function challenges theories modeling the transient dielectric function of gold particles and the effective medium.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevB.84.165121
SN  - 1098-0121
VL  - 84
IS  - 16
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Löbbicke, Ruben
A1  - Chanana, Munish
A1  - Schlaad, Helmut
A1  - Pilz-Allen, Christine
A1  - Günter, Christina
A1  - Möhwald, Helmuth
A1  - Taubert, Andreas
T1  - Polymer Brush Controlled Bioinspired Calcium Phosphate Mineralization and Bone Cell Growth
JF  - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2  - Polymer brushes on thiol-modified gold surfaces were synthesized by using terminal thiol groups for the surface initiated free radical polymerization of methacrylic acid and dimethylaminotheyl methacrylate, respectively. Atomic force microscopy shows that the resulting poly(methacrylic acid (PMAA) and poly(dimethylaminothyl methacrylate) (PDM- AEMA) brushes are homogeneous. Contact angle measurements show that the brushes are pH responsive and can reversibly be protonated and deprotonated. Mineralization of the brushes with calcium phosphate at different pH yields homogeneously mineralized surfaces, and preosteoblastic cells proliferate-on be number of living cells on the mineralized hybrid surface is ca. 3 times (P corresponding nonmineralized brushes.
Y1  - 2011
U6  - https://doi.org/10.1021/bm200991b
SN  - 1525-7797
VL  - 12
IS  - 10
SP  - 3753
EP  - 3760
PB  - American Chemical Society
CY  - Washington
ER  -