5 research outputs found
Localized Crystallization of Calcium Phosphates by Light- Induced Processes
Medical treatment options for bones and teeth can be
significantly enhanced by taking control over the crystallization
of biomaterials like hydroxyapatite in the healing process.
Light-induced techniques are particularly interesting for this
approach as they offer tremendous accuracy in spatial
resolution. However, in the field of calcium phosphates, lightinduced
crystallization has not been investigated so far. Here,
proof of principle is established to successfully induce
carbonate-hydroxyapatite precipitation by light irradiation.
Phosphoric acid is released by a photolabile molecule exclusively
after irradiation, combining with calcium ions to form a
calcium phosphate in the crystallization medium. 4-Nitrophenylphosphate
(4NPP) is established as the photolabile molecule
and the system is optimized and fully characterized. A calcium
phosphate is crystallized exclusively by irradiation in aqueous
solution and identified as carbonate apatite. Control over the
localization and stabilization of the carbonate apatite is
achieved by a pulsed laser, triggering precipitation in calcium
and 4NPP-containing gel matrices. The results of this communication
open up a wide range of new opportunities, both in the
field of chemistry for more sophisticated reaction control in
localized crystallization processes and in the field of medicine
for enhanced treatment of calcium phosphate containing
biomaterials.European Research Council for funding
project 101069348 â INPATTOpen Access funding enabled and
organized by Projekt DEA
Tunable high-index photonic glasses
Materials with extreme photonic properties such as maximum diffuse
reflectance, high albedo, or tunable band gaps are essential in many current
and future photonic devices and coatings. While photonic crystals, periodic
anisotropic structures, are well established, their disordered counterparts,
photonic glasses (PGs), are less understood despite their most interesting
isotropic photonic properties. Here, we introduce a controlled high index model
PG system. It is made of monodisperse spherical TiO colloids to exploit
strongly resonant Mie scattering for optimal turbidity. We report spectrally
resolved combined measurements of turbidity and light energy velocity from
large monolithic crack-free samples. This material class reveals pronounced
resonances enabled by the possibility to tune both the refractive index of the
extremely low polydisperse constituents and their radius. All our results are
rationalized by a model based on the energy coherent potential approximation,
which is free of any fitting parameter. Surprisingly good quantitative
agreement is found even at high index and elevated packing fraction. This class
of PGs may be the key to optimized tunable photonic materials and also central
to understand fundamental questions such as isotropic structural colors, random
lasing or strong light localization in 3D.Comment: Main text: 8 pages, 4 figures; Supporting Information: 5 pages, 5
figure
Stimuli-Responsive Particle-Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry
Amphiphiles alter the energy of surfaces, but the extent of this feature is typically constant. Smart systems with amphiphilicity as a function of an external, physical trigger are desirable. As a trigger, the exposure to a magnetic field, in particular, is desired because it is not shielded in water. Amphiphiles like surfactants are well known, but the magnetic response of molecules is typically weak. Vice-versa, magnetic particles with strong response to magnetic triggers are fully established in nanoscience, but they are not amphiphilic. In this work colloids with Janus architecture and ultra-small dimensions (25nm) have been prepared by spatial control over the Thiol-Yne click modification of organosilica-magnetite core-shell nanoparticles. The amphiphilic properties of these anisotropically modified particles are proven. Finally, a pronounced and reversible change in interfacial stabilization results from the application of a weak (<<1T) magnetic field
Stimuli-Responsive Particle-Based Amphiphiles as Active Colloids Prepared by Anisotropic Click Chemistry
Amphiphiles alter the energy of surfaces, but the extent of this feature is typically constant. Smart systems with amphiphilicity as a function of an external, physical trigger are desirable. As a trigger, the exposure to a magnetic field, in particular, is attractive because it is not shielded in water. Amphiphiles like surfactants are well known, but the magnetic response of molecules is typically weak. Viceâversa, magnetic particles with strong response to magnetic triggers are fully established in nanoscience, but they are not amphiphilic. In this work colloids with Janus architecture and ultraâsmall dimensions (25â
nm) have been prepared by spatial control over the thiolâyne click modification of organosilicaâmagnetite coreâshell nanoparticles. The amphiphilic properties of these anisotropically modified particles are proven. Finally, a pronounced and reversible change in interfacial stabilization results from the application of a weak (<1â
T) magnetic field.publishe
Modular Toolkit of Multifunctional Block Copoly(2-oxazoline)s for the Synthesis of Nanoparticles
Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.publishe