Binding Mechanism of the Model Charged Dye Carboxyfluorescein to Hyaluronan/Polylysine Multilayers.

Biopolymer-based multilayers become more and more attractive due to the vast span of biological application they can be used for, e.g., implant coatings, cell culture supports, scaffolds.

In-situ assembly of Ca-alginate gels with controlled pore loading/release capability.

Development of tailor-made porous polymer scaffolds acting as a temporary tissue-construct for cellular organization is of primary importance for tissue engineering applications. Control over the gel porosity is a critical issue due to the need for cells to proliferate and migrate and to ensure the transport of nutrition and metabolites. Gel loading with bioactive molecules is desired for target release of soluble signals to guide cell function.

Macromolecule loading into spherical, elliptical, star-like and cubic calcium carbonate carriers.

We fabricated calcium carbonate particles with spherical, elliptical, star-like and cubical morphologies by varying relative salt concentrations and adding ethylene glycol as a solvent to slow down the rate of particle formation. The loading capacity of particles of different isotropic (spherical and cubical) and anisotropic (elliptical and star-like) geometries is investigated, and the surface area of such carriers is analysed. Potential applications of such drug delivery carriers are highlighted.

Multifunctional polyelectrolyte microparticles for oral insulin delivery.

Multicomponent insulin-containing microparticles are prepared by layer-by-layer assembly of dextran sulfate and chitosan on the core of protein-polyanion complex with or without protease inhibitors. Oral bioavailability of the encapsulated insulin is improved due to the cumulative effect of each component. A physico-chemical study shows that the particle design allows adjustment of the pH-dependent profile of the insulin release, as well as mucoadhesive properties and Ca(2+) binding ability of the microparticles.

Magnetic porous sugar-functionalized PEG microgels for efficient isolation and removal of bacteria from solution.

Here, we present a new microparticle system for the selective detection and magnetic removal of bacteria from contaminated solutions. The novelty of this system lies in the combination of a biocompatible scaffold reducing unspecific interactions with high capacity for bacteria binding. We apply highly porous poly(ethylene glycol) (PEG) microparticles and functionalize them, introducing both sugar ligands for specific bacteria targeting and cationic moieties for electrostatic loading of superparamagnetic iron oxide nanoparticles.

Microfluidics as a tool to understand the build-up mechanism of exponential-like growing films.

Microfluidics is used here for the first time to efficiently tune the growth conditions for understanding the build-up mechanism of exponentially growing polyelectrolyte (PE) films. The velocity of PE supply and time of interaction can be successfully altered during the layer-by-layer assembly. Another advantage of this method is that the deposition of poly-L-lysine/hyaluronic acid (PLL/HA) films in microchannels can be monitored online by fluorescence microscopy.

Control of cell adhesion by mechanical reinforcement of soft polyelectrolyte films with nanoparticles.

Chemical cross-linking is the standard approach to tune the mechanical properties of polymer coatings for cell culture applications. Here we show that the elastic modulus of highly swollen polyelectrolyte films composed of poly(L-lysine) (PLL) and hyaluronic acid (HA) can be changed by more than 1 order of magnitude by addition of gold nanoparticles (AuNPs) in a one-step procedure. This hydrogel-nanoparticle architecture has great potential as a platform for advanced cell engineering application, for example remote release of drugs.

Synthesis of porous PEG microgels using CaCO3 microspheres as hard templates.

Porous poly(ethylene glycol) (PEG) microgels of both 17.6 and 8.3 μm in diameter are synthesized via hard templating with calcium carbonate (CaCO(3)) microparticles.

Microfluidics meets soft layer-by-layer films: selective cell growth in 3D polymer architectures.

We present here the micropatterns of layer-by-layer (LbL) assembled soft films generated using microfluidic platform that can be exploited for selective cell growth. Using this method, the issue of cell adhesion and spreading on soft LbL-derived films, and simultaneous utilisation of such unmodified soft films to exploit their reservoir properties are addressed. This also paves the way for extending the culture of cells to soft films and other demanding applications like triggered release of biomolecules.

Anisotropic multicompartment micro- and nano-capsules produced via embedding into biocompatible PLL/HA films.

We present a novel strategy to fabricate anisotropic multicompartment Janus capsules by embedding larger containers into a soft poly-L-lysine/hyaluronic acid (PLL/HA) polymeric film, followed by adsorption of smaller containers on top of their unmasked surface. This research is also attractive for developing substrates for cell cultures.

Bio-interfaces--interaction of PLL/HA thick films with nanoparticles and microcapsules.

The interaction of biocompatible, exponentially grown films composed of poly-L-lysine (PLL) and hyaluronic acid (HA) polymers with gold nanoparticles and microcapsules is studied. Both aggregated and non-aggregated nanoparticle states are achieved; desorption of PLL accounts for aggregation of nanoparticles. The presence of aggregates of gold nanoparticles on films enables remote activation by near-infrared irradiation due to local, nanometer confined heating.

Near-IR remote release from assemblies of liposomes and nanoparticles.

Set free by light: Near-IR (NIR) laser-initiated remote release of fluorescent dye from complexes of liposome-gold-nanoparticle aggregates is demonstrated (see fluorescence images). Complexes of the desired size are shown to be a viable approach to the construction of vesicle-based drug-delivery systems with light-triggered remote release characteristics. This opens up a new method to manipulate liposome-based drug-delivery systems in a biocompatible way by using the near-IR spectral range.

Real-time assessment of spatial and temporal coupled catalysis within polyelectrolyte microcapsules containing coimmobilized glucose oxidase and peroxidase.

The encapsulation of biological enzymes within polyelectrolyte microcapsules is an important step toward microscale devices for processing and analytical applications, one which could be applied to the realization of minimally invasive sensing technology. In this work, the encapsulation and functional characterization of a bienzymatic coupled catalytic system within polyelectrolyte microcapsules is described. The two components, glucose oxidase (GOx) and horseradish peroxidase (HRP), were coprecipitated with calcium carbonate microspheres, followed by layer-by-layer assembly to form ultrathin polymer film coatings that act as capsule walls after removal of the sacrificial carbonate cores.

Protein-calcium carbonate coprecipitation: a tool for protein encapsulation.

A new approach of encapsulation of proteins in polyelectrolyte microcapsules has been developed using porous calcium carbonate microparticles as microsupports for layer-by-layer (LbL) polyelectrolyte assembling. Two different ways were used to prepare protein-loaded CaCO3 microparticles: (i) physical adsorption--adsorption of proteins from the solutions onto preformed CaCO3 microparticles, and (ii) coprecipitation--protein capture by CaCO3 microparticles in the process of growth from the mixture of aqueous solutions of CaCl2 and Na2CO3. The latter was found to be about five times more effective than the former (approximately 100 vs approximately 20 mug of captured protein per 1 mg of CaCO3).

Matrix polyelectrolyte microcapsules: new system for macromolecule encapsulation.

A new approach to fabricate polyelectrolyte microcapsules is based on exploiting porous inorganic microparticles of calcium carbonate. Porous CaCO3 microparticles (4.5-5.

Protein encapsulation via porous CaCO3 microparticles templating.

Porous microparticles of calcium carbonate with an average diameter of 4.75 microm were prepared and used for protein encapsulation in polymer-filled microcapsules by means of electrostatic layer-by-layer assembly (ELbL). Loading of macromolecules in porous CaCO3 particles is affected by their molecular weight due to diffusion-limited permeation inside the particles and also by the affinity to the carbonate surface.

Loading the multilayer dextran sulfate/protamine microsized capsules with peroxidase.

Stable polyelectrolyte capsules were produced by the layer-by-layer (LbL) assembling of biodegradable polyelectrolytes, dextran sulfate and protamine, on melamine formaldehyde (MF) microcores followed by the cores decomposition at low pH. The mean diameter of the capsules at pH 3-5 was 8.0 +/- 0.