Methodologies for Formation of Encapsulation System Scaffolds

Methodologies for Formation of Encapsulation System Scaffolds

From my side I am very interested in the area of materials science for intelligent smart systems. Thus we have demonstrated recently [Adv. Mater. 24 (2012) 985; SMALL 8 (2012) 820; Adv. Funct. Mater. 23 (2013)4483 and Adv. Mater. 36 (2013) 5029] how the blocks can be nanostructured and combined to provide system “intelligence”.

In particular, my skills are:

  • methodologies for formation of encapsulation system scaffolds (e.g. mesoporous oxides, mesoporous silicon, metal sponges, including surface integrated systems, hybrids);
  • prevention of spontaneous release of encapsulated materials;
  • stimuli responsive active chemicals delivery;
  • photosensitive materials;
  • "active" surfaces (e.g. for bio-object control, antifouling, anticorrosion).

I am very interested to be actively integrated in the on-going activities and collaborate with different groups successfully in the application for our "smart" systems for bio-applications with focus on fundamental understanding.

Specific goals:

We are developing flat and curved metal (in particular titanium) surfaces with such properties as controlled nanostructuring – topography, chemistry and defined porosity, by ultrasonic and electrochemical treatments – to provide smart tissue scaffolds. A prime advantage of using nanostructured titanium is that we avoid coating it with chemicals in order to interface cells directly with the metal or rather its oxide. In addition, chemicals can be encapsulated into the implant surface to control spatially and temporary their release by desired stimuli.

(Goal 1) Knowing that cell adhesion is different in 2D and in 3D we combine my previously demonstrated expertise with metal surface nanostructuring with the expertise present in the Department of Biomaterials of the MPIKG and extend the surface treatments to three-dimensional scaffold geometries. There are a number of challenges to address for defined surface nanostructuring and its following characterization to understand the nanostructuring process specifics in vertical and horizontal directions. In particular, we develop a versatile spatially resolved methodology for effective metal nanostructuring, including 3D microchannels of different sizes and geometries. In focus will be nanostructuring of a mesoporous and 1D nanotubular periodic surface organization. 3D microchannels with different shapes including cubes, triangles, cylinders, star-like, crosses from several µm to several mm range at different distance in model microscaffolds will be analysed.

Fig. 1: Schematic view of model microscaffold. Preliminary results of Ti nanostructuring by (middle) high intensity ultrasonic treatment with formation of mesoporous layer and (right) titanium anodisation with 1D nanotube growth. Insets show pre-osteoblast cells (MC3T3-E1) after 1 day culture on the corresponding surfaces.

(Goal 2) Nanostructured metal layers can be used as encapsulation layer for active species, such as growth factors, vitamins, antibiotics to affect cell adhesion and focal contacts on 2D and 3D levels. We will develop selective encapsulation of substances into the surface to favour the growth of specific cell types and, thus, move towards three-dimensionally structured cellular co-cultures. The following points are critical: encapsulation in desired position, without molecular destruction (e.g. denaturation for proteins) and controlled release.

Fig. 2: Methodologies to prevent spontaneous release of encapsulated species: (a) reversible mobility of polyelectrolyte layer-by-layer (LbL) coating; (b) complexation of the entrapped substance; (c) blocking the pores with hydrophobic units, which can be switched into hydrophilic ones (e.g., by oxidation of quinine groups to hydroquinone groups) to provide pore opening.

We develop as the scaffold nanostructured (mesoporous, 1D nanotubes) titania layers generated at the titanium surface and in three dimensional geometry employing sonochemical and electrochemical techniques (Fig.1-Goal 1) and design the layers for surface capsules with defined release mechanisms using conformational transitions for switching the opening of capsules (Fig.1-Goal 2) to control cellular 3D response and co-cultures.

Past research and outstanding results:

My work combines fundamental understanding on dynamic interfaces with application of these findings towards development of new design strategies in material sciences. Several of my publications are decisive contributions to the advancement of the discipline (full Refs see in list of publications) and provide state-of-art of the field:

1) Research on the influence of ultrasound on metals has shown that at the heart of the given process are effects of a depassivation and a recrystallization of active metals and their alloys in cavitation conditions. This allows suggesting a one-step method to produce metal nanocomposites (effective catalysts) and hybrids (anticorrosion and biocide surfaces) [two papers in Nanoscale, Adv. Mater., Adv. Funct. Mater., Chem. Comm., Langmuir, Micropor. Mesopor. Mater., Applied Materials & Interfaces, RCS Advances, 2 book chapters].

2) A means of manipulating the structure, luminescence and porosity via the solvent and other process parameters is provided. Ultrasound-assisted formation of photoluminescent centres and defect states that could be centres for charge separation and recombination is demonstrated. A solution of an environmental dilemma: a one-step ultrasonic process was demonstrated to yield brightly luminescent silicon particles and films without use of HF at any step of the sonosynthesis. Furthermore, the patterned silicon surface can be selectively modified by ultrasound. Beyond the specific examples given here, these findings provide guidelines for expanding the concept to a wide variety of systems (C, WS2, MoS2, oxides, etc.) [Application for European Patent, Angew. Chem. Int. Ed., J. Mater. Chem. and J. Phys. Chem. C].

3) Formation of functional hybrid materials. As sonodesigned metal-based sponges, composites as a surface layer of metal capsules with the possibility of multicomponent loading and time-resolved release were presented. The capsules can be loaded with active agents, such as vitamins and drugs, enzymes, DNA fragments, or antibodies, corrosion inhibitors. The porous layer is continuous with the bulk metal allowing for excellent double-side adhesion during the construction of a feedback (anticorrosion, biocide) coating. This system could potentially be used to develop new medical therapies, such as laboratory organ/tissue growth for human transplants [Adv. Mater., SMALL, Adv. Funct. Mater., Polymer Chem., J. Mater. Chem. and book chapter].

4) Novel photocontrollable coatings consisting of micro- and nanoparticles of mesoporous oxides with polyelectrolyte shell incorporated into an organosiloxane matrix were proposed. The possibility of light-induced opening of corrosion inhibitor-loaded polyelectrolyte containers with titania core under UV and metal doped oxides under IR laser illumination and local suppression of corrosion within pits was demonstrated [European Patent, 2 book chapters, ACS Nano, Chem. Comm., J. Mater. Chem., Adv. Funct. Mater., Soft Matter.].

5) The influence of metallic and bimetallic particles on biocidal and photocatalytic activity which allows to drastically (up to 8 times) increase of the efficiency of photodestruction of adsorbed organics in air conditions and radical enhancement (up to 70 times) of the rate of photodesinfection of aqueous medium due to decrease of recombination losses, gain in superoxide photoproduction yield and the build up in hydrophilicity of the photocatalyst surface as well as its affinity to microorganisms. Method for photocatalytic-assisted prophage induction to lytic cycle [Appl. Catal. B: Environmental., J. Photochem. Photobiol. A: Chem., Industry Cat., Photochem. Photobiol. Sci., Belarusian Patent]

6) A novel method of photocatalytic lithography employing thin films of amorphous TiO2 doped with palladium ions was established. This technique permits generation of metal patterns (circuits, microelectrodes, catalytic pads for carbon nanotube growth) on conducting and dielectric substrates with the resolution down to 3 μm when UV irradiation is used for exposure and down to 100 nm in the case of synchrotron or e-beam irradiations [Belarusian Patent, J. Photochem. Photobiol. A: Chem., book chapters, Nanotechnology, J. Engineer. Phys. Thermophys., Theor. Exper. Chem.].

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