Bioactive Inorganic Scaffolds
The development of inorganic scaffold materials for bone regeneration at FMZ is based on reactive calcium- and magnesium phosphates (CaP and MgP) that set after addition of water under ambient conditions by a dissolution – precipitation reaction. Primary aims are focused on the synthesis and reactivity of the powders, their rheological optimization for injectability, the biological behavior in vitro and in vivo, and the mechanical strength of the resulting ceramics. A current development concerns bioceramics and cements based on magnesium phosphate chemistry. The rationale behind this is the good solubility of MgP phases under in vivo conditions and the fact that Mg2+ is a potent inhibitor of hydroxyapatite crystal growth thereby suppressing unwanted crystallization in vivo. In contrast to implants made of magnesium metal, magnesium phosphate ceramics and cements do not produce hydrogen gas and an alkaline environment during dissolution.
Biofabrication is the “the automated generation of biologically functional products with structural organization from living cells, bioactive molecules, biomaterials, cell aggregates such as micro-tissues, or hybrid cell-material constructs, through bioprinting or bioassembly and subsequent tissue maturation processes.” (Groll et al. 2016) The FMZ is mainly focusing on bioprinting approaches. These are e.g. processing of cell-instructive scaffolds from biomaterial inks or the fabrication of cell-containing constructs made from bioinks. The Biofabrication platform is thus divided in melt electrowriting (MEW), a novel fabrication approach to make fine structured scaffolds, and in Bioprinting where also hydrogel based Bioinks are developed in-house.
Our biological platform connects the various developments of the material-based platforms and investigates biological processes in an application-oriented manner. Interactions between materials and the biosystem are analyzed in vitro, in vivo and on a microbiological level. Focus areas of research are the quantitative assessment of cell-material and cell-cell interaction, co-culture systems of primary human cells, examination of the human immune response by biomaterials, and strategies for vascularization and 3D tissue perfusion.
In their natural environment, cells are surrounded by a matrix that enables their survival and determines their adhesion, growth, proliferation, migration, differentiation and function. Therefore, soluble factors that are reversible immobilized in the so called extracellular matrix (ECM) as well as specifically acting binding moieties are of utmost importance. Main components of the ECM are hydrogels and insoluble protein fibres that serve as mechanical scaffold for the cells. Another important structural element are basal membranes, ultrathin separation layers between tissues.
A core activity at FMZ is the preparation and evaluation of biodegradable materials and structures that mimic the ECM as closely as possible in its morphology, biochemical function and hierarchical composition. Modified biopolymers as well as biocompatible functional polymers are used as components for coatings, hydrogels and nanofibrous constructs to achieve this goal. For the generation of hierarchy, methods such as electrospinning and rapid-prototyping techniques are applied.
Another focus area of research are injectable systems for in-situ Tissue Engineering. For this, biocompatible cross-linking chemistries are essential that do not negatively affect cell viability. Examples for this are Michael-Addition or click-chemistry. Finally, the rheological properties of these systems have to be controlled properly.
Nanotechnology is a key technology for medicine which utilizes nanoscale structured materials to diagnose, treat and prevent disease. Nanoparticles are large enough to take up and transport drugs but also small enough to be taken up by cells and to use active biological transport mechanisms. This opens a wide potential for targeted transport especially of sensitive drugs over barriers in the body to the area and tissue of interest.
Research in FMZ focuses on synthesis and properties of nanoparticles for different purposes. Systematic studies regarding the influence of nanoparticle shape, size and surface chemistry on the interaction with cells are one area of interest. Inorganic and organic nanoparticles are used for the identification of suited ligands for the specific uptake of the particles exclusively into defined cellular populations.