Functionalization of polyethetherketone for application in dentistry and orthopedics

Since late 1990s, polyetheretherketone (PEEK) has presented a promising polymeric alternative to metal implant components, particularly in orthopedic and traumatic applications. However, PEEK is biologically inert, which has constrained its potential applications. In this manner, enhancing the bioactivity of PEEK is a huge challenge that must be comprehended to completely understand the potential advantages. Up to now, two noteworthy methodologies are discussed to enhance the bioactivity of PEEK, including bulk and surface modification. Although the latter is extremely challenging due to the very high physical and chemical stability of the high performance polymer, there are some stated modification reactions in the literature, which will be collocated with in the literature-reported PEEK composites in the present article. We will furthermore add information on polymer-based drug delivery systems and the biofunctionalization of polymers in general and discuss their applicability for PEEK, as we estimate that these strategies will gain greater attention in the future. At the end of the article, our own research on the development of a PEEK-associated biodegradable drug-delivery system with potential application in dentistry or orthopedics will be highlighted.

Water-based, surfactant-free cytocompatible nanoparticle-microgel-composite biomaterials – rational design by laser synthesis, processing into fiber pads and impact on cell proliferation

This work highlights the laser-based aqueous synthesis and processing of nanocomposites, composed of zinc or iron nanoparticles embedded in a

Cell communication modes and bidirectional mitochondrial exchange in direct and indirect macrophage/hMSC co-culture models

Macrophages are important cells of the innate immune system. They exhibit a high plasticity in phenotypes and play a major role in healing by initiating the early inflammatory reactions via the pro-inflammatory M1 phenotype. The anti-inflammatory M2 phenotype is assumed to induce regenerative processes and vascularization in subsequent tissue repair. Especially for regenerative processes, their interplay with multipotent human mesenchymal stromal cells (hMSCs) is decisive. Accordingly, in vitro co-culture models of these cell types are an important starting point for unraveling regenerative mechanisms. In our study, we compared direct co-culture, transwell-systems, and the use of conditioned medium to investigate the mitochondria transfer between the two cell types and the influence of hMSCs' presence on the phagocytic activity of macrophages. Using flow cytometry and fluorescence microscopy, we visualized the transfer of mitochondria in both directions: from hMSCs to macrophages and most notably also vice versa. Both cell types release mitochondria and internalize them in direct contact via tunneling nanotubes, as well as in indirect contact due to extracellular vesicles (EVs). Mitochondria were non-directionally released into the medium and could be transferred via conditioned medium. After three hours of direct and indirect co-culture, the majority of the cells showed a mitochondrial uptake. Co-cultivation also led to an increase of phagocytic activity of macrophages, with the highest phagocytic rate after 48 h and most pronounced in direct co-cultivation.

Flexible tissue-like electrode as a seamless tissue-electronic interface

Current implantable electrodes facilitate only a low cellular infiltration impairing the long-term integration into the host’s tissue. To accomplish a seamless electronic-tissue interface, conductive three-dimensional (3D) scaffolds were generated by carbonization of electro-spun fiber meshes. When introducing NaCl particles as porogens, tailored tissue-like electrodes were generated. Characterization of the porous 3D fiber electrodes demonstrated improved material and electrical characteristics compared to standard carbon fiber meshes or flat gold surfaces. The feasibility of the porous 3D electrodes was assessed by cell culture experiments, confirming the migration of cells into the electrode and the formation of contracting cardiomyocyte clusters. Finally, a complex cardiac co-culture system proved the integration of the tissue into the 3D electrode in long-term culture of 7 weeks. These results strengthen the development of tissue-like 3D scaffolds as alternative to two-dimensional (2D) electrodes.

Focal adhesion stabilization by enhanced integrin-cRGD binding affinity

In this study we investigate the impact of ligand presentation by various molecular spacers on integrin-based focal adhesion formation. Gold nanoparticles (AuNPs) arranged in hexagonal patterns were biofunctionalized with the same ligand head group, cyclic Arg-Gly-Asp [

Surface functionalization of poly(ε-caprolactone) and poly(3-hydroxybutyrate) with VEGF

In this study, surface modifications for the biodegradable polymers poly(ε-caprolactone) (PCL) and poly(3-hydroxybutyrate) [P(3HB)] were developed in order to improve their suitability as scaffold material for bioartificial vessel prostheses. The challenge of wet-chemical surface modifications is to avoid bulk adjustments resulting in undesired changes in mechanical properties of these polymers. Nevertheless subsequent immobilization and controlled release of potent angiogenic biomolecules like vascular endothelial growth factor (VEGF) from the polymer surface is required. In order to improve the biocompatibility of PCL and P(3HB), terminal hydroxyl groups on the surface of these polymers were generated via oxygen (O

Biofunctionalization of surfaces using polyelectrolyte multilayers

Biomaterials play a central role in modern strategies in regenerative medicine and tissue engineering to restore the structure and function of damaged or dysfunctional tissue and to direct cellular behavior. Both biologically derived and synthetic materials have been extensively explored in this context. However, most materials when implanted into living tissue initiate a host response. Modern implant design therefore aims to improve implant integration while avoiding chronic inflammation and foreign body reactions, and thus loss of the intended implant function. Directing these processes requires an in-depth understanding of the immunological processes that take place at the interface between biomaterials and the host tissue. The physicochemical properties of biomaterial surfaces (charge, charge density, hydrophilicity, functional molecular domains, etc.) are decisive, as are their stiffness, roughness and topography. This review outlines specific strategies, using polyelectrolyte multilayers to modulate the interactions between biomaterial surfaces and biological systems. The described coatings have the potential to control the adhesion of proteins, bacteria and mammalian cells. They can be used to decrease the risk of bacterial infections occurring after implantation and to achieve better contact between biological tissue and implants. In summary, these results are important for further development and modification of surfaces from different medical implants.

Hydration enthalpy of amorphous tricalcium phosphate resulting from partially amorphization of β-tricalcium phosphate

As it was recently shown that β-tricalcium phosphate (β-TCP), similar to α-TCP, can be mechanically activated by prolonged ball milling, partially amorphized β-TCP is promising for the development of new bone cement formulations. Hence in the present study the hydration of partially amorphized β-TCP with different contents of an amorphous phase (amorphous tricalcium phosphate, ATCP) was investigated by isothermal calorimetry and quantitative X-ray diffraction (XRD) to obtain the hydration enthalpies of β-TCP and ATCP. Measurements were conducted at 23 °C, a 0.1 M Na