Band 18, Heft 3-4

This work highlights the laser-based aqueous synthesis and processing of nanocomposites, composed of zinc or iron nanoparticles embedded in a N -Vinylcaprolactam microgel matrix, with potential applicability as ion releasing fiber pads for wound healing. An in situ laser process for microgel synthesis is developed and optimized for high embedded nanoparticle yields, evaluating influences of laser repetition rate and monomer concentration. The impact of the nanoparticles on polymerization was increased by embedded zinc oxide nanoparticles, and reduced in the presence of iron oxide. Furthermore, TEM images verified that the nanoparticles were homogeneously embedded into the polymer matrix. The nanoparticle-loaded microgels were thermally stable up to 429 °C, which ensures that the composites maintain their integrity after heat sterilization and during rapid prototyping by thermal polymer processing. The general suitability of the hydrogels as active biomaterial for wound healing was assessed in toxicity, cell proliferation and migration assays using human dermal fibroblasts and keratinocytes, where cytocompatibility was verified, while the proliferation was affected by the gel alone as well as the embedded nanoparticles. The hydrogels were processed to suit their use as a biomaterial for wound coverages via electrospinning resulting in a centimeter scale fully cytocompatible fiber pad with the nanoparticle-filled microgel capsules supported on the fiber’s surface.

Background The aim of the study was to evaluate the antibacterial effect of a drug releasing poly (3-hydroxybutyrate) (P(3HB)) implant coating in comparison to pure titanium on Aggregatibacter actinomycetemcomitans as a model periodontopathogen to prevent biofilm formation on implant surfaces. Methods Titanium discs were coated with P(3HB) containing 5% (w) and 10% (w) of metronidazole, either with and without a P(3HB) topcoat. The biofilm formation was evaluated after 1, 4 and 9 days in a dynamic flow chamber system. Microbial adherence was quantified by determination of bacterial surface coverage. Results The evaluated formulations of P(3HB)/metronidazole showed an antibacterial effect especially in the first 24 h. Prolonged incubation for 9 days showed reduced bacterial adhesion only on polymer coatings loaded with 10% (w) of metronidazole both with and without topcoat. Conclusions The evaluated coating formulations can provide protection from an Aggregatibacter actinomycetemcomitans in vitro biofilm formation for the time period which was evaluated.

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 2 HPO 4 aqueous solution was used as mixing liquid. For the hydration enthalpy of crystalline β-TCP, a value of ΔH R(β-TCP → CDHA) = −23.9 kJ/mol TCP can be calculated from literature data. In this study ΔH R(ATCP → CDHA) = −83 ± 6 kJ/mol TCP was determined from new measurement results for the hydration of amorphized β-TCP to calcium-deficient hydroxyapatite (CDHA). Hence the hydration enthalpy was shown to be increased by a factor of 3.5 due to amorphization. Additionally, the hydration enthalpy of ATCP resulting from amorphization of β-TCP was compared and demonstrated to be not significantly different to that of ATCP resulting from α-TCP amorphization, which was −78 ± 2 kJ/mol TCP . This indicates that amorphization of α-TCP and β-TCP results in an amorphous phase with the same properties.

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.

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.

Nanorods in nanotechnology called a specific type of morphology of nanoscale materials that their dimensions range is from 1 to 100 nm. Nanorods can be synthesized from metal or semi-conductive material with a surface to volume ratio of 3–5. One method of making nanorods is direct chemical method. Ligands compounds as a shape control agents cause growth the nanorods and create stretched and extended modes of them. In recent years, magnetic nanorods are one of the nanorods that have been raised in the field of nano medicine [Nath S, Kaittanis C, Ramachandran V, Dalal NS, Perez JM. Synthesis, magnetic characterization, and sensing applications of novel dextran-coated iron oxide nanorods. Chem Mater. 2009;21:1761–7.]. Superparamagnetic properties of magnetic nanorods causes to sensing be done with high accuracy. In addition, other applications of magnetic nanorods are in the field of separation and treatment [Hu B, Wang N, Han L, Chen ML, Wang JH. Magnetic nanohybrids loaded with bimetal core–shell–shell nanorods for bacteria capture, separation, and near-infrared photothermal treatment. Chemistry. 2015;21:6582–9.]. Therefore, in biomedical applications, the nanorods are used usually with biological molecules such as antibodies [Schrittwieser S, Pelaz B, Parak WJ, Lentijo-Mozo S, Soulantica K, Dieckhoff J, et al. Homogeneous protein analysis by magnetic core–shell nanorod probes. ACS Appl Mater Interfaces. 2016;8:8893–9.]. For this purpose, in the present work we will try to introduce magnetic nanorods and mention their different methods of synthesis and applications.