Comparable Studies on Nanoscale Antibacterial Polymer Coatings Based on Different Coating Procedures.

The antibacterial activity of different antibiotic and metal-free thin polymer coatings was investigated. The films comprised quaternary ammonium compounds (QAC) based on a vinyl benzyl chloride (VBC) building block. Two monomeric QAC of different alkyl chain lengths were prepared, and then polymerized by two different polymerization processes to apply them onto Ti surfaces. At first, the polymeric layer was generated directly on the surface by atom transfer radical polymerization (ATRP). For comparison purposes, in a classical route a copolymerization of the QAC-containing monomers with a metal adhesion mediating phosphonate (VBPOH) monomers was carried out and the Ti surfaces were coated via drop coating. The different coatings were characterized by X-ray photoelectron spectroscopy (XPS) illustrating a thickness in the nanomolecular range. The cytocompatibility in vitro was confirmed by both live/dead and WST-1 assay. The antimicrobial activity was evaluated by two different assays (CFU and BTG, resp.,), showing for both coating processes similar results to kill bacteria on contact. These antibacterial coatings present a simple method to protect metallic devices against microbial contamination.

Adjustable Polyurethane Foam as Filling Material for a Novel Spondyloplasty: Biomechanics and Biocompatibility.

OBJECTIVE: To investigate the biomechanics and biocompatibility of polyurethane (PU) foam with adjustable stiffness as a filling material for a novel spondyloplasty that is designed to reduce the risk of postoperative adjacent level fractures. METHODS: Sixty individual porcine lumbar vertebrae were randomly split into 4 groups: A, B, C, and D. Group A served as unmodified vertebral body controls. Groups B, C, and D consisted of hollowed vertebral bodies. Vertebrae of groups C and D were filled with adjustable PU foams of different stiffness. The compressive strength and stiffness of vertebrae from groups A-D were recorded and analyzed. 3T3 mouse fibroblasts were cultured with preformed PU foams for 4 days to test biocompatibility. RESULTS: The strength and stiffness of the hollowed groups were lower than in group A. However, the differences were not statistically significant between group A and group C (P > 0.05), and were obviously different between group A and group B or group D (P < 0.01 and <0.05, respectively). Moreover, the strength and stiffness after filling foams in group C or group D were significantly greater than in group B (P < 0.01 and <0.05, respectively). Live/dead staining of 3T3 cells confirmed the biocompatibility of the PU foam. CONCLUSIONS: The new PU foam shows adaptability regarding its stiffness and excellent cytocompatibility in vitro. The results support the clinical translation of the new PU foams as augmentation material in the development of a novel spondyloplasty.

In situ foamable, degradable polyurethane as biomaterial for soft tissue repair.

Degradable foams which can be inserted endoscopically as liquid or pasty mixtures into soft tissue defects possess a promising potential for the surgical treatment of such defects. The defects can be sealed under in situ foaming and simultaneous material expansion. We developed an in situ foamable (l-lactide-co-ε-caprolactone)-based, star-shaped prepolymer by ring opening polymerization of l-lactide and ε-caprolactone in the presence of meso-erythritol as starter. By conversion of the terminal hydroxyl groups of the formed oligoester with lysine diisocyanate ethyl ester (LDI) an isocyanate-endcapped, reactive prepolymer has been received. Foaming can be initiated by addition of 1,4-diazabicyclo[2,2,2]octane (DABCO), water, LDI and DMSO. By varying the composition of these additives, the foaming and curing time could be varied within a clinically acceptable range. A porosity of approximately 90%, and an average tensile strength of 0.3MPa with elongations of 90% were determined for the foams. In vitro cytotoxicity on cured foams was assayed on 3T3 fibroblasts and demonstrated an excellent cytocompatibility. This was also confirmed in an in vivo study using an established rat model, where prefabricated foams and in situ hardening material were inserted into subdermal skin incisions in parallel. The feature of chronic inflammation was only weakly developed in both groups and slightly more pronounced and persisted for longer time in the group of in situ foamed material. In both groups the foreign materials were vascularized, degraded and substituted by connective tissue. The results encourage to proceed with trials where the materials are used to fill more heavily loaded defects.

Continuous cellularization of calcium phosphate hybrid scaffolds induced by plasma polymer activation.

The generation of hybrid materials based on ß-tricalcium phosphate (TCP) and various biodegradable polymers like poly(l-lactide-co-d,l-lactide) (PLA) represents a common approach to overcoming the disadvantages of pure TCP devices. These disadvantages lie in TCP's mechanical properties, such as brittleness. The positive characteristic of PLA - improvement of compressive strength of calcium phosphate scaffolds - is diametrically opposed to its cell attractiveness. Therefore, the objective of this work was to optimize osteoblast migration and cellularization inside a three-dimensionally (3D) printed, PLA polymer stabilized TCP hybrid scaffold by a plasma polymer process depositing amino groups via allylamine. MG-63 osteoblastic cells inside the 10mm hybrid scaffold were dynamically cultivated for 14days in a 3D model system integrated in a perfusion reactor. The whole TCP/PLA hybrid scaffold was continuously colonized due to plasma polymerized allylamine activation inducing the migration potential of osteoblasts.

Electrospun poly(ester-Urethane)- and poly(ester-Urethane-Urea) fleeces as promising tissue engineering scaffolds for adipose-derived stem cells.

An irreversible loss of subcutaneous adipose tissue in patients after tumor removal or deep dermal burns makes soft tissue engineering one of the most important challenges in biomedical research. The ideal scaffold for adipose tissue engineering has yet not been identified though biodegradable polymers gained an increasing interest during the last years. In the present study we synthesized two novel biodegradable polymers, poly(ε-caprolactone-co-urethane-co-urea) (PEUU) and poly[(L-lactide-co-ε-caprolactone)-co-(L-lysine ethyl ester diisocyanate)-block-oligo(ethylene glycol)-urethane] (PEU), containing different types of hydrolytically cleavable bondings. Solutions of the polymers at appropriate concentrations were used to fabricate fleeces by electrospinning. Ultrastructure, tensile properties, and degradation of the produced fleeces were evaluated. Adipose-derived stem cells (ASCs) were seeded on fleeces and morphology, viability, proliferation and differentiation were assessed. The biomaterials show fine micro- and nanostructures composed of fibers with diameters of about 0.5 to 1.3 µm. PEUU fleeces were more elastic, which might be favourable in soft tissue engineering, and degraded significantly slower compared to PEU. ASCs were able to adhere, proliferate and differentiate on both scaffolds. Morphology of the cells was slightly better on PEUU than on PEU showing a more physiological appearance. ASCs differentiated into the adipogenic lineage. Gene analysis of differentiated ASCs showed typical expression of adipogenetic markers such as PPARgamma and FABP4. Based on these results, PEUU and PEU meshes show a promising potential as scaffold materials in adipose tissue engineering.

Synthesis and pharmacological activities of some sesquiterpene quinones and hydroquinones.

Synthesis of protected siphonodictyal C was achieved via drim-7-en-11-al. Some sesquiterpene quinones and hydroquinones were tested for their pharmacological activities in assays in search of antiproliferative, cytotoxic, antiphlogistic, antirheumatic and anti-inflammatory drugs. Wiedendiol B is a ten times stronger cyclooxygenase-2 inhibitor than the reference compound indomethacine. Cyclooxygenase-2 inhibitors are drugs with antiphlogistic and antirheumatic activity.