No abstract

No abstract

Application of β-1,3-glucan in production of ceramics-based elastic composite for bone repair IntroductionHydroxyapatite (HAp), especially in a porous form, is appreciated as a bone filler due to its biocompatibility, bioactivity, osteoconductivity, minimal risk of appearance of allergic reactions, lack of carcinogenic properties and lack of sensitivity to sterilization processes [1][2][3]. There are numerous commercially available bone graft materials based on biologic and synthetic HAp, including ProOsteon ® (Interpore Cross International, USA), Endobon (BIOMET Orthopaedics, Switzerland), Cerapatite (Ceraver Osteal, France), Synatite (SBM, France) and others. HAp may serve not only as a bone filler but also as a carrier of active substances: antibiotics, chemiotherapeutics, growth factors, etc. [4][5][6][7][8][9]; it can also be used in composites, as a factor increasing their cytocompatibility, bioactivity, osteoconductivity, adhesion of coatings and compression modulus [10][11][12][13][14]. On the other hand, HAp application is often limited due to its relatively poor resorption and slow replacement by the host bone after implantation, substantially high Young modulus, and low fracture toughness [15,16], although these properties may be improved by addition of elasticity-increasing polymers. It is considered that polymer-ceramic composites reveal superior properties (at least in some aspects) over polymer and ceramic alone [17]. However, most polymers used for bone filler fabrication meet only some of the criteria for implantable materials.Bone replacing material such as ceramics or crushed bone offers an insufficient surgical handiness, especially when the orthopedic surgeon has to handle granules (in case of defects in maxillary bone) or scaffolds (rigid and non-adaptable to the implantation site). Some commercially available biomaterials contain the artificial or natural polymers serving as plasticizing agents and thus significantly reduce this inconvenience. Among them, EasyGraft TM (Degradable Solutions SA, Switzerland), Plexur M and P (Osteotech, USA) and Cerapatite-Collagen (Ceraver Osteal, France) can be listed. EasyGraft TM contains PLGA-coated β-TCP granules which hardens into a compact mass via partial and temporary PLGA dissolution by organic solvent; Plexur M and P are composed of cortical bone and resorbable artificial polymer; Cerapatite-Collagen, made from HAp granules and naturally-derived collagen fibers, becomes elastic after hydration with blood or saline. Bone or ceramic granules and powders may also be turned into a paste using collagen gels (e.g., Tecnoss ® Gel O; Tecnoss, Italy) or fibrin glue [18,19]. However, the natural polymeric compounds used in commercially available composites (collagen, fibrin glue) originate from animal sources; this can be considered as a limiting factor because of the increased risk of transmissible contamination (e.g. viruses) and undesirable immune responses. Thus, the necessity of careful purification of these animal polymers exacts the high price of fin...

No abstract

No abstract

Geotrichum-like strain R59, the anamorphic form of the white-rot fungus, Bjerkandera adusta, was isolated from soil. It was found to completely decolorize and degrade 10% daunomycin post-production effluent during 10 days of incubation at 26 degrees C. Strain R59 produced only low levels of ligninolytic enzymes when grown on wheat straw- or beech sawdust-containing media, but in the presence of humic acids derived from brown coal it synthesized significant amounts of laccase and lipase. This phenomenon was coupled with the fungus entering the idiophase and the appearance of aerial mycelium. B. adusta strain R59 was found to completely decolorize 0.03% humic acids from brown coal and lessive soil and to partially decolorize humic acids isolated from a chernozem during 14 days of growth. This ability of strain R59 could be useful in constructing a new generation of biologically active filters for the purification of humic acids-contaminated drinking waters.

Titanium oxide nanotube layers with silver and zinc nanoparticles are attracting increasing attention in the design of bone and dental implants due to their antimicrobial potential and their ability to control host cell adhesion, growth, and differentiation. However, recent reports indicate that the etiology of dental infections is more complex than has been previously considered. Therefore, the antimicrobial potential of dental implants should be evaluated against at least several different microorganisms cooperating in human mouth colonization. In this study, Ag and Zn nanoparticles incorporated into titanium oxide nanotubular layers were studied with regard to how they affect Candida albicans, Candida parapsilosis, and Streptococcus mutans. Layers of titanium oxide nanotubes with an average diameter of 110 nm were fabricated by electrochemical anodization, annealed at 650 °C, and modified with approx. 5 wt % Ag or Zn nanoparticles. The surfaces were examined with the scanning electron microscopy-energy dispersive X-ray analysis, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy techniques and subjected to evaluation of microbial-killing and microbial adhesion-inhibiting potency. In a 1.5 h long adhesion test, the samples were found more effective toward yeast strains than toward S. mutans. In a release-killing test, the microorganisms were almost completely eliminated by the samples, either within 3 h of contact (for S. mutans) or 24 h of contact (for both yeast strains). Although further improvement is advisable, it seems that Ag and Zn nanoparticles incorporated into TiO nanotubular surfaces provide a powerful tool for reducing the incidence of bone implant infections. Their high bidirectional activity (against both Candida species and S. mutans) makes the layers tested particularly promising for the design of dental implants.

Covalent gentamicin immobilisation resulted in effective antibacterial protection of vascular prostheses against clinical and reference strains of S. aureus, E. coli and P. aeruginosa and allowed for a strong adherence of endothelial cells to antibiotic-modified prostheses.