Aims
Chronic osteomyelitis, including implant-related prosthetic joint infection, is extremely difficult to cure. We develop vancomycin containing release systems from poly(
d
,
l
-lactide) (PDLLA) ...and poly(
d
,
l
-lactide-co-glycolide) (PLGA) composites with beta-tricalcium phosphate (β-TCP) to treat methicillin-resistant
Staphylococcus aureus
osteomyelitis. We ask whether vancomycin containing PDLLA/β-TCP and PLGA/β-TCP composites will prevent early biofilm formation, allow cell proliferation and osteogenic differentiation, and stimulate osteogenic signaling molecules in the absence of an osteogenic medium.
Methods
Composites were produced and characterized with scanning electron microscopy.
In vitro
vancomycin release was assessed for 6 weeks. Biofilm prevention was calculated by crystal violet staining. Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and osteosarcoma cell (SaOS-2) proliferation and differentiation were assessed with water soluble tetrazolium salt and alkaline phosphatase (ALP) staining. Real-time quantitative polymerase chain reaction defined osteogenic signaling molecules for hBM-MSCs.
Results
Totally, 3.1 ± 0.2 mg and 3.4 ± 0.4 mg vancomycin released from PDLLA/β-TCP and the PLGA/β-TCP composites, respectively, and inhibited early biofilm formation. hBM-MSCs and SaOS-2 cells proliferated on the composites and stimulated ALP activity of cells. Runt-related transcription factor 2 (RUNX2) and SRY-Box transcription Factor 9 (SOX9) expressions were, however, lower with composites when compared with control.
Conclusion
Vancomycin containing PDLLA/β-TCP and PLGA/β-TCP composites inhibited early biofilm formation and proliferated and differentiated hBM-MSCs and SaOS-2 cells, but osteogenesis-related RUNX2 and SOX9 transcription factors were not strongly expressed in the absence of an osteogenic medium for 14 days.
•The synergistic interaction was observed among the additives.•The maximum flame retardant properties were achived at a ratio of 1:1.•No chemical interaction is observed between the fillers.•The ...physical interaction led to synergistic interaction.
The effect of expandable graphite (EG) was studied on the flame retardant, thermal and mechanical properties of thermoplastic polyurethane (TPU) containing huntite&hydromagnesite (HH). According to the flammability tests results, the synergistic interaction was observed between HH and EG. The maximum limiting oxygen index (LOI) value was observed at a ratio of 1:1 (HH:EG) and the highest vertical burning test (UL-94) rating of V0 was observed at a ratios of 4:1, 3:2 and 1:1. The synergistic interaction between EG and HH was also deduced at low percentage of EG (10%) by the help of the mass loss calorimeter test results. Mechanical test observations revealed that the inclusion of HH reduced the tensile strength and elongation at break values and increased the elastic modulus and glass transition temperature of pristine TPU. The addition of EG was further improved the elastic modulus of composites as the loaded amount of EG increased.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Thermoplastic polyurethane (TPU) composites with fullerene loadings varying from 0.5 to 2 weight% were prepared by melt-mixing method. Nitric acid oxidation and silanization were applied to fullerene ...surface to improve interfacial interactions with TPU matrix. The influence of surface modifications of fullerene on mechanical, melt flow and electrical properties of TPU based composites were investigated. Incorporation of fullerene leads to nearly twofold increase in tensile strength and Young's modulus of the composites in addition to enhancing the flexibility. The best results are obtained in nitric acid and silane modified fullerene containing composites at the lowest concentration (0.5%). Higher MFI values were observed for composites loaded with surface treated fullerenes compared to pristine fullerene because of their better dispersion in TPU. Electrical properties of TPU also improved by the addition of surface modified fullerene particles. Surface oxidation and silanization gave rise to dispersion homogeneity which may be the reason of both tensile strength and strain improvements at the same time.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Although there is considerable research effort in the development of halogen-free flame-retardant polylactide (PLA), a bio-based aliphatic polyester, the potential synergistic interactions of ...nanoparticles and conventional additives have scarcely been considered. Therefore, this study aimed to investigate the influence of nanofiller geometry on fire retardancy of PLA nanocomposites containing aluminium diethylphosphinate (AlPi) flame retardant. For this purpose, a variety of nanofiller geometries were utilized, spherical nanosilica (0-D), rod-like halloysite (1-D) and plate-like montmorillonite (2-D). Fire performance increased in the order of rod-like < spherical ≪ plate-like geometries which matched qualitatively with the effective surface area of nanoparticles in the nanocomposite. Owing to intercalation/exfoliation (nanodispersion) of montmorillonite, a large surface area was obtained which facilitated rapid migration and accumulation of platelets on exposed sample surface prior to intumescent char formation. By this means, intumescence was hindered and a thicker aluminium phosphate/montmorillonite nanocomposite char was formed acting as a strong transport barrier. Investigations on microstructural evolution of residues revealed extraordinarily regular, hollow-fibrillar structures during combustion of PLA/AlPi. The corresponding nanocomposites formed micro-porous ceramic-like structures composed of spherical aluminium phosphate nanoparticles, covering the surface and protecting the pyrolysing melt.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, several treatments including alkali, permanganate, peroxide and silanization were applied to flax fiber (FF) to improve its adhesion to bio-based thermoplastic polyurethane (TPU) ...matrix. TPU/FF composites were prepared at a constant ratio of 30 wt% by using extrusion process. Their mechanical properties, modulus of elasticity, water uptake behaviors, melt-flow properties and morphologies of composites were investigated. All treatments resulted in better mechanical properties with respect to untreated FF. Silane treated FF containing composite exhibited the highest tensile strength and lowest water absorption. Results confirmed that surface modifications improve the adhesion between FF and TPU matrix.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Bioceramics are type of biomaterials generally used for orthopaedic applications due to their similar structure with bone. Especially regarding to their osteoinductivity and osteoconductivity, they ...are used as biodegradable scaffolds for bone regeneration along with mesenchymal stem cells. Since chemical properties of bioceramics are important for regeneration of tissue, physical properties are also important for cell proliferation. In this respect, several different manufacturing methods are used for manufacturing nano scale bioceramics. These nano scale bioceramics are used for regeneration of bone and cartilage both alone or with other types of biomaterials. They can also act as carrier for the delivery of drugs in musculoskeletal infections without causing any systemic toxicity.
