Saiga horn extracts were analyzed with the goal of obtaining new information about compounds present in it. The purpose of this study is to find synthetic alternatives to Saiga horn extract, which is used in traditional Chinese medicine, by identifying potentially biologically active compounds in the extracts. Using high-performance liquid chromatography coupled with high-resolution mass spectrometry, we have been able to identify a series of short-chain polyhydroxybutyrates in alcoholic extracts of Saiga horn. Optimized high-performance liquid chromatography coupled with tandem mass spectrometry methods for analysis of short-chain poly-3-hydroxybutyrates were developed and subsequently applied to investigate Saiga horn extract for the presence of these compounds, which might explain its biological actions, particularly for its antipyretic and procoagulant properties.
- Klíčová slova
- Saiga horn, liquid chromatography, polyhydroxybutyrates, tandem mass spectrometry, traditional Chinese medicine,
- MeSH
- chromatografie kapalinová MeSH
- léky rostlinné čínské chemie MeSH
- polyestery analýza MeSH
- rohy chemie MeSH
- rostlinné extrakty chemie MeSH
- tandemová hmotnostní spektrometrie MeSH
- tradiční čínská medicína MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- léky rostlinné čínské MeSH
- poly(3-hydroxyoctanoic acid) MeSH Prohlížeč
- polyestery MeSH
- rostlinné extrakty MeSH
Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering.
- Klíčová slova
- Bone tissue engineering, Poly(lactic acid), Poly(ϵ-carprolactone), Polymer blends,
- MeSH
- polyestery analýza MeSH
- polymery MeSH
- viskozita * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- poly(lactide) MeSH Prohlížeč
- polycaprolactone MeSH Prohlížeč
- polyestery MeSH
- polymery MeSH
This work deals with the mechanical characterization by depth-sensing indentation (DSI) of PLLA and PLDA composites reinforced with micro-particles of Mg (up to 15wt%), which is a challenging task since the indented volume must provide information of the bulk composite, i.e. contain enough reinforcement particles. The composites were fabricated by combining hot extrusion and compression moulding. Physico-chemical characterization by TGA and DSC indicates that Mg anticipates the thermal degradation of the polymers but does not compromise their stability during processing. Especial emphasis is devoted to determine the effect of strain rate and Mg content on mechanical behavior, thus important information about the visco-elastic behavior and time-dependent response of the composites is obtained. Relevant for the intended application is that Mg addition increases the elastic modulus and hardness of the polymeric matrices and induces a higher resistance to flow. The elastic modulus obtained by DSI experiments shows good agreement with that obtained by uniaxial compression tests. The results indicate that DSI experiments are a reliable method to calculate the modulus of polymeric composites reinforced with micro-particles. Taking into consideration the mechanical properties results, PLA/Mg composite could be used as substitute for biodegradable monolithic polymeric implants already in the market for orthopedics (freeform meshes, mini plates, screws, pins, …), craniomaxillofacial, or spine.
- Klíčová slova
- Biodegradable composites, Indentation tests, Magnesium, Mechanical properties, PLA,
- MeSH
- hořčík MeSH
- modul pružnosti MeSH
- polyestery analýza MeSH
- polymery analýza MeSH
- testování materiálů * MeSH
- tvrdost MeSH
- viskozita MeSH
- vstřebatelné implantáty * MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- hořčík MeSH
- poly(lactide) MeSH Prohlížeč
- polyestery MeSH
- polymery MeSH
Application of gas chromatography-mass spectrometry (GC-MS) can significantly improve trace analyses of compounds in complex matrices from natural environments compared to gas chromatography only. A GC-MS/MS technique for determination of poly-beta-hydroxybutyrate (PHB), a bacterial storage compound, has been developed and used for analysis of two soils stored for up to 319 d, fresh samples of sewage sludge, as well as a pure culture of Bacillus megaterium. Specific derivatization of beta-hydroxybutyrate (3-OH C4:0) PHB monomer units by N-tert-butyl-dimethylsilyl-N-methyltrifluoracetamide (MTBSTFA) improved chromatographic and mass spectrometric properties of the analyte. The diagnostic fragmentation scheme of the derivates tert-butyldimethylsilyl ester and ether of beta-hydroxybutyric acid (MTBSTFA-HB) essential for the PHB identification was shown. The ion trap MS was used, therefore the scan gave the best sensitivity and with MS/MS the noise decreased, so the S/N was better and also with second fragmentation the amount of ions increased compared to SIM. The detection limit for MTBSTFA-HB by GC-MS/MS was about 10(-13) g microL(-1) of injected volume, while by GC (FID) and GC-MS (scan) it was around 10(-10) g microL(-1) of injected volume. Sensitivity of GC-MS/MS measurements of PHB in arable soil and activated sludge samples was down to 10 pg of PHB g(-1) dry matter. Comparison of MTBSTFA-HB detection in natural soil sample by GC (FID), GC-MS (scan) and by GC-MS/MS demonstrated potentials and limitations of the individual measurement techniques.
- MeSH
- Bacillus megaterium chemie růst a vývoj MeSH
- glykolipidy analýza MeSH
- hydroxybutyráty analýza MeSH
- látky znečišťující půdu analýza MeSH
- látky znečišťující životní prostředí analýza MeSH
- odpadní vody analýza MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- polyestery analýza MeSH
- senzitivita a specificita MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- glykolipidy MeSH
- hydroxybutyráty MeSH
- látky znečišťující půdu MeSH
- látky znečišťující životní prostředí MeSH
- odpadní vody MeSH
- poly-beta-hydroxybutyrate MeSH Prohlížeč
- polyestery MeSH
