Opis nedostataka u odljevcima ojačanim kompozitnim vlaknima na bazi legure AlSi11

In the paper the application of different methods: profilography, atomic force microscopy, scanning electron microscopy and mercury porosimetry for description of flaws in composites based on AlSi11 (AK11) alloy with fibrous reinforcement is presented.U članku je predstavljena primjena različitih metoda: profilografije, mikroskopija atomske sile, skening elektronske mikroskopije i živine porozimetrije za opis nedostataka u kompozitima na bazi legure AlSi11 (AK11) ojačanjem na bazi vlakana

In vitro evaluation of poly (L-lactide-co-glycolide) membrane

The aim of this study was to prepare and evaluate the properties of a new membrane dedicated for the treatment of bone defects in periodontology according to guided tissue regeneration (GTR) technique. The first part of this study was to prepare the membrane from resorbable poly(L-lactide-co-glycolide) (PLGA) and verify its microstructure. Biological evaluation was lead using the cells interesting from the point of view of GTR, e.g. human fibroblasts and mesenchymal stem cells (hMSC). It was found that the obtained membrane has asymmetric microstructure and defined pore size. Cell culture experiments show that the membrane is biocompatible with fibroblasts and hMSC. Both types of cell proliferated well on the membrane. HMSC cultured on the membrane exhibited better osteogenic differentiation and higher mineralization as compared to control tissue culture polystyrene

On the electropolishing and anodic oxidation of Ti-15Mo alloy

This paper presents research on modifying the surface of Ti-15Mo alloy using electropolishing and anodic passivation. The electropolishing process was carried out in solutions containing sulfuric acid, ethylene glycol, ammonium fluoride and oxalic acid. Whereas a voltage range from 20 to 100 V and a 1 M orthophosphoric acid solution were used during the anodic passivation. The influence of above mentioned processes parameters on the quality of the obtained oxide layer on Ti-15Mo alloy was investigated. The analysis of Ti-15Mo surface after modification was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), ellipsometry, and mechanical tests. Moreover, the corrosion resistance was investigated using a potentiostatic method in Ringer's solution. It was found that electropolishing leads to an increase in the surface homogeneity and to the form of an oxide layer, which consisted of TiO2 and MoO3. Whereas the oxide layers obtained during anodic passivation were characterized by different properties depending on the applied voltage. The anodic passivation at various voltages (20-100 V) increased the surface wettability (94.5°-87.6°) in comparison to the electropolished sample (97.5°). Moreover, the obtained oxide layer after anodization exhibited a high hardness. The electrolytic polishing and anodic passivation of Ti-15Mo also improved corrosion resistance of the alloy in contact with Ringer's solution. The sample anodized at 80 V presented the highest corrosion resistance by the smallest corrosion current density (1.4 nA cm-2) and the highest polarization resistance (37.4 MΩ cm2). © 2016 Elsevier Ltd. All rights reserved

Novel strategies for aminoglycoside antibiotic delivery in skeletal tissues - a review

This paper reviews recent advances concerning antibiotic-loaded microparticles application in osteomyelitis treatment. We discuss different methods utilized for microparticles' preparation, i.e. double emulsification, simple emulsification and spray drying. Materials comprised of sphere-shaped matrices are also presented. We point out that the most commonly used microsphere-building components are biodegrad¬able aliphatic polyesters such as poly(lactide-co-glicolide) PLGA, poly(sebacic-ricinoleic-ester-anhydride) P(SA-RA) and poly(lactic-co-hydroxymethyl glycolic acid) PLHMGA. Biopolymers like gelatin, starch or chitosan are also applied as antibiotic carriers. Relationship between preparation method, type of material and its crosslinking degree, microparticles' immobilization steps and the amount of loaded antibiotic are reported as the main factors controlling release rate of drugs in osteomyelitis treatment. And finally, several approaches to produce injectable formulations as well as implantable three dimensional scaffolds with the use of microparticles are described. All in all, this proves that antibiotic-loaded microspheres are a versatile form of biomaterials in osteomyelitis therapy

Hydrolytic Degradation of Poly(L-Lactide-co-Glycolide) Studied by Positron Annihilation Lifetime Spectroscopy and Other Techniques

Changes of the poly(L-lactide-co-glycolide) structure as a function of degradation time in phosphate-buffered saline for 7 weeks were investigated by gel permeation chromatography, differential scanning calorimetry, nuclear magnetic resonance ($\text{}^{1}$H NMR), and positron annihilation lifetime spectroscopy. Surface properties as wettability by sessile drop and topography by atomic force microscopy were also characterized. Chain-scission of polyester bonds in hydrolysis reaction causes a quite uniform decrease in molecular weight, and finally results in an increase in semicrystallinity. Molecular composition of the copolymer and water contact angle do not change considerably during degradation time. Atomic force microscopy studies suggest that the copolymer degrades by "in bulk" mechanism. The average size of the molecular-level free volume holes declines considerably after one week of degradation and remains constant till the sixth week of degradation. The free volume fraction decreases as a function of degradation time

Degradable scaffold materials for cartilage regeneration

Two scaffolding materials for cartilage regeneration were produced from poly(L-lactide-co-glycolide) (PLG) and PLG modified with sodium hyaluronate (PLG-Hyal). The scaffolds were characterized in terms of their microstructure and surface chemistry. Biological properties of the scaffolds were also evaluated by implantation of the scaffolds into auricular cartilage of the rabbits for 1 and 4 weeks. Histological and histochemical examinations show that both scaffolds promote regeneration of the cartilage, although the quickest regeneration was found after implementation of PLG-Hyal

Hydrolytic Degradation of Poly(L-Lactide-co-Glycolide) Studied by Positron Annihilation Lifetime Spectroscopy and Other Techniques

Changes of the poly(L-lactide-co-glycolide) structure as a function of degradation time in phosphate-buffered saline for 7 weeks were investigated by gel permeation chromatography, differential scanning calorimetry, nuclear magnetic resonance ($\text{}^{1}$H NMR), and positron annihilation lifetime spectroscopy. Surface properties as wettability by sessile drop and topography by atomic force microscopy were also characterized. Chain-scission of polyester bonds in hydrolysis reaction causes a quite uniform decrease in molecular weight, and finally results in an increase in semicrystallinity. Molecular composition of the copolymer and water contact angle do not change considerably during degradation time. Atomic force microscopy studies suggest that the copolymer degrades by "in bulk" mechanism. The average size of the molecular-level free volume holes declines considerably after one week of degradation and remains constant till the sixth week of degradation. The free volume fraction decreases as a function of degradation time

Immobilization of collagen - an effective method of improving cell adhesion on polymeric materials

Surface properties of poly(L-lactide-co-glycolide) (PLG), and two reference materials: hydrophobic polystyrene (PS) and hydrophilic tissue culture polystyrene (TCPS) were modified by collagen adsorption. The morphology of the obtained collagen film was observed by using atomic force microscopy. On PLG and TCPS collagen layer was uniform, while on PS collagen formed isolated patches. The differences in supramolecular organization of collagen were due to differences in surface wettability. The behaviour of L929 fibroblasts incubated on all raw and collagen-modified surfaces was then evaluated. The best adhesion and spreading of cells, as expected, were observed on TCPS. Collagen adsorbed on PLG and PS considerably improved adhesion and spreading of fibroblasts

Positron annihilation in bioactive glass/poly(glycolide-co-L-lactide) composites

Composites made of bioactive glasses and resorbable polymers are promising biomaterials for bone tissue regeneration. In this study several types of composites produced from bioactive glasses, differing in chemical composition (A2 and S2) and poly(glycolide-co-lactide) (PGLA) were obtained. The resulting composite materials were investigated with positron lifetime spectroscopy and Doppler broadening of annihilation line. It was found that for the composites made of S2 bioglass the intensity of the third positron lifetime component coming from the positronium (Ps) annihilation decreased with increasing in volume fraction of bioglass particles exhibiting behaviour characteristic of microcomposites. For the composites produced from A2 bioglass, such a dependence was not found. The differences obtained may be connected with chemical composition of the bioglass and/or its crystallinity