Bodegradable polymeric system releasing radiosensitizer - the in vitro studies

W pracy przedstawiono wyniki badań uwalniania radiouczulacza metronidazolu z jednowarstwowych oraz trójwarstwowych matryc kopolimeru glkolidu z laktydem do sztucznego płynu mózgowo rdzeniowego ACFs. Przeprowadzono analizę mikrostruktury łańcuchów polimerowych w oparciu o spektroskopię magnetycznego rezonansu jądrowego. Badanie uwalniania leku prowadzono w systemie dynamicznym z regularną wymianą buforu we fiolkach poddanych wytrząsaniu. Ekstrakty analizowano metodą spektrometrii UV-VIS. Równolegle prowadzono badania degradacji matryc z lekiem pod kątem oceny zmian w mikrostrukturze łańcucha polimerowego. Badania wykazały znacznie szybszą degradację matryc wykonanych z kopolimeru glikolidu z D,L-laktydem w porównaniu z matrycami z kopolimeru glikolidu z L-laktydem. Ponadto wykazano że opłaszczenie matrycy zawierającej lek polimerem bez leku (matryce trójwarstwowe) zapobiega nagłemu wyrzutowi leku z powierzchni w pierwszych dniach uwalniania.In this paper the results of radiosensitizer metronidazole release investigation from mono- and triple-layered copolymeric matrices in artificial cerebro- spinal fluid solution (ACFs) are presented. The analysis of polymeric chain microstructure by the NMR has been conducted. Drug release study was performed in the dynamic system with regular buffer exchange in constantly stirred glass ampoules. The extracts were analyzed by the UV-VIS spectrometry. Drug carrying matrices degradation research were conducted to evaluate possible changes in polymeric chain microstructure. The results showed that matrices containing poly(glycolide-co-D,L-lactide) demonstrate higher degradation rate than matrices containing poly(glycolide-co-L-lactide). It has been proved that drug carriers coated with drug-free polymer (triplelayered matrices) prevents from burst effect

Investigations of Interface Properties in Copper-Silicon Carbide Composites

This paper analyses the technological aspects of the interface formation in the copper-silicon carbide composite and its effect on the material’s microstructure and properties. Cu-SiC composites with two different volume content of ceramic reinforcement were fabricated by hot pressing (HP) and spark plasma sintering (SPS) technique. In order to protect SiC surface from its decomposition, the powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. Microstructural analyses provided by scanning electron microscopy revealed the significant differences at metal-ceramic interface. Adhesion force and fracture strength of the interface between SiC particles and copper matrix were measured. Thermal conductivity of composites was determined using laser flash method. The obtained results are discussed with reference to changes in the area of metal-ceramic boundary

The influence of simvastatin on terpolymer degradation with shape memory properties

Zbadany został wpływ simwastatyny na degradację terpolimerów LL-laktydu, glikolidu i węglanu trimetylenu z pamięcią kształtu. Badano mechanizm degradacji in vitro, w izotonicznym roztworze chlorku sodu buforowanym fosforanami (PBS), matryc polimerowych wykonanych z dwóch materiałów z różną zawartością leku i bez simwastatyny. Polimery charakteryzowano przy użyciu: różnicowej kalorymetrii skaningowej (DSC) (właściwości termiczne), chromatografii żelowej (GPC) (masy cząsteczkowe) i spektroskopii magnetycznego rezonansu jądrowego (NMR) (skład i mikrostruktura). Profil uwalniania leku oceniano metodą spektroskopii UV-Vis. Oceniono przydatność badanych materiałów do zastosowania w produkcji biozgodnych polimerowych resorbowalnych chirurgicznych systemów z pamięcią kształtu z własnością kontrolowanego uwalniania leku. Nie odnotowano istotnego wpływu 1% zawartości leku na przebieg degradacji.The influence of simvastatin on degradation of terpolymers synthesized from L-lactide, glycolide, and trimethylene carbonate has been analyzed. The in vitro degradation of the matrices, obtained from two terpolymers with various chain structure and amount of simvastatin, was carried out in phosphate buffered solution. The terpolymers were characterized by using differential scanning calorimetry (DSC) (thermal properties), gel permeation chromatography GPC (molecular weights) and nuclear magnetic resonance (NMR) (composition and microstructure). Release profile of simvastatin was analyzed by means of UV-Vis spectroscopy. It was determined that the tested materials are useful for development of biocompatible resorbable surgical systems with the shape memory effect and controlled drug-release capability. There was no significant difference in the degradation process between the matrices without drug and with 1% of simvastatin

The oncoprotein HBXIP – its functions and roles in oncogenesis

Nowadays, Hepatitis B X interacting protein (HBXIP) is an object of scientists’ interest worldwide. It is a protein with significant involvement in the development of malignant tumors like breast or ovarian cancer. One of the most important functions of HBXIP is the regulation of cell proliferation, which is related to the progression of a cell cycle. Many studies provide the growing number of evidence that HBXIP plays various important roles, including the regulation of a cell cycle through complexes with survivin, belonging to the inhibitors of apoptosis and interactions with transcriptional factors like STAT4, SP1, TFIID or E2F1. It also has the influence on the promotion of tumor angiogenesis thanks to the association with VEGF and FGF8. Another important role of HBXIP is a reprogramming of glucose metabolism to conditions favorable to growing cancerous cells due to regulating the activation of SCO2 and PDHA1. Furthermore, it impacts on the complement-dependent cytotoxicity, also, HBXIP affects on lipid metabolism through disturbing of metabolic pathways of FAS. According to recent studies, HBXIP can be used as a prognostic biomarker in many tumors, including cervical cancer, ovarian cancer, and esophageal squamous cell carcinoma thanks to the high expression of this protein noted exclusively in these tumor tissues. What is even more interesting, it significantly correlates with clinical attributes like metastasis to lymph nodes or grading and in some cases can potentially be used as the indicator of prognosis of treatment effectiveness. The paper is review through main functions of HBXIP and its possible applications

The effect of ceramic type reinforcement on structure and properties of Cu-Al2O3 composites

The purpose of this paper is to elaborate on mechanical alloying conditions for a composite powder consisting of copper and brittle aluminium oxides. Detailed analysis of the Cu-Al2O3 powder mixture structure obtained in the mechanical alloying process allows for the study of the homogenization phenomena and for obtaining grains (in composite form) with a high degree of uniformity. The Cu-5vol.%Al2O3 composites were obtained by means of the spark plasma sintering technique. The results presented herein were studied and discussed in terms of the impact of using a different form of aluminium oxide powder and a different shape of copper powder on composite properties. Research methodology included microstructure analysis as well as its relation to the strength of Cu-Al2O3 interfaces. It transpires from the results presented below that the application of electrocorundum as a reinforcement phase in composites decreases porosity in the ceramic phase, thus improving thermal properties and interfacial strength

The Influence of PEDOT to PSS Ratio on the Optical Properties of PEDOT:PSS Thin Solid Films - Insight from Spectroscopic Ellipsometry

In this work, we study the influence of the PEDOT to PSS ratio on the optical properties of PEDOT:PSS thin solid films using spectroscopic ellipsometry and UV-vis spectrometry. In the data analysis, we develop a consisted composition dependent optical model of PEDOT:PSS. This enabled us to account for contributions from PSS part within the Tauc-Lorentz optical model and from PEDOT part within the Drude-Lorentz optical model. Moreover, we relate the optical properties of PEDOT:PSS thin solid films to their electrical specific conductivities in the frame of the generalized effective medium theory. Determined in this manner electrical conductivities of five commercially available water dispersions of PEDOT:PSS are compared with their nominal values