Magnetoresistive Properties of Nanocomposites Based on Ferrite Nanoparticles and Polythiophene

In the presented study, we have synthesized six nanocomposites based on various magnetic nanoparticles and a conducting polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT). Nanoparticles were either coated with squalene and dodecanoic acid or with P3HT. The cores of the nanoparticles were made of one of three different ferrites: nickel ferrite, cobalt ferrite, or magnetite. All synthesized nanoparticles had average diameters below 10 nm, with magnetic saturation at 300 K varying between 20 to 80 emu/g, depending on the used material. Different magnetic fillers allowed for exploring their impact on the conducting properties of the materials, and most importantly, allowed for studying the influence of the shell on the final electromagnetic properties of the nanocomposite. The conduction mechanism was well defined with the help of the variable range hopping model, and a possible mechanism of electrical conduction was proposed. Finally, the observed negative magnetoresistance of up to 5.5% at 180 K, and up to 1.6% at room temperature, was measured and discussed. Thoroughly described results show the role of the interface in the complex materials, as well as clarify room for improvement of the well-known magnetoelectric materials

Micro- and nanospheres - synthesis and characterisation.

Celem projektowania i rozwoju nowych systemów dostarczania leków (DDS) jest zapewnienie kontrolowanego i celowanego uwalnia substancji czynnej. Takie postępowanie daje możliwość lepszej pomocy pacjentowi, zmniejszenia szkodliwości substancji czynnej i ogólnego poprawienia skuteczności terapii. Najbardziej popularną metodą dostarczania leków jest metoda doustna. Złożony skład śluzu obecnego w układzie pokarmowym oraz zmienne pH w różnych odcinkach powoduje, że biopolimery stają się pożądanym materiałem do projektowania systemów kontrolowanego dostarczania leków. Alginian jest biopolimerem, który jest szeroko badany pod kątem zastosowań do doustnego dostarczania antybiotyków, białek i bakterii enkapsulowanych we wnętrzu matrycy polimerowej zmieniającej właściwości fizykochemiczne w zależności od pH.W przeprowadzonych badaniach mikro- i nanosfery alginianowe do doustnego dostarczania leków zostały wytworzone w oparciu o metodę podwójnej emulsyfikacji oraz z wykorzystaniem mechanizmu żelowania zewnętrznego. Modelowym białkiem enkapsulowanym w matrycy polimerowej była surowicza albumina wołowa (BSA). Podczas badań zbadano wpływ użytego surfaktanta na morfologię sfer – anionowego i niejonowego. W obu przypadkach udało się otrzymać sfery o średnim rozmiarze odpowiednio: nanosfery 27.1 ± 8.2 nm i mikrosfery 400 ± 140 nm. Wyniki zostały potwierdzone z wykorzystaniem skaningowego mikroskopu elektronowego. Wydajność enkapsulacji BSA wyniosła ok. 60% i została wyznaczona za pomocą spektroskopii UV-Vis. Enkapsulacja została potwierdzona takimi technikami jak: mikroskopia konfokalna i spektroskopia IR.The goal of design and development of new drug delivery systems (DDSs) is to assure the controlled and targeted drug release. This results in guarantee of patient comfort, lessen the harm of drugs on human organism and general improvement of therapy effects. Certainly, oral administration of DDSs is one of the most popular strategy. Different composition and varying pH in successive parts of the human digestive tract enable efficient application of biopolymeric DDSs with the ability to shrink and swell in the altered pH. Alginate is a prevalent biopolymer ultimately proposed for designing a novel pH sensitive matrix for antibiotics, proteins or/and bacteria encapsulation.In this study alginate nano- and microspheres for oral drug delivery were obtained by double emulsion using external gelation mechanism. As a model protein for encapsulation, Bovine Serum Albumin (BSA) was selected. The influence of two different surfactants was checked – anionic and non-ionic. In both cases, spherical shape of product was obtained, with sizes – nanospheres (27.1 ± 8.2 nm) microspheres (400 ± 140 nm) respectively. Results were confirmed by SEM. BSA encapsulation efficiency was up to 60%, confirmed by UV-Vis spectrometry (using BCA protocole), confocal microscopy and infrared spectrometry

Impact of chemical modification of surface on phase separation in thin polymer films

Praca opisuje możliwość modyfikacji podłoża za pomocą samoorganizujących się monowarstw oraz wpływ owej modyfikacji na zachowanie się cienkich warstw mieszanin polimerówPaper describes ability of simple chemical modification by usage of self - assembled monolayers and impact of SAM on thin polymer films

Effect of Grain Size on the Corrosion Behavior of Fe-3wt.%Si-1wt.%Al Electrical Steels in Pure Water Saturated with CO2

The corrosion behavior of two silicon steels with the same chemical composition but different grains sizes (i.e., average grain area of 115.6 and 4265.9 µm2) was investigated by metallographic microscope, gravimetric, electrochemical and surface analysis techniques. The gravimetric and electrochemical results showed that the corrosion rate increased with decreasing the grain size. The scanning electron microscopy/energy dispersive x-ray spectroscopy and X-ray photoelectron spectroscopyanalyses revealed formation of a more homogeneous and compact corrosion product layer on the coarse-grained steel compared to fine-grained material. The Volta potential analysis, carried out on both steels, revealed formation of micro-galvanic sites at the grain boundaries and triple junctions. The results indicated that the decrease in corrosion resistance in the fine-grained steel could be attributed to the higher density of grain boundaries (e.g., a higher number of active sites and defects) brought by the refinement. The higher density of active sites at grain boundaries promote the metal dissolution of the and decreased the stability of the corrosion product layerformed on the metal surface

A Hybrid System for Magnetic Hyperthermia and Drug Delivery: SPION Functionalized by Curcumin Conjugate

Cancer is among the leading causes of death worldwide, thus there is a constant demand for new solutions, which may increase the effectiveness of anti-cancer therapies. We have designed and successfully obtained a novel, bifunctional, hybrid system composed of colloidally stabilized superparamagnetic iron oxide nanoparticles (SPION) and curcumin containing water-soluble conjugate with potential application in anticancer hyperthermia and as nanocarriers of curcumin. The obtained nanoparticulate system was thoroughly studied in respect to the size, morphology, surface charge, magnetic properties as well as some biological functions. The results revealed that the obtained nanoparticles, ca. 50 nm in diameter, were the agglomerates of primary particles with the magnetic, iron oxide cores of ca. 13 nm, separated by a thin layer of the applied cationic derivative of chitosan. These agglomerates were further coated with a thin layer of the sodium alginate conjugate of curcumin and the presence of both polymers was confirmed using thermogravimetry. The system was also proven to be applicable in magnetic hyperthermia induced by the oscillating magnetic field. A high specific absorption rate (SAR) of 280 [W/g] was registered. The nanoparticles were shown to be effectively uptaken by model cells. They were found also to be nontoxic in the therapeutically relevant concentration in in vitro studies. The obtained results indicate the high application potential of the new hybrid system in combination of magnetic hyperthermia with delivery of curcumin active agent