Coacervate Thermoresponsive Polysaccharide Nanoparticles as Delivery System for Piroxicam.

Low water solubility frequently compromises the therapeutic efficacy of drugs and other biologically active molecules. Here, we report on coacervate polysaccharide nanoparticles (CPNs) that can transport and release a model hydrophobic drug, piroxicam, to the cells in response to changes in temperature. The proposed, temperature-responsive drug delivery system is based on ionic derivatives of natural polysaccharides-curdlan and hydroxypropyl cellulose. Curdlan was modified with trimethylammonium groups, while the anionic derivative of hydroxypropyl cellulose was obtained by the introduction of styrenesulfonate groups. Thermally responsive nanoparticles of spherical shape and average hydrodynamic diameter in the range of 250-300 nm were spontaneously formed in water from the obtained ionic polysaccharides as a result of the coacervation process. Their morphology was visualized using SEM and AFM. The size and the surface charge of the obtained objects could be tailored by adjusting the polycation/polyanion ratio. Piroxicam (PIX) was effectively entrapped inside the nanoparticles. The release profile of the drug from the CPNs-PIX was found to be temperature-dependent in the range relevant for biomedical applications.

Gradient of zinc content in core-shell zinc ferrite nanoparticles - precise study on composition and magnetic properties.

A broad spectrum of applications of magnetic nanoparticles leads to the need for the precise tuning of their magnetic properties. In this study, a series of magnetite and zinc-ferrite nanoparticles were successfully prepared by modified high-temperature synthesis in a controlled gas atmosphere. Nanoparticles with different zinc to iron ratios and pure Fe3O4 were obtained. The structure of the nanoparticles was studied by transmission electron microscopy and Mössbauer spectroscopy. These revealed the single domain character of the nanoparticles and the influence of the synthesis temperature and zinc to iron ratio on their shape and size. Chemical structure was characterized by inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy and thermogravimetric analysis. X-ray photoelectron spectroscopy coupled with an argon gas cluster ion beam (Ar-GCIB) allowed the study of subsequent layers of the nanoparticles without altering their chemical structure. This revealed the presence of a carbon layer on all nanoparticles consisting of capping agents used in the synthesis and revealed the core-shell character of the zinc ferrite particles. In addition, different types of zinc infusions in the nanoparticle structure were observed when using different Zn/Fe ratios. Finally, magnetic studies performed by means of vibrating sample magnetometry proved the superparamagnetic behavior of all the samples.

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.

Aerogels based on cationically modified chitosan and poly(vinyl alcohol) for efficient capturing of viruses.

In this study, we developed a new filtering bioaerogel based on linear polyvinyl alcohol (PVA) and the cationic derivative of chitosan (N-[(2-hydroxy-3-trimethylamine) propyl] chitosan chloride, HTCC) with a potential antiviral application. A strong intermolecular network architecture was formed thanks to the introduction of linear PVA chains, which can efficiently interpenetrate the glutaraldehyde(GA)-crosslinked HTCC chains. The morphology of the obtained structures was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The aerogels and modified polymers' elemental composition (including the chemical environment) was determined using X-ray photoelectron spectroscopy (XPS). New aerogels with more than twice as much developed micro- and mesopore space and BET-specific surface area were obtained concerning the starting sample chitosan aerogel crosslinked by glutaraldehyde (Chit/GA). The results obtained from the XPS analysis showed the presence of cationic 3-trimethylammonium groups on the surface of the aerogel, which can interact with viral capsid proteins. No cytotoxic effect of HTCC/GA/PVA aerogel was also observed on fibroblast cells of the NIH3T3 line. Furthermore, the HTCC/GA/PVA aerogel has been shown that efficiently traps mouse hepatitis virus (MHV) from suspension. The presented concept of aerogel filters for virus capture based on modified chitosan and polyvinyl alcohol has a high application potential.

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.

Effect of CO2 Partial Pressure on the Corrosion Inhibition of N80 Carbon Steel by Gum Arabic in a CO2-Water Saline Environment for Shale Oil and Gas Industry.

The effect of CO2 partial pressure on the corrosion inhibition efficiency of gum arabic (GA) on the N80 carbon steel pipeline in a CO2-water saline environment was studied by using gravimetric and electrochemical measurements at different CO2 partial pressures (e.g., PCO2 = 1, 20 and 40 bar) and temperatures (e.g., 25 and 60 °C). The results showed that the inhibitor efficiency increased with an increase in inhibitor concentration and CO2 partial pressure. The corrosion inhibition efficiency was found to be 84.53% and 75.41% after 24 and 168 h of immersion at PCO2 = 40 bar, respectively. The surface was further evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), grazing incidence X-ray diffraction (GIXRD), and X-ray photoelectron spectroscopy (XPS) measurements. The SEM-EDS and GIXRD measurements reveal that the surface of the metal was found to be strongly affected by the presence of the inhibitor and CO2 partial pressure. In the presence of GA, the protective layer on the metal surface becomes more compact with increasing the CO2 partial pressure. The XPS measurements provided direct evidence of the adsorption of GA molecules on the carbon steel surface and corroborated the gravimetric results.

Nanohydrogels Based on Self-Assembly of Cationic Pullulan and Anionic Dextran Derivatives for Efficient Delivery of Piroxicam.

A cationic derivative of pullulan was obtained by grafting reaction and used together with dextran sulfate to form polysaccharide-based nanohydrogel cross-linked via electrostatic interactions between polyions. Due to the polycation-polyanion interactions nanohydrogel particles were formed instantly and spontaneously in water. The nanoparticles were colloidally stable and their size and surface charge could be controlled by the polycation/polyanion ratio. The morphology of the obtained particles was visualized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The resulting structures were spherical, with hydrodynamic diameters in the range of 100-150 nm. The binding constant (Ka) of a model drug, piroxicam, to the cationic pullulan (C-PUL) was determined by spectrophotometric measurements. The value of Ka was calculated according to the Benesi-Hildebrand equation to be (3.6 ± 0.2) × 103 M-1. After binding to cationic pullulan, piroxicam was effectively entrapped inside the nanohydrogel particles and released in a controlled way. The obtained system was efficiently taken up by cells and was shown to be biocompatible.

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.