The Influence of a Binder in a Composite Electrode: The Case Study of Vanadyl Phosphate in Aqueous Electrolyte.

Layered VOPO4·2H2O is synthesized by the sonochemical method. An X-ray powder diffraction is used to examine the crystal structure, while scanning electron microscopy is used to reveal the morphology of the powder. The crystal structure refinement is performed in the P4/nmmZ space group. The electrochemical intercalation of several cations (Na+, Mg2+, Ca2+, and Al3+) in saturated nitrate aqueous solutions is investigated. The most notable reversible activity is found for the cycling in aluminium nitrate aqueous solution in the voltage range from -0.1 to 0.8 V vs. SCE. During the preparation of the electrode, it is observed that the structure is prone to changes that have not been recorded in the literature so far. Namely, the use of conventional binder PVDF in NMP solution deteriorates the structure and lowers the powder's crystallinity, while the use of Nafion solution causes the rearrangement of the atoms in a new crystal form that can be described in the monoclinic P21/c space group. Consequently, these structural changes affect electrochemical performances. The observed differences in electrochemical performances are a result of structural rearrangements.

Evaluation of chitosan/xanthan gum polyelectrolyte complexes potential for pH-dependent oral delivery of escin.

Escin is an amphiphilic and weakly acidic drug that oral administration may lead to the irritation of gastric mucosa. The entrapment of escin into chitosan (CH)/xanthan gum (XG)-based polyelectrolyte complexes (PECs) can facilitate controlled drug release which may be beneficial for the reduction of its side effects. This study aimed to investigate the influence of escin content and drying method on the formation, physicochemical, and controlled, pH-dependent drug release properties of CH/XG-based PECs. Measurements of transmittance, conductivity, and rheological characterization confirmed the formation of CH/XG-based PECs with escin entrapped at escin-to-polymers mass ratios 1:1, 1:2, and 1:4. Ambient-dried PECs had higher yield, entrapment efficiency, and escin content in comparison with spray-dried ones. FT-IR spectra confirmed the interactions between CH, XG, and escin, which were stronger in ambient-dried PECs. PXRD and DSC analyses showed the amorphous escin character in all dry PECs, regardless of the drying method. The most promising controlled and pH-dependent in vitro escin release was from the ambient-dried PEC at the escin-to-polymers mass ratio of 1:1. For that reason and due to the highest yield and entrapment efficiency, this carrier has the potential to prevent the irritation of gastric mucosa after oral administration of escin.

Inorganically modified particles FeAl-LDH@SiO2 as reinforcement in poly (methyl) methacrylate matrix composite.

Silica particles were obtained from rice husk to which layered double hydroxide particles were deposited (weight ratio 1 : 1). Fe2+-Al3+ layered double hydroxides (FeAl-LDH) were synthesized by co-precipitation with ratios Fe : Al of 3 : 1 in the presence of SiO2 particles from the rice husk. Characterization of the synthesized FeAl-LDH@SiO2 particles was performed by X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR) and scanning electron microscopy with EDS. Prepared FeAl-LDH@SiO2 particles were used as reinforcing agents in 1, 3 and 5 wt% quantity in poly (methyl) methacrylate matrix. The aim of this study was to examine whether FeAl-LDH@SiO2 particles affect the mechanical properties of polymer composite materials. The morphology of the composites was examined using a field emission scanning electron microscope. Microindentation, tensile and impact testing determined the mechanical properties of the obtained composites.

Development of genistein-loaded gold nanoparticles and their antitumor potential against prostate cancer cell lines.

Soy isoflavone genistein (Gen) exerts beneficial effects against prostate cancer cells in vitro and in vivo. However, its use as a chemoprevention/therapeutic agent is largely limited due to its low bioavailability. In this study we synthesized two variants of a new delivery system, genistein-gold nanoparticles conjugates Gen@AuNPs1 and Gen@AuNPs2, by an environmentally friendly method, using a dual role of Gen to reduce Au3+ and stabilize the formed AuNPs, with no additional component. The formation of Gen@AuNPs was confirmed via UV-Vis spectroscopy, FTIR, and Raman spectra measurements. The spherical shape and uniform size of Gen@AuNPs1 and Gen@AuNPs2 (10 ± 2 and 23 ± 3 nm, respectively), were determined by transmission electron microscopy. The nano-conjugates also varied in hydrodynamic diameter (65.0 ± 1.7 and 153.0 ± 2.2 nm) but had similar negative zeta potential (-35.0 ± 2.5 and -37.0 ± 1.6 mV), as measured by dynamic light scattering. The Gen loading was estimated to be 46 and 48%, for Gen@AuNPs1 and Gen@AuNPs2, respectively. The antiproliferative activities of GenAuNPs were confirmed by MTT test in vitro on three malignant prostate carcinoma cell lines (PC3, DU 145, and LNCaP), while selectivity toward malignant phenotype was confirmed using non-cancerous MRC-5 cells. Flow cytometric analysis showed that the inhibition on cell proliferation of more potent Gen@AuNPs1 nano-conjugate is comparable with the effects of free Gen. In conclusion, the obtained results, including physicochemical characterization of newly synthesized AuNPs loaded with Gen, cytotoxicity, and IC50 assessments, indicate their stability and bioactivity as an antioxidant and anti-prostate cancer agent, with low toxicity against human primary cells.

Effect of ibuprofen entrapment procedure on physicochemical and controlled drug release performances of chitosan/xanthan gum polyelectrolyte complexes.

The effect of the entrapment procedure of a poorly water soluble drug (ibuprofen) on physicochemical and drug release performances of chitosan/xanthan polyelectrolyte complexes (PECs) was investigated to achieve controlled drug release as the ultimate goal. The formation of PECs for two drug entrapment procedures (before or after the mixing of polymers) at pH 4.6 and 5.6 and three chitosan-to-xanthan mass ratios (1:1, 1:2 and 1:3) was observed by continuous decrease in conductivity during the PECs formation and increased apparent viscosity and hysteresis values. The most extensive crosslinking was observed with ibuprofen added before the PECs formation at pH 4.6 and chitosan-to-xanthan mass ratio 1:1. The PECs prepared at polymers' mass ratios 1:2 and 1:3 had higher yield and drug entrapment efficiency. DSC and FT-IR analysis confirmed ibuprofen entrapment in PECs and the partial disruption of its crystallinity. All ibuprofen release profiles were similar, with 60-70% of drug released after 12 h, mainly by diffusion, but erosion and polymer chain relaxation were also included. Potentially optimal can be considered the PEC prepared at pH 4.6, ibuprofen entrapped before the mixing of polymers at chitosan-to-xanthan mass ratio 1:2, which provided controlled drug release by zero-order kinetics, high yield, and drug entrapment efficiency.

Comparison of Three Ratiometric Temperature Readings from the Er3+ Upconversion Emission.

The emission of Er3+ provides three combinations of emission bands suitable for ratiometric luminescence thermometry. Two combinations utilize ratios of visible emissions (2H11/2→4I15/2 at 523 nm/ 4S3/2→4I15/2 at 542 nm and 4F7/2→4I15/2 at 485 nm/ 4S3/2→4I15/2 at 545 nm), while emissions from the third combination are located in near-infrared, e.g., in the first biological window (2H11/2→4I13/2 at 793 nm/ 4S3/2→4I13/2 at 840 nm). Herein, we aimed to compare thermometric performances of these three different ratiometric readouts on account of their relative sensitivities, resolutions, and repeatability of measurements. For this aim, we prepared Yb3+,Er3+:YF3 nanopowders by oxide fluorination. The structure of the materials was confirmed by X-ray diffraction analysis and particle morphology was evaluated from FE-SEM measurements. Upconversion emission spectra were measured over the 293-473 K range upon excitation by 980 nm radiation. The obtained relative sensitivities on temperature for 523/542, 485/542, and 793/840 emission intensity ratios were 1.06 ± 0.02, 2.03 ± 0.23, and 0.98 ± 0.10%K-1 with temperature resolutions of 0.3, 0.7, and 1.8 K, respectively. The study showed that the higher relative temperature sensitivity does not necessarily lead to the more precise temperature measurement and better resolution, since it may be compromised by a larger uncertainty in measurement of low-intensity emission bands.