Comparison of Dye Adsorption of Chitosan and Polyethylenimine Modified Bentonite Clays: Optimization, Isotherm, and Kinetic Studies

The aim of this study was to compare the effect of modifying calcium bentonite (Bent-Ca) clay with two cationic polymers, chitosan (Chi) and polyethylenimine (PEI), on the removal of remazol black B (RB-B) dye from an aqueous solution. The samples were characterized by using scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The fractional factorial design of 2(6-1) was applied to investigate the effects of pH, temperature, amount of adsorbent, initial dye concentration, contact time, and shaking rate on the adsorption process. To further optimize RB-B removal from an aqueous solution, a Box-Behnken design with three factors and a response surface methodology was used. The optimum conditions were a pH of 3.77, a temperature of 40.45 °C, and an initial RB-B concentration of 77.27 mg L-1 for Bent-Ca-Chi, whereas for Bent-Ca-PEI, the optimum conditions were a pH of 5.53, a temperature of 41.06 °C, and an initial dye concentration of 238.89 mg L-1. To understand the adsorption behavior, the Langmuir and Freundlich isotherms were fitted to the experimental data. It was found that the Langmuir isotherm model matched well with the dye adsorption by Bent-Ca-Chi and Bent-Ca-PEI. The kinetics study was performed using three kinetic models: pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Among these models, the RB-B dye kinetics were best represented by the pseudo-second-order model equation for the adsorbents.

Neuro-Behçet's Disease presenting with acute psychosis: A Case Report

Behçet's disease (BD) is a chronic systemic inflammatory vasculitis of unknown etiology characterized by recurrent episodes of oral aphthous ulcers, genital ulcers, skin lesions, ocular lesions, and other manifestations. This disease affects many organs and systems and shows a wide range of clinical manifestations. The prevalence of anxiety, depression, and general psychiatric symptoms is higher among patients with BD compared with healthy individuals. However, syndromes such as psychosis appear to be less frequent. Therefore, we present a case of BD complicated by schizophrenia-like symptoms.

Removal of fluoride ions from water by cerium-carboxymethyl cellulose beads doped with CeO2 nanoparticles

A novel adsorbent for fluoride ions (F^-) removal was prepared from cerium ion cross-linked carboxymethyl cellulose (CMC) biopolymer beads loaded with CeO₂ nanoparticles (NPs). The characterization of the beads was performed by swelling experiments, scanning electron microscopy and Fourier transforms infrared spectroscopy. The adsorption of fluoride ions from aqueous solutions was carried out with both cerium ion cross-linked CMC beads (CMCCe) and CeO₂-NPs added beads (CeO₂-CMC-Ce) in a batch system. Optimized adsorption conditions were obtained by testing the parameters such as pH, contact time, adsorbent dose, and shaking rate at 25 °C. The adsorption process is well described by the Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was found as 105 and 312 mg/g F^- for CMC-Ce and CeO₂-CMC-Ce beads, respectively. Reusability studies showed that, the adsorbent beads have exhibited excellent sustainable properties up to 9 cycle usage. This study suggests that, CMC-Ce composite with CeO₂ nanoparticles is a very effective adsorbent in removing fluoride from water.

Antioxidant and antimicrobial chitosan films enriched with aqueous sage and rosemary extracts as food coating materials: Characterization of the films and detection of rosmarinic acid release

Chitosan films containing aqueous extracts of sage and rosemary were prepared as a potential food coating material with antioxidant and antibacterial properties. The effect of adding extracts at different concentrations on the mechanical, physical, and optical properties of the films was investigated. The addition of the extracts significantly increased Young's modulus values of the films compared to the chitosan film, and a significant decrease was observed in the swelling percentage and water vapor permeability of the films. Since all the prepared films were ionically cross-linked, the increase in water solubility of the films with the addition of the extract was at a low level. The release of rosmarinic acid, which is found in significant amounts in both plants, from the films was monitored by the capillary electrophoresis. The antioxidant properties imparted to the films by the addition of plant extracts were determined by DPPH and FRAP methods. The addition of plant extracts increased the antimicrobial property of chitosan films against Staphylococcus aureus and Escherichia coli. Films containing sage and rosemary extracts showed potential for use as food coating materials.

Surfactant modified alginate composite gels for controlled release of protein drug

This study aims to modify alginate with sodium dodecyl sulfate (SDS) to reduce the release of oral protein in the acidic stomach environment and transport it to the colon medium. Bovine serum albumin (BSA), which was chosen as a model protein, was loaded into surfactant modified calcium alginate beads (SDS/Ca-Alg). The encapsulation efficiency of BSA in SDS/Ca-Alg beads was found significantly higher (96.3%) compared to that of beads without SDS. The most remarkable result is that protein release from the modified gel in the stomach environment was significantly reduced compared to protein release from the plain alginate gel. At the same time, the release time of the whole drug in the intestinal environment was significantly prolonged. The SDS-modified alginate beads are proposed as suitable carriers for the passage of orally taken protein-type drugs into the colon medium by preventing their degradation in acidic gastric fluid.

Mobility of Min-proteins in Escherichia coli measured by fluorescence correlation spectroscopy

In the bacterium Escherichia coli, selection of the division site involves pole-to-pole oscillations of the proteins MinD and MinE. Different oscillation mechanisms based on cooperative effects between Min-proteins and on the exchange of Min-proteins between the cytoplasm and the cytoplasmic membrane have been proposed. The parameters characterizing the dynamics of the Min-proteins in vivo are not known. It has therefore been difficult to compare the models quantitatively with experiments. Here, we present in vivo measurements of the mobility of MinD and MinE using fluorescence correlation spectroscopy. Two distinct timescales are clearly visible in the correlation curves. While the faster timescale can be attributed to cytoplasmic diffusion, the slower timescale could result from diffusion of membrane-bound proteins or from protein exchange between the cytoplasm and the membrane. We determine the diffusion constant of cytoplasmic MinD to be approximately 16 microm(2) s(-1), while for MinE we find about 10 microm(2) s(-1), independently of the processes responsible for the slower time-scale. The implications of the measured values for the oscillation mechanism are discussed.

Reconstitution of membrane proteins into giant unilamellar vesicles via peptide-induced fusion

In this work, we present a protocol to reconstitute membrane proteins into giant unilamellar vesicles (GUV) via peptide-induced fusion. In principle, GUV provide a well-defined lipid matrix, resembling a close-to-native state for biophysical studies, including optical microspectroscopy, of transmembrane proteins at the molecular level. Furthermore, reconstitution in this manner would also eliminate potential artifacts arising from secondary interactions of proteins, when reconstituted in planar membranes supported on solid surfaces. However, assembly procedures of GUV preclude direct reconstitution. Here, for the first time, a method is described that allows the controlled incorporation of membrane proteins into GUV. We demonstrate that large unilamellar vesicles (LUV, diameter 0.1 microm), to which the small fusogenic peptide WAE has been covalently attached, readily fuse with GUV, as revealed by monitoring lipid and contents mixing by fluorescence microscopy. To monitor contents mixing, a new fluorescence-based enzymatic assay was devised. Fusion does not introduce changes in the membrane morphology, as shown by fluorescence correlation spectroscopy. Analysis of fluorescence confocal imaging intensity revealed that approximately 6 to 10 LUV fused per microm(2) of GUV surface. As a model protein, bacteriorhodopsin (BR) was reconstituted into GUV, using LUV into which BR was incorporated via detergent dialysis. BR did not affect GUV-LUV fusion and the protein was stably inserted into the GUV and functionally active. Fluorescence correlation spectroscopy experiments show that BR inserted into GUV undergoes unrestricted Brownian motion with a diffusion coefficient of 1.2 microm(2)/s. The current procedure offers new opportunities to address issues related to membrane-protein structure and dynamics in a close-to-native state.