Photocatalytic degradation of carcinogenic Congo red dye in aqueous solution,antioxidant activity and bactericidal effect of NiO nanoparticles

Journal of the Iranian Chemical Society - Face-centered cubic structure of nickel oxide (NiO) nanoparticles with 30 nm average size was synthesized by co-precipitation method with some...     

源于大肠杆菌蛋白的表达、液相色谱复性与纯化新进展

对近两年来源于大肠杆菌（Escherichia coli,E．coli）的蛋白表达和用蛋白折叠液相色谱（protein folding liquid chromatography,PFLC）法对所形成的包涵体目标蛋白的复性并同时纯化的新近发展做了简要的介绍和评述．PFLC法用于包涵体蛋白分离、纯化很广,其特点是除了在色谱柱上将目标蛋白与其他组分分开,还同时要在色谱柱上进行包涵体蛋白折叠．可以说,现代生物技术中所用的大多数有价值蛋白产品的制备仍然有赖于不同机理的液相色谱（Lc）法．而用PFLC法对源于E．coli的蛋白的制备方法更具可塑性和容易达到规模化,其生成本可以成倍地降低．该文主要内容包括了E．coli蛋白的表达及样品前处理、PFLC的实用范围、PFLC的优化、PFLC中的新技术、新设备和新方法、PFLC的分子学机理、应用事例及对未来的展望．     

Spectroscopic studies of the intermolecular interactions of Congo red and tinopal CBS with modified cellulose fibers

The adsorption of Congo red and tinopal CBS dyes on cellulose fibers was investigated using electronic absorption and fluorescence spectroscopies. Hydrogen bonds appear to be relevant for the dye-fiber interactions as indicated by the solvatochromism of Congo red in water, methanol, and dimethyl sulfoxide solutions, and when adsorbed on cellulose fibers. We also demonstrate that electrostatic interactions play an important role in the dye-medium interaction, through the analysis of absorption spectra of Congo red and fluorescence spectra of tinopal in aqueous solutions containing salt and in layer-by-layer nanostructured films with poly(allylamine hydrochloride). For instance, dye adsorption was enhanced when salt was added to the dipping solution, which was explained by the synergistic effect between the conformational changes of the cellulose and changes in the solvation layer around the cellulose chains and around dye molecules. On the basis of the fluorescence results for tinopal CBS, we inferred that dye aggregation is not relevant for adsorption on the fibers. In addition, fluorescence spectroscopy is proven very sensitive for studying the organization of dye molecules in layer-by-layer films, particularly those undergoing irreversible structural changes.     

Effective sequestration of Congo red dye with ZnO/cotton stalks biochar nanocomposite: MODELING,reusability and stability

Widespread application of dyes and disposal of their untreated effluents into water bodies adversely affect the ecosystem due to their complex aromatic structures and persistent nature. The present study aims to utilize the cotton stalks biochar (CSB) and its composite with zinc oxide nanoparticles (CSB/ZnONPs) to evaluate for the decontamination their batch scale potential of Congo red dye from wastewater. The characterization of CSB and CSB/ZnONPs was performed with Fourier-transform infra-red (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray (EDX) and point of zero charge (PZC) to get insight of their potential for the decontamination of CR. The effects of initial CR concentration (25–500 mg/L), dosage of CSB and CSB/ZnONPs (0.5–2 g/L), solution pH (2–10) and contact time (0–180 min) were evaluated on CR removal at temperature (25 ± 1.5 °C). The results disclosed that CSB/ZnONPs showed excellent adsorption potential (556.6 mg/g) in comparison with CSB (250 mg/g) and most of the other adsorbents previously studies in the literature. The equilibrium experimental data were equally explained with Freundlich and Langmuir isotherm models (R² > 0.98) while kinetic data demonstrated the best fit with pseudo second order model. The CSB/ZnONPs composite exhibited excellent reusability (89.65%) after five adsorption/desorption cycles for the sequestration of CR from contaminated systems. The present study demonstrated that metallic nanocomposite of CSB (CSB/ZnONPs) is an excellent candidate for the cost effective and environment friendly decontamination of CR from industrial wastewater and is suggested to be considered for the decontamination of other pollutants from the wastewater.     

Influence of cellulose gel matrix on BMIMCl ionic liquid dynamics and conductivity

Fast field-recycling magnetic resonance relaxometry (FFC NMR) was applied to measure the spin-lattice relaxation time, T ₁, of protons in pure ionic liquid (IL) 1-butyl-3-methylimidazolium chloride (BMIMCl) and when confined in cellulose (Cell) ion gel (Cell/BMIMCl) at different temperatures and different Larmor frequencies. The rotational and translational contributions were taken to interpret the relaxation data of neat BMIMCl and were described by Woessner’s and Torrey’s theoretical models, respectively. The ionic liquid–cellulose matrix interaction detected in 10 wt% polymer-ion gel was interpreted on the basis of a dynamical process called reorientation mediated by translational displacements (RMTD), which allow explanation of the significant slowing of the dynamics of IL cations at cellulose surfaces. Two types of cation diffusion were identified in this gel: a long-range translational diffusion within large cavities of the Cell matrix and diffusion occurring at the polymer surface. The correlational time constants and self-diffusion coefficients of the BMIMCl ionic liquid in bulk-like state and interaction with the cellulose matrix surface were determined. The conductivity measurements performed for pure IL and that confined in the Cell/BMIMCl ion gel show that the gelation only results in a small decrease of the ionic conductivity.     

Influence of a cellulose diacetate matrix on the complexation kinetics of tetraphenylporphin with Zn and Cd

The dependence of the reaction rate of tetraphenylporphin zinc and cadmium complexes in a polymer matrix on a base of cellulose diacetate and low-molecular model solutions was investigated. The characteristics of the diffusive transport of aqueous solutions of zinc and cadmium acetates through the cellulose diacetate membrane were obtained. The kinetic control of the porphyrin reaction incorporated into the polymer, and the determining influence of the steric limitations of the matrix of a rigid chain polymer on macroheterocycle deformation (and thus its reactivity) are shown.     

High-yield purification of biosynthetic human growth hormone secreted in Escherichia coli periplasmic space.

A six-step, high-yield purification procedure for the preparation of clinical grade recombinant human growth hormone (rhGH) secreted in bacterial periplasmic space is described. Particular emphasis is given to hormone recovery yields and maximum contaminant host cell elimination. The strategy adopted, in addition to using one precipitation and five chromatographic steps in a particularly efficient sequence, was also based on running E. coli proteins - immunoradiometric assay profiles right after each chromatographic elution. Thus, an overall rhGH recovery higher than 40%, with a final concentration of E. coli proteins below 10 ppm is described for the first time. The accuracy of hGH and total protein quantification, especially in the early steps of the process, and the maximum elimination of hGH-related forms were also studied in detail. For these purposes size-exclusion and reversed-phase HPLC were found to be extremely valuable analytical tools.     

Influence of Open Chain and Cyclic Structure of Peptidomimetics on Antibacterial Activity in E. coli Strains

An efficient method for the synthesis of functionalized peptidomimetics via multicomponent Ugi reaction has been developed. The application of trifluoroethanol (TFE) as a reaction medium provided desired products with good yields. Further, using the developed cyclisation reaction, the obtained peptidomimetics were transformed into the cyclic analogues (diketopiperazines, DKPs). The goal of the performed studies was to revised and compare whether the structure of the obtained structurally flexible acyclic peptidomimetics and their rigid cycling analogue DKPs affect antimicrobial activity. We studied the potential of synthesized peptidomimetics, both cyclic and acyclic, as antimicrobial drugs on model E. coli bacteria strains (k12, R2–R4). The biological assays reveal that DKPs hold more potential as antimicrobial drugs compared to open chain Ugi peptidomimetics. We believe that it can be due to the rigid cyclic structure of DKPs which promotes the membrane penetration in the cell of studied pathogens. The obtained data clearly indicate the high antibiotic potential of synthesized diketopiperazine derivatives over tested antibiotics.     

微量热法研究头孢菌素对在肠杆菌微生物活性的影响

用微量热法测定了两种头孢菌素头孢哌酮钠(CFZ)和头孢哌酮钠舒巴坦钠(CFZ-SBT)在37℃时对大肠杆菌DH5α代谢作用的影响.根据产热曲线分别获得了大肠杆菌DH5α在不同浓度的头孢哌酮钠和头孢哌酮钠舒巴坦钠作用下的生长速率常数(k)、抑制率(I)、最大产热功率(Pm)以及最大产热功率所对应的时间tm等热动力学参数.研究结果表明,头孢哌酮钠和头孢哌酮钠舒巴坦钠对大肠杆菌的致死量分别为0.1和0.25μg/mL.通过研究k,I,Pm,tm和浓度(c)间的关系发现,舒巴坦钠的加入没有增加头孢哌酮钠对大肠杆菌DH5α的抑制作用.     

微量热法研究头孢菌素对大肠杆菌微生物活性的影响

用微量热法测定了两种头孢菌素头孢哌酮钠(CFZ)和头孢哌酮钠舒巴坦钠(CFZ-SBT)在37 ℃时对大肠杆菌DH5α代谢作用的影响. 根据产热曲线分别获得了大肠杆菌DH5α在不同浓度的头孢哌酮钠和头孢哌酮钠舒巴坦钠作用下的生长速率常数(k)、抑制率(I)、最大产热功率(Pm)以及最大产热功率所对应的时间tm等热动力学参数. 研究结果表明, 头孢哌酮钠和头孢哌酮钠舒巴坦钠对大肠杆菌的致死量分别为0.1和0.25 μg/mL. 通过研究k, I, Pm, tm和浓度(c)间的关系发现, 舒巴坦钠的加入没有增加头孢哌酮钠对大肠杆菌DH5α的抑制作用.     

Free flow electrophoresis as a method for the purification of enzymes from E. coli cell extract

The application of the four techniques of free flow electrophoresis (zone electrophoresis, isotachophoresis, isoelectric focusing and field step electrophoresis) for the purification of proteins from a complex protein mixture was investigated. For this purpose alpha-amylase (EC 3.2.1.1) from Aspergillus oryzae was added and reisolated from E. coli cell extract. The chosen enzyme and the biological extract are models for many industrial separation problems. In optimized experiments purity, purification factor, yield, throughput and efficiency were calculated. The best results were obtained with field step electrophoresis in combination with zone electrophoresis. High purity (0.82 mg enzyme/mg total protein) and high throughput (111 mL sample/h) were achieved using this technique. Field step electrophoresis gave the best throughput (330 mL sample/h), but low purity (0.63 mg enzyme/mg total protein). This technique can also be used for a simple concentration of the sample. With zone electrophoresis a purity of more than 0.95 mg enzyme/mg total protein was obtained, which was the best of all techniques. However, the enzyme concentration was decreased due to dilution with buffer solution after the separation. Isotachophoresis was the most difficult technique, combined with a relatively low recovery of 31% of the enzyme activity. In a purification scheme, free flow electrophoresis is able to substitute one or even several chromatography steps with a negligible loss of biological activity.     

The research on formation enthalpy of phenanthroline monohydrate and its influence on the growth metabolism of E. coli by microcalorimetry

A precision rotating-bomb combustion calorimeter (thermistor of which was constructed in the laboratory) was calibrated using benzoic acid with purity of 99.999 %. The combustion energy of phenanthroline monohydrate (phen·H₂O) at 298.15 K was determined to be Δ_c U _m ^θ  = ?(5,757.45 ± 2.53) kJ mol^?1. Then, the standard enthalpy of combustion and the standard enthalpy of formation of phen·H₂O were calculated to be Δ_c H _m ^θ  = ?(5,759.93 ± 2.53) kJ mol^?1 and Δ_f H _m ^θ  = ?(391.34 ± 2.98) kJ mo1^?1, respectively. Particularly, the effect of phen·H₂O on growth and metabolism of Escherichia coli (E. coli) was also determined by a TAM air isothermal calorimeter at 37 °C. The thermokinetic parameters, including maximum heat output power (P _max), growth rate constant (κ), generation times (t _G), inhibitive rate (I), and half inhibition concentration (C _I,50), were obtained. The results showed that phen·H₂O possessed the bi-directional biological effect and Hormesis effect, which stimulated the growth of E. coli at lower concentration, but inhibited the growth at higher concentration. The half inhibition concentration C _I,50 of phen·H₂O was found to be 7.31 mg L^?1.     

Diabetes-induced alterations in the extracellular matrix and their impact on myocardial function

Diabetes is an increasing public health problem that is expected to escalate in the future due to the growing incidence of obesity in the western world. While this disease is well known for its devastating effects on the kidneys and vascular system, diabetic individuals can develop cardiac dysfunction, termed diabetic cardiomyopathy, in the absence of other cardiovascular risk factors such as hypertension or atherosclerosis. While much effort has gone into understanding the effects of elevated glucose or altered insulin sensitivity on cellular components within the heart, significant changes in the cardiac extracellular matrix (ECM) have also been noted. In this review article we highlight what is currently known regarding the effects diabetes has on both the expression and chemical modification of proteins within the ECM and how the fibrotic response often observed as a consequence of this disease can contribute to reduced cardiac function.     

Influence of cellulose type on the properties of extruded pellets. Part I. Physicochemical characterisation of the cellulose types after homogenisation

 The physicochemical properties of different types of powdered cellulose (PC) and microcrystalline cellulose (MCC) were studied by examining the changes in particle size, viscosity and specific surface area after a homogenisation process. An additional characterisation was carried out using X-ray diffractometry. A preliminary investigation using a type of MCC showed that increasing the homogenisation pressure and the number of passage cycles led to a significant decrease in the particle size and simultaneously to a remarkable increase in the specific surface area and viscosity. Most MCC types showed the same pattern during the homogenisation process. “Colloidal” MCC displayed a higher viscosity than the others but without significant change in the viscosity after different homogenisation cycles. In contrast to this behaviour of the MCCs, the PCs showed no remarkable change in the particle size but did show a marked change in their viscosity. Furthermore, only MCC suspensions, with the exception of “colloidal” MCC, agglomerated after the homogenisation process, whereas this was not seen in the PC suspensions. Hence, since the MCC types as well as the PC types originally had the same chemical structure, this different behaviour among these types can only be attributed to their different physical properties. Received: 27 July 1999/Accepted: 15 December 1999     

Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose,hydroxypropylmethyl cellulose,and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI)

The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T(2)) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T(2) and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T(2) of (1)H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed.     

Mechanically robust,flame-retardant and anti-bacterial nanocomposite films comprised of cellulose nanofibrils and magnesium hydroxide nanoplatelets in a regenerated cellulose matrix

Nanocomposite films consisting of cellulose nanofibrils (CNFs), magnesium hydroxide nanoplatelets (MHNPs) and regenerated cellulose were prepared via simple blending and casting processes. The CNFs were obtained from bamboo pulp by ultrasonic treatment coupled with high shear homogenization. The morphology, structure and properties of the nanocomposite films were comprehensively analyzed using various characterization techniques, including the scanning electron microscope, digital microscope, limiting oxygen index (LOI), micro-scale combustion calorimetry, antibacterial assays, tensile testing, etc. When the MHNP content was optimized to 30 wt%, the nanocomposite film exhibited the best overall properties. The LOI of the composite film increased from 20.0 (0 wt% MHNPs) to 32.7 (30 wt% MHNPs), making it a flame-retardant material in air. In addition, the film containing 30 wt% MHNPs showed excellent antibacterial activity. However, the increase in MHNP content would result in gradual deterioration of the films’ mechanical properties. However, the incorporation of CNFs could significantly suppress this trend. The present work provided a promising pathway for manufacturing multifunctional and high-performance cellulose-based composite films, which were potentially useful for a variety of packaging materials, especially in the biomedical and food packaging fields.