教学课程资源库 更多>>

关键词： Chrysin   Nanocapsules   Controlled drug delivery   Hyperlipidemia   Diabetes   Pharmacodynamic study   PLGA  

摘要： Chrysin is a flavonoid with various biological and therapeutic properties. However, its poor oral bioavailability and solubility are challenging barriers against its therapeutic use, which can be circumvented via encapsulation in a suitable nanocarrier. Therefore, the aim of this work was to prepare polymeric chrysin nanocapsules based on polylactic-glycolic acid PLGA with improved oral therapeutic potential, by optimization of their physicochemical properties using response surface methodology. Diabetes was induced in an animal model using streptozotocin to assess the anti-hyperglycemic activity of the selected formulation, and hyperlipidemia was induced in another animal model using a high fat diet to assess its anti-hyperlipidemic activity. Results revealed that the selected chrysin nanocapsular formulation exhibited particle size of 176 +/- 2.10 nm, polydispersity index of 0.22 +/- 0.01, negative zeta potential, drug entrapment efficiency of 87.10% +/- 6.71, a controlled release of chrysin over a period of 24 h, and a significant physical stability after storage for 3 months. Compared to chrysin suspension, the selected nanocapsular formulation exhibited marked anti-hyperglycemic effect for up to 24 h, as well as superior anti-hyperlipidemic potential for 28 days. These improvements in chrysin therapeutic action after its encapsulation into polymeric nanocapsules delineate it as a promising remedy for oral treatment of diabetes and hyperlipidemia.

关键词： conducting polymers   membranes   thermal properties   thermogravimetric analysis   X-ray  

摘要： Polyether ether ketone (PEEK) with a low sulfonation degree was blended using different proportions of sodium rich Smectite clay (3 and 6 wt%) to use as an electrolyte membrane for fuel cell application. The structural functionalities, surface morphologies, and the thermal stability of the resultant composite membranes were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, atom force microscopy, and thermo-gravimetric analysis. FT-IR showed that no chemical reactions take place between the sulfonated polyether ether ketone (SPEEK) and the clay with different ratios. XRD diffractograms illustrated a lower degree of crystallinity of the blended SPEEK than pristine SPEEK. The elaborated composite membranes proved to have a higher thermal stability than SPEEK. Furthermore, the SPEEK/clay composite membranes with 3 and 6 wt% in clay loading had higher water uptake and lower methanol uptake than those in pristine SPEEK It was also shown that, the incorporation of sodium ions rich Smectite clay layers between the clusters in SPEEK improved the conductivity to 2 x 10(-2)S/cm at 140 degrees C (for 6 wt% in clay) without compromising the dimensional stability of the composite membranes. These results propose the composite membranes as a potential candidate for methanol fuel cells at temperatures above 120 degrees C making SPEEK composite membrane competitive to that of Nafion membrane.

关键词： Cochlea   Hydrogels   Intracochlear administration   Intratympanic administration   Nanoparticulate systems   Round window membrane   Targeting  

摘要： Despite the high incidence of inner ear disorders, there are still no dedicated medications on the market. Drugs are currently administered by the intratympanic route, the safest way to maximize drug concentration in the inner ear. Nevertheless, therapeutic doses are ensured for only a few minutes/hours using drug solutions or suspensions. The passage through the middle ear barrier strongly depends on drug physicochemical characteristics. For the past 15 years, drug encapsulation into nanocarriers has been developed to overcome this drawback. Nanocarriers are well known to sustain drug release and protect it from degradation. In this review, in vivo studies are detailed concerning nanocarrier biodistribution, their pathway mechanisms in the inner ear and the resulting drug pharmacokinetics. Key parameters influencing nanocarrier biodistribution are identified and discussed: nanocarrier size, concentration, surface composition and shape. Recent advanced strategies that combine nanocarriers with hydrogels, specific tissue targeting or modification of the round window permeability (cell-penetrating peptide, magnetic delivery) are explored. Most of the nanocarriers appear to be safe for the inner ear and provide a significant efficacy over classic formulations in animal models. However, many challenges remain to be overcome for future clinical applications.

关键词： EDTA   HSA   Metal kinetics   PDB and log K-ML  

摘要： Bifunctional chelate EDTA-bis amide (N,N '-bis (tyramide)ethylenediamine-N,N '-diacetic acid) that has ability to mimic natural amino acids was synthesized and analyzed by various spectroscopic techniques. The physicochemical studies were performed to calculate the various thermodynamic and kinetic parameters for the synthesized poly-amino carboxylate ligand. The two protonation constant (pka's = 3.460 and 6.722) of the prepared ligand and stability constants (log K-ML's = 15.8, 18.1, 16.2, 18.4, 17.5, 18.9, 13.6 and 12.8) of the complexes formed with Ce3+, Sm3+, Eu3+, Gd3+, Tb3+, Lu3+, Zn2+ and Cu2+ were determined by potentiometric titration using 0.1 M Me4NOH as non-aqueous base. The formation kinetics of [EuEDTA-TA(2)](+) and [CeEDTA-TA(2)](+) was studied and the rate constants were found to be 2.95 x 10-5 s(-1) and 4.414 x 10-5 s(-1)respectively including the exchange reaction of [EuEDTA-TA(2)](+) with Zn2+ and Cu2+ spectrophotometrically. The Eu(III) complex of EDTA(TA)(2) gives three emission bands at 480 nm, 540 nm and 610 nm (lambda(max) = 270 nm, excitation) which shows efficacy of the ligand as an optical imaging agent. Molecular docking studies with Human Serum Albumin (HSA: PDB 1E78) showed binding pattern with the residues Arg218, Arg222, Lys195 and Lys444 in sub domain II A of site I via hydrogen bond and identifies the ligand-HSA interaction and specific insight for transportation to the target sites. Subsequently, fluorescence spectroscopy was performed at lambda(ex) = 350 nm binding constant for HSA was 5.847 x 10(4) M-1 which showed effective quenching effect. (C) 2020 Published by Elsevier B.V.

关键词： Natural fibres   Mechanical properties   Atomic force microscopy   Infrared (IR) spectroscopy   Raman spectroscopy  

摘要： As pressing needs for exploring molecular interactions in plants soar, conventional sample preparation methods come into question. Though resins used to embed plant tissues have long been assumed to bear no palpable effect on their properties, discrepancies in recent studies exploiting nanoscale microscopy suggest that their impact could be significant at small scales. By juxtaposing the traits of poplar sections prepared with and without embedding, we evaluate the diffusion (penetration depth) of acrylic and epoxy resins commonly used for embedding. Our results unveil critical quantitative differences when probing mechanical properties with a microscale nanoindentation indenter or a nanoscale tip. The latter resolves significant stiffness variations between the compound middle lamellae, the secondary cell wall layers S1 and S2, and the cell corner, not accessible with nanoindentation. Similar observations are drawn from comparing confocal Raman and nanoscale infrared spectroscopy. Our findings shed light on the effect of resin diffusion suggesting acrylic LR White to be the least diffusive for plant cell wall studies.

关键词： Sildenafil base   Solid self-nanoemulsifying drug delivery system   High-pressure homogenisation   Shirasu porous glass membrane   Nanoemulsion   In vitro dissolution   Pharmacokinetics in rats  

摘要： The purpose of this study was to compare two types of emulsification techniques in a solid self-nanoemulsifying drug delivery system (SNEDDS);high-pressure homogenisation (HPH) and Shirasu porous glass membrane (SPG). Those two emulsification processes enhanced the solubility, dissolution and oral bioavailability of poorly water-soluble sildenafil base (SB) by producing fine and well-dispersed nanoemulsion droplet. The liquid SNEDDS consisting of Labrasol/Transcutol HP/coconut oil at the weight of 72/18/10, gave the smallest emulsion droplet size among the prepared liquid SNEDDS formulations. Then, the SB-loaded liquid SNEDDS was dissolved in the deionised water and applied to HPH or SPG techniques. Aerosil 200 was suspended as a mesoporous carrier and spray-dried, producing an SB-loaded solid SNEDDS. The emulsion droplet size, solubility and dissolution of each emulsification process were compared to the solid SNEDDS fabricated without any treatment of additional emulsification. Moreover, the physicochemical properties of all formulations were compared. The crystalline state of the drug in all products was converted to the amorphous state. The solid SNEDDS, subjected to HPH technique, provided fine and well-dispersed nanoemulsion. Additionally, it increasingly improved the drug solubility and dissolution as compared to the others, including SB powder, non-treated (NT) and SPG. Furthermore, it gave improved C-m(ax) and increased AUC compared to SB powder and SPG, indicating HPH enhanced the oral bioavailability of SB the most. Thus, this solid SNEDDS with HPH would be strongly suggested as an oral SB-loaded pharmaceutical product.

关键词： lipid-based nanocarriers   surface functionalization   targeting ligands   characterization  

摘要： Surface functionalization of lipid-based nanocarriers (LBNCs) with targeting ligands has attracted huge interest in the field of nanomedicines for their ability to overcome some physiological barriers and their potential to deliver an active molecule to a specific target without causing damage to healthy tissues. The principal objective of this review is to summarize the present knowledge on LBNC decoration used for biomedical applications, with an emphasis on the ligands used, the functionalization approaches, and the purification methods after ligand corona formation. The most potent experimental techniques for the LBNC surface characterization are described. The potential of promising methods such as nuclear magnetic resonance spectroscopy and isothermal titration calorimetry to characterize ligand surface corona is also outlined.

关键词： Coal ash   disposal duration   chemical and physical characteristics   toxicity   weathering   leaching   landfills  

摘要： The quantities of coal ash disposed of in landfills over the past decades add up to billions of tons. Weathering in landfill would impact the mineralogical, chemical, physical and toxicity characteristics of coal ash. In order to investigate these effects, ashes were obtained from different depths of landfills representing different durations of disposal. These ashes were subjected to a range of physical, chemical, and toxicity tests. Aging in landfill was noted to produce significant changes in various ash properties. The trends in these changes with increasing disposal duration were identified. These trends were explained based on the weathering and leaching effects experienced by the coal ash in landfills. In addition, hydraulic activity and reactivity of the landfill coal ashes were determined to assess their potential use in alternate cement production.

关键词： Virgin coconut oil   authentication analysis   functional oil   physicochemical properties   health benefits  

摘要： Virgin coconut oil (VCO) has emerged as functional food oil due to its capability to provide some biological activities which are beneficial to human health. This is due to the fact that some minor components like tocopherols and phenolics compounds are retained. VCO is prepared from fresh, mature kernel of the coconuts by mechanical or natural means, with or without the use of heat, but specifically without any chemical refining, bleaching and deodorizing (RBD). As a consequence, VCO has slight difference in terms of some physico-chemical properties with RBD coconut oil. Due to phenolics compounds contained, VCO exhibited several pharmacological activities including antioxidant, anti-inflammatory and immunomodulatory, anti-hyperlipidemia, anticancer, antidiabetic, anti-bacterial and neuroprotective activities. VCO has commanded high price value in the fats and oils industry, hence, VCO can be target of adulteration with low priced oils. Fourier transform infrared (FTIR) spectroscopy and chromatographic techniques combined with multivariate analysis has been successfully reported for analysis of adulteration practice involving the substitution or replacement VCO with other oils. This review highlights some techniques for VCO extraction, physicochemical (characterization), biological activities and authentication analysis of VCO.

关键词： Environmental risks   heat   painting   physico-chemical changes   ultraviolet irradiation  

摘要： The study is composed of three phases to describe the paintings at normal and several aging times: modeling of new icons similar to an ancient one, aging of the icons by heat and ultraviolet irradiation, and characterization of the icons. The results showed a change in the chemical structure of the painting materials, the crystallinity of the wood and canvas materials, and the chromaticity coordinates with darkening in the heat treatment and fading in the UV irradiation treatment. There is a correlation between the exposure time, the chemical properties of the materials, and the optical properties of the paintings.