Preparation and Characterization of a Novel Salicin-Cyclodextrin Complex.

Bioactive compounds extracted from plants can provide wide health benefits. However, some molecules have limited applications as pharmaceuticals due to their limited solubility, poor bioavailability, and low stability when exposed to environmental factors. Their integration in formulations that can deliver them to physiological targets while preserving their biological activity can enhance their usage in improving human health. This research provides a delivery system design to enhance the solubility, stability and to mask the bitter taste of salicin. Thus, a novel salicin-ß-cyclodextrin complex was prepared and analyzed by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, FTIR, Raman and UV-Vis spectroscopy. The analytical and computational methods provided clear and distinct evidence for inclusion of salicin within the ß-cyclodextrin cavity and brought important findings for the characterization of the inclusion complex. The present study showed that salicin and ß-cyclodextrin can form inclusion complexes, both in solution and in solid state, and that the inclusion of salicin in the cavity of ß-cyclodextrin leads to the improvement of its solubility and stability. Thus, the study communicates both qualitative and quantitative knowledge about the preparation of a new salicin-ß-cyclodextrin inclusion complex suggesting its potential applications in pharmaceutical industry and medical sciences, as formulations with better compliance for the patient, with increased bioavailability, and easier control of dosage.

Some Brassicaceae Extracts as Potential Antioxidants and Green Corrosion Inhibitors.

Glucosinolates-rich extracts of some Brassicaceae sources, such as broccoli, cabbage, black radish, rapeseed, and cauliflower, were obtained using an eco-friendly extraction method, in a microwave field, with 70% ethanol, and evaluated in order to establish their in vitro antioxidant activities and anticorrosion effects on steel material. The DPPH method and Folin-Ciocâlteu assay proved good antioxidant activity (remaining DPPH, 9.54-22.03%) and the content of total phenolics between 1008-1713 mg GAE/L for all tested extracts. The electrochemical measurements in 0.5 M H2SO4 showed that the extracts act as mixed-type inhibitors proving their ability to inhibit corrosion in a concentration-dependent manner, with a remarkable inhibition efficiency (92.05-98.33%) achieved for concentrated extracts of broccoli, cauliflower, and black radish. The weight loss experiments revealed that the inhibition efficiency decreased with an increase in temperature and time of exposure. The apparent activation energies, enthalpies, and entropies of the dissolution process were determined and discussed, and an inhibition mechanism was proposed. An SEM/EDX surface examination shows that the compounds from extracts may attach to the steel surface and produce a barrier layer. Meanwhile, the FT-IR spectra confirm bond formation between functional groups and the steel substrate.

Novel Chloro-Substituted Salicylanilide Derivatives and Their ß-Cyclodextrin Complexes: Synthesis, Characterization, and Antibacterial Activity.

The goal of this research was to design novel chloro-substituted salicylanilide derivatives and their ß-cyclodextrin complexes in order to obtain efficient antibacterial compounds and to demonstrate the beneficial role of complexation on the efficiency of these compounds. Thus, salicylanilide derivatives, esters, and hydrazides were obtained by microwave-assisted synthesis and their structure proven based on FTIR and NMR spectra. In order to improve water solubility, chemical and physical stability, and drug distribution through biological membranes, the inclusion complexes of the ethyl esters in ß-cyclodextrin were also obtained using kneading. Inclusion-complex characterization was accomplished by modern analytical methods, X-ray diffraction, SEM, TGA, FTIR, and UV-vis spectroscopy. The newly synthesized compounds were tested against some Gram-positive and Gram-negative bacteria. Antimicrobial tests revealed good activity on Gram-positive bacteria and no inhibition against Gram-negative strains. The MIC and MBC values for compounds derived from N-(2-chlorophenyl)-2-hydroxybenzamide were 0.125-1.0 mg/mL. N-(4-chlorophenyl)-2-hydroxybenzamide derivatives were found to be less active. The inclusion complexes generally behaved similarly to the guest compounds, and antibacterial activity was not been altered by complexation.

Carbon Nanotubes for Improved Performances of Endodontic Sealer.

In order to overcome the limitations of current endodontic sealers, especially against resistant bacteria, recent developments in the field of nanotechnology have proved the necessity to reconsider the composition and physico-chemical properties of classical sealers. Nanoparticles with their unique features in terms of small size and high specific surface area, are the best choice for incorporation of antiseptic agents and effective delivery. The aim of our study is to prepare a novel platform for antibacterial drug delivery in dental adhesive systems used in endodontics. For this purpose, multi-walled carbon nanotubes (MWCNTs) encapsulating chlorhexidine (CHX) and colloidal silver nanoparticles (AgNPs) were prepared and incorporated into commercial sealer and investigated in terms of bonding performance to dentin and effectiveness against E. faecalis, S. aureus and Candida albicans, which are responsible for the majority of the failures in endodontic treatments. In this context, the challenges related to the long-term biological effects of CHX/AgNPs loaded MWCNTs are discussed.

Advances in Low-Density Flexible Polyurethane Foams by Optimized Incorporation of High Amount of Recycled Polyol.

An industrially manufactured recycled polyol, obtained by acidolysis process, was for the first time proved to be a possible replacement of the reference fossil-based polyol in a low-density formulation suitable for industrial production of flexible polyurethane foams. The influence of increasing recycled polyol amounts on the properties of the polyurethane foam has been studied, also performing foam emission tests to evaluate the environmental impact. Using 10 pbw recycled polyol in the standard formulation, significant differences of the physical properties were not observed, but increase of the recycled polyol amount to 30 pbw led to a dramatic decrease of the foam air flow and a very tight foam. To overcome this drawback, N,N'-bis[3-(dimethylamino)propyl]urea was selected as tertiary amine catalyst, enabling the preservation of foam properties even at high recycled polyol level (30 pbw). Foam emission data demonstrated that this optimized foam formulation also led to an important reduction of volatile organic compounds. The results open the way for further optimization studies in low-density flexible polyurethane foam formulations, to increase the reutilization of the polyurethane waste and reduce the amount of petroleum-based raw materials.

Recovery of Flexible Polyurethane Foam Waste for Efficient Reuse in Industrial Formulations.

Ester polyurethane (PU) foam waste was reacted at atmospheric pressure in an autoclave and using microwaves with diethylene glycol (DEG) at different PU/DEG ratios in the presence of diethanolamine as a catalyst to find the glycolysis conditions that allow for the improved recovery of the PU foam waste and enable the recycling of the whole glycolysis product in foam formulations suitable for industrial application. The recycled polyol was characterized by dynamic viscosity, hydroxyl number, water content, and density, while thermal stability was assessed using thermogravimetric analysis. In the PU foam formulation, 1% and 5% of the glycolyzed material was reused. The relationship between the reuse level of the recycled polyol and the physical properties of the foam was thoroughly investigated. It was observed that both hardness and air flow decreased with increasing recycled polyol content, particularly for the polyester type foam, while tensile strength and compression strength increased. Depending on the amount of recycled polyol and catalyst used, polyether-based foams could be obtained with a low air permeability, needed in special applications as sealed foams, or with higher air permeability desirable for comfort PU foams. The results open the way for further optimization studies of industrial polyurethane foam formulations using a glycolysis process without any separation stage.

Biodegradation Pattern of Glycopolymer Based on D-Mannose Oligomer and Hydroxypropyl Acrylate.

Glycopolymers are polymers with sugar moieties which display biodegradable and/or biocompatible character. They have emerged as an environmentally-friendly solution to classical synthetic polymers and have attracted significant research interest in the past years. Herein, we present the synthesis of a D-mannose based glycopolymer with biodegradable features. The glycopolymer was synthesized by radical copolymerization between a D-mannose oligomer bearing polymerizable double bonds and 2-hydroxypropyl acrylate, in a weight ratio of 1:2. The copolymerization kinetics was investigated by differential scanning calorimetry (DSC) and the activation energy of the process was comparatively assessed by Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods. The obtained glycopolymer displayed good thermal behavior, fact proven by thermogravimetrical (TG) analysis and it was submitted to biodegradation inside a bioreactor fed with water from the Bega River as the source of microbial inoculum. The glycopolymer sample degraded by approximately 60% in just 23 days. The biodegradation pattern of the glycopolymer was successfully fitted against a modified sigmoidal exponential function. The kinetic model coefficients and its accuracy were calculated using Matlab and the correlation coefficient is more than promising. The changes inside glycopolymer structure after biodegradation were studied using TG and FTIR analyses, which revealed that the sugar moiety is firstly attacked by the microbial consortia as nutrient source for proliferation.

Modified Chitosan for Silver Recovery-Kinetics, Thermodynamic, and Equilibrium Studies.

：The aim of this study is to investigate the silver recovery from aqueous solutions. There are a variety of recovery methods, such as hydrometallurgical, bio-metallurgical, cementation, reduction, electrocoagulation, electrodialysis, ion exchange, etc. Adsorption represents a convenient, environment friendly procedure, that can be used to recover silver from aqueous solutions. In this paper we highlight the silver adsorption mechanism on chitosan chemically modified with active groups, through kinetic, thermodynamic, and equilibrium studies. A maximum adsorption capacity of 103.6 mg Ag(I)/g of adsorbent for an initial concentration of 700 mg/L was noticed by using modified chitosan. Lower adsorption capacity has been noticed in unmodified chitosan-a maximum of 75.43 mg Ag(I)/g. Optimum contact time was 120 min and the process had a maximum efficiency when conducted at pH higher than 6. At the same time, a way is presented to obtain metallic silver from the adsorbent materials used for the recovery of the silver from aqueous solutions.

Adsorption of Orange II Onto Zn2Al-Layered Double Hydroxide Prepared From Zinc Ash.

The dye industry is one of the largest water consuming industries, and at the same time generates large quantities of wastewaters. The resulting wastewaters require proper treatment before discharge, because the dye contents have a negative effect on the water body and organisms present in it. The most efficient treatment method for water containing dyes is represented by adsorption processes. The challenge with these adsorption processes is to develop new, efficient, viable, and economic adsorbent materials. Therefore, in the present paper, the performance of Zn2Al-layered double hydroxide, prepared from an industrial waste (zinc ash) as a zinc source, was investigated in the Orange II dye adsorption process. The Zn2Al-layered double hydroxide prepared from secondary sources presents similar morphological and structural characteristics as those prepared from analytical grade reagents. The influence of initial dye concentration, adsorption time, solid:liquid ratio, pH, and temperature was evaluated in order to confirm the benefit of this waste valorization. A comparison with the reference Zn2Al-layered double hydroxide prepared from analytical grade reagents was performed and the results show that due to the small presence of impurities, the material prepared from zinc ash shows better adsorption capacities (qmax,exp = 42.5 mg/g at 293 K) than the material prepared from reagents (qmax,exp = 36.9 mg/g at 293 K), justifying the utilization of secondary sources for layered double hydroxides preparation. The proposed treatment process presents advantages from both economic and environmental protection point of view.

Complexation of Danube common nase (Chondrostoma nasus L.) oil by ß-cyclodextrin and 2-hydroxypropyl-ß-cyclodextrin.

ß-Cyclodextrin- and 2-hydroxypropyl-ß-cyclodextrin/Danube common nase (Chondrostoma nasus L.) oil complexes (ß-CD- and HP-ß-CD/CNO) have been obtained for the first time. The fatty acid (FA) profile of the CNO indicates an important content of polyunsaturated fatty acids, the most important being eicosapentaenoic acid (EPA, 6.3%) and docosahexaenoic acid (DHA, 1.6%), both ω-3 FAs. The complexes have been obtained by kneading method. The moisture content and successful of molecular encapsulation have been evaluated by thermal and spectroscopic techniques. Thermogravimetry and differential scanning calorimetry analyses reveals that the moisture content of CD/CNO complexes significantly decreased, compared to starting CDs. On the other hand, the crystallinity index was for the first time determined for such type of complexes, the ß-CD/CNO complex having values of 43.9(±18.3)%, according to X-ray diffractometry. FA profile and CD/CNO characteristics sustain the use of these ω-3 based complexes for food supplements or functional food products, but further studies are needed.

Biodegradable Oligoesters of ε-Caprolactone and 5-Hydroxymethyl-2-Furancarboxylic Acid Synthesized by Immobilized Lipases.

Following the latest developments, bio-based polyesters, obtained from renewable raw materials, mainly carbohydrates, can be competitive for the fossil-based equivalents in various industries. In particular, the furan containing monomers are valuable alternatives for the synthesis of various new biomaterials, applicable in food additive, pharmaceutical and medical field. The utilization of lipases as biocatalysts for the synthesis of such polymeric compounds can overcome the disadvantages of high temperatures and metal catalysts, used by the chemical route. In this work, the enzymatic synthesis of new copolymers of ε-caprolactone and 5-hydroxymethyl-2-furancarboxylic acid has been investigated, using commercially available immobilized lipases from Candida antarctica B. The reactions were carried out in solvent-less systems, at temperatures up to 80 °C. The structural analysis by MALDI TOF-MS, NMR, and FT-IR spectroscopy confirmed the formation of cyclic and linear oligoesters, with maximal polymerization degree of 24 and narrow molecular weight distribution (dispersity about 1.1). The operational stability of the biocatalyst was explored during several reuses, while thermal analysis (TG and DSC) indicated a lower thermal stability and higher melting point of the new products, compared to the poly(ε-caprolactone) homopolymer. The presence of the heterocyclic structure in the polymeric chain has promoted both the lipase-catalyzed degradation and the microbial degradation. Although, poly(ε-caprolactone) is a valuable biocompatible polymer with important therapeutic applications, some drawbacks such as low hydrophilicity, low melting point, and relatively slow biodegradability impeded its extensive utilization. In this regard the newly synthesized furan-based oligoesters could represent a "green" improvement route.

Gold (III) adsorption from dilute waste solutions onto Amberlite XAD7 resin modified with L-glutamic acid.

The main purpose of this paper was to obtain a material with efficient adsorbing properties and selectivity, to recover the gold (III) from residual diluted solutions resulted from the electroplating process. In this regard, a material was obtained by physico-chemical functionalization of a chemically inert support with functional groups of nitrogen and carboxyl. As a source of functional groups glutamic acid was used, and Amberlite XAD7 type acrylic resin was used as solid support. In order to establish the mechanism of the adsorption process, kinetic, thermodynamic and equilibrium studies were performed. The maximum adsorption capacity of the material has been established, and a gold (III) recovery process has been proposed using thermal decomposition of the exhausted adsorbed material. Main objective of this study was to evaluate an environmental friendly adsorbent material to recover gold from secondary industrial sources.

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with ß-cyclodextrin.

The thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) as well as its ß-cyclodextrin (ß-CD) complexation ability has been verified for the first time. The main omega-3 fatty acids, EPA and DHA, were significantly degraded, even at 50 °C. Their relative concentrations decrease from 6.1% for EPA and 4.1% for DHA to 1.7% and 1.5% after degradation at 150 °C, respectively. On the other hand, the relative concentrations of monounsaturated and saturated fatty acids remained constant or slightly increased by a few percent after degradation (e.g., from 10.7% to 12.9% for palmitic acid). Co-crystallization of ASO with ß-CD at a host-guest ratio of 1:1 and 3:1 from an ethanol-water mixture and kneading methods has been used for the preparation of ß-CD/ASO complexes. The analysis of the complexes by thermogravimetry, differential scanning calorimetry (DSC), and Karl Fischer titration (KFT) as well as the decrease of the "strongly-retained" water content confirm the formation of the inclusion compound. Furthermore, the DSC parameters correlate well with the KFT kinetic data for ß-CD/ASO complexes.