Shedding light on lipase stability in natural deep eutectic solvents

This study presents the potential role of natural deep eutectic solvents (NADESs) in a lipase-catalyzed hydrolysis reaction as both a co-solvent in an aqueous solution and as a main solvent. Ammonium salts such as choline chloride (ChCl) were paired with different hydrogen bond donors such as glycerol and malonic acid and sugars (glucose, fructose and sucrose). The hydrolysis of p-nitrophenyl palmitate by six different lipases: lipase from porcine pancreas (PR), lipase from Candida rugosa (CR), Amano lipase PS, from Burkholderia cepacia (AM), lipase from Rhizopus niveus (RN), lipase acrylic resin from Candida antartica (ARC), lipase B Candida antartica immobilized on Immobead 150, recombinant from Aspergillus oryzae (CALB), were tested in five NADESs. The results showed that NADES3 prepared from ChCl/sucrose was the most promising solvent as it enhanced the activities of both CALB and lipase from porcine pancreas to 355 % and 345 %. The kinetics investigation confirmed the higher catalytic efficiency (kcat/Km) of lipases in the 40 % of (NADES3) and compared with the aqueous form. The trend achieved by NADES may be a promising approach for applications and further perspectives as genuinely green industrial solvents

Ternary glycerol-based deep eutectic solvents: physicochemical properties and enzymatic activity

The present study investigates deep eutectic solvents (DESs) as potential media for enzymatic hydrolysis. A series of ternary ammonium and phosphonium-based DESs were prepared at different molar ratios by mixing with aqueous glycerol (85%). The physicochemical properties including surface tension, conductivity, density, and viscosity were measured at a temperature range of 298.15 K – 363.15 K. The eutectic points were highly influenced by the variation of temperature. The eutectic point of the choline chloride: glycerol: water (ratio of 1: 2.55: 2.28) and methyl triphenylphosphonium bromide:glycerol: water (ratio of 1: 4.25:3.75) is 213.4 K and 255.8 K, respectively. The stability of the lipase enzyme isolated from the porcine pancreas (PPL) and Rhizopus niveus (RNL) toward hydrolysis in ternary DESs medium was investigated. The PPL showed higher activity compared to the RNL in DESs. Molecular docking simulation of the selected DES with the substrate (p-nitrophenyl palmitate) towardPPL was also reported. It is worth noting that ternary DES systems would be viable lipaseactivators in hydrolysis reactions

Islamic art and the ethos of spirituality within a civilizational context

Islamic art is characterized by a deep-rooted vitality and distinct form of expression that arises from its intimate position with regard to Islamic civilization. While civilizational turning points and major occurrences have held deep ramifications for its growth and development, the most prominent catalysts of civilizational status are not only found in the realm of the political and economic, but rather within a deeper expanse of ideas, spirituality, and societal consciousness; of which Islamic art acts as a prime indicator. The paper aims to discuss these issues. Design/methodology/approach. This paper would seek to survey the depths inherent within Islamic spirituality’s relationship with Islamic art, and further isolate the reasons and source of their subsistence and continued prevalence. The paper further delves into the relationship shared by spirituality and art, and the influences they exert upon one another. Moreover, it attempts to delineate between the mundane and transcendental spheres of civilizational growth and development, while seeking to come to terms with the sustainability of Islamic art, and its position with respect to Islamic civilization. The paper concludes that Islamic art is sustained and defined by means of a unique catalyzing ethos responsible for Islamic civilizational culture that is altogether distinct from the temporal mundane reality of socio-political conditions of civilization

Surface analysis of early retrieved polyethylene tibial inserts for both knees in total knee replacement

This study involves the failure analysis of a pair of ultra-high-molecular-weight-polyethylene (UHMWPE) knee tibial inserts from Scorpio® fixed-bearing total knee system by Stryker, which were retrieved from Total Knee Replacements (TKR) that was performed on 64 years old male patient with periprosthetic joint infection detected on both knees. Although the implants were removed due to infection, surface analysis was essential to be studied in order to analyse the surface damage mode of short-term implants. This study reports relevant damage mechanisms seen in early-retrieved UHMWPE tibial inserts (implanted for 6 and 8 months) and further analysis of chemical, physical and mechanical properties that possibly accompanied with failure. The surface characterization was done using a 3D laser microscope and Scanning Electron Microscope (SEM) to evaluate surface damage and dimensional change of both UHMWPE tibial inserts. Nano-indentation is used to measure the hardness and elasticity modulus of the tibial inserts. Attenuated Total Reflection-Fourier Transform Infra-Red (ATR-FTIR), Differential Scanning Calorimetry (DSC) and Gel Permeation Chromatography (GPC) were used to characterize the chemical and physical properties of the inserts. In present study, retrieved polyethylene inserts with short implantation duration was considered to have high-grade wear modes. The high incidence of micro pits (with the average depth of 27.5 μm for 6 months insert and 18 μm for 8 months insert) and scratches as the observed surface defects strengthen the role played by the particles upon defects generation for both tibial inserts. The average surface roughness of 6 and 8 months inserts were 1.6798 μm and 1.2376 μm, respectively. The rough surface (4.207 μm) of region 4 at the lateral compartment proves that the 6 months tibial insert suffered more damage due to loosening defect where the radiolucencies (the gap between bone and cement) were seen below medial and lateral aspects of the tibial tray. Our data demonstrated a strong association between the change of molecular weight and degradation of mechanical properties with wear for both inserts. The oxidation induced wear mechanism was observed on 6 months old insert due to the presence of delamination features with the evidence of in vivo oxidation from IR analysis. © 2019 Elsevier Lt

Characterization of tetraethylene glycol-based deep eutectic solvents and their potential application for dissolving unsaturated fatty acids

Deep eutectic solvents (DESs) are credible alternatives for ionic liquids. Most DESs have favourable properties such as lower production cost, biodegradability and are environmental friendly. In this work, tetraethylene glycol (TTEG)-based DESs were successfully prepared by mixing TTEG and choline chloride at different molar ratios. The physicochemical properties such as conductivity, freezing point, density, surface tension and viscosity were measured at temperatures between 298.15 K and 353.15 K. It was found that the molar ratio of both compounds affected the physicochemical properties. As the solubility of unsaturated fatty acids, such as oleic acid and linoleic acid, in these DESs are industrially significant, this property became an important consideration. Computer simulations using the COSMO-RS program which is based on the interpretation of the σ-profiles, as well as the evaluation of Gibbs energy change of mixing were in excellent agreement with the experimental results. To the best of our knowledge, this is the first report on TTEG-based DESs which were used to dissolve unsaturated fatty acids. This work could introduce a new perspective in lipids chemistry, biofuel production, food processing and vegetable oil extraction

New route for preparing palmitic acid imidazole from free fatty acid using imidazole

In this study, imidazole was used for the first time in esterification of free fatty acid (FFA) from acidic oil and for palmitic acid imidazole production. The FFA content in jatropha oil mixed with crude palm oil (CPO) was significantly reduced from 10.57% to 1.73% under the following optimum conditions (25% imidazole dosage, 30 mins of reaction time, reaction temperature at 60 °C and methanol to oil molar ratio of 20:1). This research opens up new possibilities for utilizing imidazole as a catalyst in various esterification processes, offering a promising and eco-friendly pathway for industrial applications