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Optical Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
The Mg2+ PEBBLE sensor is an interesting case illustrating the relationship between design and cellular application. It achieved both high selectivity and sensitivity by using the correct combination of NP matrix and dyes. The traditional measurement of magnesium ion concentrations in biological environments has experienced severe interference from calcium ions. Coumarin 343 is a small hydrophilic dye that is unable to penetrate the cell membrane by itself but is a very sensitive Mg2+ ion probe, having a greater selectivity for magnesium over calcium than any other commercially available probe. A hydrophilic material has a strong affinity for water. The contact angle of water with its surface is acute. It has a high wettability and water spreads evenly on it.
Ecological Tools for Remediation of Soil Pollutants
Published in Amitava Rakshit, Manoj Parihar, Binoy Sarkar, Harikesh B. Singh, Leonardo Fernandes Fraceto, Bioremediation Science From Theory to Practice, 2021
Nayan Moni Gogoi, Bhaswatee Baroowa, Nirmali Gogoi
Bioremediation processes are negatively affected by the lower aqueous solubility of some contaminants This necessitates the use of biosurfactants to enhance the solubility of contaminants for their effective remediation. Biosurfactants are surface-active biomolecules produced by microorganisms with relative ease of preparation and have unique properties like specificity and low toxicity. These biomolecules play three major functions in bioremediation through the following activities: (i) increase the surface area of hydrophobic substrates (ii) increase the bioavailability of hydrophobic substrates through solubilization/desorption, and (iii) regulate the attachment and removal of microorganisms from the surfaces (Vijayakumar and Saravanan 2015). Biosurfactants contain both water soluble and water insoluble portions. The water solubility of the surfactants is due to the hydrophilic portion (polar group), while the hydrophobic portion (nonpolar chain) tends to concentrate at the air-water interfaces or in the center of micelles, reducing the surface tension of the solution. Their diverse structures along with superior properties qualify them as potential candidates for application in several industrial sectors such as organic chemicals, petroleum, petrochemicals, mining, metallurgy (mainly bioleaching), agrochemicals, fertilizers, foods, beverages, cosmetics, pharmaceuticals and many others (Rangarajan and Narayanan 2018). Mechanism of metal removal by biosurfactants is given in Figure 2.
Mobile Phase Effects in Reversed-Phase and Hydrophilic Interaction Liquid Chromatography
Published in Nelu Grinberg, Peter W. Carr, Advances in Chromatography Volume 57, 2020
Very hydrophilic samples such as carbohydrates or small polar compounds usually elute close to the column hold-up volume in RPC, so that their separation from one another and from polar matrix interferences may be difficult to accomplish, even in highly aqueous mobile phases [59]. On the other hand, some polar compounds elute late, if at all, in organic solvent normal-phase systems. The separation on polar stationary phases often improves after adding water to the mobile phase. Alpert introduced the name “hydrophilic interaction liquid chromatography” (HILIC) for the separation mode employing a “normal phase column” in combination with a “reversed-phase mobile phase,” containing less than 50% water [1]. The term “hydrophilic” refers to the affinity to water. The HILIC technique provides appropriate retention and resolution for many polar compounds, often with better separation efficiency in comparison to RP chromatography. The diffusion coefficients of ionized basic compounds in less viscous organic-rich mobile phases under HILIC conditions are approximately twice those under RP conditions, leading to improved separation efficiency (lower height equivalent of a theoretical plate, H) [60]. Further, the peak symmetry of basic compounds in the HILIC mobile phases (acetonitrile – ammonium acetate or formate buffers) often improves in comparison to reversed-phase HPLC [61]. HILIC separation of ionic/ionizable compounds needs ionic additives to aqueous-organic mobile phases [62].
A study on the influence of silanized clay on the barrier, hydrophobic and mechanical properties of epoxy coated steel in natural seawater
Published in The Journal of Adhesion, 2023
Joseph Raj Xavier, Raja Beryl J, Ravisankar N
One of the greatest techniques to detect whether a coated surface is hydrophobic or hydrophilic is by measuring the water contact angles (WCA). Hydrophobic materials are classified as non-polar materials with a low affinity for water, which makes them water-repellent. A contact angle of less than 90° denotes a hydrophilic interaction, whereas one of higher than 90° denotes a hydrophobic interaction. Hydrophobicity can be advantageous for the coating and substrate by reducing the amount of dirt that they retain, making them easier to clean themselves, being better at withstanding moisture and corrosion, and having longer lifespans. Images of water droplets on the surfaces of nanocoated steel in Figure 5 include pure EP, EP-Clay, EP-GPMS, and EP-GPMS/Clay coatings. The WCA of 74°, which is less than 90° for the neat epoxy-coated steel, shows that the pure epoxy coating is hydrophilic. Due to the high porosity of the basic epoxy layer, the passage of water takes place smoothly via the coating. While the EP-GPMS composite exhibits hydrophobic behaviour because of the silane’s potent adhesive properties, the epoxy-clay composite maintains its hydrophilicity due to the clay’s exceptional hydrophilicity. On the other hand, the silanized clay-based epoxy nanocomposites are hydrophobic. Due to its strong hydrophobicity, EP-GPMS/Clay exhibits a WCA of 144° (Figure 5d).
Synthesis of salt-resistant hyperbranched waterborne polyurethane associative thickener and its application in textile printing
Published in The Journal of The Textile Institute, 2023
Polyurethane thickener is a non-ionic associative thickener which emerged after APAT (Suzuki et al., 2012). Unlike APAT, polyurethane thickener is composed of hydrophilic segments, hydrophobic segments and urethanes as linking groups, forming a ‘hydrophobic-hydrophilic-hydrophobic’ linear molecular structure (Barmar et al., 2005). In aqueous solution, the hydrophobic segments associate with several other ones to form micellar cores, and the hydrophilic segments come into being the flower loops. Thereby the flower-like micelles are formed (Peng et al., 2014). At the same time, the hydrophilic segments act as bridges among the micelles (Peng et al., 2014). Furthermore, the hydrophilic segments can form hydrogen bonds with the surrounding water molecules and restrict the movement of water molecules, thereby increasing the viscosity of the aqueous solution (Peng et al., 2014). The polyurethane thickener is non-ionic and its thickening effect is hardly affected by the salt. In addition, polyurethane thickener possesses good stability to the change of pH and film-forming property. Therefore, polyurethane thickener has attracted much attention over the years (Liu et al., 2020; Xu et al., 2016). However, compared with APAT, the thickening effect of linear polyurethane thickener is dissatisfactory.
The modern pharmacological approach to diabetes: innovative methods of monitoring and insulin treatment
Published in Expert Review of Medical Devices, 2022
Iulian Tătaru, Oana M. Dragostin, Iuliu Fulga, Florentina Boros, Adelina Carp, Ariadna Maftei, Carmen L. Zamfir, Aurel Nechita
Inverse micelles are nanoaggregates of surfactants that form spontaneously in a non-aqueous solvent. As a transdermal carrier for the administration of hydrophilic drugs, they can effectively control the release of drugs and improve their bioavailability, thus achieving optimal therapeutic concentrations. In a recent study [54], the authors have used insulin-loaded reverse micelles, composed of isopropyl myristate (IPM) as solvent and lecithin as surfactant. Reverse micelles with insulin were obtained by pre-dissolving lecithin in IPM. After complete dissolution, the insulin solution was added, each sample containing 4 IU insulin, and then the resulting mixture was stirred until a clear yellow gel has been formed. Further, the micelles obtained, loaded with insulin, were stored cold.