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Understanding the Interaction of Nanoparticles at the Cellular Interface
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
The use of Zwitterionic materials, which have both anionic and cationic groups, such as O-carboxymethyl-chitosan (CMC), can respond to pH stimuli and increase circulation [78]. Zwitterionic polymeric materials have great potential to act as a drug delivery vehicle with many improved properties [79, 80]. These materials can respond to pH and undergo a charge reversal mechanism by the protonation of polymers or proton sponge effect. Moreover, the charge reversal can modify the properties of NPs for various activities, such as enhanced cellular uptake, improved endosomal escape, resistance to nonspecific protein adsorption, and controlled release. Zwitterionic nanocarriers possess several advantages over PEG derivatives as a biomimetic strategy [81].
Renewable Resource-Based Environmental Friendly Waterborne Polymeric Anticorrosive Nanocomposite Coatings
Published in Neha Kanwar Rawat, Iuliana Stoica, A. K. Haghi, Green Polymer Chemistry and Composites, 2021
Mohd Irfan, Halima Khatoon, Rabia Kouser, Abu Darda, Shahidul Islam Bhat, Sajid Iqbal
Polymers can also be made WB by the way of intermediate zwitterions.10 Zwitterion sometimes referred to as inner salts, which have two or more functional groups. Zwitterion is a neutral molecule with a negative and a positive electrical charge (Fig. 7.3). The common examples of such polymers include polyesteramide, alkyd, and polyepoxies.
Mobile Phase Effects in Reversed-Phase and Hydrophilic Interaction Liquid Chromatography
Published in Nelu Grinberg, Peter W. Carr, Advances in Chromatography Volume 57, 2020
Zwitterionic stationary phases also contain spatially separated positively and negatively charged moieties. The sulfobetaine stationary phases contain the active zwitterionic layer grafted either on a silica gel or on a polymer support [137,138]. An alkyl chain separates the strongly acidic sulfonic acid group at the end of the ligand from a strongly basic quaternary ammonium group closer to the silica gel support. The two oppositely charged groups are present in a 1:1 molar ratio, so that there is only a very low net negative surface charge of the bonded layer [69]. Polar (hydrogen-bonding and dipole–dipole) interactions are of primary importance, even though weak electrostatic interactions may affect the separation of partially ionized analytes, too. The sulfobetaine-bonded ZIC-HILIC silica (Figure 1.14A) is suitable for HILIC separations of a wide range of small polar metabolomes [139], glucosinolates [140], aminoglycosides [141], peptides, purine and pyrimidine bases and nucleosides [142], or glycopeptides [143,144]. The HILIC separation of peptides on ZIC-HILIC columns at pH = 3 resembles the separations on strong cation exchangers (SCX), but improves at a higher pH (7–8) [145].
Electrohydrodynamic instabilities for smart window applications
Published in Liquid Crystals, 2020
Yuanyuan Zhan, Han Lu, Mingliang Jin, Guofu Zhou
The modest solubility of electrolyte in host LCs and accumulation of ions onto electrodes tend to reduce the lifetime of devices. In order to solve those problems, hereby, we propose to replace electrolyte with zwitterion. A zwitterion is a molecule with multi-functional groups of which one possesses a positive and the other possesses a negative electrical charge, and the entire molecule appears electrically neutral [20]. In our previous research, we created zwitterions in the LC upon exposure to UV light, and the effect of EHDI in the presence of zwitterions is comparable to that of LC doped with conventional electrolyte. The principle behind is that zwitterions can oscillate between electrodes following the polarity change of the applied AC electric field and generate chaotic vortices, resulting in macroscopic light scattering. Hereby, we replace the electrolyte with zwitterions (molecules 4, 5). Transmittance measurement on UV-Vis spectra at 550 nm shows that zwitterion 5 is more efficient in triggering EHDI, and we ascribe this to the larger molecular size of zwitterion 5 which can easily create vortexes when oscillating between electrodes (Figure 2(b), Supporting Information, Figure S4). Therefore, we mainly utilise zwitterion 5 to study EHDI in this work.
Enhancing antifouling property of PVA membrane by grafting zwitterionic polymer via SI-ATRP method
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Mengmeng Cui, Mingcheng Shen, Li Zhou, Zhongkuan Luo, Haohao Zhou, Xinlin Yang, Huiyuan Hu
It was well known that zwitterions could form a hydration layer via electrostatic interaction and hydrogen bonds[46]. It was a physical and energy barrier that hindered protein adsorption, and thereby effectively prevented the interaction between the membrane surface and the protein. Therefore, PVA-based zwitterionic membranes had a better anti-protein adsorption performance compared with the pristine PVA membrane.
A review of design, operational conditions and applications of microbial fuel cells
Published in Biofuels, 2018
Rachna Goswami, Vijay Kumar Mishra
To rectify the problem created by the pH gradient between anode and cathode (one of the main causes for the sink of voltage efficiency in microbial systems), active pH control such as acid/base dosing or addition of chemical buffer (such as phosphate or bicarbonate buffer) is necessary to sustain steady current generation and some work has been performed regarding this matter [36,131-136]. The buffer assists to reduce alterations in pH in the bulk solution and in the biofilm, and therefore it retains the pH in the range fit for the growth of microorganisms. An ideal buffer should be capable of maintaining constant pH without disturbing it with chemical reactions or microbial physiology, make easy proton transfer to the electrode for high power densities in MFC and augment the solution conductivity [133,135]. Phosphate buffers are frequently used in MFCs [36,131,133,137] and it has been observed that increasing phosphate concentration within certain ranges will enhance power output [133]. However, addition of high concentrations of phosphate buffer is costly, particularly for wastewater treatment, and phosphates can cause the eutrophication conditions of water bodies if the effluents are released without the removal of these compounds, thus making it impractical for wastewater treatment. Bicarbonate buffer can be another option, a low cost and effectual pH buffer particularly for wastewater treatment, although higher carbonate concentrations can augment the growth of methanogens [131]. The effect of a borax buffer was studied by Qiang et al. [135] and they found that adding a suitable concentration of borax buffer improves the electron recovery efficiency. Several synthetic zwitterionic buffers, like MES [2(N-morpholino) ethane sulfonate], HEPES [4(2-hydroxyethyl)1-piperazine ethane sulfonic acid] and PIPES [piperazine-N,N_-bis (2-ethane sulfonate)] can be utilized as buffers in MFCs. These zwitterionic buffers have benefits in comparison to traditional buffers, like phosphate and carbonate buffers in biological research, because their pKa values are in the array of pH 6.0 and 8.0, they are chemically steady, nondeleterious and do not encumber biochemical reactions.