China
Africa
Explore chapters and articles related to this topic
Biologic Drug Substance and Drug Product Manufacture
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Ajit S. Narang, Mary E. Krause, Shelly Pizarro, Joon Chong Yee
Salts increase protein hydrophobicity by neutralizing and shielding the ionizable surface functional groups. In addition to salt, solution pH closer to the pI and the neutral pH range promotes protein surface hydrophobicity and adsorption with the HIC column. The relative propensity of salts for increasing the hydrophobicity and tendency for the salting out effect is indicated by the Hofmeister series, also known as the lyotropic series. The Hofmeister series is a rank ordering of the ability of ions to precipitate or crash out proteins from their solutions. At lower concentrations, these ions impact the stability of the secondary and tertiary structure of proteins, thus exposing hydrophobic groups that interact with the HIC column.
Conducting Polymers
Published in Ram K. Gupta, Conducting Polymers, 2022
N. Raghavendra Naveen, Girirajasekhar Dornadula, Pamayyagari Kalpana, Lakshmi Narasimha Gunturu
Many researchers have extensively studied the impact of the ionic effect [24] on the antifouling property, especially for zwitterionic surfaces [25]. In general, on the basis of their propensity to salt-out or salt-in proteins, ions are classified as chaotropes and kosmotropes, which is shortened as the Hofmeister series [26]. Earlier studies have made known that weakly hydrated chaotropes can effectively form ion pairs with zwitterionic moieties in enhancing the hydration of zwitterionic polymers, whereas, hydrated kosmotropes can degrade the antifouling property by dehydrating the zwitterionic polymers.
Bioseparation of phycocyanin from Phormidium tergestinum using an aqueous two-phase system
Published in Preparative Biochemistry & Biotechnology, 2021
Joo Shun Tan, Sahar Abbasiliasi, Japareng Lalung, Yew Joon Tam, Paramasivam Murugan, Chee Keong Lee
Present study employed ATPS based on a polymer/salt system, as it favors the one-sided partition of compounds due to larger differences in the physicochemical properties between the two phases. This is a valuable feature during the first step of purification where most of the contaminants must be separated. Selection of phase forming salts was based on their specific manners to their anionic positions in the Hofmeister series correlating to higher protein stability.[18] From the results, there were reductions in PC concentrations with approximately 30% to 60% when potassium citrate was used as phase forming salt in ATPS which could be an indication of PC denaturation as reported by Patil and Raghavarao.[19] In the use of ammonium sulfate as phase forming salt component for ATPS, PC concentration was found to vary from 13.4 to 15.0 mg/mL with decreasing salt concentrations from 20 to 10%, suggesting that the stability of the PC was in correlation with the salt concentrations. This phenomenon could be due to the changes in ion intensity lead by the differences in salt concentrations, which has consequently affected the hydrophobic group exposure and the protein tertiary structure of PC, resulting in a decrease in protein activity.[20]
Phase behavior for 1-butyl-3-methylimidazolium tetrafluoroborate with sodium oxalate/succinate/formate aqueous two-phase systems at 298.15 and 308.15 K
Published in Journal of Dispersion Science and Technology, 2020
Fatemeh Ahmadi, Mohsen Pirdashti, Seyyed Mohammad Arzideh, Ianatul Khoiroh
The formation of ATPS composed of [Bmim]BF4 and sodium has been studied in open literatures, which enabled further examination for the effect of the other anion on the phase separation process: {[Bmim]BF4 + Na3PO4 or Na2SO4 or NaCl + H2O};[16] {[Bmim]BF4 + NaC2H3O2+ H2O};[35] {[Bmim]BF4 + Na2CO3+ H2O}.[36] In the present work, 298 K was used as a reference temperature for comparison purpose. The binodal curves for several ATPS at 298 K are depicted in Figure 2 to provide the comparison of the effect of anion valence, that is, monovalent and divalent anions, on the phase equilibrium behaviors. In addition, the hydration Gibbs energy (ΔGhyd)[34] and entropy of hydration (ΔShyd)[37] were estimated to provide the sequence of the anion’s ability in inducing phase separation and the results are presented in Table 8. It is found that the salting-out strength followed the Hofmeister series with the order of:
Foaming in aqueous solutions of zwitterionic surfactant in presence of monovalent salts: The specific ion effect
Published in Chemical Engineering Communications, 2020
Shailesh R. Varade, Pallab Ghosh
The specific ion effect is important for various colloidal dispersions and complex fluids. The varied affinity of the ions towards the interface is the basis of ion specificity. Many interfacial phenomena in the colloidal systems are influenced by the specific ion effect (Knipping et al., 2000; Garrett, 2004; Lo Nostro et al., 2010). They are prevalent in most of the chemical and biological interactions. They influence numerous processes in aqueous systems such as swelling of tissues, viscosity of solutions, precipitation of proteins, ion exchange, enzymatic activities, and coalescence of bubbles. As the charged surfaces are ubiquitous, the specific ion effect regulates the overall charge of the interfacial region and influences the interfacial forces. The specific ion effect can significantly change the sign of the potential at the interface and assign a unique value to it. This is significant in tailoring the stability of colloidal systems and critical to the interactions in various physicochemical (Brown et al., 1999; Finlayson-Pitts, 2003; Kathmann et al., 2005) and biological processes as well (Kunz et al., 2004b). The specific ion effect is related to the Hofmeister series to some extent. Franz Hofmeister (1888) studied the ion specificity, which influenced many biological mechanisms. Hofmeister classified the ions in a sequence based on their tendency to salt-out proteins from the egg-white solution (Kunz et al., 2004a; Yang, 2009; Schelero and von Klitzing, 2015). The cations and anions were placed in the following order based on their ability to salt-out the proteins.