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Glycerine Analysis
Published in Eric Jungermann, Norman O.V. Sonntag, Glycerine, 2018
As pointed out by Laitinen and Harris [6], the equilibrium between periodic acid and periodate is complex, and made even more so by a dehydration reaction. In acidic solution, periodic acid exists as a dihydrate, which dehydrates as it converts to iodate: Happily, in the aqueous environments commonly used for glycerine analysis, these equilibria do not play a significant role. While pH adjustment and acid-base titrations are commonly used in glycerine assay, periodate solutions do not act as buffers in the pH range between 5 and 10, and therefore do not interfere with the endpoint in formic acid titrations to determine glycerine levels.
Ceruloplasmin
Published in René Lontie, Copper Proteins and Copper Enzymes, 1984
ApoCp differs from the holoprotein in several respects. It is more retarded on an anion exchanger,217 has a lower sedimentation coefficient (6.0 S),38 and exhibits some new antigenic determinants.217 Acid-base titrations also demonstrate that new groups become available in the apoprotein over the whole pH range.38 The hydrodynamic data indicate that the apoprotein has a more expanded structure (frictional coefficient about 1.5 to 1.6) where new regions become accessible to the surface. However, it is far from being in a random state. High concentrations of dénaturants are required before secondary structure is lost and the fragments produced by limited proteolysis dissociate (Section II. D).
The Adsorptivity of Charged and Uncharged Cellulose Ethers
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
Cotton and rayon, as well as hair, are water-swellable fibers that possess ionic sites. Their carboxyl content was determined by acid-base titration to be, respectively, 5.46× and , corresponding to net Polymer JR uptakes of and of fiber for total charge neutralization by the polycation. Although the observed uptakes of the polycation in the most favorable case (JR-125) are somewhat less than these latter figures, they are comparable, at least for cotton; this lends support to a mechanism involving penetration of the polycation into pores of the fibers. The depressing influence of added electrolytes, in which the valence of the cation exerts a dominating influence, is in agreement with this postulate, and is a consequence of the more rapid diffusion of these inorganic ions into the fibers and consequent shielding of their anionic sites by the cations. An extreme case of this is the depression caused by a cationic surfactant, in which case shielding of the sites and stabilization of this sorbate at these sites will occur. Further evidence in support of an ionic mechanism comes from the results with nylon, where adsorption of a layer of CTAB, and consequent positive charging of the surface, eliminates the sorption of the polycation altogether. Again, the slight increase in sorption of Polymer JR by nylon in the presence of added salt is likely to be the result of charge shielding between adsorbed and adsorbing polycation molecules, or between the adsorbed polycation molecules themselves.
In-depth study of anticancer drug diffusion through a cross-linked pH-responsive polymeric vesicle membrane
Published in Drug Delivery, 2023
Fen Zhang, Qian Yao, Xiaoqi Chen, Haijun Zhou, Mengmeng Zhou, Yantao Li, Hua Cheng
The morphologies of the nanoparticles were measured with transmission electron microscopy (TEM, JEM-2100 Plus electron microscope) at an accelerating voltage of 200 kV. The samples were dispersed in ethanol-water or buffer solution and then deposited on copper grids, and then stained with phosphotungstic acid before characterization. The 1H NMR spectra were carried out on a Bruker DMX500 spectrometer, and CDCl3 was used as the solvent and tetramethylsilane was used as an internal reference. Hydrodynamic diameter and zeta potential measurements were done on a dynamic light scattering (DLS) spectrometer (PPS Z3000, Particle Sizing Systems, UK). The acid-base titration was carried out on a ZDJ-4B automatic potentiometric titrator. The Fourier transform infrared (FTIR) spectroscopy was performed on a PerkinElmer Frontier FTIR spectrometer. UV-vis measurements were carried out on a TU-1901 UV-vis spectrophotometer. CLSM images were recorded on a Leica TCS SP8 microscope.
A pH/ROS cascade-responsive and self-accelerating drug release nanosystem for the targeted treatment of multi-drug-resistant colon cancer
Published in Drug Delivery, 2020
Na Chang, Yufei Zhao, Ning Ge, Liting Qian
We employed PHis to counter the barrier represented by the lysosomes, so as to release Lapa more rapidly and activate Lapa-induced ROS generation and ATP depletion. PHis contains an imidazole group that will become protonated under weakly acidic conditions, resulting in hydrophobic/hydrophilic transformation, the disassembly of PLP-NPs, and the release of Lapa (Jiang et al., 2018). The protonation process requires an abundance of H+ ions, which leads to lysosome and endosome membrane disruption through the proton-sponge effect and results in the accelerated release of PLP-NPs from endo-lysosomes (Herranz‐Blanco et al., 2016). Acid–base titration was used to evaluate the buffering capacity of PHis. The titration curve of PHis is depicted in Supplementary Figure S4, and shows that the control group (NaCl) had no buffering capacity between pH 5.5 and 7.4. In contrast, PHis exhibited a marked buffering capacity in the same pH range (27.5%).
Aspartic acid derivatized hydroxylated fullerenes as drug delivery vehicles for docetaxel: an explorative study
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Nagarani Thotakura, Gajanand Sharma, Bhupinder Singh, Vipin Kumar, Kaisar Raza
The Fullerenols synthesized were characterized for the number of hydroxyl groups using acid-base titration. Fullerenol (5 mg) was dispersed in 4 ml solution of 0.5 M succinic anhydride (in pyridine) and heated at a temperature of 60 °C. After 1 h, the dispersion was titrated against standardized sodium hydroxide (0.1 N) solution in ethanol, using phenolphthalein as an indicator [24]. Gravimetric method was employed to determine the solubility of fullerenols in distilled water at the ambient temperature.