This article reviews the state of the art of the studies on charge regulation (CR) effects in flexible weak polyelectrolytes (FWPE). The characteristic of FWPE is the strong coupling of ionization and conformational degrees of freedom. After introducing the necessary fundamental concepts, some unconventional aspects of the the physical chemistry of FWPE are discussed. These aspects are: (i) the extension of statistical mechanics techniques to include ionization equilibria and, in particular, the use of the recently proposed Site Binding-Rotational Isomeric State (SBRIS) model, which allows the calculation of ionization and conformational properties on the same foot; (ii) the recent progresses in the inclusion of proton equilibria in computer simulations; (iii) the possibility of mechanically induced CR in the stretching of FWPE; (iv) the non-trivial adsorption of FWPE on ionized surfaces with the same charge sign as the PE (the so-called "wrong side" of the isoelectric point); (v) the influence of macromolecular crowding on CR.
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http://dx.doi.org/10.3390/polym15122680 | DOI Listing |
Mol Pharm
January 2025
Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, Georgia 30341, United States.
This investigation aimed to enhance transdermal methotrexate delivery through human skin by employing Dr. Pen microneedles and poly(d,l-lactide--glycolide) acid microparticles formulated from eight polymer grades (Expansorb DLG 95-4A, DLG 75-5A, DLG 50-2A, DLG 50-5A, DLG 50-8A, DLG 50-6P, DLG 50-7P, and DLL 10-15A). A comprehensive characterization of the microparticles was performed, encompassing various parameters such as size, charge, morphology, microencapsulation efficiency, yield, release kinetics, and chemical composition.
View Article and Find Full Text PDFPhotosynth Res
January 2025
Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
Pheophytin-a derivatives possessing plastoquinone and phylloquinone analogs in the peripheral 3-substituent were prepared by Friedel-Crafts reactions of a 3-hydroxymethyl-chlorin as one of the chlorophyll-a derivatives with benzo- and naphthohydroquinones, respectively, and successive oxidation of the 1,4-dihydroxy-aryl groups in the resulting dehydration products. The 3-quinonylmethyl-chlorins exhibited ultraviolet-visible absorption and circular dichroism spectra in acetonitrile, which were composed of those of the starting 3-hydroxymethyl-chlorin and the corresponding methylated benzo- and naphthoquinones. No intramolecular interaction between the chlorin and quinone π-systems was observed in the solution owing to the methylene spacer.
View Article and Find Full Text PDFSmall
January 2025
Dept. of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 7610001, Israel.
Transient amorphous phases are known as functional precursors in the formation of crystalline materials, both in vivo and in vitro. A common route to regulate amorphous calcium carbonate (ACC) crystallization is via direct interactions with negatively charged macromolecules. However, a less explored phenomenon that can influence such systems is the electrostatically driven formation of Ca-macromolecule dense phases.
View Article and Find Full Text PDFSmall
January 2025
Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemical Engineering, College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, P. R. China.
Metal-organic frameworks (MOFs) are rigorously investigated as promising candidates for CO capture and conversion. MOF-on-MOF heterostructures integrate bolstered charger carrier separation with the intrinsic advantages of MOF components, exhibiting immense potential to substantially escalate the efficiency of photocatalytic CO reduction (CORR). However, the structural and compositional complexity poses significant challenges to the controllable development of these heterostructures.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
School of Marine Science and Engineering, Hainan University, Haikou, China.
Severe photogenerated charge carrier recombination involved in photocatalytic CO reduction leads to low photocatalytic efficiency. Here we demonstrate that a chiral hierarchical structure could facilitate charge separation in BiOBr, thus suppressing charge recombination and enhancing photocatalytic performance. Chiral helical flower-like BiOBr nanospheres were prepared a D/L-sorbitol-assisted hydrothermal process, exhibiting a 1.
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