The Polyelectrolyte Complex/Coacervate Continuum

Stoichiometric polyelectrolyte complexes (PECs) of the strong polyelectrolytes poly­(styrenesulfonate) (PSS) and poly­(diallyldimethylammonium) (PDADMA) were dissociated and dissolved in aqueous KBr. Water was added to dilute the salt, allowing polyelectrolytes to reassociate. After appropriate equilibration, these mixtures yielded compositions spanning complexes (solid) to coacervates (elastic liquid) to dissolved solutions with increasing [KBr]. These compositions were defined by a ternary polymer/water/salt phase diagram. For coacervates, transient microphase separation could be induced by a small departure from equilibration temperature. A boundary between complex and coacervate states was defined by the crossover point between loss and storage modulus. Salt ions within the complex/coacervate were identified as either ion paired with polyelectrolytes (“doping”) or unassociated. The fraction of ion pair cross-links between polyelectrolytes as a function of KBr concentration was used to account for viscosity using a model of “sticky” reptation

Extruded Superparamagnetic Saloplastic Polyelectrolyte Nanocomposites

Iron oxide nanoparticles of diameter <i>ca</i>. 12 nm were dispersed into polyelectrolyte complexes made from poly­(styrenesulfonate) and poly­(diallyldimethylammonium). These nanocomposites were plasticized with salt water and extruded into dense, tough fibers. Magnetometry of these composites showed they retained the superparamagnetic properties of their constituent nanoparticles with saturation magnetization that scaled with the loading of nanoparticles. Their superparamagnetic response allowed the composites to be heated remotely by radiofrequency fields. While the modulus of fibers was unaffected by the presence of nanoparticles the toughness and tensile strength increased significantly

Direct Arylation of 2-Methylthiophene with Isolated [PdAr(μ-O₂CR)(PPh₃)]_<i>n</i> Complexes: Kinetics and Mechanism

The palladium-catalyzed direct arylation of aromatic compounds with aryl halides has been proposed to involve an arylpalladium carboxylate intermediate. However, isolated arylpalladium complexes, which undergo C–H bond cleavage of aromatic substrates without the aid of additional activators or promoters, have been scarcely documented. This paper reports that [PdAr­(μ-O₂CR)­(PPh₃)]_<i>n</i> complexes (<b>1</b>: Ar = Ph, 2-MeC₆H₄, 2,6-Me₂C₆H₃; R = Me, ^<i>t</i>Bu) successfully react with 2-methylthiophene (<b>2</b>) in the absence of additives to afford 5-aryl-2-methylthiophenes (<b>3</b>) in high yields. The reactivity increases with increasing bulkiness of the Ar group, whereas the bulky pivalate ligand (R = ^<i>t</i>Bu) reduces the reactivity as compared with the acetate ligand (R = Me). Complex <b>1</b> is in equilibrium with the monomeric species [PdAr­(O₂CR-κ²<i>O</i>)­(PPh₃)] (<b>5</b>) in solution, as confirmed by IR spectroscopy. Kinetic examinations have suggested that the direct arylation proceeds via <b>5</b>, which undergoes C–H bond cleavage of <b>2</b>. Complex <b>1</b> serves as a good catalyst for direct arylation of <b>2</b> with aryl bromides

The release profile of the MS in PBST (pH = 7.40).

<p>The release profile of the MS in PBST (pH = 7.40).</p

The degradation profiles of MS in PBST (pH = 7.40): pH, Mw, and dry mass – release time profiles.

<p>The degradation profiles of MS in PBST (pH = 7.40): pH, Mw, and dry mass – release time profiles.</p

The process of preparing the microspheres.

<p>The process of preparing the microspheres.</p

The hemolysis rate of BF-30-loaded PLGA MS at different concentrations.

<p>The hemolysis rate of BF-30-loaded PLGA MS at different concentrations.</p

Alkaline Phosphatase Assay Based on the Chromogenic Interaction of Diethanolamine with 4‑Aminophenol

Diethanolamine (DEA) has been extensively utilized as an alkaline buffer in current assays of alkaline phosphatase (ALP) activity in the past decades. While playing the role of a buffer, the chemical reactivity of DEA has been widely ignored in such assays. Herein, we report an interesting chromogenic interaction between DEA and 4-aminophenol (AP) in the presence of H₂O for the first time, which inspires us to develop a novel DEA-participated ALP activity assay by using 4-aminophenyl phosphate (APP) as a substrate. This APP/DEA-based colorimetric approach has been proved to be comparable and even superior to the conventional <i>p</i>-nitrophenyl phosphate (pNPP)-based one, especially in the low ALP activity region, due to its higher sensitivity. The clear response mechanism and excellent sensing performance ensure that it can be further applied to determining ALP activity in real biological samples, screening potential ALP inhibitors in vitro, establishing ALP-enabled ELISA, and even fluorophore-assisted fluorescent ALP activity assay. It is demonstrated that this strategy not only possesses a good feasibility, but also exhibits a promising outlook for a series of ALP-related and -extended detections

Antimicrobial activity against Escherichia coli of the native BF-30 and the peptide released from the microspheres on the 1^st,10^th, 11^th, and 12^th days.

<p>Antimicrobial activity against Escherichia coli of the native BF-30 and the peptide released from the microspheres on the 1^st,10^th, 11^th, and 12^th days.</p

Cytotoxicity of the MS. PBST was used as the negative control.

<p>Cytotoxicity of the MS. PBST was used as the negative control.</p