The partitioning of two non-steroidal anti-inflammatory drugs (NSAIDs), flurbiprofen and ketoprofen, into cationic cetyltrimethylammonium micelles was investigated using semi-equilibrium dialysis at 37℃ in phosphate ...The partitioning of two non-steroidal anti-inflammatory drugs (NSAIDs), flurbiprofen and ketoprofen, into cationic cetyltrimethylammonium micelles was investigated using semi-equilibrium dialysis at 37℃ in phosphate buffered saline. The micellar-water solubilization equilibrium constants for both NSAIDs, in their deprotonated forms, were observed to decrease linearly with increasing mole fraction of drug in micelles. For flurbiprofen, the solubilization constant in the limit as mole fraction of drug in micelles approaches zero was found to be 11,200 (co = 1 M), while for ketoprofen the value was 1950 (co = 1 M). Using 1H-NMR and UV spectroscopic techniques, the locus of solubilization for ketoprofen was found to be towards the charged exterior of the micelles, in the Stern layer, whereas flurbiprofen was found to solubilize more in the micellar interior.展开更多
The extent to which counterions bind to polyelectrolytes influences a variety of polymer-based applications, including polyelectrolyte enhanced ultrafiltration and forward osmosis using polyelectrolytes as draw agents...The extent to which counterions bind to polyelectrolytes influences a variety of polymer-based applications, including polyelectrolyte enhanced ultrafiltration and forward osmosis using polyelectrolytes as draw agents. Potentiometric titrations of poly (2-vinylpyridine) (P2VP), poly (3-vinylpyridine) (P3VP), and poly (4-vinylpydine) (P4VP) were performed using HBr, HCl, HNO<sub>3</sub>, and HClO<sub>4</sub> in both the presence and absence of added NaCl. Because of the systematic differences among the three polyelectrolytes, titration results provide insight into the role of polymer structure in the relative extents to which various counterions bind. Titration data reveal that ionization properties vary as functions of polymer investigated, titrant used, degree of protonation, and added salt concentration. Acid dissociation constants of the pyridinium moieties were found to generally increase with increasing degree of protonation, though appreciable differences were exhibited among the three polymers investigated. For all three polymers, Cl<sup>-</sup> demonstrated the lowest affinity for the charged pyridinium residues, while the affinities associated with Br<sup>-</sup> and NO<sup>-</sup>3</sub> were nearly identical to each other. The relative extent of binding for CIO<sup>-</sup>4</sub> varied across the polymers investigated, and was greatest for P4VP.展开更多
文摘The partitioning of two non-steroidal anti-inflammatory drugs (NSAIDs), flurbiprofen and ketoprofen, into cationic cetyltrimethylammonium micelles was investigated using semi-equilibrium dialysis at 37℃ in phosphate buffered saline. The micellar-water solubilization equilibrium constants for both NSAIDs, in their deprotonated forms, were observed to decrease linearly with increasing mole fraction of drug in micelles. For flurbiprofen, the solubilization constant in the limit as mole fraction of drug in micelles approaches zero was found to be 11,200 (co = 1 M), while for ketoprofen the value was 1950 (co = 1 M). Using 1H-NMR and UV spectroscopic techniques, the locus of solubilization for ketoprofen was found to be towards the charged exterior of the micelles, in the Stern layer, whereas flurbiprofen was found to solubilize more in the micellar interior.
文摘The extent to which counterions bind to polyelectrolytes influences a variety of polymer-based applications, including polyelectrolyte enhanced ultrafiltration and forward osmosis using polyelectrolytes as draw agents. Potentiometric titrations of poly (2-vinylpyridine) (P2VP), poly (3-vinylpyridine) (P3VP), and poly (4-vinylpydine) (P4VP) were performed using HBr, HCl, HNO<sub>3</sub>, and HClO<sub>4</sub> in both the presence and absence of added NaCl. Because of the systematic differences among the three polyelectrolytes, titration results provide insight into the role of polymer structure in the relative extents to which various counterions bind. Titration data reveal that ionization properties vary as functions of polymer investigated, titrant used, degree of protonation, and added salt concentration. Acid dissociation constants of the pyridinium moieties were found to generally increase with increasing degree of protonation, though appreciable differences were exhibited among the three polymers investigated. For all three polymers, Cl<sup>-</sup> demonstrated the lowest affinity for the charged pyridinium residues, while the affinities associated with Br<sup>-</sup> and NO<sup>-</sup>3</sub> were nearly identical to each other. The relative extent of binding for CIO<sup>-</sup>4</sub> varied across the polymers investigated, and was greatest for P4VP.
