On the comparison between diafiltration and isothermal titration calorimetry: Determination of the amount of analytes bound to water-soluble polymers

Orozco, Felipe; Redondo-Gómez, Carlos; Vega-Baudrit, José; Moreno‐Villoslada, Ignacio

doi:10.1016/j.polymertesting.2019.04.003

Cited by 1 publication

(3 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the last decades, we have studied the interactions between aromatic polyelectrolytes, such as poly(sodium 4-styrenesulfonate) (PSS), and low molecular-weight aromatic species (LMWS) acting as counterions, among which we can find xanthene dyes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], redox-active tetrazolium salts [ 8 , 9 , 10 , 11 ], and different drugs [ 12 , 13 , 14 , 15 , 16 ]. Both complementary charged species bearing aromatic groups undergo secondary aromatic-aromatic interactions, additional to primary long-range electrostatic interactions, thus producing a reinforcement of the overall interaction.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism for nanocarrier formation involving the dual function of the drug has been rationalized as the consequence of ion pair formation between the charged aromatic drug and the complementary charged polymeric aromatic residues through short-range aromatic-aromatic interactions. The occurrence of aromatic-aromatic interactions between the drug chlorpheniramine maleate (CPM) and the polyelectrolyte PSS has been reported in this context [ 12 , 13 , 14 , 16 ]. It was found that the extent of binding and the aggregation state of the complexes depend on the absolute and the relative concentration of the reactants.…”

Section: Introductionmentioning

confidence: 99%

“…It was found that the extent of binding and the aggregation state of the complexes depend on the absolute and the relative concentration of the reactants. At a PSS concentration of 2 mM (in sulfonate groups per liter) DF showed drug binding of around 80% in a mixture of PSS/CPM at a sulfonate/drug stoichiometry 2:1 [ 12 , 14 ], forming clear solutions of non-aggregated complexes. On the contrary, at a PSS/CPM stoichiometry 2:3 and 5 mM of the polymer, higher binding, and the formation of nanoparticles were observed [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Concentration Dependent Single Chain Properties of Poly(sodium 4-styrenesulfonate) Subjected to Aromatic Interactions with Chlorpheniramine Maleate Studied by Diafiltration and Synchrotron-SAXS

Orozco¹,

Hoffmann

Flores

et al. 2021

Polymers

Self Cite

View full text Add to dashboard Cite

The polyelectrolyte poly(sodium 4-styrenesulfonate) undergoes aromatic–aromatic interaction with the drug chlorpheniramine, which acts as an aromatic counterion. In this work, we show that an increase in the concentration in the dilute and semidilute regimes of a complex polyelectrolyte/drug 2:1 produces the increasing confinement of the drug in hydrophobic domains, with implications in single chain thermodynamic behavior. Diafiltration analysis at polymer concentrations between 0.5 and 2.5 mM show an increase in the fraction of the aromatic counterion irreversibly bound to the polyelectrolyte, as well as a decrease in the electrostatic reversible interaction forces with the remaining fraction of drug molecules as the total concentration of the system increases. Synchrotron-SAXS results performed in the semidilute regimes show a fractal chain conformation pattern with a fractal dimension of 1.7, similar to uncharged polymers. Interestingly, static and fractal correlation lengths increase with increasing complex concentration, due to the increase in the amount of the confined drug. Nanoprecipitates are found in the range of 30–40 mM, and macroprecipitates are found at a higher system concentration. A model of molecular complexation between the two species is proposed as the total concentration increases, which involves ion pair formation and aggregation, producing increasingly confined aromatic counterions in hydrophobic domains, as well as a decreasing number of charged polymer segments at the hydrophobic/hydrophilic interphase. All of these features are of pivotal importance to the general knowledge of polyelectrolytes, with implications both in fundamental knowledge and potential technological applications considering aromatic-aromatic binding between aromatic polyelectrolytes and aromatic counterions, such as in the production of pharmaceutical formulations.

show abstract