Comparative Effect of Physiological Salts upon Micellization of T1304 and T1307

Abstract

We present a comprehensive investigation on the interaction of tetronics (T1304 and T1307) with some important physiological salts (NaH2PO4, KH2PO4, Na2CO3, NaCl, and KI). Thermodynamic and microstructural aspects of these interactions were studied as a function of the solution temperature, pH and salt concentration. Characterizations were performed using turbidimetric, calorimetric, and scattering techniques. We show that, at ambient temperature, T1304 molecules aggregated to form spherical core–shell aggregates displaying a unimodal distribution pattern. On the other hand, unimers and large clusters dominated in the case of highly hydrophilic T1307. Its micellization was promoted in the presence of salts as per the following trend: NaCl < KH2PO4 < NaH2PO4 ≪ Na2CO3. Aggregation was found to be endothermic, and hydrophobic interactions (TΔS mic > ΔH mic) prevailed. The enthalpy–entropy compensation plot was found to be linear for both copolymers. Demicellization occurred in the presence of KI as it facilitated the buildup of water structures around the copolymer chains. This could be verified from the increase in the cloud point, critical micelle concentration, and free energy. Overall, the temperature and salts inflicted a stronger hydrophobic effect upon T1304 in comparison to T1307.

Sugar-based Cryoprotectants Stabilize Liposomal Vesicles by Exhibiting a Cholesterol-like Effect

“…Except for neat SL liposomes, the enthalpograms exhibited a sigmoidal trend. The lack of a sigmoidal pattern has been related to the dominance of pre-existing assembled structures in the dispersion . Slight drops in enthalpy can be noticed in the presence of cholesterol.…”

“…Thermodynamic changes were evaluated using ITC using the protocol described earlier . After the samples were degassed, the reference cell was filled with phosphate buffer (pH 7.4; 300 μL).…”

Detailed Study on the Interfacial Interaction between Different Polyoxometalates and Tetronic Block Copolymers Exploring the Langmuir–Blodgett Technique

“…45 Their association in water can be controlled by different inorganic salts. 46,47 Inadequate literature on the effect of the presence of different polyoxometalates in solution on the tetronic monolayer at the air−water interface has encouraged the present work.…”

“…Tetronics are known as x-shaped, four armed PEO–PPO block copolymers with diverse applications in the field of biomedical and in different industries such as drug delivery, , tissue engineering, and lens care industry . Their association in water can be controlled by different inorganic salts. , Inadequate literature on the effect of the presence of different polyoxometalates in solution on the tetronic monolayer at the air–water interface has encouraged the present work.…”

Ionic Strength Effect in the Equilibrium and Rheological Behavior of an Amphiphilic Triblock Copolymer at the Air/Solution Interface

“…For instance, the addition of ionic salts can reduce the solubility of Pluronic molecules in water and disrupt the micellar structure [23]. These modifications, intricately linked to the Hofmeister series but also to the specific ratio between the number of monomers in the poly(ethylene oxide) and poly(propylene oxide) blocks, establish a relationship between the behavior of ions as promoters or disruptors of water's structural stability, depending on their ability to remain hydrated [22,24,25]. Such intricate correlations between ionic properties and phase changes within Pluronic solutions continue to foster further investigations to unravel the underlying mechanisms governing these complex systems [23,24,26].…”