Probing competitive interactions in quaternary formulations

Abstract

Hypothesis: The interaction of amphiphilic block copolymers of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) group with small molecule surfactants may be "tuned" by the presence of selected alcohols, with strong interactions leading to substantial changes in (mixed) micelle morphology, whilst weaker interactions lead to coexisting micelle types. Experiments:The nature and the strength of the interactions between Pluronic P123 (EO20PO70EO20) and small molecule surfactants (anionic sodium dodecylsulfate, SDS, C12SO4Na), (cationic dodecyltrimethylammonium bromide, C12TAB) and (non-ionic polyoxyethylene(23)lauryl ether, Brij 35, C12EO23OH) is expected to depend on the partitioning of the short, medium and long chain alcohols (ethanol, hexanol and decanol respectively) and was probed using tensiometry, pulsed-gradient spin-echo nuclear magnetic resonance (PGSE-NMR) and small-angle neutron scattering (SANS). Findings:The SANS data for aqueous P123 solutions with added alcohols were well described by a charged spherical core/shell model for the micelle morphology. The addition of the surfactants led to significantly smaller, oblate elliptical mixed micelles in the absence of alcohols. Addition of ethanol to these systems led to a decrease in the 2 micelle size, whereas larger micelles were observed upon addition of the longer chain alcohols. NMR studies provided complementary estimates of the micelle composition, and the partitioning of the various components into the micelle.

Systematic comparison of the functional physico-chemical characteristics and biocidal activity of microbial derived biosurfactants on blood-derived and breast cancer cells

“…These biosurfactants have chain lengths of 12-18 carbon atoms, a range over which only BS1a and BS1b are soluble at room temperature, while BS2 and BS3 were soluble in Tris HCl buffer at pH 8.5. The surface tension measurements were undertaken at a temperature of 25 ± 1°C using a bubble pressure tensiometer (SITA Science on-line t60, Germany), calibrated by reference to de-ionised water (Mansour et al, 2015). Surface tension was recorded at a bubble life time value of 10,000 sec.…”

Segregation versus Interdigitation in Highly Dynamic Polymer/Surfactant Layers

“…One can postulate that the thinner C 12 TAB (40 Å; 1.5 + (1.26 × N c ) × 2) layers are “coexisting” between the segregated thicker P123 layers (140 Å), without a significant change in the dimension and/or the separation of the P123 layers. Such structures would seem logical assuming distinct populations of the two species in bulk solution [33,34] associated with weak interactions between the two components.…”

“…These micelles were found to be smaller in size (≈28 Å) when compared with pure P123 micelles (≈70 Å). [34] Further, the interfacial structure of the triblock copolymer EO 23 PO 52 EO 23 in solution was also studied by neutron reflection at different concentrations, where a total layer thickness of 72 Å was noted. Upon addition of SDS, the layer thickness was found to be between 46 and 49 Å [13,14].…”

Surfactant and Block Copolymer Nanostructures: From Design and Development to Nanomedicine Preclinical Studies

“…In many instances it has been established that mixtures of polymers with surfactants exhibit enhanced properties in drug delivery applications, including formulations including the addition of more conventional non-ionic or ionic surfactants to the above block-copolymer-derived group. The incorporation of different surfactants in a single formulation exploits the possible synergistic or antagonistic interactions between them [ 62 ].…”