Fine-tuning of bulk and interfacial characteristics of two-antennary oligoglycines in aqueous solutions

Abstract

The structure of the two-antennary oligoglycines molecules presumes a complex interplay of their bola-amphiphilic nature and the possibility for the onset of Polyglycine II structural motifs in aqueous solutions. These tendencies lead to the appearance of various supramolecular self-assemblies (tectomers). The complex fluid formulations which contain them exhibit high potential for the application of easy fine-tuning procedures. In the present study the possibility for smart regulation of the properties of aqueous solutions of C8H16(-CH2-NH-Gly5)2 (T2-C8-Gly5) is investigated through the variations of pH and changes of the initial incubation time of the systems. A combined investigation protocol, including Dynamic Light Scattering, Profile Analysis Tensiometry, and microscopic Thin-Liquid-Film techniques is developed. The key results are: (i) the size distribution is bimodal in acidic conditions (pH ≤ 6.0) and becomes visibly mono-modal for pH ≥ 7.1; (ii) upon increase of the solution pH the dimensions of the tectomers is shifted towards larger structural entities. These tendencies are enhanced with the raise of the initial incubation time of the aqueous systems. The study permits to draw essential conclusions about the possible coupling mechanism of bulk and interfacial phenomena, and gives key grounds for further fine-tuning of the tectomer-formation phenomena. The obtained results add important new knowledge about the nature of these new materials in view of possible applications in the development of e.g. drug nanocarriers, for extraction of various impurities from water media, etc.