Amino-functionalized single-chain bolalipids: synthesis and aggregation behavior of new basic building blocks.

Herein, we report the synthesis of two novel, amino-functionalized single-chain bolalipids and, based on those, a general synthetic approach for the insertion of various carboxylic acids into the bolalipid headgroups, e.g. alpha-lipoic acid for one-dimensional fixation of gold nanoparticles, sorbic acid for polymerization experiments, or lysine for the use in gene delivery systems. The temperature- and pH-dependent self-assembly of amino-functionalized bolalipids into nanofibers and micelles was investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Rheological measurements were used to describe the macroscopic behavior of the formed temperature switchable hydrogels that can be fine-tuned for drug delivery applications. We showed that the viscoelastic properties of the hydrogel strongly depend on ionic interactions between bolalipid headgroups as well as on the ability to form hydrogen bonds.