Ferrofluids of Thermotropic Liquid Crystals by DNA–Lipid Hybrids

Here is the first report the creation of ferrofluids of thermotropic liquid crystals in the absence of any solvent or nanoparticle. These ferrofluids were prepared by the electrostatic coupling of single-strand (ss) DNA with paramagnetic lipids. DNA molecules, as rigid parts, offer the orientational anisotropy and lipids (surfactants) due to the flexible hydrocarbon chains suppress crystallization, hybrids with DNA significantly increase the Cure temperature (Tc) of the lipids. The ferrofluids possess good fluidity and low viscosity. They serve as excellent solvents for both hydrophilic and lipophilic compounds. Their strong magnetism further allows the solutes to be controlled by external magnetic force. The DNA–lipid hybrid ferrofluids show liquid crystal (LC) behavior at low temperatures, and the LC phase is made of ordered multilamellar structures. Compared with conventional magnetic nanoparticle dispersions, the solvent-free lipoplex ferrofluids provide potential applications for nanotechnology, material science, and biotechnology.