Bilayer properties of giant magnetic liposomes formed by cationic pyridine amphiphile and probed by active deformation under magnetic forces.

We synthesize giant magnetic liposomes by a reverse-phase evaporation method (REV) using a new self-assembling Cationic Pyridine Amphiphile (CPA) derived from 1,4-dihydropyridine as liposome-forming agent and a magnetic ferrofluid based on γ-Fe(2)O(3) nanoparticles. Having in view the potential interest of CPA in targeted transport by magnetic forces, the mechanical elastic properties of such bilayers are here directly investigated in vesicles loaded with magnetic nanoparticles. Bending elastic modulus K(b) ∼ 0.2 to 5k(B)T and pre-stress τ ∼ 3.2 to 12.10(-6) erg/cm(2) are deduced from the under-field deformations of the giant magnetic liposomes. The obtained K(b) values are discussed in terms of A. Wurgers's theory.

Elastic properties of DNA linked flexible magnetic filaments.

Elastic properties of magnetic filaments linked by DNA in solutions of univalent and bivalent salts with different pH values are investigated through their deformation in an external field. A strong dependence of the bending modulus in bivalent salt solution on the pH is shown. Experimental results are interpreted on the basis of the magnetic elastica.