Lipid vesicles decorated with polysaccharides have been proposed as vehicles for drug delivery because the polymers confer to the vesicles an enhanced stability, increasing the probability of the drug for reaching the target cell. Here, we first test the affinity of dextran sulfate (DS) for two different vesicle composition, and afterward, we study the effect of DS on the liposome mechanical properties. We found that DS binds to both tested membrane compositions. The interaction of DS with the anionic membranes studied here is mediated by the metal ions present in the aqueous solution (Na + and Ca 2+ ), being higher in the presence of Ca 2+ . Binding occurs preferentially in regions of closely packed lipids. Strikingly, DS did not affect the stability against detergent and the membrane rigidity of none of the vesicles. Thus, the proposed stability increase induced by this kind of polymers in drug delivery systems is not related with a modulation of the membrane thermodynamic properties but to other biochemical factors.

In this paper, we study the magnetic properties of orthorhombic (Pbnm) perovskites LuFe 1−x Cr x O 3 with x = 0.25, 0.45, 0.55, and 0.75 by magnetization vs temperature and neutron powder diffraction measurements at room temperature. The magnetic moments are oriented along the x direction with a G-type antiferromagnetic (AFM) arrangement that corresponds to irreducible representation 4 (G x A y F z ). Magnetization reversal (MR) is observed for 0.45 x 0.75. The MR phenomenon was modeled using Monte Carlo simulations, modeling both homogeneous and inhomogeneous cation distributions. For LuFe 0.25 Cr 0.75 O 3 , the presence of MR could only be explained using an inhomogeneous distribution with well-defined magnetic clusters. Looking at the staggered magnetization of each cluster, we propose a superparamagnetic regime of Fe 3+ clusters in a Cr 3+ -rich matrix for LuFe 0.25 Cr 0.75 O 3 . By calculating the specific heat, we found that, in LuFe 0.45 Cr 0.55 O 3 and LuFe 0.25 Cr 0.75 O 3 the clusters order at nearly the same temperature T Clus N ∼ 535 and 520 K, respectively, while the matrix orders at T Mat N ∼ 115 K. There is considerable reduction in the cluster ordering temperature as compared with the bulk, as T N ∼ 628 K for LuFeO 3 , while the matrix orders at the expected temperature as T N ∼ 115 K for LuCrO 3 .