Hybrids of manganese oxide and lipid liquid crystalline nanoparticles (LLCNPs@MnO) as potential magnetic resonance imaging (MRI) contrast agents.

Due to the health risks associated with the use of Gd-chelates and the promising effects of using nanoparticles as T1 contrast agents (CAs) for MRI, Mn-based nanoparticles are considered a highly competitive alternative. The use of hybrid constructs with paramagnetic functionality of Mn-based nanoparticles is an effective approach, in particular, the use of biocompatible lipid liquid crystalline nanoparticles (LLCNPs) as a carrier of MnO nanoparticles. LLCNPs possess a unique internal structure ensuring a payload of different polarity MnO nanoparticles. In view of MRI application, the surface properties including the polarity of MnO are crucial factors determining their relaxation rate and thus the MRI efficiency. Two novel hybrid constructs consisting of LLCNPs loaded with hydrophobic MnO-oleate and hydrophilic MnO-DMSA NPs were prepared. These nanosystems were studied in terms of their physico-chemical properties, positive T1 contrast enhancement properties (in vitro and in vivo) and biological safety. LLCNPs@MnO-oleate and LLCNPs@MnO-DMSA hybrids exhibited a heterogeneous phase composition, however with differences in the inner periodic arrangement and structural parameters, as well as in the preferable localization of MnO NPs within the LLCNPs. Also, these hybrids differed in terms of particle size-related parameters and colloidal stability, which was found to be strongly dependent on the addition of differently functionalized MnO NPs. Embedding both types of MnO NPs into LLCNPs resulted in high relaxivity parameters, in comparison to bare MnO-DMSA NPs and also commercially developed CAs (e.g. Dotarem and Teslascan). Further biosafety studies revealed that cell internalization pathways were dependent on the prepared hybrid type, while viability, effects on the mitochondria membrane potential and cytoskeletal networks were rather related to the susceptibility of the particular cell line. The high relaxation rates achieved with the developed hybrid LLCNPs@MnO enable them to be possibly used as novel and biologically safe MRI T1-enhancing CAs in in vivo imaging.

Influence of Alkyl Chain Length on Thermal Properties, Structure, and Self-Diffusion Coefficients of Alkyltriethylammonium-Based Ionic Liquids.

The application of ionic liquids (ILs) has grown enormously, from their use as simple solvents, catalysts, media in separation science, or electrolytes to that as task-specific, tunable molecular machines with appropriate properties. A thorough understanding of these properties and structure-property relationships is needed to fully exploit their potential, open new directions in IL-based research and, finally, properly implement the appropriate applications. In this work, we investigated the structure-properties relationships of a series of alkyltriethylammonium bis(trifluoromethanesulfonyl)imide [TEA-R][TFSI] ionic liquids in relation to their thermal behavior, structure organization, and self-diffusion coefficients in the bulk state using DSC, FT-IR, SAXS, and NMR diffusometry techniques. The phase transition temperatures were determined, indicating alkyl chain dependency. Fourier-transformed infrared spectroscopy studies revealed the structuration of the ionic liquids along with alkyl chain elongation. SAXS experiments clearly demonstrated the existence of polar/non-polar domains. The alkyl chain length influenced the expansion of the non-polar domains, leading to the expansion between cation heads in polar regions of the structured IL. 1H NMR self-diffusion coefficients indicated that alkyl chain elongation generally caused the lowering of the self-diffusion coefficients. Moreover, we show that the diffusion of anions and cations of ILs is similar, even though they vary in their size.

Theranostic liposomes as a bimodal carrier for magnetic resonance imaging contrast agent and photosensitizer.

The present study is focused on the development of liposomes bearing gadolinium chelate (GdLip) providing two functionalities for magnetic resonance imaging (MRI) and photodynamic therapy of cancer. A lipid derivative of gadolinium(III) diethylenetriamine pentaacetic acid salt (GdDTPA1) was inserted in the liposomal membrane and served as MRI contrast agent whereas a zinc phthalocyanine (ZnPc) was used as a model photosensitizer. In addition to conventional liposomes, pegylated lipids were used for the preparation of "stealth" liposomes. The characterization of different GdLip formulations involved evaluation of the liposomes size by nanoparticle tracking analysis, thermal phase behavior by differential scanning calorimetry and ZnPc-mediated singlet oxygen production. Furthermore, relaxivity measurements were performed as well as cytotoxicity and photodynamic activity against cancerous and normal cell lines was studied. Size and thermal behavior were only slightly influenced by GdLip composition, however it distinctly affected singlet oxygen production of ZnPc-loaded GdLip. The quantum yields of singlet oxygen generation by zinc phthalocyanine incorporated in GdLip containing cationic or/and pegylated lipids were smaller than those obtained for non-pegylated carriers with l-α-phosphatidylglycerol. In general, all formulations of GdLip, irrespectively of composition, were characterized by relaxivities higher than those of commercially used contrast agents (e.g. Magnevist®). NMR study has shown that the incorporation of ZnPc into the formulations of GdLip increases the relaxation parameters r1 and r2, compared to the values for the non-loaded vesicles. GdDTPA1 did not influence the photodynamic activity of ZnPc against HeLa cells.

Changes in water status and water distribution in maturing lupin seeds studied by MR imaging and NMR spectroscopy.

The changes in water distribution in maturing lupin (Lupinus luteus L.) seeds were visualized with magnetic resonance imaging (MRI). MRI data showed local inhomogeneities of water distribution inside the seed. At the late seed-filling stage the most intense signal was detected in the seed coat and the outer parts of cotyledons in the hilum area, but during maturation drying the decline in MR image intensity was faster in the outer part of the seed than in the central part. The changes in water status were characterized by NMR spectroscopy. Analyses of T(2) relaxation times revealed a three-component water proton system in maturing lupin seeds. Three populations of protons found during seed maturation, each with a different magnetic environment causing a different relaxation rate, were correlated with three fractions of water (structural, intracellular, and extracellular) that were observed during seed germination. This study provides evidence that lupin seeds have similar states of the different water components with regard to seed moisture content at two distinct physiological stages, seed maturation and germination. The unique feature of maturing lupin seeds is the presence of the high (1)H-NMR signal in areas corresponding to the vascular bundles. Tissue localization of dehydrins showed the presence of dehydrin protein in the area of vascular tissue. An anti-dehydrin antibody detected three polypeptides in lupin embryos with molecular masses of 73, 43 and 28 kDa, respectively. The temporal pattern of dehydrin protein accumulation correlates well with seed desiccation.