Intracellular Fate of Hydrophobic Nanocrystal Self‐Assemblies in Tumor Cells

Control of interactions between nanomaterials and cells remains a biomedical challenge. A strategy is proposed to modulate the intralysosomal distribution of nanoparticles through the design of 3D suprastructures built by hydrophilic nanocrystals (NCs) coated with alkyl chains. The intracellular fate of two water‐dispersible architectures of self‐assembled hydrophobic magnetic NCs: hollow deformable shells (colloidosomes) or solid fcc particles (supraballs) is compared. These two self‐assemblies display increased cellular uptake by tumor cells compared to dispersions of the water‐soluble NC building blocks. Moreover, the self‐assembly structures increase the NCs density in lysosomes and close to the lysosome membrane. Importantly, the structural organization of NCs in colloidosomes and supraballs are maintained in lysosomes up to 8 days after internalization, whereas initially dispersed hydrophilic NCs are randomly aggregated. Supraballs and colloidosomes are differently sensed by cells due to their different architectures and mechanical properties. Flexible and soft colloidosomes deform and spread along the biological membranes. In contrast, the more rigid supraballs remain spherical. By subjecting the internalized suprastructures to a magnetic field, they both align and form long chains. Overall, it is highlighted that the mechanical and topological properties of the self‐assemblies direct their intracellular fate allowing the control intralysosomal density, ordering, and localization of NCs.     

Silver-ion high-performance liquid chromatographic separation and identification of conjugated linoleic acid isomers

This is the first report of the application of silverion impregnated high-performance liquid chromatography (Ag⁺-HPLC) to the separation of complex mixtures of conjugated linolenic acid (CLA) isomers present in commercial CLA sources and foods and in biological specimens. This method showed a clear separation of CLA isomers into three groups related to their trans,trans, cis,trans or trans,cis, and cis,cis configuration of the conjugated double-bound system. In addition, this method separated within each geometrical isomeric group. Following Ag⁺-HPLC isolation, gas chromatography (GC)-electron impact mass spectrometry, and GC-direct deposition-Fourier transformed infrared spectroscopy were used to confirm the identity of two major positional isomers in the cis/trans region, i.e., Δ8,10- and Δ11,13-octadecadienoic acid, which had not been chromatographically resolved previously, Furthermore, the potential of this method was demonstrated by showing different Ag⁺-HPLC profiles exhibiting patterns of isomeric distributions for biological specimens from animals fed a diet containing a commerical CLA preparation, as well as for a commerical cheese product.     

Fatty acid analysis of blood serum, seminal plasma, and spermatozoa of normozoospermic vs. Asthernozoospermic males

Docosahexaenoic acid (DHA; 22∶6n−3) is found in extremely high levels in human ejaculate with the majority occurring in the spermatozoa. However, the relative concentration of DHA and other fatty acids, in blood serum, seminal plasma, and spermatozoa of asthenozoospermic vs. normozoospermic individuals is not known. We analyzed the phospholipid fatty acid composition of blood serum, seminal plasma, and spermatozoa of normozoospermic men and asthenozoospermic men in order to determine if DHA levels, as well as the levels of other fatty acids, differed. The serum phospholipid DHA levels were similar in the two groups, suggesting similar intakes of dietary DHA. On the other hand, seminal plasma levels of DHA (3.0 vs. 3.7%) and total polyunsaturated fatty acids (PUFA) (11.8 vs. 13.5%) were significantly lower in asthenozoospermic vs. normozoospermic men, respectively, while 18∶1 (19.0 vs. 16.8%) and monounsaturated fatty acids (MUFA) (24.2 vs. 21.7%) were significantly higher in the asthenozoospermic vs. the normozoospermic men. Spermatozoa from asthenozoospermic men had higher levels of 18∶1, 20∶0, 22∶0, 22∶1, and 24∶0 than sperm from normozoospermic men, and lower levels of 18∶0 and DHA (8.2 vs. 13.8%). Furthermore, total MUFA (19.3 vs. 16.5%) was higher and total PUFA (19.0 vs. 24.0%), n−3 fatty acids (9.3 vs. 14.6%), and the ratio of n−3 to n−6 fatty acids (1.0 vs. 1.6) were lower in the asthenozoospermic men. Therefore, in asthenozoospermic individuals, lower levels of DHA in the seminal plasma, but not in the blood serum, mimic the decreased concentrations of DHA in the spermatozoa. This suggests that the lower concentrations of spermatozoon DHA in these individuals are due not to dietary differences but to some type of metabolic difference in the asthenozoopermic men.     

An inequality for the empirical D.F. in the non–I.I.D. case

A generalization to the non-i.i.d. case of an inequality for the empirical df. due to Mason (1981) is proved     

Unusual Temperature Dependence of Heterogeneous Nucleation of Water Vapor on Ag Particles

Copyright 2013 American Association for Aerosol Research     

Water Uptake by NaCl Particles Prior to Deliquescence and the Phase Rule

Using an environmental transmission electron microscope (ETEM), we show that a significant amount of water, far exceeding the multilayers caused by surface adsorption, is reversibly associated prior to deliquescence with substrate-supported NaCl particles (dry diameters of ～ 40 nm to 1.5 μ m; ～ 18°C). We hypothesize that the water is present as an aqueous solution containing dissolved Na and Cl ions. Water uptake occurs at relative humidities (RH) as low as 70%, and the resulting liquid layer coating the particles is stable over extended times if the RH is held constant. We exposed CaSO ₄ and CaSO ₄ · 2H ₂ O particles to elevated RH values in the ETEM to show that chemically nonspecific condensation of gas-phase water on the TEM substrate does not explain our observations. Furthermore, damage to the NaCl surface induced by the electron beam and small fluctuations in RH do not seem to contribute to or otherwise affect water uptake. We have similar observations of water association for other alkali halide particles, including NaBr and CsCl, prior to deliquescence. To explain the observations, we derive the phase rule for this geometry and show that it allows for the coexistence of liquid, solid, and vapor for the binary NaCl/H ₂ O system across a range of RH values. The derivation includes the effects of heterogeneous pressure because of the Laplace-Young relations for the subsystems. Furthermore, in view of the lever rule and the absence of similar observations for free-floating pure NaCl aerosol particles, we hypothesize that the surface energy necessary to support these effects is provided by sample-substrate interactions. Thus, the results of this study may be relevant to atmospheric systems in which soluble compounds are associated with insoluble materials.     

Effect of fatty acid positional distribution and triacylglycerol composition on lipid by-products formation during heat treatment: I. Polymer formation

Effects of the fatty acid positional distribution and of the triacylglycerol (TG) composition on polymerization of TG during heat treatment were studied. Diacid TG molecules, acylated only with linoleic acid or linolenic acid along with palmitic acid, and positioned either in the central position (PLP and PLnP, respectively) or in one of the two outer positions (PPL and PPLn, respectively) were synthesized. Monoacid TG, i.e., trilinolein and trilinolenin, were also synthesized and mixed with tripalmitin in a 1:2 ratio. These model TG were also compared to TG models that consisted of a canola oil and its randomized counterpart, whose fatty acid positional distribution and TG composition were determined by means of high-performance liquid chromatography (HPLC). After heating, the polymer content and composition were evaluated by HPLC-size exclusion chromatography. Both pure TG and the canola oil models showed that acylation of polyunsaturated acids in the central position was protective against polymerization, although the effect was mainly observed with linolenic acid. The synthetic-TG study showed that the monoacid TG species exhibited higher sensitivity toward polymerization than the diacid species. The slight differences in the TG species between both canola oils did not allow observation of such a relationship with regard to TG composition.