Cubic nanoparticles

Narayanan R, El-Sayed MA (2004) Effect of nanocatalysis in colloidal solution on the tetrahedral and cubic nanoparticle shape electron-transfer reaction catalyzed by platinum nanoparticles. J Phys Chem B 108 5726... 

For the sake of comparison with that of HNPs, we here reestablish the MTH curves of the homogeneous cubic nanoparticles (HM-CNPs) and composite cubic nanoparticles (CM-CNPs) by using the same procedure as in the preceding section (Figs. 3 and 4) and focus on the... 

Oziim S, Yalgin O, Erdem R, Bayrakdar H, Eker HN. Martensitic and austenitic phase transformations in core-surface cubic nanoparticles. Journal of Magnetism and Magnetic Materials. 2015 373 217-221. DOI 10.1016/j.jmmm.2014.03.044. 

However, one can observe a number of other situations. Let us consider, for example, the self-organization calculation for the system consisting of 125 cubic nanoparticles, the atomic interaction of which is determined by Morse potential (Figure 9.14). 

FIGURE 9.14 The positions of the 125 cubic nanoparticles (a)-initial configuration (b)—final configuration of nanoparticles. 

FIGURE 9.16 The dependence of the moment M[Nm] of the interaction force between cubic nanoparticles 1-3 (see in Figure 9.9) on the angle of their relative rotation 6 [rad]. 

FIGURE 9.17 The plots of the change of the potential energy E [Nm] for the Interaction of two cubic nanoparticles depending on the angle of their relative rotation 0 [rad] and the distance between them (positions of the nanoparticles 1-3, Figure 9.9). 

Thus, the analysis of the interaction of two cubic nanoparticles has shown that different variants of their final stationary state of equilibrium... 

In the case of benzene hydrogenation to cyclohexane or cyclohexene on platinum single crystals, a change in selectivity is observed from Pt(lll), which catalyzes the formation of both products, to Pt(lOO), where only cyclohexane is produced. This effect is due to the structure sensitivity of the cyclohexene-forming reaction, while the cyclohexane-forming reaction is structure insensitive. Interestingly, the same effect can be observed on nanoparticles of different shapes cuboctahedral particles, which contain (111) faces, catalyze the production of both products, whereas cubic nanoparticles (with (100) faces) produce only cyclohexane (Figure 8) . ... 

The term "lipid nanoparticles" includes all colloidal systems where the nanoparticles consist of a kind of lipid matrix whereas the matrix lipid can occur in different physicochemical states (Figure 9.1) isotropic liquid (e.g. conventional fat emulsions), liquid crystalline (e.g. lyotropic cubic and thermotropic smectic ) or solid crystalline (SLN). A further distinction can be made if the lipid matrix is continuous (emulsions, SLN) or presents a discontinuous network of e.g. lipid bilayers (e.g. cubic nanoparticles). However, it should be kept in mind that lipid nanoparticles in several physicochemical states may coexist in one formulation. Generally the mean size of the nanoparticles is in the mid to lower nm-range normally between 100 and 500 nm. 

For the detection of vesicular structures in dispersions of lyotropic cubic nanoparticles NMR spectroscopy has also been used. Compared to cryo-TEM, this method allows the evaluation of the amount of vesicular fraction in a more quantitative way. To avoid misinterpretations (e.g., due to the presence of closed non-vesicular structures), it is, however, important to know as much as possible about the qualitative composition of the dispersion when using this method. 

Exclusively submicron particles obtained by high pressure homogenization were used in a study which compared skin interaction of GMO-based cubic nanoparticles (with additional vesicular structures as observed by cryo-TEM) with that of other lipidic nanoparticles with compact liquid, crystalline or thermotropic liquid crystalline matrix structure. The cubic nanodispersion, which was stable with respect to particle size for 15 months of storage at room temperature, increased skin permeation of the model substance corticosterone (used in trace amounts in this study) compared to the other types of lipid nanoparticles. Permeation from all lipidic dispersions was, however, lower than from an aqueous solution which was attributed to the retention of a certain fraction of the drug in the lipid nanoparticles. Considering only the drug present in the aqueous phase of the dispersion as available for transport through the epidermis, the presence of cubic GMO particles increased permeation by the factor 2.4. 

Figure 10.5. DSC heating curves (10°C/min) of human stratum corneum incubated with a dispersion of cubic nanoparticles and with the aqueous phase of the dispersion (control). For experimental details see Ref. 83.

Figure 10.6. Light (A-C) and fluorescence (D-F) microscope images of cross sections of human epidermis incubated with the aqueous phase (control, without Dil, A and D), solid lipid nanoparticles (B and E) and cubic nanoparticles (C and F). The lipid nanoparticles ware labeled with Dil as fluorescence marker. Bars represent 20 fim. Reprinted from Int.. Pharm, 354, J. Kuntsche, et ah, Interaction of lipid nanoparticles with human epidermis and an organotypic cell culture model, 180-195, Copyright (2008), with permission from Elsevier.

Yamamuro S, Sumiyama K (2006) Why do cubic nanoparticles favor a square array Mechanism of shape-dependent arrangement in nanocube self-assemblies. Chem Phys Lett 418 166-169... 

Thus, the analysis of the interaction of two cubic nanoparticles has shown that different variants of their final stationary state of equilibrium are possible, in which the principal vectors of forces and moments are zero. However, there are both stable and unstable stationary states of this system nanoparticle positions 2-3 are stable, and positions 3-4 and 2-5 have limited stability or they are unstable depending on the distance between the nanoparticles. 

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