Dependence of the Internal Structure on Water/Particle Volume Ratio in an Amphiphilic Janus Particle–Water–Oil Ternary System: From Micelle-like Clusters to Emulsions of Spherical Droplets

Amphiphilic Janus particles (AJP), composed of hydrophilic and hydrophobic hemispheres, are one of the simplest anisotropic colloids, and they exhibit higher surface activities than particles with homogeneous surface properties. Consequently, a ternary system of AJP, water, and oil can form extremely stable Pickering emulsions, with internal structures that depend on the Janus structure of the particles and the system composition. However, the detail of these structures has not been fully explored, especially for the composition range where the amount of the minority liquid phase and AJP are comparable, where one would expect the Janus characteristics to be directly reflected. In this study, we varied the volume ratio of the particles and the minority liquid phase, water, by 2 orders of magnitude around the comparable composition range, and observed the resultant structures at the resolution of the individual particle dimensions by optical microscopy. When the volume ratio of water is smaller than that of the Janus particles, capillary interactions between the hydrophilic hemispheres of the particles induce micelle-like clusters in which the hydrophilic sides of the particles face inward. With increasing water content, these clusters grow into a rodlike morphology. When the water volume exceeds that of the particles, the structure transforms into an emulsion state composed of spherical droplets, colloidosomes, because of the surface activity of particles at the liquid–liquid interface. Thus, we found that a change in volume fraction alters the mechanism of structure formation in the ternary system, and large resulting morphological changes in the self-assembled structures reflect the anisotropy of the particles. The self-assembly shows essential commonalities with that in microemulsions of surfactant molecules, however the AJP system is stabilized only kinetically. Analysis of the dependence of the emulsion droplet size on composition shows that almost all the particles are adsorbed at the water–oil interface; i.e., the particles show ideal surface activity

Correlation map of striatal functional subdivisions and extrastriatal regions, in addition to that of within striatal subdivisions.

<p>Correlations in brighter color (yellow) represent higher ones in terms of magnitude than those in red.</p

Correlations between striatum and extrastriatal regions and intercorrelations among striatal subdivisions in dopamine D₁ receptor BP_ND.

<p>**P<0.01, *P<0.05. Correlations in red: intercorrelations among striatal subdivisions. Correlations in blue: correlations between striatal subdivisions and extrastriatal regions. R² values are presented for the correlations.</p

Additional file 1 of Blood levels of glial fibrillary acidic protein for predicting clinical progression to Alzheimer’s disease in adults without dementia: a systematic review and meta-analysis protocol

Additional file 1: Appendix 1. Search strategies. Appendix 2. Data extraction form

Definition of striatal functional subdivisions.

<p>Upper panel: MR images and regions of interest. Lower panel: parametric images corresponding to MR images in the upper panel.</p

Correlation matrix of regions extracted as clusters using the biclustering analysis and their adjacent regions (outside of the yellow boxes).

<p>(A) The first cluster consisted of correlations between 5-HT_2A receptor binding potentials (<i>BP</i>) for the frontal and parietal cortices and D₂ receptor <i>BP</i> for broad cortical regions (71 regions). Regions in the first cluster (inside the yellow boxes): supplementary motor area (19, 20), superior parietal gyrus (53, 54), paracentral lobule (63, 64); regions adjacent to the first cluster (outside of the yellow boxes): inferior parietal gyrus (55, 56), postcentral gyrus (51, 52), precuneus (61, 62), and superior frontal gyrus (3, 4). (B) The second cluster consisted of correlations between 5-HT_2A receptor <i>BP</i> for the bilateral hippocampi and D₂ receptor <i>BP</i> for broad regions (73 regions) in the cerebral cortex. Regions in the second cluster (inside the yellow boxes): hippocampus (33, 34), regions adjacent to the second cluster (outside of the yellow boxes): parahippocampus (35, 36) and fusiform (49, 50).</p

Brain regions used for the correlation matrix analysis.

<p>Brain regions used for the correlation matrix analysis.</p

A diagram of procedures of correlation and clustering analyses.

<p>A) Individual binding potential (<i>BP)</i> values of [¹⁸F]altanserin and [¹¹C]FLB 457 were extracted for 76 regions in seven subjects. B) A correlation matrix of correlation coefficients was calculated between <i>BP</i> values of [¹⁸F]altanserin and [¹¹C]FLB 457 for the 76 regions. An example of a scatter diagram (top) shows the correlation between <i>BP</i> values of [¹¹C]FLB 457 in the left superior parietal gyrus (region #53) and the <i>BP</i> values of [¹⁸F]altanserin in the left fusiform gyrus (region #49). C) Biclustering was performed on the matrix using an iterative signature algorithm (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#sec005" target="_blank">Methods</a>). R⁽ⁿ⁾ and C⁽ⁿ⁾: sets of rows and columns at the n^th iteration, Score_row and Score_column: the evaluation scores for the rows and columns, Thr.row and Thr.column: thresholds for the rows and columns. D) Two clusters of regions were identified (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#sec014" target="_blank">Results</a>).</p

Regional binding potential (<i>BP</i>) values for 5-HT_2A and D₂ receptors in cerebral cortical regions.

<p>Mean <i>BP</i> values for [¹⁸F]altanserin for 5-HT_2A receptors (blue) and [¹¹C]FLB 457 for D₂ receptors (red) were plotted for 76 cerebral regions. The numbers represent regions defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#pone.0189318.t001" target="_blank">Table 1</a>. Raw data of <i>BP</i> values is available as supporting information (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#pone.0189318.s001" target="_blank">S1 File</a>).</p

Correlation matrix of regions containing 5-HT_2A and D₂ receptors.

<p>A correlation matrix was generated based on Spearman’s correlation coefficients (<i>r</i> values) between individual binding potential values of [¹⁸F]altanserin for 5-HT_2A receptors (columns) and [¹¹C]FLB457 for D₂ receptors (rows) in 76 regions. The numbers represent regions defined in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#pone.0189318.t001" target="_blank">Table 1</a>. Raw data of the matrix is available as supporting information (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189318#pone.0189318.s002" target="_blank">S2 File</a>).</p