Mesoporous TiO2 nanostructures: A route to minimize Pt loading on titania photocatalysts for hydrogen production

Mesostructured TiO2 nanocrystals have been prepared using Pluronic F127 as the structure-directing agent. Platinum nanoparticles at different contents (0.1-1.0 wt%) have been photochemically deposited onto the mesoporous TiO2. TEM investigation of 0.2 wt% Pt/TiO2 calcined at 450 °C reveals that the TiO2 particles are quite uniform in size and shape with the particle sizes of TiO2 and Pt being 10 and 3 nm, respectively. The photocatalytic activities of the Pt loaded TiO2 have been assessed and compared with those of nonporous commercial Pt/TiO2-P25 by determining the rates and the photonic efficiencies of molecular hydrogen production from aqueous methanol solutions. The results show that the amount of hydrogen evolved on Pt/TiO2-450 at low Pt loading (0.2 wt%) is three times higher than that evolved on Pt/TiO2-P25 and twelve times higher than that evolved on Pt/TiO 2-350. Despite the BET surface area of the TiO2-450 photocatalyst being 3.5 times higher than that of TiO2-P25, a 60% smaller amount of the Pt co-catalyst is required to obtain the optimum photocatalytic hydrogen production activity. The reduced Pt loading on the mesoporous TiO2 will be important both from a commercial and an ecological point of view. © 2011 the Owner Societies

The change in Fluctuation Score with disease progression.

<p>A: The Fluctuation Score of subjects described by the following captions were plotted. C: Control subjects (grey dots). ND: people with PD who were newly diagnosed (green dots). <3Y: non fluctuators with disease duration less than 3 years, (green dots). >3Y: non fluctuators with disease duration more than 3 years (>3Y) (green dots), EF: “early” fluctuators (EF) meaning modest non troublesome fluctuations (brown dots), NS: fluctuators but not suitable (NS) for DBS (dark red dots), PRE-S: on the waiting list for DBS (crimson red dots). POST-S: Post DBS (black dots). The dotted line with a black circle is the FS scores that separates fluctuators and non-fluctuators (the FT) and the grey shaded region is the region between the FS scores for the median and 75^th percentile of Post DBS subjects (as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124522#pone.0124522.g003" target="_blank">Fig 3</a>). Note that this coincides with the interquartile rage of controls. Note the reduction of the FS score which is described in the results section and in the Discussion. B): The FS score of 177 subjects plotted against duration since first symptoms. Subjects whose FS is blow the FT are shown as green dots. Subjects with fluctuations within the RCMS are shown as tan dots and subjects with FS above the RCMS as red dots. The FS of Control subjects (from Fig 4A) are included (grey dots). Note that the black horizontal dotted line is a continuation of the median of controls. The FS scores within or above the RCMS became frequent after 3 years. Some subjects who had disease for many years had FS scores below the median of controls (dotted line) or even below the FT (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124522#sec020" target="_blank">Discussion</a>). C: This is a cartoon depicting the possible changes in FS over the course of PD and is based on Fig A and B above. The orange horizontal band represents the range in FS produced by an intervention such as DBS with the upper limit being the upper level of an acceptable response and the lower limit being FT (shown by the dotted line). Our proposal is that as non-PD subjects have an FS in this band and newly diagnosed PD are at a point below the cross-over point, then PD must initially produce a decline in FS until a diagnosis is made. With treatment and time, many subjects will have a progressive increase in their FS, eventually crossing the cross-over point and finally becoming a frank fluctuator and suitable for an intervention.</p

Neurogenesis in the adult rodent SVZ and OB.

<p>Schematic sagittal view of the adult mouse brain. 1) Adult-born olfactory precursors (stem cells/transit amplifying cells) proliferate primarily within the SVZ where they 2) differentiate into immature neurons (neuroblasts). 3) Neuroblasts then migrate tangentially along the RMS toward the main OB, which requires 2–6 days. Arrow indicates the direction of neuroblast migration through the RMS. 4) On days 5–7 after birth, adult-born neuroblasts migrate radially towards the granular, periglomerular and external plexiform cell layers of the OB. 5) 15–30 days after birth, adult-born cells in the OB mature to form local interneurons that display extensive dendritic arborizations (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone.0031549-Ming1" target="_blank">[9]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone.0031549-Abrous1" target="_blank">[10]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone.0031549-Petreanu1" target="_blank">[32]</a>). GCL, granular cell layer; GL, glomerular layer; RMS, rostral migratory stream; SVZ, subependymal zone.</p

Effect of reduced proliferation in the SVZ on the generation of neuroblasts and their migration through the RMS.

<p>(A, B) Estimated number of DCX-ir neuroblasts in the SVZ (A) or RMS (B) of control mice (white bars), and mice 7 (grey bars) or 42 days (black bars) after 6-OHDA injections were performed to lesion the SNc (see <i>Protocol 1</i>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2A</a>). (C–M, S, T) BrdU (50 mg/kg i.p.) was administered twice daily for 3 consecutive days, beginning 7 days after 6-OHDA or sham injections, and mice were killed 6 days after the last BrdU administration (see <i>Protocol 2</i>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2B</a>). (C, D) Estimated number of BrdU+ cell bodies in the SVZ (C) or RMS (D) of control mice (white bars), and mice 15 days after 6-OHDA was injected (black bars). (E) Estimated number of BrdU+ cell bodies in the RMS of control or 6-OHDA injected mice, plotted according to distance rostral to the AC. Note the increase in BrdU+ cells in the SVZ of 6-OHDA injected animals. Photomicrographs showing BrdU-LI in the SVZ (F, G) and RMS (H, I) of control and 6-OHDA injected mice. Double-immunofluorescence confocal micrographs of BrdU- (red) and DCX-LI (green) in the SVZ (J, K) and RMS (L, M) of control (J, L) and 6-OHDA injected (K, M) mice. (S, T) Double-immunofluorescence confocal micrographs of BrdU- (red) and DCX-LI (green) in the SVZ of control (S) and 6-OHDA injected (T) mice, shown at higher magnification. Note increased number of double-labeled cells in the SVZ of 6-OHDA injected mice. (N–P) Photomicrographs of DCX-ir neuroblasts in the RMS of control mice (N), and 7 (O) or 42 days (P) after 6-OHDA injection into the SNc (see <i>Protocol 1</i>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2A</a>). (Q, R) Estimated number of GFAP-ir astrocytes in the SVZ of control mice (white bar), and 7 (grey bar) or 42 days (black bar) after 6-OHDA administration (Q) (see <i>Protocol 1</i>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2A</a>). (R) Double-immunofluorescence confocal micrograph of GFAP-LI (green) and Hoechst staining (blue) in the SVZ, the later providing a nuclear counter stain. In plots (A), (B) and (Q), white bars = control animals (n = 4), grey bars = mice 7 days after 6-OHDA injection (n = 4), and black bars = 42 days after 6-OHDA administration (n = 4). For control and lesion groups in plots C–E, n = 4. Control animals received injections of 0.9% NaCl into the SNc. Scale bars: I = 50 um, applies F–I; J = 20 um, applies J–M; P = 100 um. applies N–P; R = 10 um; T = 20 um, applies S, T. * corresponds to <i>P</i><0.05.</p

The interquartile range of bradykinesia and dyskinesia scores in fluctuators and non fluctuators.

<p>A. The BKS_IQR, DKS_IQR and IQR_C of fluctuators (F and olive colour) and non fluctuating (NF and olive colour) patients were plotted. While the two populations can be separated using either DKS_IQR or IQR_C, the separation is more distinct for the IQR_C. In each plot, the horizontal red dotted lines show values from receiver operator curves that resulted in the highest selectivity and sensitivity for separating the two populations. In the case of the IQR_C plots the red dotted line corresponds to an IQR_C of 31.4 which separates the two groups with greater sensitivity and specificity than either the BKS_IQR or DKS_IQR. Note that all IQR_C >100 are shown as = 100. Error bars show median and interquartile range. B. This is a plot of the BKS_IQR, DKS_IQR and IQR_C of patients with PD for less than 3 years (<3 and olive colour) and of patients on the waiting list for DBS (WL and olive colour). In each plot, the horizontal red dotted lines show values from receiver operator curves that resulted in the highest selectivity and sensitivity for separating the two populations. In the case of the IQR_C plots the dotted line corresponds to an IQR_C of 22.5 which separates the two groups with greater sensitivity and specificity than either the BKS_IQR or DKS_IQR. This is marked by an asterisk and is the value that becomes the FT and corresponds to an FS of 7.7 when the fluctuation formula is applied). Note that all IQR_C >100 are shown as = 100. Error bars show median and interquartile range.</p

Summary of results, demonstrating the change in the number of cell bodies in the SVZ, RMS, GCL and GL of 6-OHDA injected animals when compared to control.

<p><i>Protocol 1</i>. A single dose of BrdU (150 mg/kg i.p.) was administered 2 hours prior to death, 7 or 42 days after the 6-OHDA or NaCl injections (n = 4 for each experimental group) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2A</a>). First symbol represents 7 day group; second symbol corresponds to 42 day group. <i>Protocol 2</i>. BrdU (50 mg/kg, i.p.) was administered twice daily for 3 consecutive days beginning 7 days after 6-OHDA (n = 4) or NaCl (n = 4) injections into the SNc, and mice killed 6 days later (i.e. 15 days after 6-OHDA administration) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2B</a>). <i>Protocol 3</i>. BrdU (50 mg/kg, i.p.) was administered twice daily for 5 consecutive days, beginning 8 days after 6-OHDA (n = 4) or NaCl (n = 4) was injected into the SNc, and mice killed 30 days later (i.e. 42 days after 6-OHDA administration) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g002" target="_blank">Fig. 2C</a>). ↓ corresponds to reduced number of cell bodies in comparison to control; ↑ corresponds to increased number of cell bodies;  = corresponds to no statistical change in number of cell bodies. Numbers and letters in brackets refer to corresponding figure.</p

The Fluctuation Score before and after Insertion of Deep Brain Stimulators.

<p>Graphs showing the median and interquartile range of rating scores and PKG measures before and after DBS in 15 PD patients. The Y axis is the relevant value of the scale or PKG measure. The FS threshold for transition from non fluctuators to fluctuators (see asterisk <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124522#pone.0124522.g002" target="_blank">Fig 2B</a>) is indicated by a dotted line marked 7.7. The shaded orange region is the area between the median and 75^th percentile of FS (= 12.8) after DBS (See text for discussion). Note that the median FS after DBS (8.2) is very close to the FT: the value that separates fluctuators from non fluctuators in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0124522#pone.0124522.g002" target="_blank">Fig 2</a> (FS = 7.7) Error bars show median and interquartile range. P values are obtained using Mann Whitney.</p

Counting frame dimensions and x, y co-ordinates for estimates of proliferating cells (Ki67, BrdU 2 hours), neuroblasts, migrating cells (DCX, BrdU 5 days), interneurons and mature cells (NeuN, TH, calbindin, calretinin, GABA, BrdU 30 days) in the SVZ, RMS and OB.

<p>Counting frame dimensions and x, y co-ordinates for estimates of proliferating cells (Ki67, BrdU 2 hours), neuroblasts, migrating cells (DCX, BrdU 5 days), interneurons and mature cells (NeuN, TH, calbindin, calretinin, GABA, BrdU 30 days) in the SVZ, RMS and OB.</p

The number of adult-born cells in the OB increases when precursor proliferation in the SVZ is reduced.

<p>BrdU (50 mg/kg i.p.) was administered twice daily for 5 consecutive days, beginning 8 days after 6-OHDA (or sham) injection, and mice killed 30 days after the last BrdU administration (i.e., 42 days after 6-OHDA injection; see <i>Protocol 3</i>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0031549#pone-0031549-g005" target="_blank">Fig. 5C</a>). (A–G) Estimated number of BrdU+ cell bodies in the GCL of control (white bar) and 6-OHDA injected mice (black bar) (A). Photomicrograph of BrdU+ cell bodies in the GCL of control (B) and 6-OHDA injected (C) mice. (D) Estimated number of BrdU+ and GABA-ir double-labeled cell bodies in the GCL of control (white bar) and 6-OHDA injected mice (black bar). Photomicrograph of BrdU- (red) and GABA-LI (green) in the GCL of control (E) and 6-OHDA injected (F) mice. (G) Estimated number of BrdU+/GABA-ir co-expressing cell bodies expressed as a proportion of the total number of BrdU+ cell bodies in the GCL of control (white bar) and 6-OHDA injected mice (black bar). (H–M) Estimated number of BrdU+ cell bodies in the GL of control (white bar) and 6-OHDA injected mice (black bar) (H). Photomicrograph of BrdU+ cell bodies in the GL and EPL of control (I) and 6-OHDA injected (J) mice. (K) Double-immunofluorescence confocal micrographs of BrdU- (red) and TH-LI (green) in the GL of mouse with striatal/SVZ DA-depletion. (L) Estimated number of BrdU+ and TH-ir double labeled cell bodies in the GL of control (white bar) and 6-OHDA injected mice (black bar). (M) Estimated number of BrdU+/TH-ir co-expressing cell bodies expressed as a proportion of the total number of BrdU+ cell bodies in the GL of control (white bar) and 6-OHDA injected mice (black bar). In plots (A), (D), (G), (H), (L), (M), white bars = control animals (n = 4), and black bars = 6-OHDA-injected animals (n = 4). Control animals received injections of 0.9% NaCl into the SNc. In (G), (L) and (M) coex = co-expressing. Scale bars: C = 100 um, applies B, C; F = 40 um, applies E, F; I = 100 um, applies I, J; K = 10 um. * corresponds to <i>P</i><0.05.</p

Scores from ratings scales and PKG before and after insertion of Deep Brain Stimulators.

<p>* Mann Whitney</p><p>Scores from ratings scales and PKG before and after insertion of Deep Brain Stimulators.</p