Quantitative Analysis of the Shape Effect of Thermoplasmonics in Gold Nanostructures

The shape effect of thermoplasmonic properties of Au nanostructures remains largely unexplored. Herein, we report a systematic investigation on the photothermal effects of Au nanoparticles (NPs) of different shapes: nanosphere, nanocube, nanorod, nanostar, and nanobipyramid. The Joule (Jo) number (absorption cross section normalized by the particulate volume) is utilized for quantitatively assessing the photothermal properties of these different shaped Au NPs. It is shown that the Jo number of Au NPs greatly varies with the geometric shape and localized surface plasmon resonance (LSPR) wavelength. Specifically, the Jo number decreases with the red-shifting of the LSPR wavelength in these Au NPs, and the Au NPs of sharp structural features such as Au nanorod, nanostar and nanobipyramid have a much larger Jo number, indicative of their exceptional light-to-heat conversion ability. We further demonstrate the close correlation of the Jo number of Au NPs of different shapes with their optical absorption power density

ABR hearing thresholds for tinnitus⁽⁺⁾, tinnitus^(-), and control rats prior to intense noise or sham exposure, and on post-exposure day 0 and post-exposure week 7.

<p>Thresholds were elevated across all frequencies in tinnitus⁽⁺⁾ and tinnitus^(-) rats at post-exposure day 0, revealing immediate and significant hearing loss. By post-exposure week 7, however, thresholds recovered to pre-exposure levels. At all time points, thresholds were similar between tinnitus⁽⁺⁾ and tinnitus^(-) rats. There were no threshold elevations in control rats. Error bars represent standard error of the mean.</p

Licking rates over time for tinnitus⁽⁺⁾, tinnitus^(-), and control rats during narrowband sound trials (A-E).

<p>Tinnitus^<b>(+)</b> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 weeks following noise exposure; tinnitus^<b>(-)</b> refers to noise-exposed rats that did not meet that criteria. No significant changes in sound trial licking were observed for any group of rats.</p

Top and side views of the behavioral testing chamber.

<p>The horizontal waterspout is located in the front of the wire mesh chamber and connected to a syringe pump for water delivery. Speakers were mounted to the chamber walls on both sides of the waterspout, so that sound could be presented bilaterally to the animal. Sounds levels and frequencies were calibrated using a microphone (ACO Pacific, Belmont, CA) and the chamber was tested to ensure that sound presentation did not vibrate the chamber. The stainless steel grid floor was electrified to deliver footshocks. Behavioral sessions were monitored with a USB camera placed above the testing chamber.</p

Illustrations showing phase 4 behavioral training during 6–8 and 10–12 kHz sound and silent trials.

<p>The “x 3” and “x 1” notations refer to the number of spout licks required to obtain a water reward and a variable shock, respectively.</p

Licking rates during silent trials prior to injections (post-exposure week 8), as well as 3 hours and 5 days following saline (A) or salicylate (B) injections.

<p>After saline injections, no changes in licking rate were observed. Three hours following salicylate injections, however, all nine animals increased licking behavior during silent trials, though most robustly following high-frequency narrowband sound trials. The licking rates during silent trials returned to pre-injection levels by 5 days post-injection.</p

Noise-exposed (Exposed) and sham-exposed (Sham) rats tested without footshocks at four weeks (A) and eight weeks (B) following exposure.

<p>The dotted line and shading indicate the silent trial licking range of sham-exposed rats. A few of the noise-exposed rats exhibited silent trial licking rates higher than those of sham-exposed rats at both four and eight weeks post-exposure. This is suggestive of tinnitus-like behavior.</p

Licking rates over time for tinnitus⁽⁺⁾, tinnitus^(-), and control rats during silent trials (A-E).

<p>Tinnitus^<b>(+)</b> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 weeks following noise exposure; tinnitus^<b>(-)</b> refers to noise-exposed rats that did not meet that criteria. Tinnitus⁽⁺⁾ and tinnitus^(-) rats exceeded 1 lick per each silent trial category immediately after noise exposure (D 0), except for one rat for 6–8 and another rat for 30–32 kHz silent trials. Eleven rats exceeded 1 lick per silent trial for one or more silent trial categories over at least 5 to 7 weeks post-exposure (Wk 5 –Wk 7). These increases in silent trial licking were significant relative to the last baseline training session (T16). Control rats show no significant increases in licking over time. The dashed line and gray-shaded area indicate the ≤ 1-lick/trial threshold.</p

Baseline rates of licking during silent trials (training sessions 11–16).

<p>Tinnitus^<b>(+)</b> refers to rats that later exceeded 1 lick/trial for one or more silent trial categories over weeks 5 through 7 week following noise exposure; tinnitus^<b>(-)</b> refers to noise-exposed rats that did not meet that criteria. A silent trial category was determined by the narrowband sound trial that preceded it (i.e. 6–8 kHz, 10–12 kHz, 14–16 kHz, 22–24 kHz, 30–32 kHz) (A-E). From baseline test sessions 13–16, all rats exhibited stable baseline behavior (≤ 1 average lick/trial) for every silent trial category, as indicated by the dashed line and shaded area. There were no significant differences between tinnitus⁽⁺⁾, tinnitus^(-), or control (ctrl) rats in baseline silent trial licking.</p

Roles for B7-1/2-CD28 interaction in the accumulation of TCR β⁺NK1.1⁺ NKT cells in the thymus (A), spleen (B) and liver (C).

<p>B7KO, CD28KO and WT C57BL/6 mice were sacrificed at 8-week of age. Total lymphocytes (left column) from viable cells, CD4⁻CD8⁻ DN lymphocytes (middle column) and CD4⁺ lymphocytes (right column) were analyzed for the expression of TCRβ and NK1.1. One representative profile from each group is presented. The numbers in the panels are percentages (Mean±SD) of gated NKT cells (n = 9). The numbers shown on the side of figures are <i>p</i> value between two indicated groups.</p