Single-atom engineering of hemicyanine and its amphiphilic derivative for optimized near infrared phototheranostics.

Near-infrared (NIR) dyes are widely used in the field of in vivo phototheranostics. Hemicyanine dyes (HDs) have recently received tremendous attention due to their easy synthesis and excellent NIR features. However, HDs can easily form non-fluorescent aggregates and their potential for phototherapy still needs further exploration due to their poor ability to generate reactive oxygen species (ROS). Herein, a series of hemicyanine dyes with different chalcogen atom (O, S, Se) substitutions were constructed to achieve optimized potential for phototheranostics. By replacing O with the heavy atom Se in the xanthene skeleton, CySe-NEt2 showed much more favourable features such as extended NIR absorption/emission wavelength, boosted 1O2 generation rate and higher photothermal effect. In addition, a poly(ethylene glycol) (PEG) group was introduced into the scaffold and yielded a nanotheranostic agent CySe-mPEG5K, which easily formed nanoparticles with appealing features such as excellent photostability, effective prevention of unpleasant H-aggregation, fast/selective tumor accumulation and minimum dark toxicity. Solid tumor growth was significantly suppressed through combined photodynamic therapy (PDT) and photothermal therapy (PTT) guided by NIR fluorescence (NIRF) and photoacoustic (PA) imaging. This study not only presents the first example of selenium-substituted hemicyanine dyes, but also offers a reliable design strategy for the development of potent NIR phototheranostic agents with multi-mode imaging-guided combination therapeutic ability.

An Optical/Photoacoustic Dual-Modality Probe: Ratiometric in/ex Vivo Imaging for Stimulated H2S Upregulation in Mice.

Tracking signaling H2S in live mice demands responsive imaging with fine tissue imaging depth and low interferences from tissue scattering/autofluorescence and probe concentration. With complementary advantages of fluorescence and photoacoustic (PA) imaging, optical/PA dual-modality imaging was suggested for in/ex vivo H2S imaging. Therefore, a meso-benzoyloxyltricarboheptamethine cyanine, HS-CyBz, was prepared as the first ratiometric optical/PA dual-modality probe for H2S, profiting from a keto-enol transition sensing mechanism. Tail intravenous injection of this probe leads to probe accumulation in the liver of mice, and the endogenous H2S upregulation triggered by S-adenosyl-l-methionine has been verified by ratiometric optical/PA imaging, suggesting the promising potential of this ratiometric dual-modality imaging.

A coordinate-based meta-analysis of the n-back working memory paradigm using activation likelihood estimation.

The n-back task is a classical paradigm for functional neuroimaging studies of working memory (WM). The frontal and parietal cortical regions are known to be activated during the task. We used activation likelihood estimation (ALE) to conduct a quantitative meta-analysis of 96 primary studies of n-back task variants based on four conditions: memory loads (1-back, 2-back), object (identity, location), age (younger, older) and gender (male, female). Six cortical regions were consistently activated across all the studies: bilateral middle frontal gyrus (BA 10); bilateral inferior parietal lobule (BA 40); bilateral precuneus (BA 7); left superior frontal gyrus (BA 6); left anterior insula (aI) (BA 13); bilateral thalamus. Further meta-analyses revealed that different regions were sensitive to different conditions: compared with 1-back, 2-back increased activation in left middle frontal gyrus, left inferior frontal gyrus and left aI; compared with object location, object identity increased activation in right aI; young, compared with older subjects showed increased activation in frontal, parietal lobule, and right aI; the comparison between male and female showed no differences. Thus, our findings, showed consistent activation of frontal and parietal cortical regions, while other regions such as the aI, showed different activation patterns depending on varying experimental classification conditions.