Ultralarge Dielectric Relaxation and Self-Recovery Triggered by Hydrogen-Bonded Polar Components.

Subtle integration of rotatable polar components into dielectric crystals can contribute significantly to adjustable switching temperatures ( Ts) and dielectric relaxation behaviors. Currently, one of the biggest challenges lies in the design of optimal polar components with moderate motion resistance in a crystalline system. In this work, we demonstrate that under refrigerator conditions, rotatable hydrogen-bonded one-dimensional (1D) cationic chains, {[C2H6N5]+} n (C2H6N5 = 3,5-diamino-1,2,4-triazolinium), and two-dimensional (2D) anionic layers, {[(H2O)2·SO4]2-} n, can be generated in an organic salt, 3 ([C2H6N5]2·[(H2O)2·SO4]). Compared with the nonhydrated precursor, 2 ([C2H7N5]·[SO4]), the rotation of these 1D and 2D ionic species triggers a reversible phase transition and dielectric switching in 3. In addition, the significantly sluggish rotation of the 1D cationic chains from parallel to unparallel stacking and the counter-clockwise rotation of the 2D anionic layers, compared with their reverse processes, induce a frequency-dependent dielectric response with a more highly adjustable heating Ts↑ than the cooling Ts↓. More importantly, 3 possesses excellent self-recovery ability attributed to the highly dynamic character of the hydrogen-bonded ionic species. The strategy here can provide a fairly good model for designing dielectric crystals with desired rotatable polar components.

Single-Layered Two-Dimensional Metal-Organic Framework Nanosheets as an in Situ Visual Test Paper for Solvents.

Through a facile-operating ultrasonic force-assisted liquid exfoliation technology, the single-layered two-dimensional (2D) [Co(CNS)2(pyz)2] n (pyz = pyrazine) nanosheets, with a thickness of sub-1.0 nm, have been prepared from the bulk precursors. The atomically thickness and the presence of abundant sulfur atoms with high electronegativity arrayed on the double surfaces of the sheets are making this kind of 2D MOF (metal-organic framework) nanosheets highly sensitive to intermolecular interactions. As a result, it can be well dispersed in all kinds of solvents to give a stable colloidal suspension that can be maintained for at least one month, accompanied by significant solvatochromic behavior and various optical properties, which thus have shown the potential to be practically applicated as in situ visual test paper for solvent identification and solvent polarity measurements. More importantly, combined with a smartphone, this kind of 2D-MOF nanosheets can be developed into in situ visual test paper to identify isomers and determine the polarity of mixed solvents quantitatively and qualitatively, suggesting the promising application of a portable, economical, and in situ visual test strategy in real world.

Subcellular co-delivery of two different site-oriented payloads based on multistage targeted polymeric nanoparticles for enhanced cancer therapy.

The co-delivery of two or more anti-tumor agents using nanocarriers has shown great promise in cancer therapy, but more work is needed to selectively target drugs to specific subcellular organelles. To this end, our research has reported on "smart" polymeric nanoparticles that can encapsulate two different site-oriented pro-drug molecules, allowing them to reach their targeted subcellular organelles based on NIR-mediated controlled release, allowing for targeted modifications in the nucleus or the mitochondria. Specially, an all-trans retinoic acid (RA) conjugated cisplatin derivative (RA-Pt) can be delivered with high affinity to the nucleus of target cells, facilitating the binding of cisplatin to double-stranded DNA. Similarly, a synthesized derivative generated by conjugation of triphenylphosphine (TPP) and celastrol (TPP-Cet) may facilitate mitochondrial targeted drug delivery in tumor cells, inducing ROS accumulation and thereby leading to apoptosis. Relative to nanoparticles loaded with a single therapeutic agent, dual antitumor agent-loaded nanocarriers showed promising synergy, exhibiting significant tumor inhibition in vivo (81.5%), and less systemic toxicity than the free therapeutic agents alone or the drug-loaded nanoparticles without targeted ligands. These results indicated that site-oriented payloads can effectively enhance antitumor therapeutic efficiency and these studies offer a novel "multistage targeted-delivery" strategy in synergistic therapy for cancer treatment.