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Low cost electrodes with high activity and stability are the key to water splitting for green hydrogen production. Herein, an efficient integrated Ni/CoFe LDH array electrocatalyst is synthesized by a one-step electrodeposition strategy. The Ni/CoFe LDH shows splendid electrocatalytic performance for water oxidation, with a low overpotential (324 mV at a 50 mA cm−2 current output), a small Tafel slope (32 mV dec−1), and excellent durability. The improved activity can be attributed to the synergy of the electronic structure fine-tuning and the hydrophilic nanostructured surface.

To maximize the utilization and response to the high oxidative stress environment of tumor sites while avoiding the dilemma of enhancing reactive oxygen species (ROS) response in a single way, mitochondrial targeting combined with fluorescent self-reporting polymeric nanocarriers (1K-TPP and 2K-TPP) with grafted structures were synthesized via a chemoenzymatic method in a high yield to simultaneously enhance the drug delivery of endogenous ROS responses. 1K-TPP and 2K-TPP loaded doxorubicin (DOX) at a high content over 12% and formed homogeneous spherical micelles. In vitro, both of them showed promising high sensitivity (detection limit below 200 nM H2O2), fast response, and ratiometric fluorescent self-reporting properties (fluorescent enhancement more than 200 times) to ROS and excellent stability under physiological conditions, while achieving a rapid release of the DOX in response to 1 mM H2O2. Cell co-localization experiments exhibited that they had favorable mitochondrial targeting, and mitochondrial isolation experiments also confirmed that the TPP-modified 1K-TPP selectively accumulated nearly three times in mitochondria than that in total cells. The internalization of 1K-TPP and 2K-TPP into cancer cells was greatly improved by nearly 200% compared to that of unmodified control (1K-OH and 2K-OH) and also explored a unique energy-dependent endocytosis. Furthermore, stimulation of endogenous ROS enhanced the green fluorescence intensity (up to 51.4%) of the linked probe so as to destroy the internal structure of the nanocarriers, achieving self-reporting of the drug's intracellular release and tracking of the intracellular location of nanocarriers. The cytotoxicity of DOX-loaded 1K-TPP and 2K-TPP in tumor cells with a higher ROS content showed statistical superiority to that of 1K-OH and 2K-OH, benefiting from the extremely good endogenous ROS response sensitivity leading to the differential selective release of drugs. These results demonstrate the potential of 1K-TPP and 2K-TPP, especially for 1K-TPP, as mitochondria-targeted, fluorescent self-reporting nanocarriers for combined enhancement of endogenous ROS responsiveness.

Pyridine-Si-xanthene, a novel near-infrared fluorescent dye, dispalys better photophysical properties compared with Si-rhodamines including improved modifiability and red-shifted emission wavelength. The application is exemplified through the development of a lysosomes-targeting probe capable of imaging cysteine in cells and in vivo.

As important members of the reactive sulfur species (RSS), biological thiols including cysteine, homocysteine and glutathione play crucial roles in many physiological and pathological processes. Development of highly sensitive and selective methods for biothiol detection is of great significance. In this work, we developed a hemicyanine based probe (HXPIS) for near-infrared fluorescence detection of biological thiols in living cells and tissues. The probe HXPIS is capable of detecting biothiols with high selectivity as well as low detection limit (less than 11 nM). In addition, confocal laser scanning microscopy experiments of HeLa cells and Escherichia coli showed that HXPIS could be used to monitor intracellular and bacterial levels of biothiols. Furthermore, HXPIS was applied to distinguish live and dead Escherichia coli. Finally, the imaging of rat liver tissue slices demonstrated the outstanding staining and penetrating ability of the near infrared fluorescent probe.

A mitochondria targeting and immobilized fluorescent probe (Rd1) using triphenylphosphonium as the targeting group and methoxymaleimide as the fixed site is designed for the detection of ClO-. The methoxymaleimide fixed group can react with nucleophiles, such as the reactive thiol groups present in mitochondrial polypeptides and proteins, and form covalent bonds to immobilize the probe within mitochondria. The immobilization of Rd1 enhances its ability to withstand the risk of leakage from mitochondria. Methoxymaleimide shows better reactivity toward Cys than glutathione (GSH), which decreases the ineffective labeling of GSH when it covalently bonds with the reactive thiol residues of mitochondrial proteins; furthermore, it can resist hydrolysis during a long-term storage in water, compared with the classic benzyl chloride fixed unit. The imaging results indicate that Rd1 displays enhanced retention within the mitochondria of cells and tissues upon the decrease of mitochondrial membrane potential (MMP) caused by different stimulations. Furthermore, it possesses the ability to visualize exogenous and endogenous ClO- in living cells, tissues, and zebrafishes.

The viscosity of lysosome is reported to be a key indicator of lysosomal functionality. However, the existing mechanical methods of viscosity measurement can hardly be applied at the cellular or subcellular level. Herein, a BODIPY-based two-photon fluorescent probe was presented for monitoring lysosomal viscosity with high spatial and temporal resolution. By installing two morpholine moieties to the fluorophore as target and rotational groups, the TICT effect between the two morpholine rings and the main fluorophore scaffold endowed the probe with excellent viscosity sensitivity. Moreover, Lyso-B succeeded in showing the impact of dexamethasone on lysosomal viscosity in real time.

The substituent cross-interaction effect in the substituted benzylidene anilines ( p -X C 6 H 4 CH N C 6 H 4 Y- p ) has been observed and widely investigated. In order to investigate whether the substituent cross-interaction effect exist in all the conjugated systems containing C N polar bond, this paper employed 2-X-5-Y pyrimidines as the model compounds for study. The influences of substituents X and Y on the 1 H NMR and 13 C NMR chemical shifts of 2, 5-disubsitituted pyrimidines have been systematically investigated. Quantitative structure-chemical shifts relationship models have been built for δ (H 4,6 ), δ (C 2 ), δ (C 4,6 ) and δ (C 5 ) with four to six molecular descriptors. These models were confirmed of good stability and predictive performances by leave-one-out cross validation. This study indicates that the substituent effects of 2,5-disubstituted pyrimidines are much more complex than that of the substituted benzylidene anilines. More structural factors besides of Hammett parameter should be taken into consideration. Different from the substituted benzylidene anilines, the cross-interaction effect (Δ σ 2 ) of substituents X and Y has little contribution to δ (H 4,6 ), δ (C 2 ), δ (C 5 ) and δ (C 4,6 ) of 2,5-disubstituted pyrimidines.

A novel reaction-based fluorescent probe (ATC-Hg) was designed and synthesized via the "covalent assembly" principle, which exhibited excellent selectivity and high sensitivity for Hg2+ and CH3Hg+. Moreover, it is the first Hg(ii) sensitive fluorescent probe that has been successfully applied in imaging in both cells and Escherichia coli.

As fluorescent probes, the small Stokes shift and ACQ effect limit the application of BINOL derivatives. Herein, a new series of BINOL derivatives were synthesized which could be turned from ACQ to AIE fluorophores by changing the electron withdrawing group. Among these compounds, BIN-COP exhibits an obvious AIE property with low cytotoxicity. The bioimaging performance indicated that the designed fluorophores could be successfully used for bioimaging.

A dual-site fluorescent probe with double bond and aldehyde as reactive sites, was designed for the selective detection of sulfite and biothiols. Sulfite reacts with conjugate bond selectively, while Cys responses with aldehyde and GSH occurs substitution reaction. Different interactions cause different absorption and fluorescence responses. Moreover, it could be further applied in imaging in living cells.

A new series of purine-based derivatives with easy availability and colour tunability were synthesized and could be used for lipid droplet imaging., Recently, tetraphenylethene, triphenylamine and other man-made core AIE luminescent materials (AIEgens) have attracted significant scientific interest. However, the design and synthesis of natural product based, facile and color tunable AIEgens remains challenging. Herein, a novel series of AIEgens based on purine-core molecular rotors is reported, which can be facilely synthesized and shows color tunable emission. Moreover, these purine-based AIEgens exhibit lipid droplet specific properties in live cellular imaging with low background, high selectivity and excellent biocompatibility.

The nucleophilic substitution reactions of carboxylic esters (R1COOR2) follow 2 possible mechanisms, namely, stepwise mechanism and concerted mechanism. The reaction mechanism is affected by the structures of the nonleaving group (NLG, ie, R1), the leaving group (LG, ie, OR2) of carboxylic esters, and the nucleophiles (Nu). The traditional approach for the determination of reaction mechanism by dynamic experiments is not only laborious and time consuming but also only applicable for the situation with single structural factor variation. Benefiting from the ample existing kinetic data, this article aimed to construct a molecular structure-based classification model by support vector machine (SVM). The polarizability effect index of the NLG (PEI(NLG)), the pKa of the conjugate acid of the LG (pKa(LG)), and the pKa of the conjugate acid of the Nu (pKa(Nu)) were used to characterize the structural information of the 3 influencing factors, respectively. On the basis of these structural descriptors, the SVM classification model was established for the reaction mechanisms of 225 nucleophilic substitution reactions in the training set. The total prediction accuracy of 99.11% was achieved by 5-fold cross validation. Then the reaction mechanisms of 56 reactions in test set A were predicted by this SVM model, and the prediction accuracy was up to 98.21%. Furthermore, test set B consisting of 24 reactions were used as another external data set for prediction, where the reaction mechanisms were controversially reported by different studies. The prediction results of test set B by the SVM model built in this article were amazingly consistent with the conclusions drawn by Um et al.