Precisely modulating the chromatin tracker via substituent engineering: reporting pathological oxidative stress during mitosis.

An in-depth understanding of cancer-cell mitosis presents unprecedented advantages for solving metastasis and proliferation of tumors, which has aroused great interest in visualizing the behavior via a luminescence tool. We developed a fluorescent molecule CBTZ-yne based on substituent engineering to acquire befitting lipophilicity and electrophilicity for anchoring lipid droplets and the nucleus, in which the low polarity environment and nucleic acids triggered a "weak-strong" fluorescence and "short-long" fluorescence-lifetime response. Meaningfully, CBTZ-yne visualized chromatin condensation, alignment, pull-push, and separation as well as lipid droplet dynamics, for the first time, precisely unveiling the asynchronous cellular mitosis processes affected by photo-generation reactive oxygen species according to the subtle change of fluorescence-lifetime. Our work suggested a new guideline for tracking the issue of the proliferation of malignant tumors in photodynamic therapy.

Three-Four Photon Transition Mn(II) Complex Monitoring Lysosome-Related ATP in Real Time via Fluorescence Lifetime Imaging.

Currently, in situ monitoring of the adenosine triphosphate (ATP) level in lysosomes is critical to understand their involvement in various biological processes, but it remains difficult due to the interferences of limited targeting and low resolution of fluorescent probes. Herein, we report a classic Mn(II) probe (FX2-MnCl2) with near-infrared (NIR) nonlinear (NLO) properties, accompanied by three-four photon transition and fivefold fluorescence enhancement in the presence of ATP. FX2-MnCl2 combines with ATP through dual recognition sites of diethoxy and manganese ions to reflect slightly fluorescence lifetime change. Through the synergy of multiphoton fluorescence imaging (MP-FI) and multiphoton fluorescence lifetime imaging microscopy (MP-FLIM), it is further demonstrated that FX2-MnCl2 displays lysosome-specific targeting behavior, which can monitor lysosome-related ATP migration under NIR laser light. This work provides a novel multiphoton transformation fluorescence complex, which might be a potential candidate as a simple and straightforward biomarker of lysosome ATP in vitro for clinical diagnosis.

Tumor Stimulus-Activatable Pretheranostic Agent: One Key to Three Locks.

The uncontrollable distribution of antitumor agents remains a large obstacle for specific and efficient cancer theranostics; thus, efficient construction of tumor-specific systems is highly desirable. In this work, a general design of tumor stimulus-activatable pretheranostic agents was put forward via a series of structures-tunable triphenylamine derivatives (TPA-2T-FSQ, TPA-2T-BSZ, and TPA-2T-ML) with phenothiazine, benzothiazine, and thiomorpholine as identifying groups of hypochlorite (HClO), respectively. Notably, the sulfur atom in phenothiazine of TPA-2T-FSQ was more easily oxidized to sulfoxide groups by HClO, transforming into an electron acceptor to form an excellent push-pull electronic system, which was beneficial to a large redshift of absorbance and emission wavelengths. Based on this, TPA-2T-FSQ resorted to a key of overexpressed HClO in the tumor to open "three locks", viz, NIR fluorescence, photothermal, and photoacoustic signals for multimodal diagnostic and treatment of the tumor. This study provided an elegant design to adopt tumor stimulus-triggerable pretheranostic for improving theranostic accuracy and efficiency, which was regarded as a promising candidate for precision medicine.

Enhanced pH-Responsive Chemo/Chemodynamic Synergistic Cancer Therapy Based on In Situ Cu2+ Di-Chelation.

Considering the chemodynamic therapy and chemotherapy independent of external stimulus witnessing great advantage in the clinical translation, developing a smart nanoplatform that can realize enhanced chemo/chemodynamic synergistic therapy in the tumor microenvironment (TME) is of great significance. Herein, we highlight the enhanced pH-responsive chemo/chemodynamic synergistic cancer therapy based on in situ Cu2+ di-chelation. The alcohol-withdrawal drug disulfiram (DSF) and chemotherapeutic drug mitoxantrone (MTO) were embedded into PEGylated mesoporous CuO (denoted as PEG-CuO@DSF@MTO NPs). The acidic TME triggered the collapse of CuO and the concurrent release of Cu2+, DSF, and MTO. Then, the in situ complexation between Cu2+ and DSF, as well as the coordination between Cu2+ and MTO not only prominently enhanced the chemotherapeutic performance but also triggered the chemodynamic therapy. In vivo mouse model experiments demonstrated that the synergistic therapy can remarkably eliminate tumors. This study provides an interesting strategy to design intelligent nanosystems, which could proceed to clinical translations.

Surface modification of ZnIn2S4 layers to realize energy-transfer-mediated photocatalysis.

Photocatalytic selective aerobic oxidation reactions are crucial in designing advanced organic intermediates, but suffer from low conversion efficiency. Hence, activating O2 to create suitable reactive oxygen species, such as singlet oxygen (1O2), can significantly increase the yield of desired products. Herein, using ZnIn2S4 nanosheets as a model system, we build a surface-modified theoretical structure, where a surface-covered non-conductive macromolecular chain, polyvinyl pyrrolidone (PVP), is bound to ZnIn2S4 and influences the O2 adsorption process. PVP on the surface significantly changes the electronic structure and suppresses electron conduction of ZnIn2S4 nanosheets. Therefore, abundantly photogenerated and long-lived species transfer their energy to physically absorbed O2 to efficiently generate 1O2, which can oxidize sulphides into their corresponding sulphoxides. For sulphoxidation of different sulphides, surface modification brings a 3-9-fold increase in conversion efficiency and high selectivities ≥98%. This study provides a feasible way of boosting 1O2-generation-related photocatalytic reactions.

Spatial Band Separation in a Surface Doped Heterolayered Structure for Realizing Efficient Singlet Oxygen Generation.

Singlet oxygen (1 O2 ) with electrical neutrality and long lifetime holds great promise in producing high-added-value chemicals via a selective oxidation reaction. However, photocatalytic 1 O2 generation via the charge-transfer mechanism still suffers from low efficiency due to the mismatched redox capacities and low concentration of photogenerated carriers in confined systems. Herein, by taking bismuth oxysilicate (Bi2 O2 SiO3 ) with alternating heterogeneous layered structure as a model, it is shown that iodine doping can facilitate the spatial redistributions of bands on alternated [Bi2 O2 ] and [SiO3 ] layers, which can promote the separation and transfer of photogenerated charge carriers. Meanwhile, the band positions of Bi2 O2 SiO3 are optimized to match the redox potential of 1 O2 generation. Benefiting from these features, iodine-doped Bi2 O2 SiO3 exhibits efficient 1 O2 generation with respect to its pristine counterpart, leading to promoted performance in the selective sulfide oxidation reaction. A new strategy is offered here for optimizing charge-transfer-mediated 1 O2 generation.

Efficient Exciton Dissociation in Heterojunction Interfaces Realizing Enhanced Photoresponsive Performance.

Excitonic effects, originating from the interactions between charge carriers, influence and even dominate the photoresponsive properties of low-dimensional materials. For efficient carrier-related photoresponse, it is imperative to develop appropriate strategies to promote exciton dissociation in these systems. Herein, by taking black phosphorus nanosheets/poly(3-hexylthiophene) (BP/P3HT) as a prototype, we propose that the construction of a heterojunction with a certain band alignment and transport property can facilitate exciton dissociation into free carriers. Analyses on band structures and carrier kinetics confirmed the directional injection of holes from BP to P3HT and the excellent transport property associated with the injected holes in P3HT. Benefiting from these features, the BP/P3HT heterojunction yielded a high photocurrent on-off ratio of ∼18.3, contrasting with the much lower values in pristine BP nanosheets and P3HT. This work provides a feasible scenario for exciton regulation via constructing a heterojunction and establishes an in-depth understanding of exciton dissociation in photoresponsive properties.

Enhanced Superoxide Generation on Defective Surfaces for Selective Photooxidation.

Photocatalytic selective oxidation reactions hold great promise for the design of high-value-added organic intermediates, but many of these reactions suffer from low conversion efficiency and selectivity due to uncontrollable oxidation processes. In view of using photogenerated reactive oxygen species as the key oxidant in a selective oxidation reaction, we propose that a highly selective oxidation reaction can be achieved by modulating the corresponding photocatalytic molecular oxygen (O2) activation processes. Using cubic indium sulfide (ß-In2S3) nanosheets as a model system, we show that the charge carriers involved in O2 activation can be optimized with the introduction of surface S vacancies. Benefiting from the enhanced charge separation and transfer processes, the In2S3 nanosheets with S vacancies could simultaneously activate O2 into superoxide radicals via electron transfer under visible-light irradiation to display outstanding activity for the selective oxidation of alcohols to aldehydes with high conversion and selectivity. This study offers a new strategy to optimize photocatalytic selective oxidation reactions.

Optically Switchable Photocatalysis in Ultrathin Black Phosphorus Nanosheets.

Recently low-dimensional materials hold great potential in the field of photocatalysis, whereas the concomitantly promoted many-body effects have long been ignored. Such Coulomb interaction-mediated effects would lead to some intriguing, nontrivial band structures, thus promising versatile photocatalytic performances and optimized strategies. Here, we demonstrate that ultrathin black phosphorus (BP) nanosheets exhibit an exotic, excitation-energy-dependent, optical switching effect in photocatalytic reactive oxygen species (ROS) generation. It is, for the first time, observed that singlet oxygen (1O2) and hydroxyl radical (•OH) are the dominant ROS products under visible- and ultraviolet-light excitations, respectively. Such an effect can be understood as a result of subband structure, where energy-transfer and charge-transfer processes are feasible under excitations in the first and second subband systems, respectively. This work not only establishes an in-depth understanding on the influence of many-body effects on photocatalysis but also paves the way for optimizing catalytic performances via controllable photoexcitation.

Insights into the excitonic processes in polymeric photocatalysts.

Understanding the photoexcitation processes in semiconductors is critical for the design of advanced photocatalytic materials. Nevertheless, traditional viewpoints focus on photogenerated free charge carriers, which are somehow invalid once the many-body effects are taken into account, especially for polymeric photocatalysts. Here we systematically investigate the photoexcitation processes involved in the polymer matrix of graphitic carbon nitride (g-C3N4) by combining photoluminescence spectroscopy and ultrafast transient absorption spectroscopy, validating the strong excitonic effects in the well-known photocatalyst for the first time. The identification of the robust triplet-triplet annihilation process, in which two triplet excitons collide to produce a singlet exciton, highlights an important nonradiative depopulation pathway of excited species and thereby offers potential strategies to regulate the photocatalytic activities of polymeric g-C3N4. The work establishes a new understanding of the photocatalytic mechanism in the polymeric g-C3N4 matrix, and thus paves the way for designing effective polymeric photocatalysts through excitonic engineering.

Giant Electron-Hole Interactions in Confined Layered Structures for Molecular Oxygen Activation.

Numerous efforts have been devoted to understanding the excitation processes of photocatalysts, whereas the potential Coulomb interactions between photogenerated electrons and holes have been long ignored. Once these interactions are considered, excitonic effects will arise that undoubtedly influence the sunlight-driven catalytic processes. Herein, by taking bismuth oxyhalide as examples, we proposed that giant electron-hole interactions would be expected in confined layered structures, and excitons would be the dominating photoexcited species. Photocatalytic molecular oxygen activation tests were performed as a proof of concept, where singlet oxygen generation via energy transfer process was brightened. Further experiments verify that structural confinement is curial to the giant excitonic effects, where the involved catalytic process could be readily regulated via facet-engineering, thus enabling diverse reactive oxygen species generation. This study not only provides an excitonic prospective on photocatalytic processes, but also paves a new approach for pursuing systems with giant electron-hole interactions.

Boosting Hot-Electron Generation: Exciton Dissociation at the Order-Disorder Interfaces in Polymeric Photocatalysts.

Excitonic effects, arising from the Coulomb interactions between photogenerated electrons and holes, dominate the optical excitation properties of semiconductors, whereas their influences on photocatalytic processes have seldom been discussed. In view of the competitive generation of excitons and hot carriers, exciton dissociation is proposed as an alternative strategy for hot-carrier harvesting in photocatalysts. Herein, by taking heptazine-based melon as an example, we verified that enhanced hot-carrier generation could be obtained in semicrystalline polymeric photocatalysts, which is ascribed to the accelerated exciton dissociation at the abundant order-disorder interfaces. Moreover, driven by the accompanying electron injection toward ordered chains and hole blocking in disordered chains, semicrystalline heptazine-based melon showed an ∼7-fold promotion in electron concentration with respect to its pristine counterpart. Benefiting from these, the semicrystalline sample exhibited dramatic enhancements in electron-involved photocatalytic processes, such as superoxide radical production and selective alcohol oxidation. This work brightens excitonic aspects for the design of advanced photocatalysts.

Enhanced Singlet Oxygen Generation in Oxidized Graphitic Carbon Nitride for Organic Synthesis.

Experimental data reveal that the incorporation of carbonyl groups into polymer matrix can significantly enhance singlet oxygen ((1) O2 ) generation and suppress production of other reactive oxygen species. Excitonic processes investigated by phosphorescence spectroscopy reveal enhanced triplet-exciton generation in the modified g-C3 N4 , which facilitate (1) O2 generation through an energy transfer process. Benefiting from this, the modified g-C3 N4 shows excellent conversion and selectivity in organic synthesis.

Crystal structure of (E)-2-(2-{5-[(2-acet-oxy-eth-yl)(meth-yl)amino]-thio-phen-2-yl}vin-yl)-3-methyl-benzo-thia-zolium iodide monohydrate.

In the cation of the title hydrated salt, C19H21N2O2S2 (+)·I(-)·H2O, the benzo-thia-zolium ring system is approximately planar [maximum deviation = 0.0251 (15) Å], and it makes a small dihedral angle of 1.16 (18)° with the plane of the thio-phene ring. In the crystal, the cations, anions and crystalline water mol-ecules are linked by classical O-H⋯O, O-H⋯I and weak C-H⋯O hydrogn bonds, forming a three-dimensional supra-molecular network. π-π stacking is observed between parallel thia-zole rings of adjacent cations [centroid-centroid distance = 3.5945 (16) Å].

5-[(2-Hy-droxy-eth-yl)(meth-yl)amino]-thio-phene-2-carbaldehyde.

In the title compound, C8H11NO2S, the aldehyde group is approximately coplanar with the thio-phene ring [maximum deviation = 0.023 (2) Å]. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds into supra-molecular chains propagating along the a-axis direction.

Self-assembly of Terbium(III)-based metal-organic complexes with two-photon absorbing active.

Hybrid complexes based on D-π-A type dyes p-aminostyryl-pyridinum and Terbium(III) complex anion (1, 2) have been synthesized by ionic exchange reaction. Meanwhile two different alkyl-substituted amino groups were used as electron donors in organic dyes cations. The synthesized complexes were characterized by element analysis. In addition, the structural features of them were systematic studied by single crystal X-ray diffraction analysis. Their linear properties have been systematically investigated by absorption spectra and fluorescence, the results show that the energy transfer takes place from the trans-4-[4'-(N,N-diethylamino)styryl]-N-methyl pyridinium (2') cation to Tb(III). In addition, complex 2 exhibit a large two-photon absorption coefficient ß: 0.044cm/GW at 710nm.