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We present a dynamically switchable polarization conversion metasurface (PCM) integrated with an electromechanical actuator (EMA) that enabled the switching of states for the reflected wavefront of circularly polarized waves in the terahertz (THz) spectrum. The unit cell of the proposed PCM was composed of double L-shaped Au structures covering a dielectric layer suspended atop a bottom reflective mirror layer. The PCM showed a broad polarization conversion band ranging from 0.74 THz to 1.64 THz with a polarization conversion ratio >90% for incident linear polarized (LP) and circular polarized (CP) waves. Within this broadband, the full 2π phase shifts of the reflected orthogonal CP wave could be obtained by rotating the orientation angle of the PCM unit cell spanning a wide frequency range. The anomalous reflection effect of PCM was simulated and discussed to validate the performance of the proposed switchable coding metasurface based on Pancharatnam–Berry phase theory and the generalized Snell's law. In particular, the reflection efficiency could be tuned dynamically by transforming the movable configuration. The proposed PCM had significant potential for applications in imaging and communication systems, which opens new avenues for the development of multifunctional devices that can modulate THz wavefronts. [ABSTRACT FROM AUTHOR]

A series of defective MnmIn2S3+m (m = 1–5, integer) microflowers were successfully synthesized via a facile hydrothermal method and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). These solid solution photocatalysts have similar cubic phase crystal structures. The results of electron paramagnetic resonance (EPR) spectra showed that the concentration of sulfur vacancy (VS) increased with the increase in Mn/In atomic ratio. The photocatalytic performance of the prepared MnmIn2S3+m was evaluated by the reduction of Cr(VI) in aqueous solution under simulated sunlight, in which Mn4In2S7 showed the highest photocatalytic activity. 40 ppm K2Cr2O7(VI) was almost completely reduced to Cr(III) within 60 minutes. Additionally, the photocatalytic mechanism was investigated and it was demonstrated that the appropriate concentration of VS could accelerate the carrier separation and transfer of Mn4In2S7, so as to improve the photocatalysis efficiency. This work will expand the application of solid solution photocatalysts in the future. [ABSTRACT FROM AUTHOR]

The shuttle effect of polysulfides poses a significant obstacle to the commercialization of lithium-sulfur (Li–S) batteries. Covalent organic frameworks have been widely used in Li–S batteries as porous crystalline materials to suppress the shuttle effect. Herein, a 3,5-bis(trifluoromethyl)benzyl (BTFMB-TzDa) modified triazine-based covalent organic framework was synthesized. The high electronegativity and large steric hindrance of the BTFMB-TzDa modified separator successfully suppressed the diffusion of polysulfides, leading to improved capacity and cyclic stability of Li–S batteries. Cells with the BTFMB-TzDa modified separator exhibited a high initial capacity of 1205 mA h g−1 at 0.2C and 657 mA h g−1 at 3.0C. Furthermore, the capacity still remained at 501 mA h g−1 after 500 cycles. The BTFMB-TzDa modified separator provides an alternative strategy for the construction of high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

We constructed a high-performance biosensor for detecting uric acid by immobilizing an engineered urate oxidase on gold nanoparticles deposited on a carbon-glass electrode. This biosensor showed a low limit-of-detection (9.16 nM), a high sensitivity (14 μA/μM), a wide range of linearity (50 nM–1 mM), and more than 28 days lifetime. [ABSTRACT FROM AUTHOR]

Surface passivation has been widely accepted as an effective method to improve the stability and photoluminescence (PL) performance of perovskite quantum dots (QDs). In this paper, we report Pb3(PO4)2-coated CsPbBr3 QDs as the phosphor materials for white light-emitting diodes. The Pb3(PO4)2 coated layer could effectively improve the stability and optical properties of CsPbBr3 QDs, including PL intensity, average PL lifetime, and PL quantum yield. Moreover, the temperature-dependent PL spectra of CsPbBr3 and CsPbBr3/Pb3(PO4)2 QDs were investigated. It was found that the exciton binding energy and electron–phonon coupling effect of CsPbBr3/Pb3(PO4)2 QDs was larger than that of uncoated QDs. According to the results of transient absorption (TA), intraband hot-exciton relaxation and exciton recombination can be slowed down when the CsPbBr3 QDs are coated with Pb3(PO4)2. In addition, white light-emitting diode devices were fabricated by integrating the green CsPbBr3/Pb3(PO4)2 QDs and red CsPbBr1I2/Pb3(PO4)2 QDs on the blue GaN chips. The devices showed stable white light emission with Commission Internationale de L'Eclairage color coordinates of (0.297, 0.333). As indicated by the results, Pb3(PO4)2-coated perovskite QDs could be an ideal down-conversion fluorescent material for white light-emitting diode devices. [ABSTRACT FROM AUTHOR]

Wavelength-dependent absorbance of blood has impeded the development of fluorescence biodetection in whole blood. Here, by replacing the fluorescence working signal with a temperature signal, reliable H2S detection was performed in samples of whole blood. The developed system was based on a dual-channel lanthanide-doped nanoprobe, which further allowed precise serodiagnosis of acute pancreatitis. [ABSTRACT FROM AUTHOR]

Photoreduction of CO2 into CO, CH4 or hydrocarbons is attractive, due to environmental compatibility and economic feasibility. Optimizing the reaction engineering of CO2 reduction is an effective and general strategy that should be given special consideration. In this article, the photocatalytic CO2 reduction performances are originally investigated in a low vacuum in both dilute (10%) and pure CO2. We discover that the CH4 yield increased above one hundred times as the vacuum degree increased from barometric pressure to −80 kPa in dilute CO2. It also reveals long-term stability and good cycling performance in a low vacuum. The enhanced CO2 photoreduction performance in a low vacuum comes from better accumulation of photogenerated electrons, less intense Brownian movement of gas molecules in the environment and hindrance of the active site-blocking of gas molecules in the environment. Improved photocatalytic CO2 reduction in a low vacuum is further verified by Pt–TiO2 catalysts. This research presents a general route for producing clean fuels by photocatalytic CO2 reduction in a more effective way. [ABSTRACT FROM AUTHOR]

As a new member of carbon allotropes, graphdiyne (GDY) has the characteristics of being one-atom-thick with two-dimensional layers comprising sp and sp2 hybridized carbon atoms, and represents a trend in the development of carbon materials. Its unique chemical and electronic structures give GDY many unique and fascinating properties such as rich chemical bonds, highly conjugated and super-large π structures, infinitely distributed pores and high inhomogeneity of charge distribution. GDY has entered a period of rapid development, especially with the significant emergence of fundamental research and applied research achievements over the past five years. As one of the frontiers of chemistry and materials science, graphdiyne was listed in the Top 10 research areas in the 2020 Research Frontiers report and was jointly released in the Top 10 in the world by Clarivate and the Chinese Academy of Sciences. The research results have shown the great potential of GDY in the applications of energy, catalysis, environmental science, electronic devices, detectors, biomedicine and therapy, etc. Scientists are eager to explore and fully reveal the new properties, discover new scientific concepts and phenomena, discover the new conversion modes and mechanisms of GDY in photoelectricity, energy, and catalysis, etc., and build the important scientific value of new conversion devices. This review covers research on the foundation and application of GDY, such as the controlled preparation of new methods of GDY and GDY-based materials, studies on new mechanisms and properties in chemistry and physics, and the foundation and applications in energy, catalysis, photoelectric and devices. [ABSTRACT FROM AUTHOR]

Hydrogen is a promising substitute for non-renewable fossil fuels. Producing hydrogen fuel by electrolyzing water is an effective strategy to address the growing environmental problems. Platinum (Pt) is still the most active electrocatalyst to catalyze the hydrogen evolution reaction (HER) in alkaline media. Herein, we demonstrate that ultrafine candied haws-shaped PtWNi nanoalloys modified with the Ni species (Nin+) could be formed in the alkaline electroactivation process of PtWNi alloys. Notably, the Ni species (Nin+) promoted the decomposition of water and produced hydrogen intermediates, which were then immediately adsorbed on the surface of Pt and recombined into molecular hydrogen. Moreover, these hydrogen intermediates also enhanced the instability of the HO–H bond, leading to an increase in the total activity. [ABSTRACT FROM AUTHOR]

The nature of the carbon support has huge effects on the catalytic properties of supported catalysts. When utilized for electrochemical purposes as a support for precious metals in acid media, the oxygen functionalization behavior is even more vital to the stability of carbon because of the acceleration of carbon oxidation by precious metals. Here, we demonstrate the regulation of oxygen functionalization behavior of carbon via introducing Co during the fabrication process, and the resultant N-doped hollow carbon embedded with Co (NHC@Co) greatly boosts the catalytic stability of Pt/NHC@Co in the oxygen reduction reaction (ORR). On the one hand, the utilization of Co during fabrication promotes the graphitic level of carbon, which provides fewer anchoring points for adsorbed oxygen, and on the other hand, the remaining Co nanoparticles exhibit strong electron donating effects, which upshifts the Fermi level of C and strengthens its bonding with oxygen. As a result, a small amount of oxygen functional groups is bonded strongly on the surface of NHC@Co, hindering the further catalytic oxidation of carbon and improving the electrochemical stability of Pt/NHC@Co even under harsh acidic ORR conditions. [ABSTRACT FROM AUTHOR]

Protein sulfhydryl groups play a vital role in maintaining cellular redox homeostasis and protein functions and have attracted increasing interests for the selective detection of protein thiols over low-molecular-weight thiols (LMWTs). Herein, we reported a red-emitting and environment-sensitive probe (FM-red) for detecting and labeling protein thiols. The probe contains a maleimide unit as a thiol receptor and an environment-sensitive fluorophore as a sensor. The emission signal of the probe was exclusively switched on by binding to protein sulfhydryl groups through the twisted intramolecular charge transfer mechanism, while negligible fluorescence was observed when FM-red reacted with LMWTs. Various experiments verified that FM-red possessed fast responsivity (∼10 min) and high selectivity to sense protein thiols over LMWTs with a red emission (∼655 nm). These favorable properties enable the probe to image protein sulfhydryl groups in live cells and in vivo. In addition, as FM-red has a relatively high molecular weight (MW 688), it is able to separate the labeled proteins from the unlabeled ones after FM-red derivatization via routine protein electrophoresis, which may be applied to determine the redox states of thioredoxin, a small redox protein ubiquitous in all cells. With the aid of the probe, we demonstrated a significant decrease in the protein thiols and the accumulation of oxidized thioredoxin in a cellular model of Parkinson's disease. [ABSTRACT FROM AUTHOR]

Aptamers have recently been widely employed as recognition elements for the discovery and detection of protein biomarkers. Therefore a comprehensive and in-depth understanding of the interaction between aptamers and their target proteins is especially important. Herein we report a real-time and label-free strategy to detect the interaction between alpha-fetoprotein (AFP), a specific biomarker of hepatocellular carcinoma, and its specific ssDNA aptamer based on dual polarization interferometry (DPI). The ssDNA aptamer was immobilized on the surface of a sensor chip followed by AFP injection, while the changes of mass, thickness and density on the AFP–aptamer interface were monitored and recorded online by DPI. The experimental results showed that there were two different interaction patterns between AFP and the aptamer, which were specific binding and unspecific binding, and the former was found to be the dominant one. AFP binding makes the conformation of the aptamer change, resulting in an increase of mass/thickness and a decrease of density. The concentration of AFP is very important for the AFP–aptamer interaction, as a high AFP concentration will lead to a high probability of the aptamer capturing AFP and therefore a large binding amount and a high mass loading rate. The developed detection method proved effective to study the interaction behavior and mechanism between AFP and its aptamer, and will find wide applications in the detection and understanding of protein–aptamer interaction. [ABSTRACT FROM AUTHOR]

A highly diastereo- and enantioselective nitro-Mannich reaction of isatin-derived ketimines with α-aryl nitromethane catalyzed by Cinchona alkaloid-derived phase-transfer catalysts bearing multiple hydrogen-bonding donors (the first metal-free catalytic systems used in this reaction) was developed. A series of 3-substituted 3-amino-oxindoles were constructed using this protocol in excellent yields (96–99%) with high enantioselectivities (up to 95% ee) and diastereoselectivities (up to 95 : 5 dr). [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) represent a fascinating class of solid crystalline materials which can be self-assembled in a straightforward manner by the coordination of metal ions or clusters with organic ligands. Owing to their intrinsic porous characteristics, unique chemical versatility and abundant functionalities, MOFs have received substantial attention for diverse industrial applications, including membrane separation. Exciting research activities ranging from fabrication strategies to separation applications of MOF-based membranes have appeared. Inspired by the marvelous achievements of MOF-based membranes in gas separations, liquid separations are also being explored for the purpose of constructing continuous MOFs membranes or MOF-based mixed matrix membranes. Although these are in an emerging stage of vigorous development, most efforts are directed towards improving the liquid separation efficiency with well-designed MOF-based membranes. Therefore, as an increasing trend in membrane separation, the field of MOF-based membranes for liquid separation is highlighted in this review. The criteria for judicious selection of MOFs in fabricating MOF-based membranes are given. Special attention is paid to rational design strategies for MOF-based membranes, along with the latest application progress in the area of liquid separations, such as pervaporation, water treatment, and organic solvent nanofiltration. Moreover, some attractive dual-function applications of MOF-based membranes in the removal of micropollutants, degradation, and antibacterial activity are also reviewed. Finally, we define the remaining challenges and future opportunities in this field. This Tutorial Review provides an overview and outlook for MOF-based membranes for liquid separations. Further development of MOF-based membranes for liquid separation must consider the demands of strict separation standards and environmental safety for industrial application. [ABSTRACT FROM AUTHOR]

This study aims to immobilise molecularly imprinted polymers (MIPs) on the surface of yolk–shell magnetic mesoporous carbon (Fe3O4@void@C) spheres for phthalate ester (PAE) recognition through an effective route. To link MIPs to Fe3O4@void@C spheres, carboxyl-modified yolk–shell magnetic mesoporous carbon (Fe3O4@void@C–COOH) was synthesised by first oxidising Fe3O4@void@C with H2O2, and MIPs were subsequently grafted on the surface of Fe3O4@void@C–COOH by a surface polymerisation method with diisononyl phthalate (DINP), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as template molecule, functional monomer and cross-linker, respectively. The structure and morphology of the synthesised materials were characterised by XRD, TEM, SEM, FT-IR, N2 sorption and magnetic susceptibility measurements. The synthesis conditions for the formation of Fe3O4@void@C–COOH were systematically investigated. It was observed that the chemical modification of Fe3O4@void@C is highly influenced by the type of oxidant, the concentration of H2O2, oxidation temperature and time. The adsorption isotherm and kinetics of Fe3O4@void@C-MIPs showed that Fe3O4@void@C-MIPs possessed good recognition, fast adsorption rates (approximately 20 min to reach equilibrium) and high adsorption capacities (569.2 mg g−1) toward PAEs, which were ascribed to their uniformity and monodispersity. In addition, Fe3O4@void@C-MIPs exhibited excellent reusability for the adsorption of PAEs over six adsorption–desorption cycles. [ABSTRACT FROM AUTHOR]

Upconversion nanoparticles (UCNPs) have been used as building blocks in the construction of multimodal contrast agents for theranostics, that is, the combination of diagnostics and therapies. Upconversion luminescence (UCL) imaging is widely used for cell and tissue imaging while magnetic resonance imaging (MRI) is well-suited for in vivo imaging. Photothermal therapy (PTT) using (near-infrared) NIR laser radiation constitutes a minimally invasive alternative to the conventional surgical treatment of cancer. As such, multifunctional Mn-complex modified NaDyF4:Yb@NaLuF4:Yb,Er@polydopamine (PDA) nanocomposites (Dy@Lu@PDA–Mn) were synthesized, which was based on the fact that Yb3+ and Er3+ induce UCL, Dy3+ and Mn2+ interferes with T2 and T1 in MRI, and PDA strongly absorbs in the NIR region for PTT. Through tri-modal UCL, T1-, T2-weighted MRI guiding, an outstanding photothermal therapeutic efficacy with tumour elimination was obtained in a mice breast cancer model, by injection of Dy@Lu@PDA–Mn upon laser irradiation. A strategy for multimodal imaging-guided PTT was formulated and the potential of multifunctional nanostructures for use in cancer theranostics was demonstrated. [ABSTRACT FROM AUTHOR]

A dual-doping approach for nitrogen-doped carbon-coated SnO2–SnS/graphene nanosheets (N–C@SnO2–SnS/GN) has been developed, using hydrothermal carbonization of sucrose with SnO2-decorated graphene and ammonium thiocyanate and a subsequent thermal treatment. The resulting hybrid manifests a typical two-dimensional core–shell architecture, with a N-doped carbon coating over the SnS- and SnO2-decorated graphene nanosheets. Used as the anode material in lithium ion batteries (LIBs), N–C@SnO2–SnS/GN delivers a high specific capacity of 1236 mA h g−1 at a current density of 0.1 A g−1 after 110 cycles, which outperforms most state-of-the-art tin-based LIB anodes with core–shell structures. [ABSTRACT FROM AUTHOR]

We present a three-dimensional (3D) micro-traps array for size selective sorting and patterning of microbeads via evaporation-driven capillary flow. The interconnected micro-traps array was manufactured by silicon micromachining. Microliters of aqueous solution containing particle mixtures of different sized (0.2 to 20 μm diameter) beads were dispensed onto the micro-traps substrate. The smaller particles spontaneously wicked towards the periphery of the chip, while the larger beads were orderly docked within the micro-traps array. [ABSTRACT FROM AUTHOR]

Electron microscopy, an important technique that allows for the precise determination of structural information with high spatiotemporal resolution, has become indispensable in unravelling the complex relationships between material structure and properties ranging from mesoscale morphology to atomic arrangement. However, beam-sensitive materials, particularly those comprising organic components such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), would suffer catastrophic damage from the high energy electrons, hindering the determination of atomic structures. A low-dose approach has arisen as a possible solution to this problem based on the integration of advancements in several aspects: electron optical system, detector, image processing, and specimen preservation. This article summarizes the transmission electron microscopy characterization of MOFs and COFs, including local structures, host-guest interactions, and interfaces at the atomic level. Revolutions in advanced direct electron detectors, algorithms in image acquisition and processing, and emerging methodology for high quality low-dose imaging are also reviewed. Finally, perspectives on the future development of electron microscopy methodology with the support of computer science are presented.

A heterophase structure combining semiconducting 2H- and metallic 1T-MoS 2 exhibits significantly enhanced photoelectrochemical performance due to the electrical coupling and synergistic effect between the phases. Therefore, site-selective effective phase engineering is crucial for the fabrication of MoS 2 -based photoelectrochemical devices. Here, we employed a flash phase engineering (FPE) strategy to precisely fabricate a 2H-1T heterophase structure. This technique allows simple, efficient, and precise control over the micropatterning of MoS 2 nanofilms while enabling site-selective phase transition from the 1T to the 2H phase. The detection of reduced glutathione (GSH) showed an approximately 5-fold increase in sensitivity when using the electrode fabricated by FPE., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Wavelength-dependent absorbance of blood has impeded the development of fluorescence biodetection in whole blood. Here, by replacing the fluorescence working signal with a temperature signal, reliable H 2 S detection was performed in samples of whole blood. The developed system was based on a dual-channel lanthanide-doped nanoprobe, which further allowed precise serodiagnosis of acute pancreatitis.

Photoreduction of CO 2 into CO, CH 4 or hydrocarbons is attractive, due to environmental compatibility and economic feasibility. Optimizing the reaction engineering of CO 2 reduction is an effective and general strategy that should be given special consideration. In this article, the photocatalytic CO 2 reduction performances are originally investigated in a low vacuum in both dilute (10%) and pure CO 2 . We discover that the CH 4 yield increased above one hundred times as the vacuum degree increased from barometric pressure to -80 kPa in dilute CO 2 . It also reveals long-term stability and good cycling performance in a low vacuum. The enhanced CO 2 photoreduction performance in a low vacuum comes from better accumulation of photogenerated electrons, less intense Brownian movement of gas molecules in the environment and hindrance of the active site-blocking of gas molecules in the environment. Improved photocatalytic CO 2 reduction in a low vacuum is further verified by Pt-TiO 2 catalysts. This research presents a general route for producing clean fuels by photocatalytic CO 2 reduction in a more effective way.

Benefitting from excellent thermal and moisture stability, inorganic halide perovskite materials have established themselves quickly as promising candidates for fabricating photoelectric devices. However, due to their high trap state density and rapid carrier recombination rate, the photoelectric conversion efficiencies of current inorganic halide perovskite materials are still lower than expected. Here, after systematic research on the optoelectronic properties of CsPbBr 3 nanowires (NWs) decorated with binary CdS quantum dots (QDs), CdS@ZnS core/shell QDs, and gradient-alloyed CdS@Cd x Zn 1- x S QDs, respectively, we proposed a facile method to improve the quantum efficiency of perovskite-based photodetectors with low cost, in which the aforementioned QDs are firstly integrated with CsPbBr 3 NWs, which act as a photosensitive layer. Notably, the responsivity of the CsPbBr 3 NW photodetector decorated with CdS@Cd x Zn 1- x S QDs was enhanced about 10-fold compared to that of pristine CsPbBr 3 NW devices. This value is far superior to those for hybrids composed of binary CdS QDs and CdS@ZnS core/shell QDs. The high responsivity enhancement phenomena are interpreted based on the unique funnel-shaped energy level of CdS@Cd x Zn 1- x S QDs, which is favorable for light-harvesting and photocarrier separation. This work indicates that our unique QD/NW hybrid nanostructure is a desirable building block for fabricating high-performance photodetectors.

5-Hydroxymethylfurfural (HMF) is one of the most important platform molecules and could be transformed into a variety of fuel additives and high value-added chemicals. Multiple catalyst systems have been developed for the conversion of carbohydrates to HMF, but there are still unavoidable problems, including high temperature and pressure, difficult recovery of solvent, corrosion of equipment, poor catalyst circulation, etc. Herein, a new magnetic Fe 3 O 4 @SiO 2 @mSiO 2 -TaOPO 4 catalyst for the preparation of HMF from fructose in 2-pentanol was developed. The structures of the catalysts were characterized by FT-IR, TSM, EDS, SEM, XRD and VSM. The 2-pentanol solvent is not only conducive to the production of HMF, but also enables the reaction to be carried out at a lower pressure. The highest yield of HMF (85.4%) was obtained using 20 wt% catalyst under 10% substrate concentration (0.5 g of fructose) at 120 °C for 3 h. The catalysts can be easily separated by magnetism. The slight decrease in catalyst activity after 7 cycles was mainly due to the loss of catalyst during the cycle operation. Simultaneously, the total yield of HMF was 51.3% after scale-up to 15 g of fructose, showing the possible industrial application potential of this catalyst system., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Hydrogen is a promising substitute for non-renewable fossil fuels. Producing hydrogen fuel by electrolyzing water is an effective strategy to address the growing environmental problems. Platinum (Pt) is still the most active electrocatalyst to catalyze the hydrogen evolution reaction (HER) in alkaline media. Herein, we demonstrate that ultrafine candied haws-shaped PtWNi nanoalloys modified with the Ni species (Ni n+ ) could be formed in the alkaline electroactivation process of PtWNi alloys. Notably, the Ni species (Ni n+ ) promoted the decomposition of water and produced hydrogen intermediates, which were then immediately adsorbed on the surface of Pt and recombined into molecular hydrogen. Moreover, these hydrogen intermediates also enhanced the instability of the HO-H bond, leading to an increase in the total activity.

We report a facile surface-induced method for the in situ growth of single-/few-layered crystalline fluorographdiyne film on the surface of carbon fibers (cFGDY). The crystallized structure of cFGDY was directly confirmed by the scanning/transmission electron microscopy (SEM/TEM), high-resolution TEM (HRTEM) and computer simulation, selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. cFGDY showed a 9-fold stacking mode. Our results show that cFGDY is a metal-free electrocatalyst with unique structure and excellent performance for ammonia production from nitrogen and water efficiently at room temperature and ambient pressure, achieving a high NH 3 production rate and Faraday efficiency in neutral conditions. This work provides an efficient catalyst system with determined chemical and electronic structures for highly selective and active nitrogen reduction, serving as a promising platform towards the development of novel metal-free catalysts.

Lung injury is a hydrogen sulfide (H 2 S)-associated complication with high mortality in acute pancreatitis (AP) cases. Herein, we used Prussian Blue (PB) as a H 2 S-responsive acceptor to develop a novel pure-inorganic upconversion nanoprobe for detecting and eliminating H 2 S, which can be used for diagnosing AP and alleviating lung injury. Upconversion nanoprobes with 5 nm PB shells were optimized to achieve outstanding in vitro H 2 S detection capacity (linear range: 0-150 μM, LOD: 50 nM), which met the in vivo serum H 2 S range, and thus were feasible for imaging H 2 S in vivo . More importantly, when combined with the traditional H 2 S synthetase inhibitor dl-PAG, the nanoprobes also served as a therapeutic agent that synergistically alleviated lung injury. As PB is an FDA-approved drug, our work proposes a potential clinical modality for the early diagnosis of AP, which will decrease lung injury-induced mortality and increase the survival rates of AP cases.

Upconversion nanoparticles (UCNPs) have been used as building blocks in the construction of multimodal contrast agents for theranostics, that is, the combination of diagnostics and therapies. Upconversion luminescence (UCL) imaging is widely used for cell and tissue imaging while magnetic resonance imaging (MRI) is well-suited for in vivo imaging. Photothermal therapy (PTT) using (near-infrared) NIR laser radiation constitutes a minimally invasive alternative to the conventional surgical treatment of cancer. As such, multifunctional Mn-complex modified NaDyF 4 :Yb@NaLuF 4 :Yb,Er@polydopamine (PDA) nanocomposites (Dy@Lu@PDA-Mn) were synthesized, which was based on the fact that Yb 3+ and Er 3+ induce UCL, Dy 3+ and Mn 2+ interferes with T 2 and T 1 in MRI, and PDA strongly absorbs in the NIR region for PTT. Through tri-modal UCL, T 1 -, T 2 -weighted MRI guiding, an outstanding photothermal therapeutic efficacy with tumour elimination was obtained in a mice breast cancer model, by injection of Dy@Lu@PDA-Mn upon laser irradiation. A strategy for multimodal imaging-guided PTT was formulated and the potential of multifunctional nanostructures for use in cancer theranostics was demonstrated.