Latest ArticlesSulfates are always promising short-wave ultraviolet (UV) nonlinear optical (NLO) candidates, if their birefringence could be greatly improved. Here, in terms of the insufficient birefringence, the unity of heteroleptic tetrahedral groups and triangular ones was proposed and implemented. Thus, a new semi-organic crystal, [C(NH2)3]S3O6 (G2S3O6), was obtained, which is composed of [S3O6]2− and [C(NH2)3]+ groups. It exhibits excellent optical properties with a short absorption cutoff edge of 218 nm, a strong NLO response of 1.4 × KH2PO4, and more especially, a large birefringence of 0.097@546 nm. This birefringence leap makes the G2S3O6 crystal achieve a phase-matching behavior under a 532 nm laser. Thus, the synergy of [S3O6]2− and [C(NH2)3]+ groups results in excellent optical performances. This finding opens a new horizon for exploring novel UV NLO crystals.
Platinum (Pt) nanoparticle catalysts remain the most popular cathode materials for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. Non-metallic alloying of Pt has become an emerging strategy to improve electrocatalytic performance, however, the electrocatalytic ORR mechanisms still need to be understood for further improvement toward practical application. Herein, a rapid microwave reduction method is employed for alloying phosphorous (P) into Pt to form a carbon supported phosphorus-alloyed Pt nanoparticle catalyst (P-Pt/C), which demonstrates the ability to replace commercial Pt/C. By a combination of density functional theory calculations and in-situ electrochemical Raman spectroscopy, the regulation role of P-alloying in the electrocatalytic mechanisms is revealed. It is found that the nearby Pt atoms can convert the ORR pathway from associative one to dissociative one, exhibiting a spontaneous dissociation of *OOH intermediate to *OH and *O species as well as a change of potential determining step to *O protonation. Furthermore, the strategy of large-scale economic synthesis of such alloying Pt-based catalyst is also established, demonstrated by a gram-level synthesis per batch. This study puts insight into the electrocatalytic ORR fundamentals of Pt-alloying with non-metals and provides a basis for the reasonable design and synthesis of efficient nonmetals-alloyed Pt catalysts.
Prostaglandin E2 (PGE2) serves as the ultimate mediator of fever induced by inflammatory factors. In contrast to cyclooxygenase inhibitors that suppress arachidonic acid metabolism, antipyretic herbs possess a well-established clinical history in effectively managing fever. However, the specific mechanisms underlying their efficacy remain unclear. Following the screening for lead compounds that inhibit PGE2 from antipyretic herbs, alkynylated active molecule probes were designed and synthesized to track and identify potential targets. The target investigation revealed that three antipyretic compounds, namely cinnamaldehyde, 2,4-decadienal, and perillaldehyde, containing α,β-unsaturated aldehyde groups irreversibly targeted the microsomal PGES1-TM4 helix (mPGES1-TM4) at Ser139. This specific interaction effectually inhibited PGE2 production in the cerebral vasculature, leading to exert potent antipyretic effects. α,β-Unsaturated aldehydes targeting mPGES1-TM4 offer a new approach for antipyretic effects with significant potential for various applications.
Polyphosphazene with phenoxy or 4-ester phenoxy as pendent groups are demonstrated as both ligands and host matrices for CsPbBr3 perovskite nanocrystals (NCs). These polymers produced flexible nanocomposite films with excellent NCs dispersion, optical transparency and stability in various extreme conditions. Both films remained stable even after 30 days of air storage. CsPbBr3/poly[bis(phenoxy phosphazene)] (PBPP) delivered better air and light stability, and CsPbBr3/poly[bis(4-esterphenoxy)phosphazene] (PBEPP) exhibited superior water and heat resistance. CsPbBr3/PBEPP showed a greater increase in fluorescence intensity under 365 nm UV light and demonstrated a 10% luminescence increase after 96 h of water immersion and even at high temperature (150 ℃). These findings thus provide new insight into flexible luminescent CsPbBr3 films with high stability in optoelectronic applications.
Molecular recognition of fullerene using various host compounds is well-known in literature. But most studies focus on host-guest complexation in solution using host compounds with a single binding cavity. Herein, we report a series of highly preorganized janusarene derivatives with homoditopic binding sites. These novel janusarenes can bind and align various fullerenes such as C60, C70, C84, and Gd@C82 in a highly efficient manner. Robust shape complementary association and assembly are observed in solution, in the bulk solid state, in the liquid crystalline state, or on surface, and the assembled structures are characterized by nuclear magnetic resonance (NMR) titration, X-ray diffraction, polarized optical microscopy, and scanning tunneling microscopy.
Visual assessment of tumor metastatic capacity is crucial for predicting hepatocellular carcinoma (HCC) prognosis and guiding clinical therapeutic approaches. In this study, we developed an enzyme-responsive probe based on the peptide GK10, which is selectively cleaved by matrix metalloproteinase-9 (MMP-9), a critical marker for metastasis in HCC. The GK10 peptide was conjugated with near-infrared fluorescent molecule IR783, fluorescent quencher black hole quencher 3 (BHQ3), and magnetic resonance (MR) contrast agent DOTA-Gd, forming the IR783-GK10-BHQ3-Gd probe. Upon MMP-9 cleavage of GK10, BHQ3 is released from the probe, thereby amplifying the previously quenched IR783 fluorescence signal. In vitro experiments demonstrate the probe’s impressive detection limit for MMP-9, as low as 1.84 ng/mL. Moreover, in vivo imaging results reveal that the probe can differentiate liver cancers with varying metastatic capacities. The fluorescence and MR imaging signal intensity of high metastatic HCC are approximately 1.2 times greater than that of low metastatic HCC. Thus, this engineered probe holds promise as a valuable tool for evaluating HCC metastatic capacity through fluorescence-MR dual-mode imaging.
The oxygen evolution reaction (OER) is the bottleneck in the overall photocatalytic splitting of water. The active sites (terminal titanium or bridging oxygen) and active species (molecular or dissociative water) of the initial step of the photocatalyzed OER on the prototypical photocatalyst TiO2, remain debatable. Herein, the photocatalytic chemistry of monolayer water on oxygen-pretreated TiO2(110) (o-TiO2(110)) and reduced TiO2(110) (r-TiO2(110)) surfaces initiated by 400 nm light illumination was investigated by time-dependent two-photon photoemission spectroscopy (TD-2PPE). The photoinduced reduction of the H2O/o-TiO2(110) interface rather than the H2O/r-TiO2(110) interface was detected by TD-2PPE. The difference in 2PPE originated from the presence of the terminal hydroxyl anions (OHt¯) on H2O/o-TiO2(110), as identified by X-ray photoelectron spectroscopy and temperature-programmed desorption. Therefore, the evolution of the electronic structure of H2O/o-TiO2(110) was attributed to the photocatalyzed oxidation of the terminal hydroxyl anions, which most likely formed gaseous •OH radicals, reducing the interface. This work suggested that the oxidation of hydroxyl anions on top of the terminal titanium ions on TiO2, which were excluded previously in solution, need to be considered in the mechanistic studies of the photocatalyzed OER.
Acute lung injury (ALI) is a critical respiratory disorder with a high mortality rate and is caused by several factors. Addressing oxidative stress and inflammation is a pivotal strategy for ALI treatment. In this study, we introduced a novel nanotherapeutic approach involving a curcumin-loaded ceria nanoenzyme delivery system tailored to counteract the multifaceted aspects of ALI. This system leverages the individual and combined effects of the components to provide a comprehensive therapeutic solution. The dual-action capability of this nanosystem was manifested by mitigating mitochondrial oxidative stress in lung epithelial cells and inhibiting the transient receptor potential melanosome-associated protein 2 (TRPM2)-NOD-like receptor thermal protein domain associated protein 3 (NLRP3) signaling pathway, offering a highly effective therapeutic approach to ALI. Our findings reveal the underlying mechanisms of this innovative nanodelivery system, showcasing its potential as a versatile strategy for ALI treatment and encouraging further exploration of nanoenzyme-based therapies for ALI.
Developing high-efficient and low-loading Pt based catalyst is significant for the electrocatalytic pH-universal hydrogen evolution reaction (HER). Herein, the molybdenum carbide nanoparticles supported on the polyhedral N-doped carbon nanotube skeleton (MoC/NCT) composite has been synthesized by a pyrolysis of polyacid organo-metallic phosphate framework precursor. Then, only 2.15 wt% Pt are loaded on the MoC/NCT to form Pt-MoC/NCT catalyst, which performs superior HER activity and stability in entire pH range. Specially, the overpotentials of 22 and 74 mV are respectively attained at 10 mA/cm2 in 1.0 mol/L KOH and 0.5 mol/L H2SO4 electrolytes, approaching or even exceeding commercial Pt/C. More importantly, it can be used as excellent catalyst for efficient hydrogen production at 0–14 pH range. Density functional theory (DFT) calculations demonstrate that the interaction between MoC and Pt leads to the electron redistribution at the corresponding interfaces and the downward shift of the d-band centers, thus optimizing H* adsorption and desorption for promoting the HER activity. Besides, the unique three-dimensional network structure is conductive to the transmission of mass and electrons. In the application of both alkaline and acidic electrolysers, only 1.52 V voltage of solar panel can drive a hydrogen production current density of 10 mA/cm2.
Lead-free hybrid double perovskites (LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic properties has not yet been investigated. Herein, we synthesized two new Ruddlesden–Popper LFHDPs, namely (C5H12N)4AgBiI8 (CAB-1) and (C6H14N)4AgBiI8 (CAB-2) using cyclopentylamine and cyclohexylamine as monoamine ligands. Indeed, these two Ag(Ⅰ)-Bi(Ⅲ) LFHDPs form smooth and uniform films ranging in thickness from 250 nm to 1 µm, with preferred orientations. Notably, the studies on the optical properties showed that the direct band gap value decreased from 2.17 eV to 1.91 eV for CAB-1 and from 2.05 eV to 1.86 eV for CAB-2 with increasing thickness. Accordingly, photo-current response using a xenon lamp revealed a significant difference of over 1000 nA between light and dark conditions for 1 µm-thickness films, suggesting potential for light harvesting. Other than that, thicker films of CAB-1 and CAB-2 exhibit high stability for 90 days in a relatively humid environment (RH of 55%), paving the way for promising optoelectronic applications.
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