Improving Photophysical Properties and Hydrophily of Conjugated Polymers Simultaneously by Side-Chain Modification for Near-Infrared Cell Imaging.

Conjugated polymers (CPs)-based near-infrared phototheranostics are receiving increasing attention due to their high molar extinction coefficient, wide emission wavelength, easy preparation and excellent biocompatibility. Herein, several new conjugated polymers with D2-D1-A structures were easily prepared through one-pot coupling using triphenylamine (D2) as well as thiophenes (D1) as electron donors and benzothiadiazole (A) as electron acceptors. Interesting, their optical performance and power conversion efficiency could be tuned by side chains on thiophenes (D1). The introduction of ethylenedioxy into D1 as side chain significantly improves fluorescence imaging brightness, photothermal conversion efficiency and hydrophilicity, and extends emission wavelength, which are beneficial for phototheranostic. The side chain modification provides new opportunity to design efficient phototheranostics without construction new fluorescent skeletons.

Dual Enzyme-Locked Activation Reporter for Accurate Liver Cancer Surveillance.

Activatable probes with a higher signal-to-background ratio and accuracy are essential for monitoring liver cancer as well as intraoperative fluorescence navigation. However, the presence of only one biomarker is usually not sufficient to meet the high requirement of a signal-to-background ratio in cancer surveillance, leading to the risk of misdiagnosis. In this work, a dual-locked activation response probe, Si-NTR-LAP, for nitroreductase and leucine aminopeptidase was reported. This dual-locked probe provides better tumor recognition and a higher signal-to-noise ratio than that of single-locked probes (Si-LAP and Si-NTR). In both the subcutaneous tumor model and the more complex orthotopic hepatocellular carcinoma model, the probe was able to identify tumor tissue with high specificity and accurately differentiate the boundaries between tumor tissue and normal tissue. Therefore, the dual-locked probe may provide a new and practical strategy for applying to real patient tumor tissue samples.

Machine-Learning-Assisted Rational Design of Si─Rhodamine as Cathepsin-pH-Activated Probe for Accurate Fluorescence Navigation.

High-performance fluorescent probes stand as indispensable tools in fluorescence-guided imaging, and are crucial for precise delineation of focal tissue while minimizing unnecessary removal of healthy tissue. Herein, machine-learning-assisted strategy to investigate the current available xanthene dyes is first proposed, and a quantitative prediction model to guide the rational synthesis of novel fluorescent molecules with the desired pH responsivity is constructed. Two novel Si─rhodamine derivatives are successfully achieved and the cathepsin/pH sequentially activated probe Si─rhodamine─cathepsin-pH (SiR─CTS-pH) is constructed. The results reveal that SiR─CTS-pH exhibits higher signal-to-noise ratio of fluorescence imaging, compared to single pH or cathepsin-activated probe. Moreover, SiR─CTS-pH shows strong differentiation abilities for tumor cells and tissues and accurately discriminates the complex hepatocellular carcinoma tissues from normal ones, indicating its significant application potential in clinical practice. Therefore, the continuous development of xanthene dyes and the rational design of superior fluorescent molecules through machine-learning-assisted model broaden the path and provide more advanced methods to researchers.

Coupling Nano and Atomic Electric Field Confinement for Robust Alkaline Oxygen Evolution.

The alkaline oxygen evolution reaction (OER) is a promising avenue for producing clean fuels and storing intermittent energy. However, challenges such as excessive OH- consumption and strong adsorption of oxygen-containing intermediates hinder the development of alkaline OER. In this study, we propose a cooperative strategy by leveraging both nano-scale and atomically local electric fields for alkaline OER, demonstrated through the synthesis of Mn single atom doped CoP nanoneedles (Mn SA-CoP NNs). Finite element method simulations and density functional theory calculations predict that the nano-scale local electric field enriches OH- around the catalyst surface, while the atomically local electric field improves *O desorption. Experimental validation using in situ attenuated total reflection infrared and Raman spectroscopy confirms the effectiveness of the nano-scale and atomically electric fields. Mn SA-CoP NNs exhibit an ultra-low overpotential of 189 mV at 10 mA cm-2 and stable operation over 100 hours at ~100 mA cm-2 during alkaline OER. This innovative strategy provides new insights for enhancing catalyst performance in energy conversion reactions.

Rational design of type-I photosensitizer molecules for mitochondrion-targeted photodynamic therapy.

Photodynamic therapy (PDT) has emerged as a promising approach for tumor treatment. However, traditional type II PDT faces limitations due to its oxygen-dependent nature. Type-I photosensitizers (PSs) exhibit superiority over conventional type-II PSs owing to their diminished oxygen dependence. Nevertheless, designing effective type-I PSs remains a significant challenge. In this work, we provide a novel strategy to tune the PDT mechanism of an excited photosensitizer through aryl substituent engineering. Using S-rhodamine as the base structure, three PSs were synthesized by incorporating phenyl, furyl, or thienyl groups at the meso position. Interestingly, furyl- or thienyl-substituted S-rhodamine are type-I-dominated PSs that produce O2˙-, while phenyl S-rhodamine results in O2˙- and 1O2 through type-I and type-II mechanisms, respectively. Experimental analyses and theoretical calculations showed that the introduction of a five-membered heterocycle at the meso position promoted intersystem crossing (ISC) and electron transfer, facilitating the production of O2˙-. Furthermore, furyl- or thienyl-substituted S-rhodamine exhibited high phototoxicity at ultralow concentrations. Thienyl-substituted S-rhodamine showed promising PDT efficacy against hypoxic solid tumors. This innovative strategy provides an alternative approach to developing new type-I PSs without the necessity for creating entirely new skeletons.

Identification and quantification of N6-methyladenosine by chemical derivatization coupled with 19F NMR spectroscopy.

N 6-Methyladenosine (6mA) is a well-known prokaryotic DNA modification that has been shown to play epigenetic roles in eukaryotic DNA. Accurate detection and quantification of 6mA are prerequisites for molecular understanding of the impact of 6mA modification on DNA. However, the existing methods have several problems, such as high false-positive rate, time-consuming and complex operating procedures. Chemical sensors for the selective detection of 6mA modification are rarely reported in the literature. Fluorinated phenylboronic acid combined with 19F NMR analysis is an effective method for determining DNA or RNA modification. In this study, we presented a simple and fast chemical method for labelling the 6th imino group of 6mA using a boric-acid-derived probe. Besides, the trifluoromethyl group of trifluoromethyl phenylboronic acid (2a) could detect 6mA modification through 19F NMR. Combined with this sensor system, 6mA modification could be detected well and quickly in 6 types of deoxynucleoside mixtures and DNA samples. Taken together, the method developed in the current study has potential for specific detection of 6mA in biological samples.

Sustainable conversion of alkaline nitrate to ammonia at activities greater than 2 A cm-2.

Nitrate (NO3‒) pollution poses significant threats to water quality and global nitrogen cycles. Alkaline electrocatalytic NO3‒ reduction reaction (NO3RR) emerges as an attractive route for enabling NO3‒ removal and sustainable ammonia (NH3) synthesis. However, it suffers from insufficient proton (H+) supply in high pH conditions, restricting NO3‒-to-NH3 activity. Herein, we propose a halogen-mediated H+ feeding strategy to enhance the alkaline NO3RR performance. Our platform achieves near-100% NH3 Faradaic efficiency (pH = 14) with a current density of 2 A cm-2 and enables an over 99% NO3--to-NH3 conversion efficiency. We also convert NO3‒ to high-purity NH4Cl with near-unity efficiency, suggesting a practical approach to valorizing pollutants into valuable ammonia products. Theoretical simulations and in situ experiments reveal that Cl-coordination endows a shifted d-band center of Pd atoms to construct local H+-abundant environments, through arousing dangling O-H water dissociation and fast *H desorption, for *NO intermediate hydrogenation and finally effective NO3‒-to-NH3 conversion.

Three-Dimensional Porous Indium Single-Atom Catalysts with Improved Accessibility for CO2 Reduction to Formate.

Single-atom catalysts (SACs) present substantial potential in electrocatalytic CO2 reduction reactions; however, inferior accessibility of single-atom sites to CO2 limits the overall CO2RR performances. Herein, we propose to improve the accessibility between In sites and CO2 through the construction of a three-dimensional (3D) porous indium single-atom catalyst (In1/NC-3D). The NaCl template-mediated synthesis strategy generates the unique 3D porous nanostructure of In1/NC-3D. Multiple characterizations validate that In1/NC-3D exhibits increased exposure of active sites and enhanced CO2 transport/adsorption capacity compared to the bulk In1/NC, thus improving accessibility of active sites to CO2. As a result, the In1/NC-3D presents superior CO2RR performance to the bulk In1/NC, with a partial current density of formate of 67.24 mA cm-2 at -1.41 V, relative to a reversible hydrogen electrode (vs RHE). The CO2RR performances with high formate selectivity at a large current density also outperform most reported In-based SACs. Importantly, the In1/NC-3D is demonstrated to maintain an FEformate of >82% at -66.83 mA·cm-2 over 21 h. This work highlights the design of a 3D porous single-atom catalyst for efficient CO2RR, promoting the development of advanced catalysts toward advanced energy conversion.

Wet Film Leveling for Promoting the Uniformity and Conductivity of Silver Nanowire Transparent Electrode.

Wet film leveling can greatly promote film uniformity. However, in the field of metal nanowire, wet film leveling is rarely mentioned. For low-viscosity inks like metal nanowire ink, how to realize wet film leveling is still unclear. Herein, we study the wet film leveling of silver nanowire ink and systematically investigate the relationship between leveling effect and influence factors: (1) there is a uniformity-promotion limit for traditional methods, while wet film leveling can break through this limit and further promote the film uniformity; (2) for wet film leveling, lowering ink's surface tension has no effect, and eliminating surface tension gradient by high-surface-tension leveling agent is the main task; (3) leveling process includes wet film destruction process and ink reflow process; (4) in the destruction process, the leveling-agent solubility and quantity dominate the leveling effect, while the influence of surface tension is little; (5) for solubility and quantity, there is a suitable range to realize optimum leveling effect, and the leveling effect exhibits a contrary relationship with the solubility in a suitable range (2-11%); (6) in the reflow process, the main influence factor is ink viscosity, and the leveling effect exhibits a contrary relationship with ink viscosity. After being leveled by 1.5% n-pentanol, the sheet resistance and sheet-resistance variation coefficient of film decrease from 38.3 Ω/sq/3.83% to 25.7 Ω/sq/1.88%. Further study reveals that the film improvement is not from the ink wettability and drying. Above theoretical results possess certain universality for film preparation by a wet process and can be used by the science and industry field.

Mn Single-Atom Tuning Fe-N-C Catalyst Enables Highly Efficient and Durable Oxygen Electrocatalysis and Zinc-Air Batteries.

Fe-N-C catalyst is one of most promising candidates for oxygen electrocatalysis reaction in zinc-air batteries (ZABs), but achieving sustained high activity is still a challenging issue. Herein, we demonstrate that introducing Mn single atoms into Fe-N-C (Mn1@Fe-N-C/CNTs) enables the realization of highly efficient and durable oxygen electrocatalysis performance and application in ZABs. Multiple characterizations confirm that Mn1@Fe-N-C/CNTs is equipped with Mn-N2O2 and Fe-N4 sites and Fe nanoparticles. The Mn-N2O2 sites not only tune the electron structure of Fe-Nx sites to enhance intrinsic activity, but also scavenge the attack of radicals from Fe-Nx sites for improvement in ORR durability. As a result, Mn1@Fe-N-C/CNTs exhibits enhanced ORR performance to traditional Fe-N-C catalysts with high E1/2 of 0.89 V vs reversible hydrogen electrode (RHE) and maintains ORR activity after 15 000 CV. Impressively, Mn1@Fe-N-C/CNTs also presents excellent OER activity and the difference (ΔE) between E1/2 of ORR and OER potential at 10 mA cm-2 (Ej10) is only 0.59 V, outperforming most reported catalysts. In addition, the maintainable bifunctional activity of Mn1@Fe-N-C/CNTs is demonstrated in ZABs with almost unchanged cycle voltage efficiency up to 200 h. This work highlights the critical role of Mn single atoms in enhancing ORR activity and stability, promoting the development of advanced catalysts.

Molecular Engineering of Sulfone-Xanthone Chromophore for Enhanced Fluorescence Navigation.

Enriching the palette of high-performance fluorescent dyes is vital to support the frontier of biomedical imaging. Although various rhodamine skeletons remain the premier type of small-molecule fluorophores due to the apparent high brightness and flexible modifiability, they still suffer from the inherent defect of small Stokes shift due to the nonideal fluorescence imaging signal-to-background ratio. Especially, the rising class of fluorescent dyes, sulfone-substituted xanthone, exhibits great potential, but low chemical stability is also pointed out as the problem. Molecular engineering of sulfone-xanthone to obtain a large Stokes shift and high stability is highly desired, but it is still scarce. Herein, we present the combination modification method for optimizing the performance of sulfone-xanthone. These redesigned fluorescent skeletons owned greatly improved stability and Stokes shift compared with the parent sulfone-rhodamine. To the proof of bioimaging capacity, annexin protein-targeted peptide LS301 was introduced to the most promising dyes, J-S-ARh, to form the tumor-targeted fluorescent probe, J-S-LS301. The resulting probe, J-S-LS301, can be an outstanding fluorescence tool for the orthotopic transplantation tumor model of hepatocellular carcinoma imaging and on-site pathological analysis. In summary, the combination method could serve as a basis for rational optimization of sulfone-xanthone. Overall, the chemistry reported here broadens the scope of accessible sulfone-xanthone functionality and, in turn, enables to facilitate the translation of biomedical research toward the clinical domain.

Design and implementation of a dual aspheric integrated shaping element for a high-power fiber laser.

A dual aspheric integrated beam shaper suitable for a high-power laser situation has been designed and realized. The model for this lens was derived theoretically and the performance was evaluated using a detailed simulation. The ultrasonic vibration assisted cutting and the high-precision grinding and polishing technology were used for the processing. The surface accuracy was less than 200 nm measured with a profiler, and the roughness was smaller than 20 nm with the help of the white light interferometer. Shaping experiments were carried out, which verified that the Gaussian beam has uniform intensity distribution with a uniformity of 85.13% in the near field and converges to a point in the far field, which is exactly as expected. It thus provides an actual selection for high-power laser shaping.

Dipole field in nitrogen-enriched carbon nitride with external forces to boost the artificial photosynthesis of hydrogen peroxide.

Artificial photosynthesis is a promising strategy for efficient hydrogen peroxide production, but the poor directional charge transfer from bulk to active sites restricts the overall photocatalytic efficiency. To address this, a new process of dipole field-driven spontaneous polarization in nitrogen-rich triazole-based carbon nitride (C3N5) to harness photogenerated charge kinetics for hydrogen peroxide production is constructed. Here, C3N5 achieves a hydrogen peroxide photosynthesis rate of 3809.5 µmol g-1 h-1 and a 2e- transfer selectivity of 92% under simulated sunlight and ultrasonic forces. This high performance is attributed to the introduction of rich nitrogen active sites of the triazole ring in C3N5, which brings a dipole field. This dipole field induces a spontaneous polarization field to accelerate a rapid directional electron transfer process to nitrogen active sites and therefore induces Pauling-type adsorption of oxygen through an indirect 2e- transfer pathway to form hydrogen peroxide. This innovative concept using a dipole field to harness the migration and transport of photogenerated carriers provides a new route to improve photosynthesis efficiency via structural engineering.

Fine control for the preparation of ceria nanorods (111).

The morphologies and exposed surfaces of ceria nanocrystals are important factors in determining their performance. In order to establish a structure-property relationship for ceria nanomaterials, it is essential to have materials with well-defined morphologies and specific exposed facets. This is also crucial for acquiring high resolution 17O solid-state NMR spectra. In this study, we explore the synthesis conditions for preparing CeO2 nanorods with exposed (111) facets. The effects of alkali concentration, hydrothermal temperature and time, cerium source and oxidation agent are investigated and optimal synthesis conditions are found. The resulting CeO2 nanorods show very narrow 17O NMR peaks for the oxygen ions in the first, second and third layers, providing a foundation for future research on mechanisms involving ceria materials using 17O solid-state NMR spectroscopy.

Rational Design of pH-Independent and High-Fidelity Near-Infrared Tunable Fluorescent Probes for Tracking Leucine Aminopeptidase In Vivo.

Accurate detection of target analytes and generation of high-fidelity fluorescence signals are particularly critical in life sciences and clinical diagnostics. However, the majority of current NIR-I fluorescent probes are vulnerable to pH effects resulting in signal distortion. In this work, a series of fluorescence-tunable and pH-independent probes are reported by combining optically tunable groups of unsymmetric Si-rhodamines and introducing the methoxy instead of the spiro ring on the benzene ring at position 9. To validate the concept, the leucine aminopeptidase response site was introduced into Si-2,6OMe-NH2 with the best optical properties to synthesize Si-LAP for monitoring the intrahepatic LAP in vivo. Therefore, the design approach may provide a new and practical strategy for designing innovative functional fluorescent probes and generating high-stability and high-fidelity fluorescent signals.

Enhanced Electron Confinement of p-Block Indium Site in Extended Macrocyclic Conjugation Boosting Oxygen Reduction to Hydrogen Peroxide.

The electrocatalytic oxygen reduction reaction via a two-electron pathway (2e- ORR) is a promising route for hydrogen peroxide (H2O2) production. However, the strong electron interaction between the metal site and oxygen-containing intermediates usually generates 4-electron ORR, limiting H2O2 selectivity. Here, combining theoretical and experimental studies, we propose to enhance the electron confinement of the indium (In) center in an extended macrocyclic conjugation system toward high-efficiency H2O2 production. The extended macrocyclic conjugation in indium polyphthalocyanine (InPPc) evokes the attenuated transfer electron ability of the In center and weakens the interaction between the s orbital of In and the p obital of OOH*, favoring protonation of OOH* to H2O2. Experimentally, the prepared InPPc catalyst exhibits a noticeable H2O2 selectivity above 90% in 0.1-0.6 V vs RHE, outperforming the counterpart InPc. Importantly, the InPPc displays a high average H2O2 production rate of 23.77 mg/cm2/h in a flow cell. This study proposes a novel strategy to engineer molecular catalysts and provides new insights into the ORR mechanism.

Asymmetric Coordination Induces Electron Localization at Ca Sites for Robust CO2 Electroreduction to CO.

Main group single atom catalysts (SACs) are promising for CO2 electroreduction to CO by virtue of their ability in preventing the hydrogen evolution reaction and CO poisoning. Unfortunately, their delocalized orbitals reduce the CO2 activation to *COOH. Herein, an O doping strategy to localize electrons on p-orbitals through asymmetric coordination of Ca SAC sites (Ca-N3 O) is developed, thus enhancing the CO2 activation. Theoretical calculations indicate that asymmetric coordination of Ca-N3 O improves electron-localization around Ca sites and thus promotes *COOH formation. X-ray absorption fine spectroscopy shows the obtained Ca-N3 O features: one O and three N coordinated atoms with one Ca as a reactive site. In situ attenuated total reflection infrared spectroscopy proves that Ca-N3 O promotes *COOH formation. As a result, the Ca-N3 O catalyst exhibits a state-of-the-art turnover frequency of ≈15 000 per hour in an H-cell and a large current density of -400 mA cm-2 with a CO Faradaic efficiency (FE) ≥ 90% in a flow cell. Moreover, Ca-N3 O sites retain a FE above 90% even with a 30% diluted CO2 concentration.

Proton Transfer Dynamics-Mediated CO2 Electroreduction.

Electrochemical CO2 reduction reaction (CO2 RR) is crucial to addressing environmental crises and producing chemicals. Proton activation and transfer are essential in CO2 RR. To date, few research reviews have focused on this process and its effect on catalytic performance. Recent studies have demonstrated ways to improve CO2 RR by regulating proton transfer dynamics. This Concept highlights the use of regulating proton transfer dynamics to enhance CO2 RR for the target product and discusses modulation strategies for proton transfer dynamics and operative mechanisms in typical systems, including single-atom catalysts, molecular catalysts, metal heterointerfaces, and organic-ligand modified metal catalysts. Characterization methods for proton transfer dynamics during CO2 RR are also discussed, providing powerful tools for the hydrogen-involving electrochemical study. This Concept offers new insights into the CO2 RR mechanism and guides the design of efficient CO2 RR systems.

Engineering a conformal optical window of a square-to-circular transition isolator.

To realize the flow visualization of shock train structures by Schlieren measurements in a square-to-circular transition isolator, a high-precision conformal optical window was manufactured by fly-cutting technology. According to the light refraction principle, the window's outer surface was iteratively optimized based on the super-elliptic curves of the internal flow channel. Through tolerance analysis and processing parameter optimization, the transmitted wavefront error (RMS value) of the finished window was 0.823λ (λ=632.8n m). Based on a z-type Schlieren apparatus, the high-precision Schlieren measurements were conducted through the window and processed by an image filtering process method. The results promote high-precision Schlieren observation towards square-to-circular transition isolators.

γ-Glutamyltranspeptidase and pH based "AND" logic gate fluorescent probe for orthotopic breast tumor imaging.

An "AND" logic gate-based NIR fluorescent probe Si-NH2-Glu was developed based on novel meso-amine Si-Rhodamine, which combined γ-glutamyl transpeptidase and pH dual-responsive sites. The features of Si-NH2-Glu enable it to be applied in orthotopic tumor imaging and fluorescence-guided surgery.