Advances and challenges in identifying and characterizing G-quadruplex-protein interactions.

G-quadruplexes (G4s) are peculiar nucleic acid secondary structures formed by DNA or RNA and are considered as fundamental features of the genome. Many proteins can specifically bind to G4 structures. There is increasing evidence that G4-protein interactions involve in the regulation of important cellular processes, such as DNA replication, transcription, RNA splicing, and translation. Additionally, G4-protein interactions have been demonstrated to be potential targets for disease treatment. In order to unravel the detailed regulatory mechanisms of G4-binding proteins (G4BPs), biochemical methods for detecting G4-protein interactions with high specificity and sensitivity are highly demanded. Here, we review recent advances in screening and validation of new G4BPs and highlight both their features and limitations.

Dynamic single-molecule sensing by actively tuning binding kinetics for ultrasensitive biomarker detection.

SignificanceThe detection of low-abundance molecular biomarkers is key to the liquid-biopsy-based disease diagnosis. Existing methods are limited by the affinity and specificity of recognition probes and the mass transportation of analyte molecules onto the sensor surfaces, resulting in insufficient sensitivity and long assay time. This work establishes a rapid and ultrasensitive approach by actively tuning binding kinetics and accelerating the mass transportation via nanoparticle micromanipulations. This is significant because it permits extremely sensitive measurements within clinically acceptable assay time. It is incubation-free, washing-free, and compatible with low- and high-affinity probes.

Functional Interface for Glycoprotein Sensing: Focusing on Biosensors.

Glycosylated proteins or glycoproteins make up a large family of glycoconjugates, and they participate in a variety of fundamental biological events. Glycoproteins have become important biomarkers in the diagnosis and treatment of a number of tumors. Biosensors are quite suitable for glycoprotein detection. The design and fabrication of a functional sensing interface play a crucial role in the biosensor construction to target glycoproteins. The functional interface, particularly receptors, typically determines the key characteristics of a biosensor, such as selectivity and sensitivity. Antibody, peptide, aptamer, boronic acid derivative, lectin, and molecularly imprinted polymer are all capable receptors for glycoprotein recognition, and each of these will be discussed. Most glycoproteins exist in low abundance, thus rendering signal amplification techniques indispensable. Nucleic acid-mediated and nanomaterial-mediated signal amplification for the detection of glycoproteins will be focused on herein. This review aims to highlight these different functional interfaces for glycoprotein sensing.

Cardiac complications caused by biliary diseases: A review of clinical manifestations, pathogenesis and treatment strategies of cholecardia syndrome.

Gallbladder and biliary diseases (GBDs) are one of the most common digestive diseases. The connections between GBDs and several organs other than the liver have gradually surfaced accompanied by the changes in people's diet structure and the continuous improvement of medical diagnosis technology. Among them, cholecardia syndrome that takes the heart as the important target of GBDs complications has been paid close attention. However, there are still no systematic report about its corresponding clinical manifestations and pathogenesis. This review summarized recent reported types of cholecardia syndrome and found that arrhythmia, myocardial injury, acute coronary syndrome and heart failure are common in the general population. Besides, the clinical diagnosis rate of intrahepatic cholestasis of pregnancy (ICP) and Alagille syndrome associated with gene mutation is also increasing. Accordingly, the underlying pathogenesis including abnormal secretion of bile acid, gene mutation, translocation and deletion (JAG1, NOTCH2, ABCG5/8 and CYP7A1), nerve reflex and autonomic neuropathy were further revealed. Finally, the potential treatment measures and clinical medication represented by ursodeoxycholic acid were summarized to provide assistance for clinical diagnosis and treatment.

Enhanced Mineralization of Organic Pollutants through Atomic Hydrogen-Mediated Alternative Transformation Pathways.

Electrocatalytic hydrogen atom-hydroxyl radical (H*-·OH) redox system is a promising approach for contaminant removal and mineralization. However, its working mechanism, especially the effect of H*, remains unclear, hindering its practical application. Herein, we constructed an electrochemical reactor equipped with our self-made Pd-loaded Ti/TiO2 nanotube cathode and a commercial boron-doped diamond anode. After fulfilling the electrode characterization and free radical detection, we employed coumarin and 7-azido-4-methylcoumarin as probes to confirm the participation of H* in the transformation of organic compounds. A comprehensive study on the degradation kinetics, reaction, and mineralization mechanisms using benzoic acid (BA) and 4-chlorophenol (4-CP) as model compounds was further conducted. The rate constants and total organic carbon removal of BA and 4-CP in the redox system increased compared with those of the individual oxidation and reduction processes. Theoretical calculations demonstrate that H* opens up alternative pathways for BA and 4-CP ring cleavage, forming quinones as reactive intermediates. Furthermore, H* facilitates the mineralization of the typical intermediates, maleic acid and fumaric acid, through C=C bond addition and H-abstraction from the 1,1-diol structure. The presence of H* provides alternative pathways for pollutant transformation, consequently reducing the treatment duration.

Direct Photo-Patterning of Efficient and Stable Quantum Dot Light-Emitting Diodes via Light-Triggered, Carbocation-Enabled Ligand Stripping.

Next generation displays based on quantum dot light-emitting diodes (QLEDs) require robust patterning methods for quantum dot layers. However, existing patterning methods mostly yield QLEDs with performance far inferior to the state-of-the-art individual devices. Here, we report a light-triggered, carbocation-enabled ligand stripping (CELS) approach to pattern QLEDs with high efficiency and stability. During CELS, photogenerated carbocations from triphenylmethyl chlorides remove native ligands of quantum dots, thereby producing patterns at microscale precision. Chloride anions passivate surface defects and endow patterned quantum dots with preserved photoluminescent quantum yields. It works for both cadmium-based and heavy-metal-free quantum dots. CELS-patterned QLEDs show remarkable external quantum efficiencies (19.1%, 17.5%, 12.0% for red, green, blue, respectively) and a long operation lifetime (T95 at 1000 nits up to 8700 h). Both are among the highest for patterned QLEDs and approach the records for nonpatterned devices, which makes CELS promising for building high-performance QLED displays and related integrated devices.

Canonical and non-canonical functions of STAT in germline stem cell maintenance.

BACKGROUND: Maintenance of the Drosophila male germline stem cells (GSCs) requires activation of the Janus kinase/signal transducer and activators of transcription (JAK/STAT) pathway by niche signals. The precise role of JAK/STAT signaling in GSC maintenance, however, remains incompletely understood. RESULTS: Here, we show that, GSC maintenance requires both canonical and non-canonical JAK/STAT signaling, in which unphosphorylated STAT (uSTAT) maintains heterochromatin stability by binding to heterochromatin protein 1 (HP1). We found that GSC-specific overexpressing STAT, or even the transcriptionally inactive mutant STAT, increases GSC number and partially rescues the GSC-loss mutant phenotype due to reduced JAK activity. Furthermore, we found that both HP1 and STAT are transcriptional targets of the canonical JAK/STAT pathway in GSCs, and that GSCs exhibit higher heterochromatin content. CONCLUSIONS: These results suggest that persistent JAK/STAT activation by niche signals leads to the accumulation of HP1 and uSTAT in GSCs, which promote heterochromatin formation important for maintaining GSC identity. Thus, the maintenance of Drosophila GSCs requires both canonical and non-canonical STAT functions within GSCs for heterochromatin regulation.

A Unified Gas-Kinetic Particle Method for Radiation Transport in an Anisotropic Scattering Medium.

In this paper, a unified gas kinetic particle (UGKP) method is developed for radiative transfer in both absorbing and anisotropic scattering media. This numerical method is constructed based on our theoretical work on the model reduction for an anisotropic scattering system. The macroscopic solver of this method directly solves the macroscopic anisotropic diffusion equations, eliminating the need to solve higher-order moment equations. The reconstruction of macroscopic scattering source in the microscopic solver, based on the multiscale equivalent phase function we proposed in this work, has also been simplified as one single scattering process, significantly reducing the computational costs. The proposed method has also the property of asymptotic preserving. In the optically thick regime, the proposed method solves the diffusion limit equations for an anisotropic system. In the optically thin regime, the kinetic processes of photon transport are simulated. The consistency and efficiency of the proposed method have been validated by numerical tests in a wide range of flow regimes. The novel equivalent scattering source reconstruction can be used for various transport processes, and the proposed numerical scheme is widely applicable in high-energy density engineering applications.

Discovery of A G-Quadruplex Unwinder That Unleashes the Translation of G-Quadruplex-Containing mRNA without Inducing DNA Damage.

To explore the mechanisms and therapeutic strategies for G-quadruplex (G4) mediated diseases, it is crucial to manipulate and intervene in intracellular G4 structures using small molecular tools. While hundreds of G4 stabilizers have been developed, there is a significant gap in the availability of G4 unwinding agents. Here, we propose a strategy to disrupt G-quadruplexes by forming G-C hydrogen bonds with chemically modified cytidine trimers. We validated a good G4 unwinder, the 2'-F cytidine trimer (2'-F C3). 2'-F C3 does not inhibit cell growth nor cause severe DNA damage at a concentration below 10 µM. Moreover, 2'-F C3 does not affect gene transcription nor RNA splicing, while it significantly enhances the translation of G4-containing mRNA and upregulates RNA splicing, RNA processing and cell cycle pathways. The discovery of this G4 unwinder provides a functional tool for the chemical modulation of G4s in living cells.

Reverse Separation of Carbon Dioxide and Acetylene in Two Isostructural Copper Pyridine-Carboxylate Frameworks.

Separating acetylene from carbon dioxide is important but highly challenging due to their similar molecular shapes and physical properties. Adsorptive separation of carbon dioxide from acetylene can directly produce pure acetylene but is hardly realized because of relatively polarizable acetylene binds more strongly. Here, we reverse the CO2 and C2H2 separation by adjusting the pore structures in two isoreticular ultramicroporous metal-organic frameworks (MOFs). Under ambient conditions, copper isonicotinate (Cu(ina)2), with relatively large pore channels shows C2H2-selective adsorption with a C2H2/CO2 selectivity of 3.4, whereas its smaller-pore analogue, copper quinoline-5-carboxylate (Cu(Qc)2) shows an inverse CO2/C2H2 selectivity of 5.6. Cu(Qc)2 shows compact pore space that well matches the optimal orientation of CO2 but is not compatible for C2H2. Neutron powder diffraction experiments confirmed that CO2 molecules adopt preferential orientation along the pore channels during adsorption binding, whereas C2H2 molecules bind in an opposite fashion with distorted configurations due to their opposite quadrupole moments. Dynamic breakthrough experiments have validated the separation performance of Cu(Qc)2 for CO2/C2H2 separation.

Radiotherapy-Triggered Proteolysis Targeting Chimera Prodrug Activation in Tumors.

Proteolysis targeting chimera (PROTAC) is an emerging protein degradation strategy, which shows excellent advantages in targeting those so-called "undruggable" proteins. However, the potential systemic toxicity of PROTACs caused by undesired off-tissue protein degradation may limit the application of PROTACs in clinical practice. Here we reported a radiotherapy-triggered PROTAC prodrug (RT-PROTAC) activation strategy to precisely and spatiotemporally control protein degradation through X-ray radiation. We demonstrated this concept by incorporating an X-ray inducible phenyl azide-cage to a bromodomain (BRD)-targeting PROTAC to form the first RT-PROTAC. The RT-PROTAC prodrug exhibits little activity but can be activated by X-ray radiation in vitro and in vivo. Activated RT-PROTAC degrades BRD4 and BRD2 with a comparable effect to the PROTAC degrader and shows a synergistic antitumor potency with radiotherapy in the MCF-7 xenograft model. Our work provides an alternative strategy to spatiotemporally control protein degradation in vivo and points to an avenue for reducing the undesired systemic toxicity of PROTACs.

Modification of Low-Energy Surfaces Using Bicyclic Peptides Discovered by Phage Display.

Solid-binding peptides are a simple and versatile tool for the non-covalent modification of solid material surfaces, and a variety of peptides have been developed by reference to natural proteins or de novo design. Here, for the first time, we report the discovery of a bicyclic peptide targeting the heterogeneous material polypropylene by combining phage display technology and next-generation sequencing. We find that the enrichment properties of bicyclic peptides capable of binding to polypropylene are distinct from linear peptides, as reflected in amino acid abundance and a trend toward negative net charges and high hydrophobicity. The selected bicyclic peptide has a higher binding affinity for polypropylene compared with a previously reported linear peptide, enabling the hydrophilic and adhesive properties of the polypropylene to be more effectively enhanced. Our work paves the way for the exploration and utilization of conformational-restricted cyclic peptides as a new family of functionally evolvable agents for material surface modification.

Uncovering the Dominant Role of an Extended Asymmetric Four-Coordinated Water Network in the Hydrogen Evolution Reaction.

In situ and accurate measurement of the structure and dynamics of interfacial water in the hydrogen evolution reaction (HER) is a well-known challenge because of the coupling of water among varied structures and its dual role as reactants and solvents. Further, the interference of bulk water and intricate interfacial interactions always hinders the probing of interfacial water. Surface-enhanced infrared absorption spectroscopy is extremely sensitive for the measurement of interfacial water; herein, we develop a nanoconfinement strategy by introducing nonaqueous ionic liquids to decouple and tailor the water structure in the electric double layer and further combined with molecular dynamics simulations, successfully gaining the correlation between isolated water, water clusters, and the water network with HER activity. Our results clearly disclosed that the potential-dependent asymmetric four-coordinated water network, whose connectivity could be regulated by hydrophilic and hydrophobic cations, was positively correlated with HER activity, which provided a pioneering guidance framework for revealing the function of water in catalysis, energy, and surface science.

Enhanced π-π Stacking between Dipole-Bearing Single Molecules Revealed by Conductance Measurement.

Dipoles are widely involved in π-π interactions and are central to many chemical and biological functions, but their influence on the strength of π-π interactions remains unclear. Here, we report a study of π-π interaction between azulene-based, polar single molecules and between naphthalene-based, nonpolar single molecules. By performing scanning tunneling microscopy break junction measurements of single-molecule conductance, we show that the π-stacked dimers formed by the azulene-based, polar aromatic structures feature higher electrical conductivity and mechanical stability than those formed by the naphthalene-based, nonpolar molecules. Mechanical control of π-π interactions in both rotational and translational motion reveals a sensitive dependence of the stacking strength on relative alignment between the dipoles. The antiparallel alignment of the dipoles was found to be the optimal stacking configuration that underpins the observed enhancement of π-π stacking between azulene-based single molecules. Density functional theory calculations further explained the observed enhancement of stacking strength and the corresponding charge transport efficiency. Our experimental and theoretical results show that the antiparallel alignment of the dipole moments significantly enhances the electronic coupling and mechanical stability of π-π stacking. In addition, in the formation of single-molecule junctions, the azulene group was experimentally and theoretically proved to form a Au-π contact with electrodes with high charge transport efficiency. This paper provides evidence and interpretation of the role of dipoles in π-π interactions at the single-molecule level and offers new insights into potential applications in supramolecular devices.

Observation of Interpenetrated Topology Isomerism for Covalent Organic Frameworks with Atom-Resolution Single Crystal Structures.

Rational control and understanding of isomerism are of significance but still remain a great challenge in reticular frameworks, in particular, for covalent organic frameworks (COFs) due to the complicated synthesis and energy factors. Herein, reaction of 3,3',5,5'-tetra(4-formylphenyl)-2,2',6,6'-tetramethoxy-1,1'-biphenyl (TFTB) with 3,3',5,5'-tetrakis(4-aminophenyl)bimesityl (TAPB) under different reaction conditions affords single crystals of two 3D COF isomers, namely, USTB-20-dia and USTB-20-qtz. Their structures with resolutions up to 0.9-1.1 Å have been directly solved by three-dimensional electron diffraction (3D ED) and synchrotron single crystal X-ray diffraction, respectively. USTB-20-dia and USTB-20-qtz show rare 2 × 2-fold interpenetrated dia-b nets and 3-fold interpenetrated qtz-b frameworks. Comparative studies of the crystal structures of these COFs and theoretical simulation results indicate the crucial role of the flexible molecular configurations of building blocks in the present interpenetrated topology isomerism. This work not only presents the rare COF isomers but also gains an understanding of the formation of framework isomerism from both single crystal structures and theoretical simulation perspectives.

Polarization-Sensitive Asymmetric Scattering at the Single-Particle Scale via Surface Plasmon Resonance Microscopy.

Surface plasmon resonance microscopy (SPRM), based on the scattering of single molecules at the interface, is a highly efficient analytical platform widely used in the fields of biology and chemistry. Due to the interference scattering, the imaging pattern exhibits typical parabolic tail and phase transition features, providing a quantitative means of observing the changes in the physical and chemical properties of single molecules. In this work, we reported another unique asymmetric parabolic distribution pattern resulting from polarization conversion in the experiment based on SPRM. This microscopic-level feature is derived from the switching between SPR resonant and nonresonant states. Starting from energy flux theory, we constructed an analysis model and conducted full-wave numerical simulations to verify the experimental results. Furthermore, we demonstrate that the optical rotation induced by chiral thin films can be directly measured through imaging with asymmetric features, providing valuable insights into the field of chiral materials. The quantitative interpretation of asymmetric scattering not only advances the fundamental understanding of the imaging mechanism of SPRM, but also opens up possibilities for utilizing this polarization-sensitive characteristic for single-particle detection and sensing in the future.

Rapid and Sensitive Detection of Fungicide-Resistant Crop Fungal Pathogens Using an Isothermal Amplification Refractory Mutation System.

Fungicide abuse leads to the emergence of fungicide-resistant fungal pathogens, thus posing a threat to agriculture and food safety. Here, we developed an isothermal amplification refractory mutation system (termed iARMS) allowing us to resolve genetic mutations, enabling rapid, sensitive, and potentially field-applicable detection of fungicide-resistant crop fungal pathogens. iARMS yielded a limit of detection of 25 aM via a cascade signal amplification strategy of recombinase polymerase amplification (RPA) and Cas12a-mediated collateral cleavage at 37 °C within 40 min. Specificity for fungicide-resistant Puccinia striiformis (P. striiformis) detection was guaranteed by RPA primers and the flexible sequence of gRNA. The iARMS assay allowed us to detect as low as 0.1% cyp51-mutated P. striiformis that showed resistance to the demethylase inhibitor (DMI), which was 50 times more sensitive than the sequencing techniques. Thus, it is promising for the discovery of rare fungicide-resistant isolates. We applied iARMS to investigate the emergence of fungicide-resistant P. striiformis in western China and found that its proportion was over 50% in Qinghai, Sichuan, and Xinjiang Province. iARMS can serve as a molecular diagnostic tool for crop diseases and facilitate precision plant disease management.

CasSABER for Programmable In Situ Visualization of Low and Nonrepetitive Gene Loci.

Site-specific imaging of target genes using CRISPR probes is essential for understanding the molecular mechanisms of gene function and engineering tools to modulate its downstream pathways. Herein, we develop CRISPR/Cas9-mediated signal amplification by exchange reaction (CasSABER) for programmable in situ imaging of low and nonrepetitive regions of the target gene in the cell nucleus. The presynthesized primer-exchange reaction (PER) probe is able to hybridize multiple fluorophore-bearing imager strands to specifically light up dCas9/sgRNA target-bound gene loci, enabling in situ imaging of fixed cellular gene loci with high specificity and signal-to-noise ratio. In combination with a multiround branching strategy, we successfully detected nonrepetitive gene regions using a single sgRNA. As an intensity-codable and orthogonal probe system, CasSABER enables the adjustable amplification of local signals in fixed cells, resulting in the simultaneous visualization of multicopy and single-copy gene loci with similar fluorescence intensity. Owing to avoiding the complexity of controlling in situ mutistep enzymatic reactions, CasSABER shows good reliability, sensitivity, and ease of implementation, providing a rapid and cost-effective molecular toolkit for studying multigene interaction in fundamental research and gene diagnosis.

CRISPR-based nucleic acid diagnostics for pathogens.

Pathogenic infection remains the primary threat to human health, such as the global COVID-19 pandemic. It is important to develop rapid, sensitive and multiplexed tools for detecting pathogens and their mutated variants, particularly the tailor-made strategies for point-of-care diagnosis allowing for use in resource-constrained settings. The rapidly evolving CRISPR/Cas systems have provided a powerful toolbox for pathogenic diagnostics via nucleic acid tests. In this review, we firstly describe the resultant promising class 2 (single, multidomain effector) and recently explored class 1 (multisubunit effector complexes) CRISPR tools. We present diverse engineering nucleic acid diagnostics based on CRISPR/Cas systems for pathogenic viruses, bacteria and fungi, and highlight the application for detecting viral variants and drug-resistant bacteria enabled by CRISPR-based mutation profiling. Finally, we discuss the challenges involved in on-site diagnostic assays and present emerging CRISPR systems and CRISPR cascade that potentially enable multiplexed and preamplification-free pathogenic diagnostics.

Burnout, moral injury, and suicidal/self-harm ideation among healthcare professionals in Mainland China: Insights from an online survey during the COVID-19 pandemic.

OBJECTIVE: This survey aimed to explore the relationships between burnout, moral injury, and suicidal/self-harm ideation among Chinese health professionals to provide a reference for protecting their mental health. METHOD: Health professionals were surveyed online using the Maslach Burnout Inventory-Human Services Survey for Medical Personnel, Patient Health Questionnaire-9, and the Moral Injury Symptoms Scale-Health Professional. RESULTS: In the analysis, 6146 eligible respondents were included in the study. The average participant age was 34.9 ± 8.5 years, and suicidal/self-harm ideation was detected in 2338 participants (38.0%). The prevalence of suicidal/self-harm ideation among those with severe burnout in the dimensions of emotional exhaustion, depersonalisation, and decreased personal accomplishment was significantly higher than those with mild burnout. The prevalence of suicidal/self-harm ideation among those with significant moral injury symptoms was higher than those without moral injury. Unconditional logistic regression analysis showed that those with moderate or severe emotional exhaustion, moderate or severe reduced sense of professional accomplishment and moderate or severe depersonalisation had increased risks of suicidal/self-harm ideation. CONCLUSIONS: Structural equation modelling demonstrated that burnout significantly mediated the relationship between moral injury and suicidal/self-harm ideation. The proportion of mediation (PM) by burnout was 43.0%. Burnout and moral injury were potential predictors of suicidal/self-harm ideation among health professionals. Both moral injury and burnout had positive and direct effects on suicidal/self-harm ideation, and burnout was a mediator in this relationship among Chinese health professionals. Therefore, to alleviate the moral injury and subsequent burnout of healthcare workers and enhance their mental qualities, active interventions should be developed in the future.