DDX5 inhibits inflammation by modulating m6A levels of TLR2/4 transcripts during bacterial infection.

DExD/H-box helicases are crucial regulators of RNA metabolism and antiviral innate immune responses; however, their role in bacteria-induced inflammation remains unclear. Here, we report that DDX5 interacts with METTL3 and METTL14 to form an m6A writing complex, which adds N6-methyladenosine to transcripts of toll-like receptor (TLR) 2 and TLR4, promoting their decay via YTHDF2-mediated RNA degradation, resulting in reduced expression of TLR2/4. Upon bacterial infection, DDX5 is recruited to Hrd1 at the endoplasmic reticulum in an MyD88-dependent manner and is degraded by the ubiquitin-proteasome pathway. This process disrupts the DDX5 m6A writing complex and halts m6A modification as well as degradation of TLR2/4 mRNAs, thereby promoting the expression of TLR2 and TLR4 and downstream NF-κB activation. The role of DDX5 in regulating inflammation is also validated in vivo, as DDX5- and METTL3-KO mice exhibit enhanced expression of inflammatory cytokines. Our findings show that DDX5 acts as a molecular switch to regulate inflammation during bacterial infection and shed light on mechanisms of quiescent inflammation during homeostasis.

The GE296_RS03820 and GE296_RS03830 genes are involved in capsular polysaccharide biosynthesis in Riemerella anatipestifer.

Riemerella anatipestifer is a pathogenic bacterium that causes duck serositis and meningitis, leading to significant harm to the duck industry. To escape from the host immune system, the meningitis-causing bacteria must survive and multiply in the bloodstream, relying on specific virulence factors such as capsules. Therefore, it is essential to study the genes involved in capsule biosynthesis in R. anatipestifer. In this study, we successfully constructed gene deletion mutants Δ3820 and Δ3830, targeting the GE296_RS03820 and GE296_RS03830 genes, respectively, using the RA-LZ01 strain as the parental strain. The growth kinetics analysis revealed that these two genes contribute to bacterial growth. Transmission and scanning electron microscopy (TEM and SEM) and silver staining showed that Δ3820 and Δ3830 produced the altered capsules and compounds of capsular polysaccharides (CPSs). Serum resistance test showed the mutants also exhibited reduced C3b deposition and decreased resistance serum killing. In vivo, Δ3820 and Δ3830 exhibited markedly declining capacity to cross the blood-brain barrier, compared to RA-LZ01. These findings indicate that the GE296_RS03820 and GE296_RS03830 genes are involved in CPSs biosynthesis and play a key role in the pathogenicity of R. anatipestifer. Furthermore, Δ3820 and Δ3830 mutants presented a tendency toward higher survival rates from RA-LZ01 challenge in vivo. Additionally, sera from ducklings immunized with the mutants showed cross-immunoreactivity with different serotypes of R. anatipestifer, including 1, 2, 7 and 10. Western blot and SDS-PAGE assays revealed that the altered CPSs of Δ3820 and Δ3830 resulted in the exposure of some conserved proteins playing the key role in the cross-immunoreactivity. Our study clearly demonstrated that the GE296_RS03820 and GE296_RS03830 genes are involved in CPS biosynthesis in R. anatipestifer and the capsule is a target for attenuation in vaccine development.

Effectively Sieving Alkali Metal Ions Using Functionalized Graphene Oxide Membranes by Exploiting Water-Repellent Interactions.

Sieving membranes capable of discerning different alkali metal ions are important for many technologies, such as energy, environment, and life science. Recently, two-dimensional (2D) materials have been extensively explored for the creation of sieving membranes with angstrom-scale channels. However, because of the same charge and similar hydrated sizes, mostly laminated membranes typically show low selectivity (<10). Herein, we report a facile and scalable method for functionalizing graphene oxide (GO) laminates by dually grafting cations and water-repellent dimethylsiloxane (DMDMS) molecules to achieve high selectivities of ∼50 and ∼20 toward the transport of Cs+/Li+ and K+/Li+ ion pairs, surpassing many of the state-of-the-art laminated membranes. The enhanced selectivity for alkali metal ions can be credited to a dual impact: (i) strong hydrophobic interactions between the incident cations' hydration shells and the water-repellent DMDMS; (ii) the efficient screening of electrostatic interactions that hamper selectivity.

Construction of a tumor mutational burden-derived LncRNA prognostic computational framework associated with therapy sensitivity in skin cutaneous melanoma.

BACKGROUND: Skin cutaneous melanoma (SKCM) poses a significant public health challenge due to its aggressive nature and limited treatment options. To address this, the study introduces the Tumor Mutational Burden-Derived Immune lncRNA Prognostic Index (TILPI) as a potential prognostic tool for SKCM. METHODS: TILPI was developed using a combination of gene set variation analysis, differential expression analysis, and COX regression analysis. Additionally, functional experiments were conducted to validate the findings, focusing on the effects of STARD4-AS1 knockdown on SKCM tumor cell behavior. These experiments encompassed assessments of tumor cell proliferation, gene and protein expression, migration, invasion, and in vivo tumor growth. RESULTS: The results demonstrated that knockdown of STARD4-AS1 led to a significant reduction in tumor cell proliferation and impaired migration and invasion abilities. Moreover, it resulted in the downregulation of ADCY4, PRKACA, and SOX10 gene expression, as well as decreased protein expression of ADCY4, PRKACA, and SOX10. In vivo experiments further confirmed the efficacy of STARD4-AS1 knockdown in reducing tumor growth. CONCLUSIONS: This study elucidates the mechanistic role of STARD4-AS1 and its downstream targets in SKCM progression, highlighting the importance of the ADCY4/PRKACA/SOX10 pathway. The integration of computational analysis with experimental validation enhances the understanding of TILPI and its clinical implications. Overall, the findings underscore the potential of novel computational frameworks like TILPI in predicting and managing SKCM, particularly through targeting the ADCY4/PRKACA/SOX10 pathway.

IPr*F - Highly Hindered, Fluorinated N-Heterocyclic Carbenes.

The introduction of fluorine atom has attracted considerable interest in molecular design owing to the high electronegativity and the resulting polarization of carbon-fluorine bonds. Simultaneously, sterically-hindered N-heterocyclic carbenes (NHCs) have received major interest due to high stabilization of the reactive metal centers, which has paved the way for the synthesis of stable and reactive organometallic compounds with broad applications in main group chemistry, inorganic synthesis and transition-metal-catalysis. Herein, we report the first class of sterically-hindered, fluorinated N-heterocyclic carbenes. These ligands feature variable fluorine substitution at the N-aromatic wingtip, permitting to rationally vary steric and electronic characteristics of the carbene center imparted by the fluorine atom. An efficient, one-pot synthesis of fluorinated IPr*F ligands is presented, enabling broad access of academic and industrial researchers to the fluorinated ligands. The evaluation of steric, electron-donating and π-accepting properties as well as coordination chemistry to Au(I), Rh(I) and Se is presented. Considering the unique properties of carbon-fluorine bonds, we anticipate that this novel class of fluorinated carbene ligands will find widespread application in stabilizing reactive metal centers.

A genome-wide transposon mutagenesis screening identifies LppB as a key factor associated with Mycoplasma bovis colonization and invasion into host cells.

Mycoplasma spp., the smallest self-replicating and genome-reduced organisms, have raised a great concern in both the medical and veterinary fields due to their pathogenicity. The molecular determinants of these wall-less bacterium efficiently use their limited genes to ensure successful infection of the host remain unclear. In the present study, we used the ruminant pathogen Mycoplasma bovis as a model to identify the key factors for colonization and invasion into host cells. We constructed a nonredundant fluorescent transposon mutant library of M. bovis using a modified transposon plasmid, and identified 34 novel adhesion-related genes based on a high-throughput screening approach. Among them, the ΔLppB mutant exhibited the most apparent decrease in adhesion to embryonic bovine lung (EBL) cells. The surface-localized lipoprotein LppB, which is highly conserved in Mycoplasma species, was then confirmed as a key factor for M. bovis adhesion with great immunogenicity. LppB interacted with various components (fibronectin, vitronectin, collagen IV, and laminin) of host extracellular matrix (ECM) and promoted plasminogen activation through tPA to degrade ECM. The 439-502 amino acid region of LppB is a critical domain, and F465 and Y493 are important residues for the plasminogen activation activity. We further revealed LppB as a key factor facilitating internalization through clathrin- and lipid raft-mediated endocytosis, which helps the Mycoplasma invade the host cells. Our study indicates that LppB plays a key role in Mycoplasma infection and is a potential new therapeutic and vaccine target for Mycoplasma species.

The Dual Roles of Activating Transcription Factor 3 (ATF3) in Inflammation, Apoptosis, Ferroptosis, and Pathogen Infection Responses.

Transcription factors are pivotal regulators in the cellular life process. Activating transcription factor 3 (ATF3), a member of the ATF/CREB (cAMP response element-binding protein) family, plays a crucial role as cells respond to various stresses and damage. As a transcription factor, ATF3 significantly influences signal transduction regulation, orchestrating a variety of signaling pathways, including apoptosis, ferroptosis, and cellular differentiation. In addition, ATF3 serves as an essential link between inflammation, oxidative stress, and immune responses. This review summarizes the recent advances in research on ATF3 activation and its role in regulating inflammatory responses, cell apoptosis, and ferroptosis while exploring the dual functions of ATF3 in these processes. Additionally, this article discusses the role of ATF3 in diseases related to pathogenic microbial infections. Our review may be helpful to better understand the role of ATF3 in cellular responses and disease progression, thus promoting advancements in clinical treatments for inflammation and oxidative stress-related diseases.

Early Introduction and Community Transmission of SARS-CoV-2 Omicron Variant, New York, New York, USA.

The Omicron variant of SARS-CoV-2 has become dominant in most countries and has raised significant global health concerns. As a global commerce center, New York, New York, USA, constantly faces the risk for multiple variant introductions of SARS-CoV-2. To elucidate the introduction and transmission of the Omicron variant in the city of New York, we created a comprehensive genomic and epidemiologic analysis of 392 Omicron virus specimens collected during November 25-December 11, 2021. We found evidence of 4 independent introductions of Omicron subclades, including the Omicron subclade BA.1.1 with defining substitution of R346K in the spike protein. The continuous genetic divergence within each Omicron subclade revealed their local community transmission and co-circulation in New York, including both household and workplace transmissions supported by epidemiologic evidence. Our study highlights the urgent need for enhanced genomic surveillance and effective response planning for better prevention and management of emerging SARS-CoV-2 variants.

Hydration Reactions Catalyzed by Transition Metal-NHC (NHC = N-Heterocyclic Carbene) Complexes.

The catalytic addition of water to unsaturated C-C or C-N π bonds represent one of the most important and environmentally sustainable methods to form C-O bonds for the production of synthetic intermediates, medicinal agents and natural products. The traditional acid-catalyzed hydration of unsaturated compounds typically requires strong acids or toxic mercury salts, which limits practical applications and presents safety and environmental concerns. Today, transition-metal-catalyzed hydration supported by NHC (NHC = N-heterocyclic carbene) ligands has attracted major attention. By rational design of ligands, choice of metals and counterions as well as mechanistic studies and the development of heterogeneous systems, major progress has been achieved for a broad range of hydration processes. In particular, the combination of NHC ligands with gold shows excellent reactivity compared with other catalytic systems; however, other systems based on silver, ruthenium, osmium, platinum, rhodium and nickel have also been discovered. Ancillary NHC ligands provide stabilization of transition metals and ensure high catalytic activity in hydration owing to their unique electronic and steric properties. NHC-Au(I) complexes are particularly favored for hydration of unsaturated hydrocarbons due to soft and carbophilic properties of gold. In this review, we present a comprehensive overview of hydration reactions catalyzed by transition metal-NHC complexes and their applications in catalytic hydration of different classes of π-substrates with a focus on the role of NHC ligands, types of metals and counterions.

LppA is a novel plasminogen receptor of Mycoplasma bovis that contributes to adhesion by binding the host extracellular matrix and Annexin A2.

Mycoplasma bovis is responsible for various inflammatory diseases in cattle. The prevention and control of M. bovis are complicated by the absence of effective vaccines and the emergence of multidrug-resistant strains, resulting in substantial economic losses worldwide in the cattle industry. Lipoproteins, vital components of the Mycoplasmas cell membrane, are deemed potent antigens for eliciting immune responses in the host upon infection. However, the functions of lipoproteins in M. bovis remain underexplored due to their low sequence similarity with those of other bacteria and the scarcity of genetic manipulation tools for M. bovis. In this study, the lipoprotein LppA was identified in all examined M. bovis strains. Utilizing immunoelectron microscopy and Western blotting, it was observed that LppA localizes to the surface membrane. Recombinant LppA demonstrated dose-dependent adherence to the membrane of embryonic bovine lung (EBL) cells, and this adhesion was inhibited by anti-LppA serum. In vitro binding assays confirmed LppA's ability to associate with fibronectin, collagen IV, laminin, vitronectin, plasminogen, and tPA, thereby facilitating the conversion of plasminogen to plasmin. Moreover, LppA was found to bind and enhance the accumulation of Annexin A2 (ANXA2) on the cell membrane. Disrupting LppA in M. bovis significantly diminished the bacterium's capacity to adhere to EBL cells, underscoring LppA's function as a bacterial adhesin. In conclusion, LppA emerges as a novel adhesion protein that interacts with multiple host extracellular matrix proteins and ANXA2, playing a crucial role in M. bovis's adherence to host cells and dissemination. These insights substantially deepen our comprehension of the molecular pathogenesis of M. bovis.

Classes of Amides that Undergo Selective N-C Amide Bond Activation: The Emergence of Ground-State Destabilization.

Ground-state destabilization of the N-C(O) linkage represents a powerful tool to functionalize the historically inert amide bond. This burgeoning reaction manifold relies on the availability of amide bond precursors that participate in weakening of the nN → π*C=O conjugation through N-C twisting, N pyramidalization, and nN electronic delocalization. Since 2015, acyl N-C amide bond activation through ground-state destabilization of the amide bond has been achieved by transition-metal-catalyzed oxidative addition of the N-C(O) bond, generation of acyl radicals, and transition-metal-free acyl addition. This Perspective summarizes contributions of our laboratory in the development of new ground-state-destabilized amide precursors enabled by twist and electronic activation of the amide bond and synthetic utility of ground-state-destabilized amides in cross-coupling reactions and acyl addition reactions. The use of ground-state-destabilized amides as electrophiles enables a plethora of previously unknown transformations of the amide bond, such as acyl coupling, decarbonylative coupling, radical coupling, and transition-metal-free coupling to forge new C-C, C-N, C-O, C-S, C-P, and C-B bonds. Structural studies of activated amides and catalytic systems developed in the past decade enable the view of the amide bond to change from the "traditionally inert" to "readily modifiable" functional group with a continuum of reactivity dictated by ground-state destabilization.

Hybrid Path Planning for Unmanned Surface Vehicles in Inland Rivers Based on Collision Avoidance Regulations.

In recent years, with the continuous advancement of the construction of the Yangtze River's intelligent waterway system, unmanned surface vehicles have been increasingly used in the river's inland waterways. This article proposes a hybrid path planning method that combines an improved A* algorithm with an improved model predictive control algorithm for the autonomous navigation of the "Jinghai-I" unmanned surface vehicle in inland rivers. To ensure global optimization, the heuristic function was refined in the A* algorithm. Additionally, constraints such as channel boundaries and courses were added to the cost function of A* and the planned path was smoothed to meet the collision avoidance regulations for inland rivers. The model predictive control algorithm incorporated a new path-deviation cost while imposing a cost constraint on the yaw angle, significantly minimizing the path-tracking error. Furthermore, the improved model predictive control algorithm took into account the requirements of rules in the cost function and adopted different collision avoidance parameters for different encounter scenarios, improving the rationality of local path planning. Finally, the proposed algorithm's effectiveness was verified through simulation experiments that closely approximated real-world navigation conditions.

Fluoride contents in commonly used commercial phosphate fertilizers and their potential risks in China.

The application of phosphate fertilizer is an important source of anthropogenic fluoride in agricultural soil. However, relatively few studies have examined the fluoride content of phosphate fertilizers, and that has limited our understanding of the phosphate fertilizer contribution to soil fluoride accumulation and distribution. To examine this problem, we first quantified the total fluoride (TF) and water-soluble fluoride (WF) contents of six of the most commonly used commercial phosphate fertilizers in China (potassium dihydrogen phosphate (MKP), calcium superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), ternary compound fertilizer (NPK), and water-soluble macroelement fertilizer (WSF)). After calculating the [P2O5]/TF ratio for each of those fertilizers, we used those ratios and the average P2O5 application per crop of five typical crops grown in China (apples, greenhouse vegetables, wheat, corn, and rice) to estimate the annual fluoride accumulations in their soils after application of each type of phosphate fertilizer. Among the six fertilizer types, SSP, DAP, and NPK had much higher total fluoride and water-soluble fluoride contents than MKP, MAP, and WSF had. During crop production, the risk of fluoride accumulation was lower with MKP, MAP, and WSF (high [P2O5]/TF ratios) and higher with SSP, DAP, and NPK (low [P2O5]/TF ratios), especially in cash crops (fruit and greenhouse vegetables), which traditionally have unreasonably high P2O5 applications. Based on our findings, we proposed steps that should be taken to help effectively mitigate fluoride accumulation in China's agricultural soils.

L-Shaped Heterobidentate Imidazo[1,5-a]pyridin-3-ylidene (N,C)-Ligands for Oxidant-Free AuI /AuIII Catalysis.

In the last decade, major advances have been made in homogeneous gold catalysis. However, AuI /AuIII catalytic cycle remains much less explored due to the reluctance of AuI to undergo oxidative addition and the stability of the AuIII intermediate. Herein, we report activation of aryl halides at gold(I) enabled by NHC (NHC=N-heterocyclic carbene) ligands through the development of a new class of L-shaped heterobidentate ImPy (ImPy=imidazo[1,5-a]pyridin-3-ylidene) N,C ligands that feature hemilabile character of the amino group in combination with strong σ-donation of the carbene center in a rigid conformation, imposed by the ligand architecture. Detailed characterization and control studies reveal key ligand features for AuI /AuIII redox cycle, wherein the hemilabile nitrogen is placed at the coordinating position of a rigid framework. Given the tremendous significance of homogeneous gold catalysis, we anticipate that this ligand platform will find widespread application.

Revealing the Role of Surface Wettability in Ionic Detection Signals of Nanofluidic-Based Chemical Sensors.

The nanofluidic ionic signal is governed by the interactions between ion species and the surface charge, surface wettability, and pore diameter of nanofluidic membranes. However, the effect of surface wettability on the ionic detection signal across the nanofluidic membrane remains poorly explored, limited nanofluidic applications in biochemical sensing. Here, we investigate the effect of surface wettability of the nanofluidic membrane on the ionic signal for the detection of hydrophobic drug molecules using a heterogeneous nanofluidic system. This ionic signal can be tuned by light or the presence of certain ions due to the tailoring of hydrophobic interactions between the ion species and membrane surface. Compared with traditional nanofluidic membranes whose ionic signal is governed by surface charge, the regulation mechanism reported here mainly dependents on specific hydrophobic interactions, which shows a more sensitive ionic signal to environments. By virtue of the mechanism, the selective detection of the three drug molecules was realized owing to their different hydrophobic interactions with membrane surfaces. These findings have implications for understanding mass transport in nanofluidic devices and biological components and porous media involving surface wettability in nanofluidic systems.

Polydopamine-Induced Modification on the Highly Charged Surface of Asymmetric Nanofluidics: A Strategy for Adjustable Ion Current Rectification Properties.

Surface charge effects in nanoconfines is one of the fundamentals in the ion current rectification (ICR) of nanofluidics, which provides entropic driving force by asymmetric surface charges and causes ion enrichment/depletion by the electrostatic interaction of fixed surface charges. However, the surface charge effect causes a significant electrostatic repulsion in nanoconfines, restricting additional like charge or elaborate chemistry on the highly charged confined surface, which limits ICR manipulation. Here, we use polydopamine (PDA), a nearly universal adhesive, that adheres to the highly positive-charged poly(ethyleneimine) (PEI) gel network in a nanochannel array. PDA enhances the ICR effect from a low rectification ratio of 9.5 to 92.6 by increasing the surface charge and hydrophobicity of the PEI gel network and, meanwhile, shrinking its gap spacing. Theoretical and experimental results demonstrate the determinants of the fixed surface charge in the enrichment/depletion region on ICR properties, which is adjustable by PDA-induced change in a nanoconfined environment. Chemically active PDA brings Au nanoparticles by chloroauric reduction for further hydrophobization and the modification of negative-charged DNA complexes in nanochannels, whereby ICR effects can be manipulated in versatile means. The results describe an adjustable and versatile strategy for adjusting the ICR behaviors of nanofluidics by manipulating local surface charge effects using PDA.

Universal and Stable Slippery Coatings: Chemical Combination Induced Adhesive-Lubricant Cooperation.

Liquid lubricant of low affinity makes slippery coatings widely used in lubricating, anti-biofouling, anti-icing, fluid guiding, and drag reduction. Two critical challenges, however, remain in the practical application of slippery coatings consisting of liquid lubricants: (1) universality regardless of roughness and chemical composition of substrates, (2) stability of surface lubricity against evaporation. Herein, a chemical method is reported to create a universal and stable slippery lubricant-adhesive cooperated coating (SLACC) through acid catalyzed dehydration reaction between the phenolic hydroxyl of polydopamine (PDA), with universal (for challenge-1) and strong (for challenge-2) adhesion properties, and liquid-like polydimethylsiloxane (PDMS), with lubricant properties. Through overlying PDMS on PDA, a spatial gradient interpenetration of chemical combined PDA and PDMS leaving lubricant PDMS at the outermost of coating is achieved. This structure contributes to the following performances of SLACC: nearly universality suitable for 100 different abiotic or biotic substrates and stability sustainable for long-term usages, UV radiating, refrigerating, hot air drying, freeze drying, knife scratch and abrasion. This proposed strategy is envisioned anti-fouling from plane to tube and exhibits drag reduction in confined space.

Revealing the Critical Role of Probe Grafting Density in Nanometric Confinement in Ionic Signal via an Experimental and Theoretical Study.

The grafting density of probes at sensor interface plays a critical role in the performance of biochemical sensors. However, compared with macroscopic interface, the effects of probe grafting density at nanometric confinement are rarely studied due to the limitation of precise grafting density regulation and characterization at the nanoscale. Here, we investigate the effect from the grafting density of DNA probes on ionic signal for nucleic acid detection in a cylindrical nanochannel array (with diameter of 25 nm) by combing experiments and theories. We set up a theoretical model of charge distribution from close to inner wall of nanochannels at low probe grafting density to spreading in whole space at high probe grafting density. The theoretical results fit well with the experimental results. A reverse of ionic output from signal-off to signal-on occurs with increasing probe grafting density. Low probe grafting density offers a high current change ratio that is further enhanced using long-chain DNA probes or the electrolyte with a low salt concentration. This work develops an approach to enhance performance of nanochannel-based sensors and explore physicochemical properties in nanometric confines.

Ionic Signal Enhancement by the Space Charge Effect through the DNA Rolling Circle Amplification on the Outer Surface of Nanochannels.

DNA species are recognized as a powerful probe for nanochannel analyses to address the issues of specific target recognition and highly efficient signal conversion due to their programmable and predictable Watson-Crick bases. However, in the conventional view, abundant sophisticated DNA structures synthesized by DNA amplification strategies are unsuitable for use in nanochannel analyses owing to their low probability to enter a nanochannel restricted by the smaller opening of the nanochannel, as well as the faint ion signal produced by the steric effect. Here, we present an integrated strategy of nanochannel analyses that combines the target recognitions by encoded rolling circle amplification (RCA) in solution and the ionic signal enhancement by the space charge effect through the immobilization of highly negative-charged RCA amplicons on the outer surface of the nanochannels. Owing to the highly negative-charged RCA amplicons with 100 nm sizes, a sharp increase of ionic current up to 7454% has been achieved. The RCA amplicon triggered by mRNA-21 on the outer surface of the poly(ethylene terephthalate) membrane with a single nanochannel realized the single-base mismatch detection of mRNA-21 with a sensitivity of 6 fM. The DNA amplicon endows the nanochannel with high sensitivity and selectivity that could extend to other applications, such as DNA sequencing, desalination, sieving, and water-energy nexus.

Revealing Ionic Signal Enhancement with Probe Grafting Density on the Outer Surface of Nanochannels.

Probe-modified nanopores/nanochannels are one of the most advanced sensors because the probes interact strongly with ions and targets in nanoconfinement and create a sensitive and selective ionic signal. Recently, ionic signals have been demonstrated to be sensitive to the probe-target interaction on the outer surface of nanopores/nanochannels, which can offer more open space for target recognition and signal conversion than nanoconfined cavities. To enhance the ionic signal, we investigated the effect of grafting density, a critical parameter of the sensing interface, of the probe on the outer surface of nanochannels on the change rate of the ionic signal before and after target recognition (ß). Electroneutral peptide nucleic acids and negatively charged DNA are selected as probes and targets, respectively. The experimental results showed that when adding the same number of targets, the ß value increased with the probe grafting density on the outer surface. A theoretical model with clearly defined physical properties of each probe and target has been established. Numerical simulations suggest that the decrease of the background current and the aggregation of targets at the mouth of nanochannels with increasing probe grafting density contribute to this enhancement. This work reveals the signal mechanism of probe-target recognition on the outer surface of nanochannels and suggests a general approach to the nanochannel/nanopore design leading to sensitivity improvement on the basis of relatively good selectivity.