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Semiconducting organic molecules are used extensively in the fabrication of next-generation electronics, which have increased flexibility, processability, and versatility. The use of imide-based aromatic molecules in particular is widespread in n-type electronics, and modifications to naphthalene-diimide and rylene-diimide structures have advanced the properties and applications of these molecules. Here we report the use of the perylene-diimide-inspired helicene N[5]HDI as a new building block of electronic materials. The gram-scale accessibility and selective bromination at key core-extending positions make N[5]HDI an appealing monomeric unit for incorporation into larger molecules with electronically-coupled subcomponents. Specifically, we demonstrate that N[5]HDI undergoes several different palladium-catalyzed cross-coupling reactions (Suzuki, Sonogashira, Stille, and Heck) in near-quantitative yields. The resultant π-extended derivatives of N[5]HDI electronically couple the helicene core to the terminal aryl, alkenyl, or alkynyl units despite the overall coiled shape of these molecules. Copolymers of N[5]HDI show continued extension of electronic communication and a further decreased HOMO-LUMO gap with increased chain length. N[5]HDI exhibits strong potential as a helical building block of electronically-coupled materials and for future explorations in organic electronic applications.

White light emitting (WLE) materials are of considerable interest with commercial and societal applications in video displays and lighting devices. A characteristic property of WLE materials is the luminescence profile spanning from 380 to 700 nm. The design of molecules, in particular, that emit white light is not so straightforward due to Kasha's rule. However, in recent years, significant progress has been made in the understanding of new photophysical mechanisms. Photochemical concepts such as excited state intramolecular proton transfer (ESIPT), twisted internal charge transfer (TICT), vibration-induced emission (VIE) and aggregation-induced emission (AIE) are among the designs in the field. Sensory molecules emitting white light remain uncommon, while those with logic-based capabilities for sensing two or more analytes or physicochemical properties, are even rarer. These latter gems are the focus of this review. Some fundamental concepts of Boolean logic are introduced for the non-expert, followed by a survey of molecular sensors and molecular logic gates that emit white light. Our aim is to introduce the reader to logic-based molecules for addressing societal challenges.

Chronic atrophic gastritis (CAG) is a precancerous gastric lesion characterized by persistent inflammatory injury, glandular atrophy, and impairment of gastric mucosal barrier-associated integrity. Huangjin Shuangshen Decoction (HJSS) has shown therapeutic potential in gastritis-related disorders, but its effects on CAG and the underlying mechanism remain unclear. This study investigated whether HJSS alleviates CAG by modulating inflammation-associated barrier dysfunction. CAG was induced in mice by MNNG combined with ranitidine and irregular feeding, followed by treatment with different doses of HJSS, with folic acid as a positive control. Histopathology, gastric function indices, inflammatory mediators, apoptosis-related markers, and barrier-associated molecules were assessed in vivo. MNNG-injured GES-1 cells treated with HJSS-medicated serum were used for in vitro validation. Transcriptomic analysis, network pharmacology, and pharmacological inhibition were integrated to explore the underlying mechanisms. HJSS alleviated gastric mucosal atrophy and histopathological injury, improved gastric functional impairment, reduced inflammatory burden, and attenuated apoptosis-associated epithelial injury in experimental CAG. HJSS also promoted the recovery of gastric mucosal barrier-associated molecules, including CFTR, ZO-1, MUC5AC, Occludin, and Claudin-1. Integrated transcriptomic and network pharmacology analyses highlighted an inflammation-barrier framework involving TNF-related signaling and CFTR-associated regulation. In vitro, HJSS mitigated MNNG-induced epithelial injury, whereas CFTR inhibition attenuated the HJSS-associated restoration of CFTR and ZO-1. HJSS was further associated with suppression of TNF/NF-κB signaling and reduced p65 nuclear translocation. HJSS alleviates MNNG-induced CAG by attenuating inflammatory injury and promoting the recovery of gastric mucosal barrier-associated molecular features. Its protective effects are associated with suppression of TNF/NF-κB signaling and involvement of CFTR-associated regulation, supporting an inflammation-barrier mechanism underlying the action of HJSS in CAG.

Due to their adjustable physicochemical properties and easy incorporation with functional nanomaterials, nanocomposites based on polyvinyl alcohol (PVA) have garnered significant interest for gas and humidity sensing applications. This study systematically examined the structural, electronic, adsorption, and sensing-related properties of PVA/ZnO/graphene oxide (GO) nanocomposites using density functional theory (DFT) at the B3LYP/LanL2DZ level. Strong interfacial interactions and hydrogen-bond-assisted stabilization within the nanocomposite structure were revealed by the calculated infrared spectra, molecular electrostatic potential (MESP), quantum theory of atoms in molecules (QTAIM), and non-covalent interaction (NCI) analyses. The electronic properties of PVA were significantly modified by the addition of ZnO and GO, as demonstrated by a reduction in the HOMO -LUMO energy gap from 7.334 eV to 1.075 eV and an increase in the total dipole moment from 7.147 to 12.243 Debye, which suggests that charge transfer and electronic polarization have been enhanced. Adsorption studies on H₂O and CO₂ molecules revealed that interactions are thermodynamically favorable, with adsorption energies of -0.306 eV and - 0.381 eV, respectively. PVA/OZn/GO-CO₂ showed the smallest energy gap (0.539 eV) and the largest dipole moment (14.264 Debye) among all configurations examined, indicating a marked electronic responsiveness and potential applicability in gas sensing. The analysis of the density of states further substantiated the emergence of electronic states that promote charge transport and enhance conductivity upon adsorption. The incorporation of ZnO/GO is offers an effective strategy for designing potential PVA-based nanocomposites for CO₂ gas and humidity sensing applications, as evidenced by the combined electronic modulation, strong adsorption affinity, and favorable charge redistribution.

Room temperature phosphorescent (RTP) molecules, owing to their unique afterglow characteristics, can translate microscopic electronic transitions into macroscopic smart responses, and have gradually emerged as a research hotspot in the field of smart molecules. Benefiting from the renewability, biocompatibility, and structural tunability of cellulose, these materials provide an ideal and sustainable platform for constructing RTP systems. Significant progress has been made in this field, leading to the emergence of numerous cellulose-based RTP material systems with novel structures and excellent performance. This review summarizes recent advances in RTP systems cellulose derivatives. First, it elucidates the underlying mechanisms of cluster-triggered emission, followed by a detailed discussion of four key construction strategies: regulation of aggregation structures, reconstruction of clustered emission centers, hydroxyl functionalization, and host-guest doping. In addition, innovative applications in information security and environmental monitoring are highlighted. Finally, current challenges are discussed, and perspectives on the rational design of future biomass-based RTP materials are provided.

We investigated the photophysical properties of three branched diquinoxaline (DQ) derivatives and their potential application as photoinitiators (PIs) for two-photon polymerization (2PP). These compounds exhibit a quasi-centrosymmetric quadrupolar configuration, functionalized with different electron-donating (ED) moieties. We performed detailed linear spectroscopic characterization, as well as the determination of two- and three-photon absorption cross sections (σ2PA and σ3PA ), using the spectrally resolved multiphoton-excited fluorescence technique. We complemented the study by performing quantum chemical calculations at the (TD-)-DFT level to obtain relevant information about the electronic structure of the compounds and to model their spectroscopic data. The results showed that the compounds exhibit broad one-photon absorption in the UV-vis region and fluorescence emission at ca. 543 nm. Due to their quadrupolar nature, all molecules exhibit significant intramolecular charge transfer. Despite their essentially quadrupolar nature, we observed a symmetry-breaking effect in the relaxed excited state, conferring a dipolar character to the molecules. We observed significant σ2PA , exhibiting the values up to 230 GM, which was attributed to the enhanced structural planarity, facilitating electron delocalization across all ED branches and resulting in a more efficient additive effect on 2PA response. Additionally, we noted a σ3PA of approximately 0.02 × 10-78 cm6 s2 photon-2 at 1100 nm. Finally, we confirmed the ability of the DQ derivatives to act as two-photon PIs, as demonstrated by the fabrication of 3D microstructures with inherent emissive properties.

The reversible transformation between organic molecules and radicals is an effective method for realizing dual emissions in a single material. Herein, in this work, we report a high proportion n-electron [2,2'-biisoindoline]-1,1',3,3'-tetraone (4A2B) crystal with the reversible homolysis. The crystal exhibits dual room-temperature phosphorescence (RTP) emissions at 400 nm (τ = 114.28 μs) and 575 nm (τ = 35.78 μs), originating from the 4A2B molecule and the corresponding radical ion pair generated by reversible homolysis of the weak N-N bond, respectively. Thanks to that, the radical ion pair performed a great photostability (t 1/2 = 1.64 × 105 s) and an outstanding repeatability under 100 times on-off excitation cycles. The RTP emission of the 4A2B molecule has a strong response on high energy excitation due to the ultrafast intersystem crossing process (1.22 × 1013 s-1) within the high-lying excited states. Furthermore, the 4A2B crystal with these two long-lived RTP emissions is able to be applied in optical anti-counterfeiting, optical encryption and high-resolution bioimaging. This research elucidates that the incorporation of organic molecules and radical ion pairs may provide a new method to achieve dual emissions containing RTP emissions, fluorescence or thermally activated delayed fluorescence.

Alzheimer's disease (AD) is the most common cause of dementia worldwide and remains a major public health burden. Although amyloid-beta deposition and tau pathology are the defining pathological features of AD, increasing evidence indicates that immune dysregulation and chronic neuroinflammation also contribute to disease onset and progression. However, the specific immune pathways involved in AD and their mechanistic relevance remain incompletely understood. The major histocompatibility complex class I (MHC-I) antigen processing and presentation pathway has attracted growing attention because of its classical role in adaptive immunity and its potential functions within the central nervous system. In this narrative review, we summarize current evidence linking AD to the MHC-I, or human leukocyte antigen class I (HLA-I), pathway from genetic, molecular, cellular, and immunological perspectives. Available studies implicate the broader HLA region in AD susceptibility and suggest that alterations in HLA-I-related loci, antigen-processing machinery, MHC-I-associated molecules, and downstream immune responses may contribute to disease heterogeneity. At the molecular and cellular levels, changes in MHC-I molecules, antigen-processing machinery, and associated signaling pathways have been reported in microglia, neurons, astrocytes, and oligodendroglial lineage cells. In parallel, changes involving β2-microglobulin and the presence of expanded or cytotoxic like CD8+ T cells suggest that adaptive immune mechanisms may participate in AD pathology. Nevertheless, direct evidence demonstrating immune responses specific to particular antigens and restricted by HLA-I in human AD remains limited. Overall, current findings indicate that the MHC-I/HLA-I pathway may represent an important component of AD pathophysiology and contribute to disease progression by influencing immune homeostasis and cellular interactions within the central nervous system. Further studies integrating human tissue analysis, immunopeptidomics, spatial profiling, and paired T cell receptor approaches are needed to clarify its mechanistic, biomarker, and therapeutic significance.

Atomistic molecular dynamics simulations are presented for a prototypical all-aromatic calamitic liquid crystal that has recently emerged as a benchmark system for testing theories of nematic order. By performing simulations with progressively larger systems, up to an unprecedented total of 12,600 molecules, we investigate the impact of system size on the structural and dynamic properties of the material in the nematic and smectic A mesophases. Our results demonstrate that using a number of molecules on the order of 104 not only improves statistical sampling, thereby reducing uncertainty in all the computed quantities, but is also necessary to minimize finite-size and boundary-condition effects. This, in turn, enables unbiased estimates of key thermodynamic properties (such as transition temperatures and enthalpies, order parameters, and diffusion coefficients) and allows for a correct determination of the nature of the phase transitions (first- versus second-order). Moreover, we emphasize that large simulation boxes are essential to capture mesoscale structural features with characteristic length scales of several tens of nanometres, underscoring the unique capability of atomistic molecular dynamics simulations to complement experimental studies.

Near-infrared II (NIR-II, 1000-1700 nm) emissive molecules are highly valued for biomedical imaging, phototherapy, and optoelectronic applications due to their deep tissue penetration, reduced autofluorescence, and high signal-to-noise ratio. However, their rational design remains challenging, as conventional discovery relies heavily on labor-intensive synthesis, limited quantum chemical calculations, and inefficient trial-and-error exploration. To overcome these limitations, an iterative AI-driven molecular evolution strategy (AI4NIR-II 1.0) is introduced that integrates time-dependent density functional theory (TDDFT), transformer-based predictive modeling, and generative molecular design. Starting from donor-acceptor-donor (D-A-D) and donor-donor-acceptor-donor-donor (D-D-A-D-D) fragment scaffolds, a predictive model for both absorption and emission properties was trained based on a high quality dataset containing ∼16,000 molecules annotated by the optimally-tuned range-separated LC-ωHPBE* (OTRS) functional. A fine-tuned generative model was subsequently incorporated into a self-refining-loop workflow that cycles through molecular generation, property screening, and dataset augmentation. The model achieves excellent predictive performance for both emission and absorption properties, that is mean absolute errors of 19 nm for emission peak wavelengths and of 11 nm for absorption peak wavelengths, and correlation coefficient (R 2) exceeding 0.98 for wavelengths and oscillator strengths compared to OTRS-TDDFT calculations. In addition, the resulting framework efficiently identifies promising NIR-II candidates with accurate photophysical property predictions, and achieves speed improvements of three to four orders of magnitude over TDDFT calculations. Beyond accelerating NIR-II fluorophore discovery, this self-driven approach establishes a scalable and generalizable paradigm for NIR-II molecular design, with applicability extending to optoelectronic materials and therapeutic compounds.

Idiopathic Sudden Sensorineural Hearing Loss (ISSNHL) is a common otological emergency driven by intertwined microcirculatory disorders, immune-inflammatory activation and metabolic dysregulation.This narrative overview collates representative published evidence to summarize research advances on hematological, immunological and metabolomic biomarkers, with a focus on their investigational-not yet clinically validated- diagnostic and prognostic potential. Key observational findings from existing cohorts are outlined as follows: (i) inflammatory and coagulation markers display promising discriminatory performance in single-center exploratory analyses, yet consistent cut-off values across populations remain absent; (ii) multi-indicator combined nomograms yield favorable predictive metrics within isolated research groups, though external multi-center validation is still required; (iii) exosomal molecules, complement C3, and other novel metabolic markers provide new analytical angles to interpret disease mechanisms and guide tentative individualized intervention research. Despite these preliminary observational results, widespread clinical translation is hindered by limited sample scales, non-uniform detection protocols and confounding comorbidities. Future multi-omics combined modeling aided by artificial intelligence may only serve as auxiliary stratification tools after rigorous prospective verification, rather than supporting definitive clinical classification at the current stage.This narrative collation merely offers preliminary analytical references for auxiliary clinical assessment and personalized research design of ISSNHL, without claiming validated diagnostic utility for routine practice.

Antibody-based cancer therapies have long been valued for their high target specificity and favorable safety profiles compared with conventional chemotherapy and radiotherapy. The field has expanded rapidly, driven in part by advances in antibody engineering and the emergence of antibody-derived modalities. Among these, bispecific antibodies (bsAbs) and agonists have independently reshaped the therapeutic landscape by enabling novel mechanisms of action. However, the clinical development of agonists has been hampered by challenges such as systemic toxicity arising from excessive receptor activation and limited efficacy associated with inadequate receptor clustering or context-dependent signaling. To address these limitations, a distinct class of engineered molecules-agonistic bsAbs-has recently emerged as a promising therapeutic strategy. By spatially and contextually restricting receptor activation, these antibodies aim to enhance agonistic potency while improving safety and therapeutic index. Notably, in addition to their roles in cancer therapy, agonistic bsAbs also exhibit therapeutic potential in metabolic diseases. In this review, we classify agonistic bsAbs according to the nature of the receptors requiring activation, including immune co-stimulatory receptors, death receptors, and growth factor receptors. For each category, we summarize representative agonistic bsAbs, with a focus on their molecular design principles, mechanisms of action, preclinical and clinical progress, and current limitations. Together, this overview highlights agonistic bispecific antibodies as an evolving and versatile platform with the potential to redefine antibody-based therapeutics.

Proximal hip fractures represent a profound acute physiological stress in older adults and are often followed by infections, delayed recovery, and functional decline. These complications occur more frequently in frail individuals with reduced physiological resilience and impaired immune responses. As natural killer (NK) cells are central to early immune defense, we aimed to define how acute fracture, hospitalization and frailty shape NK cell homeostasis and function in older patients. We conducted a prospective study including older patients (> 65 years) with acute fractures (SMART cohort; n = 103) and compared them to matched healthy older people from the RESIST senior individuals (SI) cohort (n = 550). A subset of SMART patients (n = 55) was longitudinally followed-up post-surgery. NK cell frequency, phenotype and function were investigated using multiparametric flow cytometry, and plasma soluble immune mediators (SIMs) were analyzed. SMART patients were clinically frailer than matched SI individuals, as indicated by reduced grip strength and lower Barthel scores, and exhibited an inflammatory state with elevated CRP levels and leukocyte counts. NK cell frequencies were significantly reduced in SMART patients and inversely correlated with grip strength and systemic inflammation. Furthermore, NK cells from SMART patients showed a distinct immune phenotype and altered chemokine receptor expression compared with SI individuals. Of note, differences between frail and non-frail patients within the SMART cohort were modest and substantially smaller than those observed between SMART patients and SI individuals. Functionally, frail patients displayed reduced baseline expression of cytotoxic molecules, whereas cytokine-induced NK cell responses were preserved. Furthermore, longitudinal analyses revealed stable NK cell frequencies but surgical intervention remodeled NK cell subset distribution and marker expression. In conclusion, our findings indicate that NK cell alterations in older patients with fractures are likely driven by the combined impact of acute injury, hospitalization and surgery rather than by frailty alone.

Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder caused primarily by loss-of-function mutations in the voltage-gated potassium channel Kv1.1 (KCNA1). Small molecules that restore Kv1.1 activity hold promise as targeted therapies for EA1, yet current pharmacological strategies remain limited. Two electrode voltage-clamp electrophysiology and the Xenopus laevis oocyte expression system were used to study effects of carnosic acid, a phenolic diterpene from Salvia rosmarinus (rosemary) leaf extract on Kv1.1-linked EA1 mutant channels. We assessed ataxia therapeutic efficacy by comparing performance of Kcna1+/+ and Kcna1E283K/+ mice, a model of human EA1, on a balance beam under isoproterenol challenge in the absence or presence of 0.3-mg·kg-1 carnosic acid. Rosemary leaf extract and rosemary metabolite carnosic acid are efficacious Kv1.1 openers. Carnosic acid fully or partially corrects heterozygous, heteromeric Kv1.1 EA1 mutant channel activity in vitro and restores normal function in Kv1.1E283K/+ mice at 0.3 mg·kg-1. Experimental validation of unbiased in silico docking reveals carnosic acid occupies a binding pocket between the S1 and S4 helices of the voltage-sensing domain (VSD) of Kv1.1. Finally, we determined the chemical properties that endow carnosic acid with the ability to open Kv1.1 channels. Our findings uncover a Kv1.1 opener with the potential to reverse EA1 and other Kv1.1-linked disorders.

Polymers overcome the solubility issue of organic small molecules and offer superior structure-function designability compared to inorganic counterparts, representing a promising class of anode materials for aqueous magnesium-ion batteries (MIBs). However, their capacity remains relatively low (<200 mAh g-1) due to the insufficient density of accessible redox-active motifs and restricted electron transfer, thereby resulting in an inherent trade-off between electrochemical stability and capacity. Herein, we demonstrate a capacity-stability trade-off-breaking design of hexaazatrinaphthylene self-fused multi-N-heterocycles (PDP) through single-component self-dehalogenation polymerization of the six-electron-transfer 2,8,14-tribromodiquinoxalino[2,3-a:2',3'-c]phenazine (DP) acceptor. The hexaazatrinaphthylene extended &#x3c0;-conjugated structure of PDP maximizes the density of accessible imine sites and enables extensive electron delocalization with a narrow bandgap of 2.48 (vs. 3.13 eV for DP). These features activate rapid multielectron Mg2+ redox reactions at N-heterocyclic motifs with a low activation barrier (0.28 eV), delivering an impressive capacity (375 mAh g-1) for the PDP anode. Moreover, the intramolecular &#x3c0;-&#x3c0; interaction in PDP (-10.2 kcal mol-1) is stronger than the water solvation force (4.9 kcal mol-1), conferring excellent structural anti-dissolution in aqueous electrolytes for long-life MIBs (20&#x2009;000 cycles). When paired with a high-voltage Prussian blue cathode, the high-capacity PDP anode delivers state-of-the-art energy density (252 Wh kg-1) and cycling stability (88.9% capacity retention over 20&#x2009;000 cycles). This work broadens the structural diversity of multi-active and stable polymers, marking a good start for advanced MIBs.

Psychological distress may be associated with systemic immune regulation through neuroendocrine-immune pathways. Emergency medical services (EMS) personnel represent a high-demand occupational group, but their circulating cytokine and chemokine profiles and their relationship with psychological distress remain poorly characterized. This exploratory cross-sectional study examined inflammatory and physiological markers in EMS personnel compared with matched controls, with particular attention to the association between cortisol and CX3CL1 and exploratory sex-related patterns. Seventy-eight participants, including 39 EMS personnel and 39 matched controls, underwent assessment of blood pressure, plasma cortisol, cytokines, chemokines, soluble adhesion molecules, and an exploratory panel of cardiovascular-related proteins. Psychological distress, including depression, anxiety, and stress symptoms, was assessed using the Depression, Anxiety and Stress Scale-21 in EMS personnel. Plasma concentrations of inflammatory mediators were analyzed after log10 transformation using two-way analysis of variance with group and sex as fixed factors. Spearman correlation analyses were used to explore associations between cortisol and inflammatory mediators. The EMS group showed higher systolic blood pressure and cortisol levels than the control group. The EMS group also exhibited a broad cytokine-chemokine alteration characterized by increased concentrations of several cytokines, including GM-CSF, IFN-&#x3b1;, IL-1&#x3b1;, IL-1&#x3b2;, IL-6, IL-10, and IL-13, and chemokines, including CCL2 and CX3CL1/fractalkine. In contrast, circulating E-selectin, P-selectin, and sICAM-1 were reduced in the EMS group. Most cytokines and chemokines formed a highly intercorrelated inflammatory cluster. However, CX3CL1 showed a more independent correlation pattern and was selectively associated with cortisol, whereas cortisol was not associated with the broader cytokine-chemokine network. This cortisol-CX3CL1 association was more evident among women. Within the EMS group, women reported higher anxiety and stress scores than men, whereas men showed higher systolic and diastolic blood pressure. EMS personnel exhibited an altered systemic cytokine-chemokine profile together with physiological changes and exploratory sex-related patterns. The selective association between cortisol and CX3CL1 suggests that circulating CX3CL1/fractalkine may reflect a stress-sensitive chemokine and a candidate marker of neuroendocrine-immune interaction. These findings support the relevance of integrating psychological, endocrine, and immune markers to characterize biological responses to psychological distress in high-demand healthcare populations.

How NaV channel isoforms set their activation voltages - and thereby define their specific functional roles in excitable cells - remains poorly understood. We show that extracellular charges in the domain II (DII) S3-S4 loop critically tune voltage-sensor activation in NaV1.7. Introducing positively charged residues in this loop depolarizes activation, whereas additional negative charges shift it in the hyperpolarizing direction. Extracellular Ca2 + further modulates these effects through electrostatic screening, demonstrating that local surface charge is a key determinant of voltage-sensor function. The NaV1.7-selective spider toxin Pn3a, which binds the DII S3-S4 loop, produces enhanced depolarizing shifts when its net positive charge is increased, showing that ligand electrostatics can fine-tune gating. Together, these results demonstrate that the local electrostatic environment near the DII voltage sensor controls NaV1.7 activation, providing a general mechanism - likely conserved across all voltage-gated ion channels - by which loop charges, extracellular ions or bound ligands can modulate channel function. By showing that local electrostatics near the DII voltage sensor govern activation, our findings provide a mechanistic explanation for isoform-specific gating and a framework for precisely tuning NaV channel function with engineered charged ligands. KEY POINTS: Voltage-gated sodium (NaV) channels are essential for generating electrical signals in nerves, muscles and the heart, yet how different NaV types are tuned to open at specific voltages was not well understood. This study shows that charged amino acids on the outer part of NaV1.7&#xa0;help set the voltage at which the channel activates, with positive charges making it harder to open and negative charges making it easier. We find that extracellular calcium can influence this process, demonstrating that the local electrical environment around the channel shapes its activity. A naturally occurring spider toxin, Pn3a, can also adjust channel activation depending on its surface charge, suggesting that we can engineer ligands to fine-tune excitability. Together, these results explain how NaV channels achieve isoform-specific gating and provide a framework for designing molecules that selectively control activation, with potential implications for pain and other disorders.

Backgrounds: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype with a unique tumor microenvironment, and while Programmed cell death protein 1/Programmed cell death ligand 1 (PD-1/PD-L1) blockade represents a standard immunotherapy, most patients develop primary or acquired resistance, with few alternative immunotherapeutic targets currently available. Therefore, we aimed to identify potential immune checkpoint-related molecules involved in TNBC-macrophage crosstalk, clarify the underlying molecular mechanism mediated by small extracellular vesicles (sEVs), and provide a theoretical basis for the future development of novel immunotherapeutic targets against TNBC. Methods: Single-cell RNA-sequencing (scRNA-seq) datasets for various breast cancer subtypes were used. Pseudotime trajectory, cell&#x2012;cell communication and Tumor Immune Estimation Resource 2.0 (TIMER2) analyses were conducted to characterize the tumour microenvironment (TME). Immunochemistry and immunofluorescence were used to confirm the results of the above analyses. Single-nucleus RNA sequencing (snRNA-seq) was conducted on three pairs of TNBC tumour and adjacent normal tissues. The functions of tumour-associated macrophages (TAMs) and sEVs in TNBC metastasis were explored by Western blotting, flow cytometry and cell-based experiments. Results: A total of nearly 60,000 high-quality single cells were subjected to scRNA-seq analysis, from which seven major cell types were identified. An overall increase in immune cell proportion was observed in TNBC compared with other subtypes, with the immune cell fraction in TNBC tissues being ~1.8-fold higher than that in luminal A/HER2+ subtypes (p < 0.001). Cell&#x2012;cell communication analysis indicated that TNBC cells mainly interact with macrophages. Interestingly, HAVCR2, an immune checkpoint, is expressed mainly in macrophages in the TNBC TME. HAVCR2 is associated with macrophage pseudotime progression in TNBC, which was validated by immunofluorescence staining. Moreover, analysis of The Cancer Genome Atlas (TCGA) bulk RNA-seq data revealed that HAVCR2 expression is significantly correlated with M2-like macrophage gene signatures and computationally inferred macrophage infiltration levels in TNBC, and this tissue-level transcriptional correlation is associated with poor patient prognosis. Notably, bulk RNA-seq data cannot define discrete cell subsets, and the identification of HAVCR2+ M2 macrophage subsets was independently validated by scRNA-seq and snRNA-seq at the single-cell level. Furthermore, treatment with TNBC-derived sEVs is associated with concurrent increases in the expression of HAVCR2 and M2-associated markers (CD163, CD206) in macrophages. These findings reflect a correlative association rather than a demonstrated causal or regulatory relationship between HAVCR2 and M2-associated marker upregulation. Conclusion: sEVs derived from TNBC cells are associated with the upregulation of M2-associated markers and concomitant HAVCR2 upregulation in macrophages, both of which correlate with TNBC progression and metastasis. We propose that HAVCR2 may serve as a candidate prognostic marker associated with M2-like macrophage features in TNBC, and these foundational in vitro findings from Human acute monocytic leukemia cell line (THP-1) macrophages warrant further validation in primary human monocyte-derived macrophages and in vivo TNBC models.