ZIF-8-modified hydrogel sequentially delivers angiogenic and osteogenic growth factors to accelerate vascularized bone regeneration.

To realize high-quality vascularized bone regeneration, we developed a multifunctional hydrogel (SHPP-ZB) by incorporating BMP-2@ZIF-8/PEG-NH2 nanoparticles (NPs) into a sodium alginate/hydroxyapatite/polyvinyl alcohol hydrogel loaded with PDGF-BB, allowing for the sequential release of angiogenic and osteogenic growth factors (GFs) during bone repair. ZIF-8 served as a protective host for BMP-2 from degradation, ensuring high encapsulation efficiency and long-term bioactivity. The SHPP-ZB hydrogel exhibited enhanced mechanical strength and injectability, making it suitable for complex bone defects. It provided a swelling interface for tissue interlocking and the early release of Zn2+ and tannin acid (TA) to exert antioxidant and antibacterial effects, followed by the sequential release of angiogenic and osteogenic GFs to promote high-quality vascularized bone regeneration. In vitro experiments demonstrated the superior angiogenic and osteogenic properties of SHPP-ZB compared to other groups. In vivo experiments indicated that the sequential delivery of GFs via SHPP-ZB hydrogel could improve vascularized bone regeneration. Further, RNA sequencing analysis of regenerative bone tissue revealed that SHPP-ZB hydrogel promoted vascularized bone regeneration by regulating JUN, MAPK, Wnt, and calcium signaling pathways in vivo. This study presented a promising approach for efficient vascularized bone regeneration in large-scale bone defects.

An enhanced tri-layer bionic periosteum with gradient structure loaded by mineralized collagen for guided bone regeneration and in-situ repair.

Severe fracture non-union often accompanied by damaged or even absent periosteum remains a significant challenge. This paper presents a novel tri-layer bionic periosteum with gradient structure and mineralized collagen (MC) mimics natural periosteum for in-situ repair and bone regeneration. The construct with ultrasonic polylactic acid as the loose outer fibrous layer (UPLA), poly(ε-caprolactone) as the intermediate barrier layer (PCL-M), and poly(ε-caprolactone)/MC as the inner osteoblastic layer (PM) was prepared. The physicochemical properties of layers were investigated. UPLA/PCL-M/PM exhibited a tensile strength (3.55 ± 0.23 MPa) close to that of natural periosteum and excellent adhesion between the layers. In vitro experiments demonstrated that all layers had no toxicity to cells. UPLA promoted inward growth of mouse fibroblasts. PCL-M with a uniform pore size (2.82 ± 0.05 µm) could achieve a barrier effect against fibroblasts according to the live/dead assay. Meanwhile, PM could effectively promote cell migration with high alkaline phosphatase expression and significant mineralization of the extracellular matrix. Besides, in vivo experiments showed that UPLA/PCL-M/PM significantly promoted the regeneration of bone and early angiogenesis. Therefore, this construct with gradient structure developed in this paper would have great application potential in the efficient and high-quality treatment of severe fractures with periosteal defects.

The contribution of silencer variants to human diseases.

BACKGROUND: Although disease-causal genetic variants have been found within silencer sequences, we still lack a comprehensive analysis of the association of silencers with diseases. Here, we profiled GWAS variants in 2.8 million candidate silencers across 97 human samples derived from a diverse panel of tissues and developmental time points, using deep learning models. RESULTS: We show that candidate silencers exhibit strong enrichment in disease-associated variants, and several diseases display a much stronger association with silencer variants than enhancer variants. Close to 52% of candidate silencers cluster, forming silencer-rich loci, and, in the loci of Parkinson's-disease-hallmark genes TRIM31 and MAL, the associated SNPs densely populate clustered candidate silencers rather than enhancers displaying an overall twofold enrichment in silencers versus enhancers. The disruption of apoptosis in neuronal cells is associated with both schizophrenia and bipolar disorder and can largely be attributed to variants within candidate silencers. Our model permits a mechanistic explanation of causative SNP effects by identifying altered binding of tissue-specific repressors and activators, validated with a 70% of directional concordance using SNP-SELEX. Narrowing the focus of the analysis to individual silencer variants, experimental data confirms the role of the rs62055708 SNP in Parkinson's disease, rs2535629 in schizophrenia, and rs6207121 in type 1 diabetes. CONCLUSIONS: In summary, our results indicate that advances in deep learning models for the discovery of disease-causal variants within candidate silencers effectively "double" the number of functionally characterized GWAS variants. This provides a basis for explaining mechanisms of action and designing novel diagnostics and therapeutics.

Rational design of ROS generation nanosystems to regulate innate immunity of macrophages, dendrtical and natural killing cells for immunotherapy.

Innate immunity serves as the first line of host defense in the body against pathogenic infections or malignant diseases. Reactive oxygen species (ROS), as vital signaling mediators, can efficiently elicit innate immune responses to oxidative-related stress or damage. In the era of nanomedicine, various immunostimulatory nanosystems have been extensively designed and synthesized to elicit immune responses for the immunotherapy of cancer or infectious diseases. In this review, we emphasize that ROS derived from nanosystems regulates innate immune cells to potentiate immunotherapeutic efficacy, such as primarily dendritic cells, macrophages, or natural killer cells. Meanwhile, we also summarize the pathway of ROS generation triggered by exogenous nanosystems in innate immune cells of DCs, macrophages, and NK cells.

Fluorescent probe applications and prospects in gastrointestinal cancer: A bibliometric analysis.

BACKGROUND: Gastrointestinal tumors, as one of the most common cancers worldwide, pose a significant threat to human health. In this context, the advent of fluorescence probe technology has offered new perspectives and methods for the diagnosis and surgical treatment of gastrointestinal tumors. However, there is currently a lack of systematic bibliometric analysis on the research concerning gastrointestinal cancer and fluorescence probes. METHOD: This study retrieved and comprehensively analyzed 1816 documents from the Web of Science database using the Cite Space tool, exploring the spatiotemporal distribution, author and subject category distribution, research themes, and keywords in this field. RESULTS: As of February 3, 2024, a total of 1816 records were retrieved, encompassing nine document types. Original research papers dominated the dataset, accounting for 89.922 %, followed by review articles at 6.773 %. We conducted a comprehensive analysis from various perspectives including countries, authors, institutions, keywords, journals, and references. Our findings reveal a strengthening trend in research on gastrointestinal cancer and fluorescent probes since 2010, with primary focus on drug delivery, endoscopy techniques, and genomic hybridization. CONCLUSION: In recent years, there has been a growing interest in the design, application, and quantitative analysis techniques of fluorescent probes, marking a notable frontier in this field. Our research findings offer fundamental insights and aid in identifying potential collaborators for future endeavors in this area.

Spin-Locked WS2 Vortex Emission via Photonic Crystal Bound States in the Continuum.

Owing to their strong exciton effects and valley polarization properties, monolayer transition-metal dichalcogenides (1L TMDs) have unfolded the prospects of spin-polarized light-emitting devices. However, the wavefront control of exciton emission, which is critical to generate structured optical fields, remains elusive. In this work, the experimental demonstration of spin-locked vortex emission from monolayer Tungsten Disulfide (1L WS2) integrated with Silicon Nitride (SiNx) PhC slabs is presented. The symmetry-protected bound states in the continuum (BIC) in the SiNx PhC slabs engender azimuthal polarization field distribution in the momentum space with a topological singularity in the center of the Brillouin zone, which imposes the resonantly enhanced WS2 exciton emission with a spin-correlated spiral phase front by taking advantage of the winding topologies of resonances with the assistance of geometric phase scheme. As a result, exciton emission from 1L WS2 exhibits helical wavefront and doughnut-shaped intensity beam profile in the momentum space with topological charges locked to the spins of light. This strategy on spin-dependent excitonic vortex emission may offer the unparalleled capability of valley-polarized structured light generation for 1L TMDs.

Peracetic Acid Activation by Modified Hematite for Water Purification: Performance, Degradation Pathways, and Mechanism.

Natural mineral-based advanced oxidation processes (AOPs) are now receiving increasing attention for the efficient degradation of pollutants. In this work, we used a common reducing agent (NaBH4) to treat natural Hematite to obtain modified Hematite (Hematite-(R)) and applied it to activate peracetic acid (PAA) for efficient degradation of cefazolin (CFZ). Compared with Hematite, the Hematite-(R)/PAA system increased the degradation rate of CFZ by 21.7% within 80 min under neutral conditions. Scavenging experiments and electron paramagnetic resonance (EPR) technology were introduced to identify the principal roles of 1O2, CH3C(O)OO•, and •OH for CFZ removal over the Hematite-(R)/PAA process. The outstanding capability of Hematite-(R) could be mainly due to the higher percentage of Fe(II) (52%) on the surface of catalysts. Furthermore, the possible degradation pathways of CFZ were explored. Moreover, the Hematite-(R)/PAA process showed a superior CFZ removal efficiency with a wide initial pH scope of 1.0-9.0. The degradation efficiency of CFZ showed a negligible effect in the presence of Cl-, SO42-, and NO3-, while significant inhibition was recorded after the addition of H2PO4- and CO32-. The inhibition of humic acid (HA) on CFZ degradation via the Hematite-(R)/PAA process showed an obvious concentration dependence. This work could provide strong support for the use of natural Hematite in water purification.

Efficacy of pars plana vitrectomy combined with internal limiting membrane peeling and gas tamponade for treating myopic foveoschisis: a meta-analysis.

OBJECTIVE: This study aimed to evaluate and explore the efficacy of pars plana vitrectomy (PPV) combined with internal limiting membrane (ILM) peeling and gas tamponade in treating myopic foveoschisis (MF) through a meta-analysis. METHODS: Systematic searches were conducted on the PubMed, Web of Science and National Library of Medicine (NLM) English-language databases and the China National Knowledge Infrastructure (CNKI) and Wanfang Chinese-language databases. The primary outcome measures were postoperative best-corrected visual acuity (BCVA) and central foveal thickness (CFT), with the secondary outcome being the postoperative complication rate. Data analysis was performed using RevMan5.3 software. RESULTS: A total of 10 studies involving 234 eyes were included. The meta-analysis results showed the following: (1) The average postoperative BCVA improved compared with preoperative levels, with an average improvement in the logarithm of the minimum angle of resolution of 0.40, a statistically significant difference (95% CI: -0.44, - 0.20, p < 0.001); (2) the rate of postoperative BCVA improvement was 77% (95% CI: 65%, 90%, p < 0.001); (3) the postoperative CFT significantly decreased by an average of 385.92 µm, a statistically significant difference (95% CI: -437.85, - 333.98, p < 0.001); (4) the postoperative macular retinal complete reattachment rate was 90% (95% CI: 83%, 97%, p < 0.001); (5) the most common postoperative complication was a cataract, with an incidence of 55.9%. CONCLUSION: Using PPV combined with ILM peeling and gas tamponade to treat MF is reliable.

Evaluation and clinical application of a bracketing calibration-based isotope dilution liquid chromatography-tandem mass spectrometry candidate reference measurement procedure for serum theophylline.

A candidate reference measurement procedure (RMP) for serum theophylline via isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. With a single-step precipitation pretreatment and a 6-min gradient elution, the method achieved baseline separation of theophylline and its analogs on a C18-packed column. A bracketing calibration method was used to ensure repeatable signal intensity and high measurement precision. The intra-assay and inter-assay imprecisions were 1.06%, 0.84%, 0.72% and 0.47%, 0.41%, 0.25% at concentrations of 4.22 µg/mL (23.40 µmol/L), 8.45 µg/mL (46.90 µmol/L), and 15.21 µg/mL (84.43 µmol/L), respectively. Recoveries ranged from 99.35 to 102.34%. The limit of detection (LoD) was 2 ng/mL, and the lowest limit of quantification (LLoQ) was 5 ng/mL. The linearity range extended from 0.47 to 60 µg/mL (2.61-333.04 µmol/L). No ion suppression and carry-over (< 0.68%) were observed. The relative bias for this candidate RMP that participated in 2023 External Quality Control for Reference Laboratories (RELA) conducted by the International Federation of Clinical Chemistry (IFCC) was within a range of 0.17 to 0.93%. Furthermore, two clinical immunoassay systems were compared with this candidate RMP, demonstrating good correlations. The results of the Trueness Verification Plan indicate significant differences among routine systems, highlighting the need for standardization efforts. The developed candidate RMP for serum theophylline serves as a precise reference baseline for standardizing clinical systems and assigning values to reference materials.

Excitonic van der Waals Metasurfaces for Resonant Wavefront Shaping at Deep Subwavelength Thickness Scale.

Dielectric phase gradient metasurfaces have emerged as promising candidates to shrink bulky optical elements to subwavelength thickness scale based on dielectric meta-atoms. These meta-atoms strongly interact with light, thus offering excellent phase manipulation of incident light. However, to fulfill 2π phase control using meta-atoms, the metasurface thickness, to date, is limited to the order of 102 nm. Here, we present the thickness scaling down of phase gradient metasurfaces to <λ/20 by using excitonic van der Waals metasurfaces. High-refractive-index enabled by exciton resonances and symmetry-breaking nanostructures in the patterned layered tungsten disulfide (WS2) corporately enable quasibound states in the continuum in WS2 metasurfaces, which consequently yield complete phase regulation of 2π with the thickness down to 35 nm. To illustrate the concept, we have experimentally demonstrated beam steering, focusing, and holographic display using WS2 metasurfaces. We envision our results unveiling new venues for ultimate thin phase gradient metasurfaces.

OTAMatch: Optimal Transport Assignment with PseudoNCE for Semi-supervised Learning.

In semi-supervised learning (SSL), many approaches follow the effective self-training paradigm with consistency regularization, utilizing threshold heuristics to alleviate label noise. However, such threshold heuristics lead to the underutilization of crucial discriminative information from the excluded data. In this paper, we present OTAMatch, a novel SSL framework that reformulates pseudo-labeling as an optimal transport (OT) assignment problem and simultaneously exploits data with high confidence to mitigate the confirmation bias. Firstly, OTAMatch models the pseudo-label allocation task as a convex minimization problem, facilitating end-to-end optimization with all pseudo-labels and employing the Sinkhorn-Knopp algorithm for efficient approximation. Meanwhile, we incorporate epsilon-greedy posterior regularization and curriculum bias correction strategies to constrain the distribution of OT assignments, improving the robustness with noisy pseudo-labels. Secondly, we propose PseudoNCE, which explicitly exploits pseudo-label consistency with threshold heuristics to maximize mutual information within self-training, significantly boosting the balance of convergence speed and performance. Consequently, our proposed approach achieves competitive performance on various SSL benchmarks. Specifically, OTAMatch substantially outperforms the previous state-of-the-art SSL algorithms in realistic and challenging scenarios, exemplified by a notable 9.45% error rate reduction over SoftMatch on ImageNet with 100K-label split, underlining its robustness and effectiveness.

Chiral absorption enhancement via critically coupled resonances in atomically thin photonic crystal exciton-polaritons.

Atomically thin transition metal dichalcogenides (TMDS) offer a promising route to the scaling down of optoelectronic devices to the ultimate thickness limit. But the weak light-matter interaction caused by their atomically thin nature makes them inevitably rely on external photonic structures to enhance optical absorption. Here, we report chiral absorption enhancement in atomically thin tungsten diselenide (WSe2) using chiral resonances in photonic crystal (PhC) nanostructures patterned directly in WSe2 itself. We show that the quality factors (Q factors) of the resonances grow exponentially as the PhC thickness approaches atomic limit. As such, the strong interaction of high Q factor photonic resonance with the coexisting exciton resonance in WSe2 results into self-coupled exciton-polaritons. By balancing the light coupling and absorption rates, the incident light can critically couple to chiral resonances in WSe2 PhC exciton-polaritons, leading to the theoretically limited 50% optical absorptance with over 84% circular dichroism (CD).

LncRNA ZFPM2-AS1 promotes phyllodes tumor progression by binding to CDC42 and inhibiting STAT1 activation.

Breast phyllodes tumor (PT) is a rare fibroepithelial neoplasm with potential malignant behavior. Long non-coding RNAs (lncRNAs) play multifaceted roles in various cancers, but their involvement in breast PT remains largely unexplored. In this study, microarray was leveraged for the first time to investigate the role of lncRNA in PT. We identified lncRNA ZFPM2-AS1 was significantly upregulated in malignant PT, and its overexpression endowed PT with high tumor grade and adverse prognosis. Furthermore, we elucidated that ZFPM2-AS1 promotes the proliferation, migration, and invasion of malignant PT in vitro. Targeting ZFPM2-AS1 through nanomaterial-mediated siRNA delivery in patient-derived xenograft (PDX) model could effectively inhibit tumor progression in vivo. Mechanistically, our findings showed that ZFPM2-AS1 is competitively bound to CDC42, inhibiting ACK1 and STAT1 activation, thereby launching the transcription of TNFRSF19. In conclusion, our study provides evidence that ZFPM2-AS1 plays a pivotal role in the pathogenesis of breast PT, and suggests that ZFPM2-AS1 could serve as a prognostic indicator for patients with PT as well as a promising novel therapeutic target.

Gelatin­sodium alginate composite hydrogel doped with black phosphorus@ZnO heterojunction for cutaneous wound healing with antibacterial, immunomodulatory, and angiogenic properties.

Hydrogels with novel antimicrobial properties and accelerated wound healing are of great interest in the field of wound dressings because they not only prevent bacterial infections but also fulfill the essential needs of wound healing. In this study, multifunctional hydrogel dressings consisting of black phosphorus nanosheets(BPNS) surface-modified Zinc oxide (BP@ZnO heterojunction) based on gelatin (Gel), sodium alginate (SA), glutamine transferase (mTG), and calcium ions with a three-dimensional crosslinked network were prepared. The BP@ZnO-Gel/SA hydrogel has excellent mechanical properties, hemocompatibility (hemolysis rate: 3.29 %), swelling rate(832.8 ± 19.2 %), cytocompatibility, photothermal and photodynamic antibacterial properties(Sterilization rate: 96.4 ± 3.3 %). In addition, the hydrogel accelerates wound healing by promoting cell migration, immune regulation and angiogenesis. Thus, this hydrogel achieves the triple effect of antimicrobial, immunomodulation and angiogenesis, and is a tissue engineering strategy with great potential.

A new fossil species of the extant genus Vicelva from mid-Cretaceous Kachin amber (Coleoptera: Staphylinidae).

A new species of the extant staphylinid genus Vicelva Moore & Legner, V. rasilis sp. nov., is reported from mid-Cretaceous Kachin amber of northern Myanmar. Vicelva rasilis is distinguishable from extant members of Vicelva by the smoother dorsal surface of head, pronotum and elytra, less prominent median projection of clypeus, unnotched mesal edge of mandibles, semiglabrous antennomere 6, and longer tarsomere 1. The pollen-containing coprolite attached to the beetle and the crystals within the beetle body provide valuable information about the biology and taphonomy of the fossil.

Impact of must clarification treatments on chemical and sensory profiles of kiwifruit wine.

This study examined the effect of various clarification treatments on the physicochemical properties, volatile compounds, and sensory attributes of kiwi wines produced from five different kiwifruit (Actinidia deliciosa) varieties. The degree of clarification had a minimal impact on physicochemical parameters, including the content of residual sugar, ethanol, volatile acid, titratable acidity (except for the kiwifruit variety 'Qinmei'), and the pH value. However, wines made from unclarified juices (muddy juice and pulp) displayed a higher glycerol content than those made from clarified juices. The cluster heat map and principal component analyses (PCA) demonstrated that kiwi wines produced from clarified kiwi juices possessed a higher ester content, whereas muddy juice and pulp wines contained elevated levels of higher alcohols. Quantitative descriptive analysis (QDA) indicated that clarified juice wines outperformed muddy juice and pulp wines in terms of purity, typicality, harmony, intensity, and freshness, with negligible differences in terms of palate acidity. Moreover, the clarified juice wines featured more characteristic kiwi wine aromas (kiwifruit, passionfruit, and pineapple) compared with that of the muddy juice and pulp wines, which exhibited an increased grassy flavour. Although the 100-NTU kiwifruit juice-fermented wine did not show an advantage in the cluster heat map and PCA, it presented better freshness, typicality, and intensity in the QDA, as well as a more passionfruit aroma. Based on the orthogonal partial least-squares discriminant analysis, A. deliciosa 'Xuxiang' was deemed to be the most suitable variety for vinification. This study provides crucial insights for enhancing the production of high-quality kiwi wine.

Electrohydrodynamic Direct-Writing Micro/Nanofibrous Architectures: Principle, Materials, and Biomedical Applications.

Electrohydrodynamic (EHD) direct-writing has recently gained attention as a highly promising additive manufacturing strategy for fabricating intricate micro/nanoscale architectures. This technique is particularly well-suited for mimicking the extracellular matrix (ECM) present in biological tissue, which serves a vital function in facilitating cell colonization, migration, and growth. The integration of EHD direct-writing with other techniques has been employed to enhance the biological performance of scaffolds, and significant advancements have been made in the development of tailored scaffold architectures and constituents to meet the specific requirements of various biomedical applications. Here, a comprehensive overview of EHD direct-writing is provided, including its underlying principles, demonstrated materials systems, and biomedical applications. A brief chronology of EHD direct-writing is provided, along with an examination of the observed phenomena that occur during the printing process. The impact of biomaterial selection and architectural topographic cues on biological performance is also highlighted. Finally, the major limitations associated with EHD direct-writing are discussed.

Engineered Probiotic Bio-Heterojunction with Robust Antibiofilm Modality via "Eating" Extracellular Polymeric Substances for Wound Regeneration.

The compact three-dimensional (3D) structure of extracellular polymeric substances (EPS) within biofilms significantly hinders the penetration of antimicrobial agents, making biofilm eradication challenging and resulting in persistent biofilm-associated infections. To address this challenge, a solution is proposed: a probiotic bio-heterojunction (P-bioHJ) combining Lactobacillus rhamnosus with MXene (Ti3C2) quantum dots (MQDs)/FeS heterojunction. This innovation aims to break down the saccharides in EPS, enabling effective combat against biofilm-associated infections. Initially, the P-bioHJ targets saccharides through metabolic processes, causing the collapse of EPS and allowing infiltration into bacterial colonies. Simultaneously, upon exposure to near-infrared (NIR) irradiation, the P-bioHJ produces reactive oxygen species (ROS) and thermal energy, deploying physical mechanisms to combat bacterial biofilms effectively. Following antibiofilm treatment, the P-bioHJ adjusts the oxidative environment, reduces wound inflammation by scavenging ROS, boosts antioxidant enzyme activity, and mitigates the NF-κB inflammatory pathway, thereby accelerating wound healing. In vitro and in vivo experiments confirm the exceptional antibiofilm, antioxidant/anti-inflammatory, and wound-regeneration properties of P-bioHJ. In conclusion, this study provides a promising approach for treating biofilm-related infections.

Identification and functional analysis of floral terpene synthase genes in Curcuma alismatifolia.

MAIN CONCLUSION: CaTPS2 and CaTPS3 were significantly expressed in flowers of Curcuma alismatifolia 'Shadow' and demonstrated bifunctional enzyme activity, CaTPS2 generated linalool and nerolidol as products, and CaTPS3 catalyzed ß-myrcene and ß-farnesene formation. This study presents the discovery and functional characterization of floral terpene synthase (TPS) genes in Curcuma alismatifolia 'Shadow', a cultivar renowned for its unique fragrance. Addressing the gap in understanding the genetic basis of floral scent in this species, we identified eight TPS genes through comprehensive transcriptome sequencing. Among these, CaTPS2 and CaTPS3 were significantly expressed in floral tissues and demonstrated bifunctional enzyme activity corresponding to the major volatile compounds detected in 'Shadow'. Functional analyses, including in vitro assays complemented with rigorous controls and alternative identification methods, elucidated the roles of these TPS genes in terpenoid biosynthesis. In vitro studies were conducted via heterologous expression in E. coli, followed by purification of the recombinant protein using affinity chromatography, enzyme assays were performed with GPP/FPP as the substrate, and volatile products were inserted into the GC-MS for analysis. Partially purified recombinant protein of CaTPS2 catalyzed GPP and FPP to produce linalool and nerolidol, respectively, while partially purified recombinant protein of CaTPS3 generated ß-myrcene and ß-farnesene with GPP and FPP as substrates, respectively. Real-time quantitative PCR further validated the expression patterns of these genes, correlating with terpenoid accumulation in different plant tissues. Our findings illuminate the molecular mechanisms underpinning floral fragrance in C. alismatifolia and provide a foundation for future genetic enhancements of floral scent in ornamental plants. This study, therefore, contributes to the broader understanding of terpenoid biosynthesis in plant fragrances, paving the way for biotechnological applications in horticulture plant breeding.

Distinct Photochemistry of Odd-Carbon PAHs from the Even-Carbon Ones During the Photoaging and Analysis of Soot.

Polycyclic aromatic hydrocarbons (PAHs) are the primary organic carbons in soot. In addition to PAHs with even carbon numbers (PAHeven), substantial odd-carbon PAHs (PAHodd) have been widely observed in soot and ambient particles. Analyzing and understanding the photoaging of these compounds are essential for assessing their environmental effects. Here, using laser desorption ionization mass spectrometry (LDI-MS), we reveal the substantially different photoreactivity of PAHodd from PAHeven in the aging process and their MS detection through their distinct behaviors in the presence and absence of elemental carbon (EC) in soot. During direct photooxidation of organic carbon (OC) alone, the PAHeven are oxidized more rapidly than the PAHodd. However, the degradation of PAHodd becomes preponderant over PAHeven in the presence of EC during photoaging of the whole soot. All of these observations are proposed to originate from the more rapid hydrogen abstraction reaction from PAHodd in the EC-photosensitized reaction, owing to its unique structure of a single sp3-hybridized carbon site. Our findings reveal the photoreactivity and reaction mechanism of PAHodd for the first time, providing a comprehensive understanding of the oxidation of PAHs at a molecular level during soot aging and highlight the enhanced effect of EC on PAHodd ionization in LDI-MS analysis.