A dynamic cascade DNA nanocomplex to synergistically disrupt the pyroptosis checkpoint and relieve tumor hypoxia for efficient pyroptosis cancer therapy

Pyroptosis has attracted widespread concerns in cancer therapy, while the therapeutic efficiency could be significantly restricted by using the crucial pyroptosis checkpoint of autophagy and tumor hypoxia. Herein, a DNA nanocomplex (DNFs@ZnMn), containing cascade DNAzymes, promoter-like ZnO2-Mn nanozymes and photosensitizers, was constructed in one pot through rolling circle amplification reactions to induce pyroptosis through disrupting autophagy. After targeting cancer cells with a high expression of H+ and glutathione, DNFs@ZnMn decomposed to expose DNAzymes and promoter-like ZnO2-Mn nanozymes. Then, sufficient metal ions and O2 were released to promote cascade DNA/RNA cleavage and relieving of tumor hypoxia. The released DNAzyme-1 self-cleaved long DNA strands with Zn2+ as the cofactor and simultaneously exposed DNAzyme-2 to cleave ATG-5 mRNA (with Mn2+ as the cofactor). This cascade DNAzyme-mediated gene regulation process induced downregulation of ATG-5 proteins to disrupt autophagy. Simultaneously, the released ZnO2 donated sufficient H2O2 to generate adequate O2 to relieve tumor hypoxia, obtaining highly cytotoxic 1O2 to trigger pyroptosis. By using dynamic cascade gene silencing to disrupt the pyroptosis checkpoint and synergistic relieving of hypoxia, this DNA nanocomplex significantly weakened cellular resistance to achieve efficient pyroptosis therapy both in vitro and in vivo.

Multienzyme-Like Polyoxometalate-Based Single-Atom Enzymes for Cancer-Specific Therapy Through Acid-Triggered Nontoxicity-to-Toxicity Transition

Single-atom enzymes (SAzymes) exhibit great potential for chemodynamic therapy (CDT); while, general application is still challenged by their instability and unavoidable side effects during delivery. Herein, a manganese-based polyoxometalate single-atom enzyme (Mn-POM SAE) is first introduced into tumor-specific CDT, which exhibits tumor microenvironment (TME)-activated transition of nontoxicity-to-toxicity. Different from traditional POM materials, the aggregates of low-toxic Mn-POM SAE nanospheres are obtained at neutral conditions, facilitating efficient delivery and avoiding toxicity problems in normal tissues. Under acid TME conditions, these nanospheres are degraded into smaller units of toxic Mn(II)-PW11; thus, initiating cancer cell-specific therapy. The released active units of Mn(II)-PW11 exhibit excellent multienzyme-like activities (including peroxidase (POD)-like, oxidase (OXD)-like, catalase (CAT)-like, and glutathione peroxidase (Gpx)-like activities) for the synergistic cancer therapy due to the stabilized high valence Mn species (MnIII/MnIV). As demonstrated by both intracellular evaluations and in vivo experiments, ROS is generated to cause damage to lysosome membranes, further facilitating acidification and impaired autophagy to enhance cancer therapy. This study provides a detailed investigation on the acid-triggered releasing of active units and the electron transfer in multienzyme-mimic-like therapy, further enlarging the application of POMs from catalytical engineering into cancer therapy.

Tumor-activated in situ synthesis of single-atom catalysts for O2-independent photodynamic therapy based on water-splitting

Single-atom catalysts (SACs) have attracted interest in photodynamic therapy (PDT), while they are normally limited by the side effects on normal tissues and the interference from the Tumor Microenvironment (TME). Here we show a TME-activated in situ synthesis of SACs for efficient tumor-specific water-based PDT. Upon reduction by upregulated GSH in TME, C3N4-Mn SACs are obtained in TME with Mn atomically coordinated into the cavity of C3N4 nanosheets. This in situ synthesis overcomes toxicity from random distribution and catalyst release in healthy tissues. Based on the Ligand-to-Metal charge transfer (LMCT) process, C3N4-Mn SACs exhibit enhanced absorption in the red-light region. Thereby, a water-splitting process is induced by C3N4-Mn SACs under 660 nm irradiation, which initiates the O2-independent generation of highly toxic hydroxyl radical (·OH) for cancer-specific PDT. Subsequently, the ·OH-initiated lipid peroxidation process is demonstrated to devote effective cancer cell death. The in situ synthesized SACs facilitate the precise cancer-specific conversion of inert H2O to reactive ·OH, which facilitates efficient cancer therapy in female mice. This strategy achieves efficient and precise cancer therapy, not only avoiding the side effects on normal tissues but also overcoming tumor hypoxia.

DNA conformational change embrace ultraviolet photolysis: A dual-mode sensing platform for electrochemical and fluorescent signaling

We developed a dual-mode biosensor that utilizes DNA conformational changes and ultraviolet photolysis for electrochemical (EC) and fluorescence (FL) detection. In this study, a stem-loop-structured carcinoembryonic antigen (CEA) aptamer was modified on an Au electrode, and this aptamer contained a redox-labeled methylene blue (MB), short-chain DNA with a 6-carboxylic fluorescein (FAM) and a PC linker that can be cleaved by ultraviolet light. Subsequently, CEA and CEA antibody-modified upconversion nanoparticle bioconjugates (CEA-Ab@UCNPs) were added. In the presence of CEA, Ab@UCNPs can bind CEA and push the MB which was originally close to the electrode surface, away from the electrode surface, resulting in a reduced redox current. Under irradiation with a 980 nm laser, the UCNPs emit ultraviolet light, leading to photocleavage of the PC linker and the release of FAM for FL sensing. Under optimal conditions, the EC and FL modes showed good responses to CEA within 0.01-50 ng/mL and 0.1-80 ng/mL, respectively.

Functionalized DNA nanoplatform for multi-target simultaneous imaging: Establish the atlas of cancer cell species

Detection and imaging of cell membrane receptor proteins have gained widespread interest in recent years. However, recognition based on a single biomarker can induce false positive feedback, including off-target phenomenon caused by the absence of tumor-specific antigens. In addition, nucleic acid probes often cause nonspecific and undesired cell internalization during cell imaging. In this work, we constructed a logic gate DNA nano-platform (LGDP) for single-molecule imaging of cell membrane proteins to synergistically diagnose cancer cells. The traffic light-like color response of LGDP facilitates the precise discrimination among different cell lines. Combined with single molecule technology, the target proteins were qualitatively and quantitatively analyzed synergistically. Logic-gated recognition integrated in aptamer-functionalized molecular machines will prompt fast cells analysis, laying the foundation of cancer early diagnosis and treatment.

[Construction and preliminary validation of a risk prediction model for the recurrence of diabetic foot ulcer in diabetic patients]

Objective: To develop a risk prediction model for the recurrence of diabetic foot ulcer (DFU) in diabetic patients and primarily validate its predictive value. Methods: Meta-analysis combined with retrospective cohort study was conducted. The Chinese and English papers on risk factors related to DFU recurrence publicly published in China Biology Medicine disc, China National Knowledge Infrastructure, Wanfang Database, VIP Database, and PubMed, Embase, Cochrane Library, and Web of Science, and the search time was from the establishment date of each database until March 31st, 2022. The papers were screened and evaluated, the data were extracted, a meta-analysis was performed using RevMan 5.4.1 statistical software to screen risk factors for DFU recurrence, and Egger's linear regression was used to assess the publication bias of the study results. Risk factors for DFU recurrence mentioned in ≥3 studies and with statistically significant differences in the meta-analysis were selected as the independent variables to develop a logistic regression model for risk prediction of DFU recurrence. The medical records of 101 patients with DFU who met the inclusion criteria and were admitted to Affiliated Hospital of Guizhou Medical University from January 2019 to June 2022 were collected. There were 69 males and 32 females, aged (63±14) years. The receiver operating characteristic (ROC) curve of the predictive performance of the above constructed predictive model for DFU recurrence was drawn, and the area under the ROC curve, maximum Youden index, and sensitivity and specificity at the point were calculated. Dataset including data of 8 risk factors for DFU recurrence and the DFU recurrence rates of 10 000 cases was simulated using RStudio software and a scatter plot was drawn to determine two probabilities for risk division of DFU recurrence. Using the β coefficients corresponding to 8 DFU recurrence risk factors ×10 and taking the integer as the score of coefficient weight of each risk factor, the total score was obtained by summing up, and the cutoff scores for risk level division were calculated based on the total score × two probabilities for risk division of DFU recurrence. Results: Finally, 20 papers were included, including 3 case-control studies and 17 cohort studies, with a total of 4 238 cases and DFU recurrence rate of 22.7% to 71.2%. Meta-analysis showed that glycosylated hemoglobin >7.5% and with plantar ulcer, diabetic peripheral neuropathy, diabetic peripheral vascular disease, smoking, osteomyelitis, history of amputation/toe amputation, and multidrug-resistant bacterial infection were risk factors for the recurrence of DFU (with odds ratios of 3.27, 3.66, 4.05, 3.94, 1.98, 7.17, 11.96, 3.61, 95% confidence intervals of 2.79-3.84, 2.06-6.50, 2.50-6.58, 2.65-5.84, 1.65-2.38, 2.29-22.47, 4.60-31.14, 3.13-4.17, respectively, P<0.05). There were no statistically significant differences in publication biases of diabetic peripheral neuropathy, diabetic peripheral vascular disease, glycosylated hemoglobin >7.5%, plantar ulcer, smoking, multidrug-resistant bacterial infection, or osteomyelitis (P>0.05), but there was a statistically significant difference in the publication bias of amputation/toe amputation (t=-30.39, P<0.05). The area under the ROC curve of the predictive model was 0.81 (with 95% confidence interval of 0.71-0.91) and the maximum Youden index was 0.59, at which the sensitivity was 72% and the specificity was 86%. Ultimately, 29.0% and 44.8% were identified respectively as the cutoff for dividing the probability of low risk and medium risk, and medium risk and high risk for DFU recurrence, while the corresponding total scores of low, medium, and high risks of DFU recurrence were <37, 37-57, and 58-118, respectively. Conclusions: Eight risk factors for DFU recurrence are screened through meta-analysis and the risk prediction model for DFU recurrence is developed, which has moderate predictive accuracy and can provide guidance for healthcare workers to take interventions for patient with DFU recurrence risk.

Ultrathin 2D Pd/Cu Single-Atom MOF Nanozyme to Synergistically Overcome Chemoresistance for Multienzyme Catalytic Cancer Therapy

Single-atom nanozymes (SAzymes) have obtained increasing interest to mimic natural enzymes for efficient cancer therapy, while challenged by chemoresistance from cellular redox homeostasis and the interface of reductive species in tumor microenvironment (TME). Herein, a dual single-atomic ultrathin 2D metal organic framework (MOF) nanosheet of multienzyme (Pd/Cu SAzyme@Dzy) is prepared to synergistically overcome chemoresistance for multienzyme enhanced cancer catalytic therapy. The Pd SAzyme exhibits peroxidase (POD)-like catalytic activity for overcoming chemoresistance via disturbing cellular redox balance. This is further enhanced by cascade generation of more ∙OH via Cu+ -catalyzed POD-like reactions, initiated by in situ-reduction of Cu2+ into Cu+ upon GSH depletion. This process can also avoid the consumption of ∙OH by endogenous reductive GSH in TME, ensuring the adequate amount of ∙OH for highly efficient therapy. Besides, the DNAzyme is also delivered for gene therapy of silencing cancer-cell-targeting VEGFR2 protein to further enhance the therapy. Based on both experiments and theoretical calculations, the synergetic multienzyme-based cancer therapy is examined and the enhancement by the cascade tumor antichemoresistance is revealed.

Synergistically remodulating H+/Ca2+ gradients to induce mitochondrial depolarization for enhanced synergistic cancer therapy

The remodulation of H+/Ca2+ gradients in the mitochondria matrix could be effective to induce mitochondria depolarization for the enhancement of cancer therapy. However, it is still challenged by H+ homeostasis, insufficient Ca2+, uncoordinated regulations, and inefficient loading/delivery strategies. Herein, a supramolecular DNA nanocomplex (Ca@DNA-MF) was prepared to synergistically remodulate H+/Ca2+ gradients for mitochondrial depolarization. Upon targeted functionalization and TME-triggered delivery, multiple reagents were released in cancer cells for synergistic three-channel mitochondrial depolarization: the gene reagent of siMCT4 blocked the LA metabolism to induce mitochondrial acidification by downregulating monocarboxylate transporter 4 (MCT4); released Ca2+ disrupted Ca2+ homeostasis to facilitate Ca2+-based mitochondrial depolarization; specifically, TME-activated glutathione (GSH) depletion facilitated efficient generation of hydroxyl radicals (˙OH), further enhancing the mitochondrial depolarization. The remodulation not only triggered apoptosis but also led to ferroptosis to generate abundant ROS for efficient LPO-based apoptosis, providing a synergistic strategy for enhanced synergistic cancer therapy.

Generative Adversarial Network-Enhanced Ultra-Low-Dose [18F]-PI-2620 τ PET/MRI in Aging and Neurodegenerative Populations

BACKGROUND AND PURPOSE

With the utility of hybrid τ PET/MR imaging in the screening, diagnosis, and follow-up of individuals with neurodegenerative diseases, we investigated whether deep learning techniques can be used in enhancing ultra-low-dose [18F]-PI-2620 τ PET/MR images to produce diagnostic-quality images.

MATERIALS AND METHODS

Forty-four healthy aging participants and patients with neurodegenerative diseases were recruited for this study, and [18F]-PI-2620 τ PET/MR data were simultaneously acquired. A generative adversarial network was trained to enhance ultra-low-dose τ images, which were reconstructed from a random sampling of 1/20 (approximately 5% of original count level) of the original full-dose data. MR images were also used as additional input channels. Region-based analyses as well as a reader study were conducted to assess the image quality of the enhanced images compared with their full-dose counterparts.

RESULTS

The enhanced ultra-low-dose τ images showed apparent noise reduction compared with the ultra-low-dose images. The regional standard uptake value ratios showed that while, in general, there is an underestimation for both image types, especially in regions with higher uptake, when focusing on the healthy-but-amyloid-positive population (with relatively lower τ uptake), this bias was reduced in the enhanced ultra-low-dose images. The radiotracer uptake patterns in the enhanced images were read accurately compared with their full-dose counterparts.

CONCLUSIONS

The clinical readings of deep learning-enhanced ultra-low-dose τ PET images were consistent with those performed with full-dose imaging, suggesting the possibility of reducing the dose and enabling more frequent examinations for dementia monitoring.

[Summary of the best evidence on exercise for the prevention and treatment of diabetic foot]

Objective: To summarize the best evidence on exercise for the prevention and treatment of diabetic foot. Methods: A bibliometric approach was used. Systematic searches were carried out to retrieve all the publicly published evidences till July 2022 on exercise for the prevention and treatment of diabetic foot, including guidelines, evidence summary, recommended practices, expert consensus, systematic review, and original research, from foreign language databases including BMJ Best Practice, UpToDate, Joanna Briggs Institute Evidence-Based Practice Database, Cochrane Library, Embase, PubMed, Guideline International Network, National Guideline Clearinghouse, Chinese databases including China National Knowledge Infrastructure, Wanfang Database, VIP Database, China Biology Medicine disc, China Clinical Guidelines Library, and the official websites of relevant academic organizations including National Institute for Health and Care Excellence of the United Kingdom, Registered Nurses' Association of Ontario of Canada, the International Working Group on the Diabetic Foot, International Diabetes Federation, American College of Sports Medicine, American Diabetes Association, and Chinese Diabetes Society. The literature was screened and evaluated for the quality, from which the evidences were extracted and evaluated to summarize the best evidences. Results: Nine guidelines, three expert consensuses, one evidence summary (with two systematic reviews being traced), two systematic reviews, 6 randomized controlled trials were retrieved and included, with good quality of literature. Totally 33 pieces of best evidences on exercise for the prevention and treatment of diabetic foot were summarized from the aspects of appropriate exercise prevention of diabetic foot, exercise therapy of diabetic foot, precautions for exercise, health education, and establishment of a multidisciplinary limb salvage team. Conclusions: Totally 33 pieces of best evidences on exercise for the prevention and treatment of diabetic foot were summarized from 5 aspects, providing decision-making basis for clinical guidance on exercise practice for patients with diabetic foot.

Oxygen Bridge Formed by Doping Nonmetal Atoms into Cationic Vacancies To Enhance the Photoelectrochemical Oxygen Evolution Reaction

To enhance photoelectrochemical (PEC) water splitting for renewable energy conversion, the conventional strategy is doping nonmetals into anionic vacancies. Compared to anionic vacancies, cationic vacancies are theoretically more effective and reliable for anchoring nonmetals owing to their larger radii and unique advantages. The current research mainly focuses on anionic vacancies, while there are few studies on cationic vacancies due to high formation energy and challenging characterizations by convenient techniques. To overcome the current limitations, nonmetallic S and P atoms are successfully doped into cationic vacancies on the TiO₂ surface for tuning local electronic structures. In contrast to the traditional strategy of reducing the bandgaps, nonmetallic atom doping into cationic vacancies facilitates efficient electronic regulation for PEC enhancement without changing the bandgap. The enhanced performance is attributed to the formation of an oxygen bridge, which can accumulate electrons from surrounding S/P atoms. Significantly, the electron-enriched oxygen bridge efficiently transfers electrons to activate reaction site Ti, which can promote the oxygen evolution reaction performance. Density functional theory calculations reveal that the decrease of reaction energy barriers and the optimization of local electron distribution are conducive to electronic transmission. This would provide a high-efficiency electronic tuning strategy for improving PEC performance.

Dual Active Centers Linked by a Reversible Electron Station as a Multifunctional Nanozyme to Induce Synergetically Enhanced Cascade Catalysis for Tumor-Specific Therapy

Nanozymes have shown great promise in reactive oxygen species (ROS)-mediated tumor therapy with mitigated side effects but are normally limited by the complex tumor microenvironment (TME). Herein, to overcome the adverse effects of TME, such as tumor hypoxia and high endogenous glutathione (GSH), an aptamer-functionalized Pd@MoO_3-x nano-hydrangea (A-Pd@MoO_3-x NH) is constructed for high-efficiency cancer therapy. Utilizing the irregular shape characteristics of nano Pd, the A-Pd@MoO_3-x NH nanozyme simultaneously exposes catalase-like Pd(111) and oxidase-like Pd(100) surface facets as dual active centers. This can catalyze cascade enzymatic reactions to overcome the negative effects of tumor hypoxia caused by the accumulation of cytotoxic superoxide (O₂^•-) radicals in TME without any external stimuli. In addition, the nanozyme can effectively degrade the overexpressed glutathione (GSH) through the redox reaction to avoid nontherapeutic consumption of O₂^•- radicals. More significantly, as a reversible electron station, MoO_3-x can extract electrons from H₂O₂ decomposing on Pd(111) or GSH degradation and transfer them back to Pd(100) through oxygen bridges or few Mo-Pd bonds. This can synergistically enhance enzyme-like activities of dual active centers and the GSH-degrading ability to enrich O₂^•- radicals. In this way, the A-Pd@MoO_3-x NH nanozyme can selectively and remarkably kill tumor cells while keeping the normal cell line unharmed.

Regulating donor-acceptor system toward highly efficient dual-state emission for sensitive response of nitroaromatic explosives

Dual-state emission luminogens (DSEgens) as fluorophores emit efficiently in solution and solid forms have gained increasing concern in the field of chemical sensing. Recent efforts by our group led to the identification of DSEgens as an easy-to-visualize nitroaromatic explosives (NAEs) detection platform. However, none of the previously studied NAEs probes show effective improvement in sensitivity. Here, we designed a series of benzoxazole-based DSEgens through multiple strategies driven by theoretical calculations, revealing their improved detecting performance on NAEs. Compounds 4a-4e exhibit thermal- and photo-stability, large Stokes shift as well as sensitivity solvatochromism (except for 4a and 4b). A subtle balance between rigid conjugation and distorted conformation endows these D-A type fluorophores 4a-4e with DSE properties. Furthermore, 4d and 4e show aggregation-induced emission phenomenon caused by distorted molecular conformation and restricted intramolecular rotation. Interestingly, DSEgen 4e displays anti-interference and sensitivity towards NAEs with a detection limit of 10^-8 M. It can be applied for expedient and distinct visual identification of NAEs not only in solution but also on filter paper and film, supporting this new DSEgen as reliable NAEs chemoprobe.

Computation-Assisted Design of ssDNA Framework Nanorobots for Cancer Logical Recognition, Toehold Disintegration, Visual Dual-Diagnosis, and Synergistic Therapy

Single-stranded DNA (ssDNA) allows flexible and directional modifications for multiple biological applications, while being greatly limited by their poor stability, increased folding errors, and complicated sequence optimizations. This greatly challenges the design and optimization of ssDNA sequences to fold stable 3D structures for diversified bioapplications. Herein, the stable pentahedral ssDNA framework nanorobots (ssDNA nanorobots) were intelligently designed, assisted by examining dynamic folding of ssDNA in self-assemblies via all-atom molecular dynamics simulations. Assisted by two functional siRNAs (S1 and S2), two ssDNA strands were successfully assembled into ssDNA nanorobots, which include five functional modules (skeleton fixation, logical dual recognition of tumor cell membrane proteins, enzyme loading, dual-miRNA detection and synergy siRNA loading) for multiple applications. By both theoretical calculations and experiments, ssDNA nanorobots were demonstrated to be stable, flexible, highly utilized with low folding errors. Thereafter, ssDNA nanorobots were successfully applied to logical dual-recognition targeting, efficient and cancer-selective internalization, visual dual-detection of miRNAs, selective siRNA delivery and synergistic gene silencing. This work has provided a computational pathway for constructing flexible and multifunctional ssDNA frameworks, enlarging biological application of nucleic acid nanostructures.

Single-Molecule Evaluation of the SARS-CoV-2 Nucleocapsid Protein Using Gold Particle-in-a-Frame Nanostructures Enhanced Fluorescent Assay

Ultrasensitive evaluation of low-abundance analytes, particularly with limits approaching a single molecule, is a key challenge in the design of an assay for profiling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen. Herein, we report an aptamer claw strategy for directly evaluating the SARS-CoV-2 antigen based on gold particle-in-a-frame nanostructures (Au PIAFs). Au PIAF was used as a metal-enhanced fluorescence material. The assay integrated with a microplate reader achieved a sensitivity of 44 fg·mL-1 in under 3 min and accurately detected the SARS-CoV-2 nucleocapsid protein (N protein) in human saliva samples. When our assay is combined with a single-molecule counting platform, the limit of detection can be as low as 0.84 ag·mL-1. This rapid and ultrasensitive assay holds promise as a tool for screening SARS-CoV-2 and other contagious viruses.

Examination of electronically mismatched Diels-Alder reaction by on-line mass spectrometry

RATIONALE

Electronically mismatched Diels-Alder reactions have gained much attention as an alternative pathway for C-C bond formation. To facilitate the development of facile organic transformations, mechanistic investigations are required. Spectroscopic methods (NMR, electron paramagnetic resonance and UV-visible) are normally adopted for mechanistic examinations, but further improvements in directly obtaining structural information of short-lived intermediates are encouraged. Herein, an electronically mismatched Diels-Alder reaction between indole and 1,3-cyclohexadiene was studied using in situ electrospray ionization mass spectrometry (in situ ESI-MS). Based on direct sampling and detection of the in situ ESI-MS without sample pretreatment, the structures and dynamics of important intermediates were examined on-line.

METHODS

A syringe-based photocatalytic reactor and in situ ambient MS (AMS) evaluation system was constructed for mechanism studies. The role of oxygen was confirmed via control reaction employed in the N₂ -bubbled system. The stepwise cation radical-based pathway and the [2 + 2] cycloaddition process were determined through a series of experiments, including solvent evaluation, MS/MS experiments and dynamic monitoring.

RESULTS

The dependence of the reaction on solvent polarity demonstrated that the reaction occurs via the formation of cation radicals, which were captured, identified and dynamically monitored via in situ ESI-MS. Without pre-separation, the intermediate of [2 + 2] cycloaddition was identified and the cycloaddition process was thereby determined to be the combination of [4 + 2] cycloaddition and [2 + 2] cycloaddition. In addition, oxygen was proved to act as an electron mediator for both catalyst Ru(bpz)₃ (PF₆ )₂ and radical cations.

CONCLUSIONS

The mechanism of an electronically mismatched Diels-Alder reaction was successfully deduced by in situ MS associated with a syringe-based photocatalytic reactor. The structures and dynamics of cation radicals, the effect of O₂ for the reaction and the detailed process of [2 + 2] cycloaddition have been well demonstrated. This work could not only promote the understanding and development of facile photocatalytic transformations, but also enlarge the application range of AMS in on-line monitoring.

OH radical-initiated single-electron transfer for accelerated degradation via carbocation intermediates

Single electron transfer (SET) has made great contributions to a broad range of chemical processes, whose radical cation and carbocation intermediates are important for mechanism studies. Herein, hydroxyl radical (˙OH)-initiated SET was revealed in accelerated degradations, via the online examination of radical cations and carbocations by electrosonic spray ionization mass spectrometry (ESSI-MS). In the green and efficient non-thermal plasma catalysis system (MnO₂-plasma), hydroxychloroquine was efficiently degraded upon SET via carbocations. In the plasma field full of active oxygen species, ˙OH was generated on the MnO₂ surface to initiate SET-based degradations. Furthermore, theoretical calculations revealed that ˙OH preferred to withdraw the electron from the N atom that was conjugated to the benzene ring. This facilitated the generation of radical cations through SET, which was followed by the sequential formation of two carbocations for accelerated degradations. Transition states and energy barriers were calculated to study the formation of radical cations and subsequent carbocation intermediates. This work demonstrates an ˙OH-initiated SET for accelerated degradation via carbocations, providing a deeper understanding and the potential for the wider application of SET in green degradations.

Confined surface-enhanced indole cation-radical cyclization studied by mass spectrometry

Reactions in confined spaces exhibit unique reactivity, while how the confinement effect enhances reactions remains unclear. Herein, the reaction in the confined space of a nanopipette reactor was examined by in situ nano-electrospray mass spectrometry (nanoESI-MS). The indole cation-radical cyclization was selected as the model reaction, catalyzed by a common visible-light-harvesting complex Ru(bpz)₃(PF₆)₂ (1% eq.) rather than traditional harsh reaction conditions (high temperature or pressure, etc.). As demonstrated by in situ nanoESI-MS, this reaction was readily promoted in the nanopipette under mild conditions, while it was inefficient in both normal flasks and microdroplets. Both experimental and theoretical evidence demonstrated the formation of concentrated Ru(II)-complexes on the inner surface of the nanopipette, which facilitated the accelerated reactions. As a result, dissociative reactive cation radicals with lower HOMO-LUMO gap were generated from the Ru(II)-complexes by ligand-to-metal charge transfer (LMCT). Furthermore, the crucial cation radical intermediates were captured and dynamically monitored via in situ nanoESI-MS, responsible for the electronically matched [4 + 2] cycloaddition and subsequent intramolecular dehydrogenation. This work inspires a deeper understanding of the unique reactions in confined spaces.

CRISPR/Cas9-based coronal nanostructures for targeted mitochondria single molecule imaging

The biological state at the subcellular level is highly relevant to many diseases, and the monitoring of organelles such as mitochondria is crucial based on this. However, most DNA and protein based nanoprobes used for the detection of mitochondrial RNAs (mitomiRs) lack spatial selectivity, which leads to inefficiencies in probe delivery and signal turn-on. Herein, we constructed a novel DNA nanoprobe named protein delivery nano-corona (PDNC) to improve the delivery efficiency of Cas protein, for spatially selective imaging of mitomiRs in living cells switched on by a CRISPR/Cas system. Combined with a single-molecule counting method, this strategy enables highly sensitive detection of low-abundance mitomiR. Therefore, the strategy in this work opens up new opportunities for cell identification, early clinical diagnosis, and research in biological behaviour at the subcellular level.

Identification of a apoptosis-related LncRNA signature to improve prognosis prediction and immunotherapy response in lung adenocarcinoma patients

Apoptosis is closely associated with the development of various cancers, including lung adenocarcinoma (LUAD). However, the prognostic value of apoptosis-related lncRNAs (ApoRLs) in LUAD has not been fully elucidated. In the present study, we screened 2, 960 ApoRLs by constructing a co-expression network of mRNAs-lncRNAs associated with apoptosis, and identified 421 ApoRLs that were differentially expressed between LUAD samples and normal lung samples. Sixteen differentially expressed apoptosis-related lncRNAs (DE-ApoRLs) with prognostic relevance to LUAD patients were screened using univariate Cox regression analysis. An apoptosis-related lncRNA signature (ApoRLSig ) containing 10 ApoRLs was constructed by applying the Least Absolute Shrinkage and Selection Operator (LASSO) Cox regression method, and all LUAD patients in the TCGA cohort were divided into high or low risk groups. Moreover, patients in the high-risk group had a worse prognosis (p < 0.05). When analyzed in conjunction with clinical features, we found ApoRLSig to be an independent predictor of LUAD patients and established a prognostic nomogram combining ApoRLSig and clinical features. Gene set enrichment analysis (GSEA) revealed that ApoRLSig is involved in many malignancy-associated immunomodulatory pathways. In addition, there were significant differences in the immune microenvironment and immune cells between the high-risk and low-risk groups. Further analysis revealed that the expression levels of most immune checkpoint genes (ICGs) were higher in the high-risk group, which suggested that the immunotherapy effect was better in the high-risk group than in the low-risk group. And we found that the high-risk group was also better than the low-risk group in terms of chemotherapy effect. In conclusion, we successfully constructed an ApoRLSig which could predict the prognosis of LUAD patients and provide a novel strategy for the antitumor treatment of LUAD patients.

Near-Infrared Fluorescent Probe for H2S Detection: Will pH Affect the Intracellular Sensing?

Near-infrared (NIR) fluorescent probe has exhibited unique advantages for in vitro and in vivo detection of hydrogen sulfide (H₂S), an important endogenous gasotransmitter in redox homeostasis and multiple life processes. However, both the pH-dependent emission of NIR probes and H₂S conversions would normally affect the accurate detection in cellular environments in different acidic conditions. Herein, both experiments and theoretical calculations were carried out to examine the effect of pH on intracellular sensing of H₂S by the NIR probe. Selecting a NIR probe of R1 with dual-excited NIR responses to H₂S as the model, the pH-dependent R1 emission was confirmed by optical measurements, whose structural changes were further examined by mass spectrometry (MS). Significantly, the dynamic changes versus pH increase were employed for the online monitoring of ambient MS (AMS), observing important intermediate species without sample pretreatments. Thereby, intermediates and transition states were confirmed by theoretical calculations, which proposed the mechanism of nucleophilic substitution, followed by the hydrolysis process with increasing pH. As examined, R1 exhibited a relatively stable NIR emission at pH 4-8, while a dramatic change in signals occurred at higher-pH conditions. Therefore, R1 was demonstrated to be reliable for intracellular sensing of H₂S and had been confirmed by cell imaging. This work has initiated a comprehensive strategy for evaluating fluorescence (FL) probes, showing potential for the development of fluorescent probes.

Water-resistant organic-inorganic hybrid perovskite quantum dots activated by the electron-deficient d-orbital of platinum atoms for nitrogen fixation

Due to their special physicochemical properties, organic-inorganic hybrid perovskite quantum dots (OIP QDs) are ideal and potential catalysts for the nitrogen reduction reaction (NRR). However, the OIP QD-based NRR is limited by poor water resistance, competitive suppression by the hydrogen evolution reaction, and inefficient active sites on the catalyst surfaces. Herein, to ensure an efficient NRR in aqueous solution, a water-resistant polycarbonate-part-encapsulated heterojunction of Zn,Pt^IV co-doped PbO-MAPbBr₃ (Pt^IV/Zn/PbO/PC-Zn/MAPbBr₃) is prepared through one-step electrospray-based microdroplet synthesis. Confirmed by both experimental and theoretical examinations, PbO is exposed on the PC-part-encapsulated surface to construct a Type I heterojunction. This heterojunction is further improved by synergistic co-doping with Pt^IV to facilitate efficient electron transfer for efficient photocatalysis of the NRR. Due to the active sites of the d-orbital electron-deficient Pt atoms (exhibiting a lower reaction energy barrier and highly selective N₂ adsorption), the ammonia yield rate is 40 times higher than that without doping. This work initiates and develops on the application of OIP QDs in the NRR.

Nematicidal Activity of Burkholderia arboris J211 Against Meloidogyne incognita on Tobacco

Root-knot nematode (Meloidogyne incognita) is the most widespread nematode affecting Solanaceae crops. Due to the lack of effective measures to control this nematode, its management can be achieved, using biocontrol agents. This study investigated in vitro efficacy of the antagonistic bacterial strain J211 isolated from tobacco rhizosphere soil against M. incognita, and further assessed its role in controlling nematodes, both in pot and field trials. Phylogenetic analysis of the 16S rRNA gene sequence of strain J211 assigned to Burkholderia arboris. Culture filtrates B. arboris J211 exhibited anematicidal activity against the second-stage juveniles (J2s) of M. incognita, with a 96.6% mortality after 24 h exposure. Inoculation of J211 in tobacco roots significantly reduced the root galling caused by M. incognita, both in pot and field trials. Meanwhile, plant growth-promoting (PGP) traits results showed that J211 had outstanding IAA-producing activity, and the IAA production reached 66.60 mg L⁻¹. In the field study, B. arboris J211 also promoted tobacco growth and increase flue-cured tobacco yield by 8.7–24.3%. Overall, B. arboris J211 as a high-yielding IAA nematicidal strain effectively controlled M. incognita and improved tobacco yield making it a promising alternative bionematocide.

Detection of glutathione, cysteine, and homocysteine by online derivatization-based electrospray mass spectrometry

RATIONALE

Electrospray ionization mass spectrometry (ESI-MS) is one of the most popular techniques for obtaining structural information, which is commonly used in bioanalysis and clinical diagnostics. However, for the detection of complicated samples with high reactivities (such as reactive sulfur species, RSS), traditional ESI-MS usually suffers from overlapped and inaccurate signals. In this study, based on the multiphase flow of extractive electrospray ionization (MF-EESI), an ambient MS technique of online derivatization was proposed to detect thiols without any other sample pretreatment.

METHODS

RSS molecules and the derivatization reagent of 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) were introduced into the internal and innermost capillary of the MF-EESI system, respectively. By a high-velocity nebulizing stream of N₂ gas through an external capillary, both flows of innermost biothiols and internal NBD-Cl were electrosprayed and mixed for online reactions. Therefore, the fast derivatization of thiols was used to generate stable ionized derivatives for MS detection.

RESULTS

By evaluating the changes in MS signals before and after the derivatization, the ions of RSS were identified simply and correctly. Without any sample pretreatment, the fast detection of cysteine, homocysteine, and glutathione has been achieved in the complicated samples.

CONCLUSIONS

The present online derivatization-based MF-EESI was successfully used for fast, simple, and accurate detection of biothiols. This presented a potential pathway for the fast identification of thiols in complicated samples.

Mechanism of ALDH2 improves the neuronal damage caused by hypoxia/reoxygenation

OBJECTIVE

To investigate the protective effect and mechanism of ALDH2 on PC12 cells and brain nerve tissue injury under hypoxia.

MATERIALS AND METHODS

The hypoxia model of PC12 cells with low ALDH2 expression was established and screened. The eukaryotic expression vector of wild type pEGFP-N1-ALDH2 and blank plasmid pEGFP-N1 were constructed and transfected into PC12 hypoxia cells respectively. After reoxygenation culture, the morphology, quantity, ALDH2 expression level and apoptosis rate of the two groups were observed, and the role of ALDH2 in cell hypoxia injury was analyzed. Eighty SD rats were randomly divided into model group (ischemia-reperfusion injury group), Alda-1 group (intraperitoneal injection of alda-1 12 hours before and after modeling), DMSO group (intraperitoneal injection of dimethyl sulfoxide) and sham operation group, with 20 rats in each group. The neurobehavioral score, apoptosis rate of nerve cells, the content and activity of ALDH2 in active cerebral cortex and hippocampal CA1 area were compared.

RESULTS

The number of PC12 cells in hypoxia group was lower than that in control group. The expression level of ALDH2 protein in PC12 cells after 4 hours of hypoxia was lower than that in normal culture group. The number of PC12 cells transfected with wild-type recombinant plasmid was significantly more than that of blank plasmid group. Compared with the hypoxia group, the pre apoptotic and post apoptotic cells in wild type transfection group decreased after hypoxia treatment. Compared with sham operation group, nerve injury and apoptosis were increased in group M and DMSO, while ALDH2 activity and expression did not change significantly. Compared with M group and DMSO group, the nerve injury and apoptosis in Alda-1 group were improved, ALDH2 activity was increased, and ALDH2 expression was not significantly changed in Alda-1 group.

CONCLUSIONS

Increasing the expression of ALDH2 or enhancing the activity of ALDH2 can improve the injury of neurons induced by hypoxia/reoxygenation.

Construction and evaluation of a nomogram for predicting survival in patients with lung cancer

BACKGROUND

Lung cancer is a heterogeneous disease with a severe disease burden. Because the prognosis of patients with lung cancer varies, it is critical to identify effective biomarkers for prognosis prediction.

METHODS

A total of 2325 lung cancer patients were integrated into four independent sets (training set, validation set I, II and III) after removing batch effects in our study. We applied the microarray data algorithm to screen the differentially expressed genes in the training set. The most robust markers for prognosis were identified using the LASSO-Cox regression model, which was then used to create a Cox model and nomogram.

RESULTS

Through LASSO and multivariate Cox regression analysis, eight genes were identified as prognosis-associated hub genes, followed by the creation of prognosis-associated risk scores (PRS). The results of the Kaplan-Meier analysis in the three validation sets demonstrate the good predictive performance of PRS, with hazard ratios of 2.38 (95% confidence interval (CI), 1.61-3.53) in the validation set I, 1.35 (95% CI, 1.06-1.71) in the validation set II, and 2.71 (95% CI, 1.77-4.18) in the validation set III. Additionally, the PRS demonstrated superior survival prediction in subgroups by age, gender, p-stage, and histologic type (p < 0.0001). The complex model integrating PRS and clinical risk factors also have a good predictive performance for 3-year overall survival.

CONCLUSIONS

In this study, we developed a PRS signature to help predict the survival of lung cancer. By combining it with clinical risk factors, a nomogram was established to quantify the individual risk assessments.

Label- and enzyme-free plasmon-enhanced single molecule fluorescence detection of HIV DNA fragments based on a catalytic hairpin assembly

We developed a label- and enzyme-free single molecule fluorescence counting strategy for HIV DNA fragments detection. The nucleic acid biosensor consists of a 5' terminal connected with a triangular gold nanoplate, 3' terminal rich in guanine hairpin probe (HP1) and a hairpin probe HP2 complementary to the partial sequence of HP1. Without the existence of the target DNA, the DNA fragment rich in the guanine region is locked in a hairpin structure and cannot form a G-quadruplex, hence NMM exhibits a low fluorescence signal. When the target DNA exists, the hairpin assembly will trigger a strand displacement amplification reaction that produces a great number of G-quadruplexes, and the fluorescence brightness of NMM will be enhanced. The plasmon resonance effect of the triangular gold nanoplates will further amplify the fluorescence signal. This method can analyze the target DNA with high sensitivity and selectivity, and the detection limit is 0.83 fM. The analysis of the HIV DNA fragments in diluted human serum samples was successfully achieved, and the recovery rate was 92%-104%. Because of its easy operation and low cost, it has broad development potential in biochemical analysis and clinical applications.

Modular and hierarchical self-assembly of siRNAs into supramolecular nanomaterials for soft and homogeneous siRNA loading and precise and visualized intracellular delivery

siRNA therapeutics are challenged by homogeneous and efficient loading, maintenance of biological activities, and precise, dynamic and monitorable site-release. Herein, supramolecular nanomaterials of WP5⊃G–siRNA were constructed by modular and hierarchical self-assembly of siRNA with guest (3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione derivative, G) and host (pillar[5]arene, WP5) molecules in the same system. Demonstrated by experiments and theoretical calculations, WP5⊃G–siRNA was constructed via comprehensive weak interactions including electrostatic, hydrophobic–hydrophilic, host–guest and π–π interactions. Therefore, siRNAs were efficiently loaded, maintaining good stability, bioactivities and biocompatibilities. At pH 6.8, G was protonated to give weak acidic-responsive “turn-on” fluorescent signals, which realized the precise location of cancer sites. This triggered a subsequent delivery and a dynamic release of siRNA in cancer cells under acidic conditions for the entire collapse of WP5⊃G–siRNA by the protonation of both WP5 and G. By both in vitro and in vivo experiments, precise and visualized delivery to cancer sites was achieved to exhibit effective tumour inhibition. This provided an efficient and soft strategy of siRNA therapies and expanded the application of supramolecular nanomaterials in diagnosis and treatment.

Supramolecular nanomaterials of WP5⊃G–siRNA were constructed by modular and hierarchical self-assembly of siRNA with guest and host molecules, initiating weak acidic-responsive, precise and visualized intracellular delivery for efficient therapies.

SiRNA-templated 3D framework nucleic acids for chemotactic recognition, and programmable and visualized precise delivery for synergistic cancer therapy

Developments in framework nucleic acids (FNAs) are limited by complicated synthesis, by-product interference, and low framework utilization. Herein, simple core-shell spherical 3D FNAs (ST-SFNAs) preparation is presented based on siRNA-templated linear polymerization followed by hybridization chain reaction branched polymerization. Without by-products, all components exhibited their special functions to obtain high space utilization of ST-SFNAs. ST-SFNAs were covered by catalase and folic acid-functionalized liposome membranes. The catalase endowed ST-SFNAs with chemotactic activities in the H₂O₂ reaction catalyzed by catalase. Furthermore, combined with functionalized folic acids' targeting folate receptors, the synergistic chemotactic recognition of cancer cells was obtained. This dramatically promoted targeted cellular uptakes compared with traditional active or passive targeting pathways. Subsequently, the cascaded-logical programmable release of drugs was precisely controlled by targeting glutathione and ATP (via S-S bond and ATP aptamer on the inner g-DNA cover). This was visualized by "turn on" fluorescent signals generated by special hybridization of released hairpin DNAs with survivin mRNA biomarkers. Simultaneously, biocompatible synergistic therapy was achieved by simultaneously releasing doxorubicin and siRNA. With its high utilization for synergistic chemotactic recognition, programmable and visualized delivery, as well as synergistic therapy, an efficient platform for maximizing the therapeutic efficacy has been developed. This would initiate further FNA-based material development for a variety of biological applications.

Spatiotemporally Controlled DNA Nanoclamps: Single-Molecule Imaging of Receptor Protein Oligomerization

Cell membrane surface receptor proteins play an important role in cellular biological processes. There are numerous methods to detect receptors, yet developing an artificially controlled and specific detection and treatment strategy remains a challenge. Herein, we develop such a strategy based on upconversion nanoparticles (UCNPs) loaded DNA probes that enable two-color ratiometric imaging excitated by a 980 nm laser. The light response controllable signal opening strategy avoids waste during probe transportation and improves sensitivity. Thereby the number of receptors on individual DU145 cell membranes is counted by single-molecule detection. Due to the different expression of specific receptor proteins, the number of single fluorescent dots counted can be used as a basis for distinguishing DU145 from other cells. This work is highly controllable to increase sensitivity, providing a platform for cancer diagnosis and treatment.

One-Step Prepared Water-Resistant Organic-Inorganic-Hybrid Perovskite Quantum Dots with Zn-Oxygen Vacancies for Attempts at Nitrogen Fixation

Applying organic-inorganic hybrid perovskite quantum dots (PQDs) to photocatalytic nitrogen fixation is hindered long-term by the inherent instability in water and tedious preparations. Here, to realize PQD-catalyzed photocatalytic N₂ reduction reaction (NRR), water-resistant PQDs are simply prepared through one-step electrospray synthesis in microseconds. During the fast electrospray, PQDs of Zn/PbO-doped methylammonium lead bromide (Zn/PbO/PC-Zn/MAPbBr₃ , MA: CH₃ NH₃ ) are prepared and part-encapsulated by polycarbonate. The synthesis maintains good water resistance, whose restriction on charge transport is overcome skillfully. Simultaneously, substitution of Zn with Pb on water-resistant surface is also achieved, which fabricates new Zn-oxygen vacancies (Zn-OVs) with Zn/PbO-Zn/MAPbBr₃ type I heterojunction. This facilitates efficient electron transfer from internal heterojunction interface of Zn/MAPbBr₃ PQDs to the surface of Zn/PbO. Demonstrated by theoretical calculations, Zn-OVs promote chemisorption and polarization of N₂ . In addition, s-electrons in exposed Zn become active due to changes of electron filling of Zn orbitals under OVs' co-doping. Thus, photocatalytic N₂ reduction reaction catalyzed by organic-inorganic hybrid PQDs is first achieved in aqueous phase without sacrificial agents being added. This initiates possibilities for photocatalytic applications of organic-inorganic hybrid PQDs in aqueous phase.

Particle-in-a-frame gold nanomaterials with an interior nanogap-based sensor array for versatile analyte detection

In this work, we studied the catalytic performance of gold nanomaterials, specifically a particle-in-a-frame nanostructure (PIAF) with interior nanogaps. Au PIAF was used to catalyse the 3,3',5,5'-tetramethylbenzidine (TMB) reaction. This array could accurately identify 7 proteins, 5 antioxidants, and 3 cell types.

Target-triggered and controlled release plasmon-enhanced fluorescent AIE probe for conformational monitoring of insulin fibrillation

In this work, we constructed a target-triggered and controlled-release plasmon-enhanced fluorescent AIE probe to realize the purpose of conformational monitoring of insulin fibrillation. We synthesized a novel water-soluble anthracene derivative, 4,4',4'',4'''-(anthracene-9,10-diylbis(ethene-2,1,1-triyl))tetrakis(N,N,N-trimethylbenzenaminium) iodide (BDVAI), with AIE properties, high biocompatibility and good self-assembly effect. Gold nanocages (AuNCs) were selected as the substrate for PEF, and the inner space of hollow AuNCs was filled with BDVAI. Thiol-modified DNA chains were bonded to the surface of AuNCs by Au-S bonds, and an insulin aptamer was combined with the sulfhydryl chain to seal the AuNCs. This PEF-AIE sensor produces different fluorescence signals when interacting with native insulin and fibrillar insulin; thus, monitoring conformational changes in insulin can be realized by detecting fluorescence intensity changes during insulin fibrillation. Based on this design, this system realized sensitive detection of fibrillar insulin with a detection limit of 23.6 pM. This AIE molecular-based PEF fluorescence enhancement system improves the optical properties of fluorescent substances, which is of great significance in improving the detection sensitivity of amyloid fibrils conformational changes and providing a reliable basis for further understanding the pathogenesis of amyloidosis.

Multifunctional Spiky Topological Nanocapsules for the Discrimination and Differential Inhibition of Inflammation and Cancer

Accurate discrimination of inflammations and cancers as well as differential inhibition of cancers are significant for early diagnoses and timely treatments. Nanoparticles have become new modalities for diagnosis and therapy. However, they are still challenged by the efficient delivery of multiple reagents into living cells, discriminating multisignals without any interference, and differential treatments of different diseases. Here, multifunctional spiky topological nanocapsules (STNs) are prepared for the discrimination and differential inhibition of inflammation and cancer. With unique spiky hollow architectures, STNs' advantages including excellent loading capacity, enhanced cellular uptake, DNAs' protection against degradation, target-controlled drug release, and efficient endo-/lysosome escape are demonstrated. Therefore, sequential detection of inflammation-related miR-155 (by external modified hairpin DNAs) and the cancer target of monocarboxylate transporter 1 (MCT1) (by internal loaded pH-sensitive carbon dots and MCT1 inhibitor-AZD3965) are achieved. Furthermore, the release of AZD3965 from the cavities of STNs is controlled by the miR-155 amount (first target). Therefore, the released drug of AZD3965 realizes the stage-dependent differential treatment of diseases via cellular acidosis induced by MCT1 inhibition. Via in vivo evaluations of normal, inflammatory, and liver cancer cells/mice, as well as the efficient inhibition of tumor growth, the possibility of STN-based discrimination and differential treatment is confirmed. This would encourage new strategies for multidiagnosis and differential treatment of early-stage cancer.

Tissue at Risk and Ischemic Core Estimation Using Deep Learning in Acute Stroke

BACKGROUND AND PURPOSE

In acute stroke patients with large vessel occlusions, it would be helpful to be able to predict the difference in the size and location of the final infarct based on the outcome of reperfusion therapy. Our aim was to demonstrate the value of deep learning-based tissue at risk and ischemic core estimation. We trained deep learning models using a baseline MR image in 3 multicenter trials.

MATERIALS AND METHODS

Patients with acute ischemic stroke from 3 multicenter trials were identified and grouped into minimal (≤20%), partial (20%-80%), and major (≥80%) reperfusion status based on 4- to 24-hour follow-up MR imaging if available or into unknown status if not. Attention-gated convolutional neural networks were trained with admission imaging as input and the final infarct as ground truth. We explored 3 approaches: 1) separate: train 2 independent models with patients with minimal and major reperfusion; 2) pretraining: develop a single model using patients with partial and unknown reperfusion, then fine-tune it to create 2 separate models for minimal and major reperfusion; and 3) thresholding: use the current clinical method relying on apparent diffusion coefficient and time-to-maximum of the residue function maps. Models were evaluated using area under the curve, the Dice score coefficient, and lesion volume difference.

RESULTS

Two hundred thirty-seven patients were included (minimal, major, partial, and unknown reperfusion: n = 52, 80, 57, and 48, respectively). The pretraining approach achieved the highest median Dice score coefficient (tissue at risk = 0.60, interquartile range, 0.43-0.70; core = 0.57, interquartile range, 0.30-0.69). This was higher than the separate approach (tissue at risk = 0.55; interquartile range, 0.41-0.69; P = .01; core = 0.49; interquartile range, 0.35-0.66; P = .04) or thresholding (tissue at risk = 0.56; interquartile range, 0.42-0.65; P = .008; core = 0.46; interquartile range, 0.16-0.54; P < .001).

CONCLUSIONS

Deep learning models with fine-tuning lead to better performance for predicting tissue at risk and ischemic core, outperforming conventional thresholding methods.

Observation of intermediates by online mass spectrometry to demonstrate the multiple mechanisms of dye-sensitized photocatalysis

Online mass spectrometry was applied to reveal multiple mechanisms of visible-light irradiated dye-sensitized photocatalysis for o-phenylenediamine oxidation. The reactants, products and short-lived intermediates were recorded and dynamically tracked. Dimer and unexpected trimer intermediates were observed to deduce the stepwise aerobic photooxidation mechanism with multiple routes, which was supported by theoretical calculations.

Understanding of TEMPO-electrocatalyzed acceptorless dehydrogenation of tetrahydroquinoline by in situ extractive electrospray ionization mass spectrometry

The TEMPO-electrocatalyzed acceptorless dehydrogenation of tetrahydroquinoline, a transformation in green synthesis and hydrogen storage, has been investigated by coupling of an electrocatalytic system with in situ extraction electrospray ionization mass spectrometry. Dynamic changes in important species and intermediates were monitored, which evoked an updated AD understanding.

Integrating Near-Infrared Visual Fluorescence with a Photoelectrochemical Sensing System for Dual Readout Detection of Biomolecules

Compared with traditional visible light-driven fluorescence visualization (FV), near-infrared (NIR)-induced FV is an interesting and promising method, while photoelectrochemical (PEC) immunoassay sensing possesses the advantages of high sensitivity, low cost, and simple instrumentation. We combined PEC sensing with NIR-induced FV together and developed a dual readout sensing platform. In this protocol, based on the antibody-analyte (i.e., antigen, DNA, and RNA) reaction and the sandwich-type structure, CuInS₂ microflowers as the matrix provided the original background photocurrent; chlorin e6 (Ce6) was conjugated to antibody-modified upconversion nanoparticles and formed a signal label for the PEC sensing and naked-eye readout. Different from traditional PEC immunosensors, under NIR illumination, the developed dual mode sensing platform could achieve quick qualitative analysis and quantitative analysis. Preliminary application performance of the proposed biosensor in prostate-specific antigen analysis is acceptable, indicating its promising potential in clinical/biological studies.

[Association of hyperuricemia-induced renal damage with sirtuin 1 and endothelial nitric oxide synthase in rats]

Objective: To investigate the association of hyperuricemia-induced renal damage with sirtuin 1 (SIRT1) and endothelial nitric oxide synthase (eNOS) in rats. Methods: Using the random number table method, 32 Sprague-Dawley rats were randomly divided into 4 groups: control group, model A group (the model was generated using oxonic acid potassium salt alone), model B group (hyperuricemia model was generated using oxonic acid potassium salt combined with uric acid) and resveratrol group, with 8 rats in each group. The experiment lasted 12 weeks. Serum uric acid and cystatin C levels were monitored regularly. In week 12, serum creatinine and urea nitrogen levels were measured, and the kidneys were extracted. The expression of SIRT1 and eNOS in renal tissues was measured and determined by immunohistochemistry, quantitative reverse-transcription polymerase chain reaction (RT-qPCR) and western blotting. Immunohistochemistry of alpha-smooth muscle actin combined with Masson staining was employed to evaluate the degree of renal fibrosis, and pathological changes were observed based on hematoxylin and eosin staining. Results: In week 12, the uric acid levels in both the model A and model B groups were higher than those in the control group [(316±43) μmol/L, (297±40) μmol/L vs (118±44) μmol/L, both P<0.05]. The levels of cystatin C in the model A, model B, and resveratrol groups were all higher than those in the control group [(156±20) ng/ml, (143±29) ng/ml, (128±26) ng/ml vs (62±18) ng/ml, all P<0.05]. Creatinine levels were higher in the model A and model B groups than those in the control group [(68.5±10.3) μmol/L, (64.5±13.9) μmol/L vs (43.2±10.6) μmol/L, both P<0.05]. The levels of uric acid, cystatin C and creatinine in the resveratrol group were lower than those in the model A group (all P<0.05). Immunohistochemistry, RT-qPCR, and Western blotting for renal SIRT1 and eNOS showed that the expression in the model A and model B groups was inhibited, while the expression in the resveratrol group was not significantly inhibited, compared with that in the control group. Microscopically, obvious abnormalities were not found in the renal tissue of the control group. Renal inflammatory cell aggregation and edema occurred, and interstitial fibrosis was obvious in both the model A and model B groups, while these lesions in the resveratrol group were significantly improved. Conclusions: Hyperuricemia may cause renal injury by inhibiting the expression of SIRT1 and eNOS.

Metal-DNA coordination based bioinspired hybrid nanospheres for in situ amplification and sensing of microRNA

Sufficient delivery of biomolecules into cells with high loading efficiency and easy cleavability would be significant for the visualization of biomolecules in living cells. Herein, a facile approach based on nano-wire balls (NWs) for efficient loading, intracellular delivery of nucleic acids and in situ targeted miRNA bioimaging is proposed, by feeding of Zn ions for generating DNA-inorganic hybrid structures with large surface areas and good stability. Given that the versatile and robust hybridization chain reaction (HCR) amplification strategy combines DNA assembly with intracellular assay, the resulting NWs without any complicated modification are capable of enhanced signals for the targeted imaging of cancer cells. This method realized a linear detection range of 100 fM to 10 nM, with a low detection limit of 83.6 fM in vitro, and could be used to effectively differentiate the expression levels of miRNA-21 in living cells. Due to its high loading efficiency, excellent biocompatibility and low toxicity, this system can be used to construct a coordination-based delivery nanoplatform for in situ enzyme-free amplified imaging of miRNAs, expanding the application of DNA-based nanomaterials for cellular delivery and intracellular molecule analysis.

Chemiluminescence Resonance Energy Transfer-Based Mesoporous Silica Nanosensors for the Detection of miRNA

The chemiluminescence resonance energy transfer (CRET)-based method is free of autofluorescence interference, which can achieve an extremely high signal-to-background ratio for detection. Nevertheless, this method is still hindered by the inner filter effect, quenching effect, and nonspecific absorption of reported nanoparticles. Herein, mesoporous silica nanomaterials (MSNs) acted as carriers to load both the donor (horseradish peroxidase, HRP) and the acceptor (a functional DNA duplex). This approach realized the construction of a new CRET-based nanosensor for the sensitive detection of miRNA. By controlling the energy-transfer distance with the designed DNAs, the donor emission at 430 nm could be quenched by the adsorption of the dye labeled on the acceptor DNA. The CRET system could be destroyed by releasing acceptor DNA from linker DNA via the competitive hybridization of target miRNA, resulting in emission recovery for quantification. With the cancer biomarker miR-155 as the model, the sensitive and selective detection of miR-155 was achieved, which showed high energy-transfer efficiency, good specificity, favorable biodegradability, and low toxicity. This work provides a potential pathway for biological detection and clinical diagnosis.