Circular single-stranded DNA as a programmable vector for gene regulation in cell-free protein expression systems.

Cell-free protein expression (CFE) systems have emerged as a critical platform for synthetic biology research. The vectors for protein expression in CFE systems mainly rely on double-stranded DNA and single-stranded RNA for transcription and translation processing. Here, we introduce a programmable vector - circular single-stranded DNA (CssDNA), which is shown to be processed by DNA and RNA polymerases for gene expression in a yeast-based CFE system. CssDNA is already widely employed in DNA nanotechnology due to its addressability and programmability. To apply above methods in the context of synthetic biology, CssDNA can not only be engineered for gene regulation via the different pathways of sense CssDNA and antisense CssDNA, but also be constructed into several gene regulatory logic gates in CFE systems. Our findings advance the understanding of how CssDNA can be utilized in gene expression and gene regulation, and thus enrich the synthetic biology toolbox.

Pathological pain: Non-motor manifestations in Parkinson disease and its treatment.

In addition to motor symptoms, non-motor manifestations of Parkinson's disease (PD), i.e. pain, depression, sleep disturbance, and autonomic disorders, have received increasing attention. As one of the non-motor symptoms, pain has a high prevalence and is considered an early pre-motor symptom in the development of PD. In relation to pathological pain and its management in PD, particularly in the early stages, it is hypothesized that the loss of dopaminergic neurons causes a functional deficit in supraspinal structures, leading to an imbalance in endogenous descending modulation. Deficits in dopaminergic-dependent pathways also affect non-dopaminergic neurotransmitter systems that contribute to the pathological processing of nociceptive input, the integration, and modulation of pain in PD. This review examines the onset and progression of pain in PD, with a particular focus on alterations in the central modulation of nociception. The discussion highlights the importance of abnormal endogenous descending facilitation and inhibition in PD pain, which may provide potential clues to a better understanding of the nature of pathological pain and its effective clinical management.

Circular Single-Stranded DNA: Discovery, Biological Effects, and Applications.

The field of nucleic acid therapeutics has witnessed a significant surge in recent times, as evidenced by the increasing number of approved genetic drugs. However, current platform technologies containing plasmids, lipid nanoparticle-mRNAs, and adeno-associated virus vectors encounter various limitations and challenges. Thus, we are devoted to finding a novel nucleic acid vector and have directed our efforts toward investigating circular single-stranded DNA (CssDNA), an ancient form of nucleic acid. CssDNAs are ubiquitous, but generally ignored. Accumulating evidence suggests that CssDNAs possess exceptional properties as nucleic acid vectors, exhibiting great potential for clinical applications in genetic disorders, gene editing, and immune cell therapy. Here, we comprehensively review the discovery and biological effects of CssDNAs as well as their applications in the field of biomedical research for the first time. Undoubtedly, as an ancient form of DNA, CssDNA holds immense potential and promises novel insights for biomedical research.

A pharmacovigilance study on antibody-drug conjugate (ADC)-related neurotoxicity based on the FDA adverse event reporting system (FAERS).

Background: Antibody-drug conjugates (ADCs) are a relatively new class of anticancer agents that use monoclonal antibodies to specifically recognize tumour cell surface antigens. However, off-target effects may lead to severe adverse events. This study evaluated the neurotoxicity of ADCs using the FDA Adverse Event Reporting System (FAERS) database. Research design and methods: Data were extracted from the FAERS database for 2004 Q1 to 2022 Q4. We analysed the clinical characteristics of ADC-related neurological adverse events (AEs). We used the reporting odds ratio (ROR) and proportional reporting ratio (PRR) for the disproportionality analysis to evaluate the potential association between AEs and ADCs. Results: A total of 562 cases of neurological AEs were attributed to ADCs. The median age was 65 years old [(Min; Max) = 3; 92]. Neurotoxic signals were detected in patients receiving brentuximab vedotin, enfortumab vedotin, polatuzumab vedotin, trastuzumab emtansine, gemtuzumab ozogamicin, inotuzumab ozogamicin, and trastuzumab deruxtecan. The payloads of brentuximab vedotin, enfortumab vedotin, polatuzumab vedotin, and trastuzumab emtansine were microtubule polymerization inhibitors, which are more likely to develop neurotoxicity. We also found that brentuximab vedotin- and gemtuzumab ozogamicin-related neurological AEs were more likely to result in serious outcomes. The eight most common ADC-related nervous system AE signals were peripheral neuropathy [ROR (95% CI) = 16.98 (14.94-19.30), PRR (95% CI) = 16.0 (14.21-18.09)], cerebral haemorrhage [ROR (95% CI) = 9.45 (7.01-12.73), PRR (95% CI) = 9.32 (6.95-12.50)], peripheral sensory neuropathy [ROR (95% CI) = 47.87 (33.13-69.19), PRR (95% CI) = 47.43 (32.93-68.30)], polyneuropathy [ROR (95% CI) = 26.01 (18.61-36.33), PRR (95% CI) = 25.75 (18.50-35.86)], encephalopathy [ROR (95% CI) = 5.16 (3.32-8.01), PRR (95% CI) = 5.14 (3.32-7.96)], progressive multifocal leukoencephalopathy [ROR (95% CI) = 22.67 (14.05-36.58), PRR (95% CI) = 22.52 (14.01-36.21)], taste disorder [ROR (95% CI) = 26.09 (15.92-42.76), PRR (95% CI) = 25.78 (15.83-42.00)], and guillain barrier syndrome [ROR (95% CI) = 17.844 (10.11-31.51), PRR (95% CI) = 17.79 (10.09-31.35)]. The mortality rate appeared to be relatively high concomitantly with AEs in the central nervous system. Conclusion: ADCs may increase the risk of neurotoxicity in cancer patients, leading to serious mortality. With the widespread application of newly launched ADC drugs, combining the FAERS data with other data sources is crucial for monitoring the neurotoxicity of ADCs. Further studies on the potential mechanisms and preventive measures for ADC-related neurotoxicity are necessary.

A Real-World Disproportionality Analysis of Drug-Induced Immune Hemolytic Anemia in the FDA Adverse Event Reporting System.

BACKGROUND: Drug-induced immune hemolytic anemia (DIIHA) is a rare but potentially life-threatening pharmacogenic hematological adverse effect. Updating the risk of DIIHA among the currently available drugs based on spontaneously reported adverse event data is of great significance. OBJECTIVE: This study aimed to identify the top 50 drugs associated with immune hemolytic anemia in adults as well as common drugs that could cause immune hemolytic anemia in children based on the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database. METHODS: We extracted adverse events (AE) in the FAERS database from Q1 2004 to Q3 2022 using Open vigil2.1. We use the high-level term "anaemias haemolytic immune" according to the Medical Dictionary for Regulatory Activities (MedDRA) Dictionary (version 24.0). The reported correlation between drugs and DIIHA risk was identified by reported odds ratio (ROR) and proportional reporting ratio (PRR). RESULTS: There were 10500309 AEs in FAERS from 2004Q1 to 2022Q3, of which 2326 (0.02%) were DIIHA cases. The incidence of DIIHA is comparable between males and females. The most common drugs associated with DIIHA in adults and children are summarized according to the number of AE reports. The top 3 categories in terms of quantity of drugs are antineoplastic agents, immunosuppressants, and antibiotics for systemic use. The top 5 drugs in terms of ROR and PRR are alemtuzumab, daclizumab, fludarabine, busulfan, and bendamustine in adults, with entecavir, treosulfan, vinorelbine, pegademase, and alemtuzumab for children. CONCLUSIONS: Our study identified the most common drugs that could induce DIIHA in adults and children, as well as the respective ROR and PRR value to discover new drug signals. This study provides references to clinicians for the management of rare DIIHA.

A pharmacovigilance study of adverse event profiles and haemorrhagic safety of bevacizumab based on the FAERS database.

BACKGROUND: Bevacizumab is used for the treatment of advanced malignant tumors; it acts by inhibiting angiogenesis. This study aimed to examine adverse events (AEs) of bevacizumab, especially hemorrhage, using the Food and Drug Administration Adverse Event Reporting System (FAERS) database. RESEARCH DESIGN AND METHODS: The reporting odds ratio (ROR) and proportional reporting ratio (PRR) were used to analyze the AEs of bevacizumab using FAERS registration data from January 2004 to September 2022. Clinical information regarding hemorrhagic signals was further analyzed. RESULTS: The number of bevacizumab-associated AE reports was 96,477. Our study found that 892 significant preferred terms (PTs) were spread throughout 25 organ systems. The system organ classes (SOCs) focus on general disorders, administration site conditions, blood and lymphatic system disorders, injury, poisoning, and procedural complications. A total of 2,847 bevacizumab-related hemorrhage cases were reported, and 37 hemorrhagic signals were identified. Hemorrhagic signals were focused on SOC levels in vascular, gastrointestinal, and nervous system disorders. Colorectal, lung, and breast cancers are the three most common malignancies associated with BV-induced hemorrhage. CONCLUSION: The AE report from the present study confirms the majority of label information for bevacizumab, while also identifying new AEs. In addition, this was a large descriptive study of bevacizumab-induced hemorrhage.

Airway management with Hi-flow nasal cannula oxygen in children with severe laryngeal obstruction.

BACKGROUND: The aim of this study was to report our initial experience in airway management in young children with severe laryngeal obstruction. Hi-flow nasal cannula oxygen (HFNO) with spontaneous respiration was used as a new airway management strategy in young children undergoing suspension laryngoscopic surgery. METHODS: Children aged between 1 day and 24 months scheduled for suspension laryngoscopy were retrospectively studied. The data collected included the patients' age, gender, American Society of Anaesthesiologists physical status classification, comorbidities, preoperative physiological status, methods of induction and maintenance of anesthesia, course of the disease and surgical options, lowest oxygen saturation recorded, transcutaneous CO2, duration of operation, and patients' need for rescue methods. RESULTS: A total of 38 patients successfully underwent suspension laryngoscopy under HFNO with spontaneous respiration. 19 patients were less than 1 year old (7 neonates), while the other half were less than or equal to 2 years old. The median [IQR (range)] lowest oxygen saturation recorded during the operation was 98 [93-99 (91-99)] %. The median [IQR (range)] duration of HFNO with spontaneous respiration was 65 [45-100 (30-200)] minutes. The median [IQR (range)] PCO2/PtcCO2 at the end of the spontaneous ventilation period was 54 [48-63 (39-70)] mmHg, which was the same as the preoperative PCO2 despite a long operation time. CONCLUSIONS: HFNO with spontaneous respiration emerged as a new airway management strategy in young children with severe laryngeal obstruction that was beneficial in maintaining oxygenation and was superior to transnasal humidified rapid insufflation ventilatory exchange (THRIVE) in terms of the rising rate of PCO2 in these patients, thereby prolonging the safety time of the operation.

A pharmacovigilance study on drug-induced liver injury associated with antibody-drug conjugates (ADCs) based on the food and drug administration adverse event reporting system.

BACKGROUND: This study aimed to assess the association between drug-induced liver injury (DILI) and antibody-drug conjugates (ADCs) by comprehensively evaluating spontaneous reports submitted to the Food and Drug Administration Adverse Event Reporting System (FAERS) database from 2004Q1 to 2022Q3. RESEARCH DESIGN AND METHODS: All DILI cases with ADCs as primary suspected drugs were extracted from the FAERS database from 2004Q1 to 2022Q3 using OpenVigil 2.1. The reporting odds ratio (ROR) and the proportional reporting ratio (PRR) for reporting the association between different drugs and DILI risk were calculated. RESULTS: A total of 504 DILI cases were attributed to ADCs during the study period. Patients with ADCs-related DILI (n = 504) had a mean age of 56.2 ± 18.4 years, with 167 cases not reporting patients' age. Females and males comprised 42.5% and 44.0% of the cases, respectively, while there was no information on gender in 13.5% of the cases. The DILI signals were detected in trastuzumab emtansine, enfortumab vedotin, brentuximab vedotin, polatuzumab vedotin, gemtuzumab ozogamicin, inotuzumab ozogamicin, and trastuzumab deruxtecan. CONCLUSIONS: The FAERS data mining suggested an association between DILI and some ADCs. Further studies are warranted to unraveling the underlying mechanisms and taking preventive measures for ADCs-related DILI.

Association of folic acid dosage with circulating unmetabolized folic acid in Chinese adults with H-type hypertension: a multicenter, double-blind, randomized controlled trial.

Background: There is growing concern regarding elevated levels of circulating unmetabolized folic acid (UMFA) due to excessive intake of folic acid (FA). However, no randomized clinical trial has been conducted to examine the FA-UMFA dose-response relationship. Objective: This study aimed to investigate the FA-UMFA dose-response relationship in Chinese adults with hypertension and elevated homocysteine (H-type hypertension), a population with clear clinical indication for FA treatment. Methods: The data for this study were derived from a randomized, double-blind, multicenter clinical trial of 8 FA dosages on efficacy of homocysteine (Hcy) lowering. The parent trial had three 3 stages: screening period (2-10 days), run-in period (0-2 weeks, baseline visit), and double-blind treatment period (8 weeks) with follow-up visits at the end of the 2nd, 4th, 6th, and 8th weeks of treatment. Participants were randomly assigned to 8 treatment groups corresponding to FA dosages of 0, 0.4, 0.6, 0.8, 1.2, 1.6, 2.0 mg to 2.4 mg. Results: This study included 1,567 Chinese adults aged ≥45 years with H-type hypertension. There was a positive but non-linear association between FA supplementation and UMFA levels in the dosage range of 0 mg to 2.4 mg. In the regression analysis, the coefficients for the linear and quadratic terms of FA dosage were both statistically significant (P < 0.001). Notably, the slope for UMFA was greater for FA dosages >0.8 mg (ß = 11.21, 95% CI: 8.97, 13.45) compared to FA dosages ≤0.8 mg (ß = 2.94, 95% CI: 2.59, 3.29). Furthermore, FA dosages higher than 0.8 mg did not confer additional benefits in terms of increasing 5-methyl tetrahydrofolic acid (5-MTHF, active form of folate) or reducing homocysteine (Hcy). Conclusion: In Chinese adults with H-type hypertension, this study showed a positive, non-linear, dosage-response relationship between FA supplementation ranging from 0 to 2.4 mg and circulating UMFA levels. It revealed that 0.8 mg FA is an optimal dosage in terms of balancing efficacy (increasing 5-MTHF and lowering Hcy) while minimizing undesirable elevation of UMFA. Clinical trial registration: https://clinicaltrials.gov/ct2/show/NCT03472508?term=NCT03472508&draw=2&rank=1, identifier NCT03472508.

Circular single-stranded DNA as switchable vector for gene expression in mammalian cells.

Synthetic gene networks in mammalian cells are currently limited to either protein-based transcription factors or RNA-based regulators. Here, we demonstrate a regulatory approach based on circular single-stranded DNA (Css DNA), which can be used as an efficient expression vector with switchable activity, enabling gene regulation in mammalian cells. The Css DNA is transformed into its double-stranded form via DNA replication and used as vectors encoding a variety of different proteins in a wide range of cell lines as well as in mice. The rich repository of DNA nanotechnology allows to use sort single-stranded DNA effectors to fold Css DNA into DNA nanostructures of different complexity, leading the gene expression to programmable inhibition and subsequently re-activation via toehold-mediated strand displacement. The regulatory strategy from Css DNA can thus expand the molecular toolbox for the realization of synthetic regulatory networks with potential applications in genetic diagnosis and gene therapy.

[Progress on the mechanism and treatment of Parkinson's disease-related pathological pain].

Parkinson's disease (PD) is a common neurodegenerative disease characterized by motor symptoms, including bradykinesia, resting tremor, and progressive rigidity. More recently, non-motor symptoms of PD, such as pain, depression and anxiety, and autonomic dysfunction, have attracted increasing attention from scientists and clinicians. As one of non-motor symptoms, pain has high prevalence and early onset feature. Because the mechanism of PD-related pathological pain is unclear, the clinical therapy for treating PD-related pathological pain is very limited, with a focus on relieving the symptoms. This paper reviewed the clinical features, pathogenesis, and therapeutic strategies of PD-related pathological pain and discussed the mechanism of the chronicity of PD-related pathological pain, hoping to provide useful data for the study of drugs and clinical intervention for PD-related pathological pain.

Identification of natural product inhibitors of PTP1B based on high-throughput virtual screening strategy: In silico, in vitro and in vivo studies.

Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathway, which is a potential therapeutic target for the treatment of type 2 diabetes mellitus (T2DM). In this study, we identified several PTP1B inhibitors with high activity by using high-throughput virtual screening and in vitro enzyme inhibition activity verification strategies. Among them, baicalin was first reported as a selective mixed inhibitor of PTP1B, with IC50 value of 3.87 ± 0.45 µM, and its inhibitory activity against homologous proteins TCPTP, SHP2, and SHP1 exceeded 50 µM. Molecular docking study found that baicalin and PTP1B could bind stably, and revealed that baicalin had a dual inhibitory effect. Cell experiments showed that baicalin was almost non-toxic and could significantly enhance the phosphorylation of IRS-1 in C2C12 myotube cells. Animal experiments showed that baicalin could significantly reduce the blood sugar of STZ-induced diabetic mice models, and had a liver protective effect. In conclusion, this study can provide new ideas for the development of PTP1B selective inhibitors.

Principles of nucleic acid toehold mediated strand displacement (TMSD) reaction model and its applications in cell environment.

Programmable modular reaction, combined with excellent biocompatibility, has endowed biological circuits based on the nucleic acid TMSD (toehold-mediated strand displacement) reaction with great potential for bioanalysis and biomedical research. In this review, we summarize recent research on the principles of TMSD reaction and its applications in the cell environment. Based on the basic reaction units of the TD (toehold displacement) reaction, TE (toehold exchange) reaction, and CD (cooperation displacement) reaction, different reaction models could be obtained through the recombination of the basic reaction units. We highlight the successful development of the application of TMSD reaction for cell recognition, targeted therapy, molecular sensing and imaging and gene manipulations in the cell environment. Finally, we discuss the challenges and future opportunities of TMSD reaction for cellular applications.

De Novo Evolution of an Antibody-Mimicking Multivalent Aptamer via a DNA Framework.

Multivalent interactions can often endow ligands with more efficient binding performance toward target molecules. Generally speaking, a multivalent aptamer can be constructed via post-assembly based on chemical structural information of target molecules and pre-identified monovalent aptamers derived from traditional systematic evolution of ligands by exponential enrichment (SELEX) technology. However, many target molecules may not have known matched aptamer partners, thus a de novo evolution will be highly desired as an alternative strategy for directed selection of a high-avidity, multivalent aptamer. Here, inspired by the superiority of multivalent interactions between antibodies and antigens, a direct SELEX strategy with a preorganized DNA framework library for an "Antibody-mimicking multivalent aptamer" (Amap) selection to epithelial cell adhesion molecule (EpCAM), a model target protein is reported. The Amap presents a relatively good binding affinity through both aptamer moieties concurrently binding to EpCAM, which has been confirmed by affinity analysis and molecular modeling. Furthermore, dynamic interactions between Amap and EpCAM are directly visualized by magnetic tweezers at the single-molecule level. A nice binding affinity of Amap to EpCAM-positive cancer cells has also been verified, which hints that their Amap-SELEX strategy has the potential to be a new route for de novo evolution of multivalent aptamers.

General anaesthesia for photodynamic therapy of port-wine stain in children: A retrospective study.

AIMS: This report intended to assess the safety and efficiency of general anaesthesia with preserved spontaneous breathing for pain management in photodynamic therapy (PDT) of port-wine stains (PWS) in paediatric patients. METHODS: This study included 1960 Hemoporfin PDT procedures performed under general anaesthesia on 560 PWS patients. Medical records were retrospectively analysed. All of the procedures performed under general anaesthesia with preserved spontaneous breathing. RESULTS: The patients comprised males (43.93%) and females (56.07%). Ninety percent of cases were ASA class I, and 10% were class II, no case was class III or higher. Adverse events accompanying general anaesthesia included postoperative irritability (8.98%), carbon dioxide pressure (PCO2) >50 mmHg (15.97%), movement during surgery (6.98%), vomiting (0.2%), laryngospasm (0.2%), unplanned endotracheal intubation (0.05%), upper airway obstruction (0.05%), and hypoxia (0.1%). The FLACC score was <4 points in 84% of cases and 4∼6 points in 16% of cases. CONCLUSIONS: General anaesthesia with preserved spontaneous breathing has few complications and appears safe and feasible for PDT in most children with PWS.

Elastic statistical analysis of interval-valued time series.

We investigate the problem of statistical analysis of interval-valued time series data - two nonintersecting real-valued functions, representing lower and upper limits, over a period of time. Specifically, we pay attention to the two concepts of phase (or horizontal) variability and amplitude (or vertical) variability, and propose a phase-amplitude separation method. We view interval-valued time series as elements of a function (Hilbert) space and impose a Riemannian structure on it. We separate phase and amplitude variability in observed interval functions using a metric-based alignment solution. The key idea is to map an interval to a point in R 2 , view interval-valued time series as parameterized curves in R 2 , and borrow ideas from elastic shape analysis of planar curves, including PCA, to perform registration, summarization, analysis, and modeling of multiple series. The proposed phase-amplitude separation provides a new way of PCA and modeling for interval-valued time series, and enables shape clustering of interval-valued time series. We apply this framework to three different applications, including finance, meteorology and physiology, proves the effectiveness of proposed methods, and discovers some underlying patterns in the data. Experimental results on simulated data show that our method applies to the point-valued time series.

Hyperosmotic-stress-induced liquid-liquid phase separation of ALS-related proteins in the nucleus.

Hyperosmotic stress as physiologic dysfunction can reduce the cell volume and then redistribute both protein concentration and ionic strength, but its effect on liquid-liquid phase separation (LLPS) is not well understood. Here, we map the hyperosmotic-stress-induced nuclear LLPS of amyotrophic lateral sclerosis (ALS)-related proteins (fused in sarcoma [FUS], TAR DNA-binding protein 43 [TDP-43]). The dynamic and reversibility of FUS granules are continuable with the increase of hypertonic stimulation time, but those of TDP-43 granules decrease significantly. Strikingly, FUS granules, but not TDP-43 granules, contain essential chaperone Hsp40, which can protect amyloid protein from solid aggregation. Moreover, FUS nuclear granules can co-localize with paraspeckles, but not promyelocytic leukemia (PML) bodies or nuclear speckles, while TDP-43 nuclear granules cannot co-localize with the above nuclear bodies. Together, these results may broaden our understanding of the LLPS of ALS-related proteins in response to cellular stress.

Engineering CpG-ASO-Pt-Loaded Macrophages (CAP@M) for Synergistic Chemo-/Gene-/Immuno-Therapy.

Adoptive cell therapy by natural cells for drug delivery has achieved encouraging progress in cancer treatment over small-molecule drugs. Macrophages have a great potential in antitumor drug delivery due to their innate capability of sensing chemotactic cues and homing toward tumors. However, major challenge in current macrophage-based cell therapy is loading macrophages with adequate amounts of therapeutic, while allowing them to play a role in immunity without compromising cell functions. Herein, a potent strategy to construct a macrophage-mediated drug delivery platform loaded with a nanosphere (CpG-ASO-Pt) (CAP) composed of functional nucleic acid therapeutic (CpG-ASO) and chemotherapeutic drug cisplatin (Pt) is demonstrated. These CAP nanosphere loaded macrophages (CAP@M) are employed not only as carriers to deliver this nanosphere toward the tumor sites, but also simultaneously to guide the differentiation and maintain immunostimulatory effects. Both in vitro and in vivo experiments indicate that CAP@M is a promising nanomedicine by macrophage-mediated nanospheres delivery and synergistically immunostimulatory activities. Taken together, this study provides a new strategy to construct a macrophage-based drug delivery system for synergistic chemo-/gene-/immuno-therapy.

Structure-Guided Designing Pre-Organization in Bivalent Aptamers.

Multivalent interaction is often used in molecular design and leads to engineered multivalent ligands with increased binding avidities toward target molecules. The resulting binding avidity relies critically on the rigid scaffold that joins multiple ligands as the scaffold controls the relative spatial positions and orientations toward target molecules. Currently, no general design rules exist to construct a simple and rigid DNA scaffold for properly joining multiple ligands. Herein, we report a crystal structure-guided strategy for the rational design of a rigid bivalent aptamer with precise control over spatial separation and orientation. Such a pre-organization allows the two aptamer moieties simultaneously to bind to the target protein at their native conformations. The bivalent aptamer binding has been extensively characterized, and an enhanced binding has been clearly observed. This strategy, we believe, could potentially be generally applicable to design multivalent aptamers.

Spherical Ni Nanoparticles Supported by Nanosheet-Assembled Al2O3 for Dry Reforming of CH4: Elucidating the Induction Period and Its Excellent Resistance to Coking.

The design and preparation of efficient coking-resistant catalysts for dry reforming of methane (DRM) is significant for industrial applications but a challenge for supported Ni catalysts. Nanosheet-assembled Al2O3 (NA-Al2O3) with hierarchical hollow microspheres was used to support Ni nanoparticles, which exhibits superior long-time stability and coking resistance for the DRM reaction from 700 to 800 °C without coke deposition. Active Ni species, exsolved from NiAl2O4 spinel, are aggregated into Ni nanoparticles and finally stabilize as spherical Ni nanoparticles of 18.0 nm due to the spatial confinement of hierarchical hollow microspheres of the NA-Al2O3 support after the DRM reaction for 60 h. The catalytic activity in the induction period of the Ni/(NA-Al2O3) catalyst increases because of the enhancement of the surface Ni0/(Ni0+Ni2+) ratio, that is, the increment of the amount of active Ni sites. The spherical Ni nanoparticles embedded in the NA-Al2O3 support, superior CO2 adsorption ability, and more surface hydroxyl groups on the Ni/(NA-Al2O3) catalyst are the determining factors for its long-time stability and excellent anti-coking for the DRM reaction.