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BACKGROUND & AIMS: Endoplasmic reticulum (ER) membrane protein complex subunit 10 (EMC10) has been implicated in obesity. Here we investigated the roles of the two isoforms of EMC10, including a secreted isoform (scEMC10) and an ER membrane-bound isoform (mEMC10), in metabolic dysfunction-associated steatotic liver disease (MASLD). METHODS: Manifold steatotic mouse models and HepG2 cells were employed to investigate the role of EMC10 in the regulation of hepatic PERK-eIF2α-ATF4 signaling and hepatosteatosis. The therapeutic effect of scEMC10-neutralizing antibody on mouse hepatosteatosis was explored. Associations of MASLD with serum scEMC10 and hepatic mEMC10 were determined in two cohorts of participants with MASLD. RESULTS: scEMC10 promoted, while mEMC10 suppressed, the activation of hepatic PERK-eIF2α-ATF4 signaling. Emc10 gene knockout exacerbated, while hepatic overexpression of mEMC10 ameliorated, hepatic ER stress and steatosis in mice challenged with either a methionine- and choline-deficient diet or tunicamycin, highlighting a direct, suppressive role of mEMC10 in MASLD via modulation of hepatic ER stress. Overexpression of scEMC10 promoted, whereas neutralization of circulating scEMC10 prevented, hepatosteatosis in mice with fatty liver, suggesting a role of scEMC10 in MASLD development. Clinically, serum scEMC10 was increased, while hepatic mEMC10 was decreased, in participants with MASLD. Correlative analysis indicated that serum scEMC10 positively, whereas hepatic mEMC10 negatively, correlated with liver fat content and serum ALT, AST, and GGT. CONCLUSIONS: These findings demonstrate a novel isoform-specific role for EMC10 in the pathogenesis of MASLD and identify the secreted isoform as a tractable therapeutic target for MASLD via antibody-based neutralization. IMPACT AND IMPLICATIONS: We have shown the role of EMC10 in the regulation of energy homeostasis and obesity. In this study, we determine the distinct roles of the two isoforms of EMC10 in the regulation of hepatic endoplasmic reticulum stress and steatosis in mice, and report on the associations of the different EMC10 isoforms with metabolic dysfunction-associated steatotic liver disease in humans. Our findings delineate a novel regulatory axis for hepatosteatosis and identify EMC10 as a modulator of the PERK-eIF2α-ATF4 signaling cascade that may be of broad physiological significance. Moreover, our pre-clinical and clinical studies provide evidence of the therapeutic potential of targeting scEMC10 in MASLD.
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Fator 4 Ativador da Transcrição , Estresse do Retículo Endoplasmático , Fígado Gorduroso , Isoformas de Proteínas , Animais , Estresse do Retículo Endoplasmático/fisiologia , Camundongos , Humanos , Fígado Gorduroso/metabolismo , Fígado Gorduroso/etiologia , Masculino , Isoformas de Proteínas/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Fator 4 Ativador da Transcrição/genética , Células Hep G2 , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , eIF-2 Quinase/metabolismo , Transdução de Sinais , Fígado/metabolismo , Fígado/patologia , Camundongos Knockout , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Fator de Iniciação 2 em Eucariotos/metabolismo , FemininoRESUMO
Mitosis entails global and dramatic alterations, such as higher-order chromatin organization disruption, concomitant with global transcription downregulation. Cells reliably re-establishing gene expression patterns upon mitotic exit and maintaining cellular identities remain poorly understood. Previous studies indicated that certain transcription factors (TFs) remain associated with individual loci during mitosis and serve as mitotic bookmarkers. However, it is unclear which regulatory factors remain bound to the compacted mitotic chromosomes. We developed formaldehyde-assisted isolation of regulatory elements-coupled mass spectrometry (FAIRE-MS) that combines FAIRE-based open chromatin-associated protein pull-down and mass spectrometry (MS) to quantify the open chromatin-associated proteome during the interphase and mitosis. We identified 189 interphase and mitosis maintained (IM) regulatory factors using FAIRE-MS and found intrinsically disordered proteins and regions (IDP(R)s) are highly enriched, which plays a crucial role in liquid-liquid phase separation (LLPS) and chromatin organization during the cell cycle. Notably, in these IDP(R)s, we identified mitotic bookmarkers, such as CEBPB, HMGB1, and TFAP2A, and several factors, including MAX, HMGB3, hnRNP A2/B1, FUS, hnRNP D, and TIAL1, which are at least partially bound to the mitotic chromosome. Furthermore, it will be essential to study whether these IDP(R)s through LLPS helps cells transit from mitosis to the G1 phase during the cell cycle.
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Cromatina , Proteoma , Proteoma/genética , Cromatina/genética , Cromossomos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Mitose , Espectrometria de MassasRESUMO
Connectivity isomerization of the same aromatic molecular core with different substitution positions profoundly affects electron transport pathways and single-molecule conductance. Herein, we designed and synthesized all connectivity isomers of a thiophene (TP) aromatic ring substituted by two dihydrobenzo[b]thiophene (BT) groups with ethynyl spacers (m,n-TP-BT, (m,n = 2,3; 2,4; 2,5; 3,4)), to systematically probe how connectivity contributes to single-molecule conductance. Single-molecule conductance measurements using a scanning tunneling microscopy break junction (STM-BJ) technique show â¼12-fold change in conductance values, which follow an order of 10-4.83 G0 (2,4-TP-BT) < 10-4.78 G0 (3,4-TP-BT) < 10-4.06 G0 (2,3-TP-BT) < 10-3.75 G0 (2,5-TP-BT). Electronic structure analysis and theoretical simulations show that the connectivity isomerization significantly changes electron delocalization and HOMO-LUMO energy gaps. Moreover, the connectivity-dependent molecular structures lead to different quantum interference (QI) effects in electron transport, e.g., a strong destructive QI near E = EF leads the smallest conductance value for 2,4-TP-BT. This work proves a clear relationship between the connectivity isomerization and single-molecule conductance of thiophene heterocyclic molecular junctions for the future design of molecular devices.
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Chinese herbal medicines (CHMs) derived from nature have received increasing attention and become more popular. Due to their diverse production processes, complex ingredients, and different storage conditions, it is highly desirable to develop simple, rapid, efficient and trace detection methods to ensure the drug quality. Surface-enhanced Raman spectroscopy has the advantages of being time-saving, non-destructive, usable in aqueous environments, and highly compatible with various biomolecular samples, providing a promising analytical method for CHM. In this review, we outline the major advances in the application of SERS to the identification of raw materials, detection of bioactive constituents, characterization of adulterants, and detection of contaminants. This clearly shows that SERS has strong potential in the quality control of CHM, which greatly promotes the modernization of CHM.
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Medicamentos de Ervas Chinesas , Medicamentos de Ervas Chinesas/química , Análise Espectral Raman/métodos , Controle de Qualidade , ÁguaRESUMO
Recent studies have shown the promotive effect of resveratrol on wound healing. This study aims to explore the underlying molecular mechanism of resveratrol in type 1 diabetes mellitus (T1DM) through microRNA (miR)-129-containing extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) based on in silico analysis. The rat model of T1DM was established by intraperitoneal injection of sodium citrate containing streptozotocin, and the wound was made around the deep fascia. Rat MSCs were isolated and treated with resveratrol (SRT501), and the corresponding EVs (SRT501-EVs) were isolated, where the expression of miR-129 was determined. By performing function experiments, the effect of SRT501-EVs and miR-129 on the biological functions of human umbilical vein endothelial cells (HUVECs) was determined. Finally, the binding relationship between miR-129 and tumor necrosis factor receptor-associated factor 6 (TRAF6) was also determined by the dual-luciferase reporter gene assay. miR-129 was shown as a candidate related to both resveratrol and wound healing in T1DM. SRT501-EVs promoted the skin wound healing of T1DM rats and also further improved the proliferative, migratory, and tube formation potentials of HUVECs. Resveratrol inhibited the expression of TRAF6 in HUVECs stimulated by MSC-conditioned medium and promoted the transfer of miR-129 via EVs, while TRAF6 was confirmed as a target gene of miR-129. Furthermore, inhibition of miR-129 attenuated the proangiogenic effect of resveratrol on HUVECs. Resveratrol exerts promotive role in wound healing in T1DM through downregulation of TRAF6 via MSC-EV-carried miR-129, suggesting a regulatory network involved in the wound healing process in T1DM.
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Diabetes Mellitus Tipo 1 , Vesículas Extracelulares , Células-Tronco Mesenquimais , MicroRNAs , Animais , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/metabolismo , Vesículas Extracelulares/patologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Células-Tronco Mesenquimais/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Ratos , Resveratrol/metabolismo , Resveratrol/farmacologia , CicatrizaçãoRESUMO
BACKGROUND: Zinc finger protein 143(ZNF143), a member of the Krüppel C2H2-type zinc finger protein family, is strongly associated with cell cycle regulation and cancer development. A recent study suggested that ZNF143 plays as a transcriptional activator that promotes hepatocellular cancer (HCC) cell proliferation and cell cycle transition. However, the exact biological role of ZNF143 in liver regeneration and normal liver cell proliferation has not yet been investigated. METHODS: In our study, we constructed a stable rat liver cell line (BRL-3A) overexpressing ZNF143 and then integrated RNA-seq and Cleavage Under Targets and Tagmentation (CUT&Tag) data to identify the mechanism underlying differential gene expression. RESULTS: Our results show that ZNF143 expression is upregulated during the proliferation phase of liver regeneration after 2/3 partial hepatectomy (PH). The cell counting kit-8 (CCK-8) assay, EdU staining and RNA-seq data analyses revealed that ZNF143 overexpression (OE) significantly inhibited BRL-3A cell proliferation and cell cycle progression. We then performed CUT&Tag assays and found that approximately 10% of ZNF143-binding sites (BSs) were significantly changed genome-wide by ZNF143 OE. However, CCCTC-binding factor (CTCF) binding to chromatin was not affected. Interestingly, the integration analysis of RNA-seq and CUT&Tag data showed that some of genes affected by ZNF143 differential BSs are in the center of each gene regulation module. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses indicated that these genes are critical in the maintenance of cell identity. CONCLUSION: These results indicated that the expression level of ZNF143 in the liver is important for the maintenance of cell identity. ZNF143 plays different roles in HCC and normal liver cells and may be considered as a potential therapeutic target in liver disease.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Animais , Proliferação de Células/genética , Ratos , Transativadores/genética , Transativadores/metabolismoRESUMO
BACKGROUND: Exenatide is a stable analogue of glucagon-like peptide 1 that can reduce postprandial hyperglycemia and has been utilized as adjunctive therapy for type 1 diabetes mellitus (T1DM). The human umbilical cord is a rich source of MSCs, and human umbilical cord mesenchymal stem cells (hUCMSCs) also show potential to enhance insulin secretion. Here, we aimed to explore the effects of hUCMSCs carrying exenatide in T1DM and further identify the possible mechanisms involved. METHODS: hUCMSCs were isolated from human umbilical cord tissues, identified, and transduced with recombinant lentivirus carrying exenatide to obtain exenatide-carrying hUCMSCs (hUCMSCs@Ex-4). RESULTS: The results showed that hUCMSCs@Ex-4 restored the blood glucose levels and body weight of NOD mice, and repressed immune cell infiltration and islet tissue changes. Additionally, in T1DM mice, treatment with hUCMSCs@Ex-4 reduced the blood glucose levels and promoted repair of islet tissue damage. Moreover, hUCMSCs@Ex-4 attenuated renal tissue lesions in T1DM mice. Applying bioinformatic analysis, the effects of hUCMSCs@Ex-4 were suggested to correlate with decreased abundance of pro-inflammatory intestinal bacteria and increased abundance of anti-inflammatory intestinal bacteria. CONCLUSION: Overall, the study indicated that hUCMSCs carrying exenatide might improve beneficial intestinal microflora abundance and promote islet tissue damage repair, thereby alleviating T1DM.
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Diabetes Mellitus Tipo 1 , Microbioma Gastrointestinal , Células-Tronco Mesenquimais , Humanos , Camundongos , Animais , Exenatida/farmacologia , Glicemia , Camundongos Endogâmicos NODRESUMO
Room-temperature ionic liquids (RTILs) emerged as ideal solvents, and bipyridine as one of the most used ligands have been widely employed in surface science, catalysis, and molecular electronics. Herein, in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and STM break junction (STM-BJ) technique has been employed to probe the electrochemical process of bipyridine at Au(111)/IL interfaces. It is interestingly found that these molecules undertake a redox process with a pair of well-defined reversible peaks in cyclic voltammograms (CVs). The spectroscopic evidence shows a radical cation generated with rising new Raman peaks related to parallel CC stretching of a positively charged pyridyl ring. Furthermore, these electrochemically charged bipyridine is also confirmed by electrochemical STM-BJ at the single-molecule level, which displays a binary conductance switch ratio of about 400% at the redox potentials. This present work offers a molecular-level insight into the pyridine-mediated reaction process and electron transport in RTILs.
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OBJECTIVE: To explore the relationship between C-peptide and glycaemic control rate and diabetic complications (microvascular complication and cerebral infarction) and provide evidence for stratified treatment of type 2 diabetes mellitus (T2DM)-based C-peptide. METHOD: This is a cross-sectional real-world observational study. According to the inclusion and exclusion criteria, we studied 1377 patients with T2DM, grouped by fasting C-peptide and HOMA-IR. Blood samples were collected after fasting overnight. Logistic regression was used to analyse the relationship among fasting C-peptide, HOMA-IR, C2/C0 ratio (the ratio of 2 h postprandial C-peptide to fasting C-peptide), glycaemic control rate, and occurrence of diabetic complications. Restricted cubic spline (RCS) curves based on logistic regression were used to evaluate the relationship between C-peptide, glycaemic control rate, and diabetic kidney disease (DKD). RESULTS: Patients were subdivided according to their fasting C-peptide in 4 groups (Q1,Q2,Q3,Q4). Patients of group Q3 (1.71 ≤ C-peptide < 2.51 ng/ml) showed the lowest incidence of DKD, diabetic retinopathy (DR), and rate of insulin absorption as welll as higher glycaemic control rate. Logistic regression shows that the probability of reaching glycemic control increased with higher levels of C-peptide, compared with group Q1, after adjusting for age, gender, duration of diabetes, body mass index, systolic blood pressure, diastolic blood pressure, creatinine, low-density lipoprotein, triglyceride, total cholesterol, and high-density lipoprotein. RCS curve shows that, when C-peptide is ≤2.68 ng/ml, the incidence of not reaching glycaemic control decreases with increasing C-peptide. The possibility of not reaching glycaemic control decreased with increasing C2/C0, when C-peptide is ≥1.71 ng/ml. RCS curve shows that the relationship between C-peptide and DKD follows a U-style curve. When C-peptide is <2.84 ng/ml, the incidence of DKD decreased with increasing C-peptide. With the increase in the C2/C0 ratio, the incidence of DKD, DR, and fatty liver did not decrease. CONCLUSION: When C-peptide is ≥ 1.71 and < 2.51 ng/ml, patients with T2DM had a higher glycemic control rate. Excessive C-peptide plays different roles in DKD and DR; C-peptide may promote the incidence of DKD but protects patients from DR. Higher C2/C0 ratio is important for reaching glycaemic control but cannot reduce the risk of DKD, DR, and fatty liver.
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Diabetes Mellitus Tipo 2 , Nefropatias Diabéticas , Retinopatia Diabética , Fígado Gorduroso , Peptídeo C , Estudos Transversais , Diabetes Mellitus Tipo 2/epidemiologia , Nefropatias Diabéticas/complicações , Retinopatia Diabética/epidemiologia , Retinopatia Diabética/etiologia , Retinopatia Diabética/prevenção & controle , Feminino , Controle Glicêmico , Humanos , MasculinoRESUMO
Probing the adlayer structures on an electrode/electrolyte interface is one of the most important tasks in modern electrochemistry for clarifying the electrochemical processes. Herein, we have combined cyclic voltammetry and electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy techniques to explore the potential-dependent adlayer structures on Au(111) in a room-temperature ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) without or with pyridine (Py). It is clearly found that the BMI+ cations strongly adsorb on the negatively charged surface with a flat-lying orientation, leaving a little space for Py adsorption. Upon increasing the potentials of the electrode, the variations of Raman band intensities and frequencies reveal that the interaction between the BMI+ cations and the Au surface becomes weak; meanwhile, the Py adsorption becomes strong, and its geometry turns from flat, tilted to vertical. Finally, BMI+ cations desorb and leave plenty of surface sites for Py adsorption in bulk solution, and a N-bonded compact Py adlayer is formed on the very positively charged surface. This causes obvious anodic peaks in cyclic voltammograms, and the peak currents increase with the square root of the scanning rate. The present work provides a fair molecular-level understanding of electrochemical interfaces and molecular adsorption of Py in ionic liquids.
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Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) share common pathogenic mechanisms and risk factors. We aim to evaluate the association between NAFLD and CKD in a non-diabetic gouty population. The retrospective cross sectional study was performed on 1049 non-diabetic gouty participants, who were hospitalized between 2014 and 2020, across 4 districts in Shandong, China. Demographic and clinical characteristics of the study population were collected. The odds ratios (OR) and corresponding 95% confidence intervals (CI) about the NAFLD severity determined by ultrasonography were obtained by multiple logistic regression analysis. An unexpectedly inverse relationship was found between NAFLD severity and the risk of CKD in people with gout. Multivariate logistic regression analysis demonstrated that a higher degree of NAFLD severity is independently associated with a lower risk of CKD in people with gout, after adjusted for age, sex, smoking, gout duration, and metabolic risk factors including obesity, hypertension, hyperglycemia, hyperuricemia, and dyslipidemia, with OR 0.392 (95% CI 0.248-0.619, p<0.001), 0.379 (95% CI 0.233-0.616, p<0.001) and 0.148 (95% CI 0.043-0.512, p=0.003) in participants with mild, moderate, and severe NAFLD, respectively, compared to those without NAFLD. We also observed a weakened association of serum uric acid (SUA) with metabolic risk factors and NAFLD under circumstances of CKD in people with gout (r=-0.054, p=0.466). In conclusion, the presence and severity of NAFLD were negatively associated with the risk of CKD in the non-diabetic gouty population.
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Gota , Hepatopatia Gordurosa não Alcoólica , Insuficiência Renal Crônica , Estudos Transversais , Feminino , Gota/complicações , Gota/epidemiologia , Humanos , Masculino , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Ácido ÚricoRESUMO
The electroreductive cleavage of carbon-halogen bonds has attracted increasing attention in both electrosynthesis and pollution remediation. Herein, by employing the in situ electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique, we have successfully investigated the electroreductive dehalogenation process of aryl halides with the thiol group on a smooth Au electrode in aqueous solution at different pH values. The obtained potential-dependent Raman spectra directly reveal a mixture of the reduction products 4,4'-biphenyldithiol (BPDT) and thiophenol (TP). The conversion ratios of the C-Cl and C-Br bonds at pH = 7 are 37% and 55%, respectively. Furthermore, quantitative analysis of the intensity variations of ν(C-Cl), ν(C-Br) and aromatic ν(CC) stretching modes suggests electroreductive dehalogenation via both direct electron transfer reduction and electrocatalytic hydrodehalogenation. Molecular evidence for the C-C cross coupling process through TP reaction with benzene free radical intermediates is found at negative potentials, which leads to the increasing selectivity of biphenyl products.
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Endoplasmic reticulum membrane protein complex subunit 10 (EMC10) is an evolutionarily conserved and multifunctional factor across species. We previously reported that Emc10 knockout (KO) leads to mouse male infertility. Emc10-null spermatozoa exhibit multiple aspects of dysfunction, including reduced sperm motility. Two subunits of a Na/K-ATPase, ATP1A4 and ATP1B3, are nearly absent in Emc10 KO spermatozoa. Here, two isoforms of EMC10 were characterized in the mouse testis and epididymis: the membrane-bound (mEMC10) and secreted (scEMC10) isoforms. We present evidence that mEMC10, rather than scEMC10, is required for cytoplasm sodium homeostasis by positively regulating ATP1B3 expression in germ cells. Intra-testis mEMC10 overexpression rescued the sperm motility defect caused by Emc10 KO, while exogenous recombinant scEMC10 protein could not improve the motility of spermatozoa from either Emc10 KO mouse or asthenospermic subjects. Clinically, there is a positive association between ATP1B3 and EMC10 protein levels in human spermatozoa, whereas no correlation was proven between seminal plasma scEMC10 levels and sperm motility. These results highlight the important role of the membrane-bound EMC10 isoform in maintaining cytoplasm sodium homeostasis and sperm motility. Based on the present results, the mEMC10-Na, K/ATPase α4ß3 axis is proposed as a novel mechanism underlying the regulation of cytoplasmic sodium and sperm motility, and its components seem to have therapeutic potential for asthenospermia.
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Astenozoospermia , Motilidade dos Espermatozoides , Animais , Astenozoospermia/metabolismo , Citoplasma/metabolismo , Homeostase , Humanos , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Isoformas de Proteínas/metabolismo , Sêmen/metabolismo , Sódio/metabolismo , ATPase Trocadora de Sódio-Potássio/genética , ATPase Trocadora de Sódio-Potássio/metabolismo , Motilidade dos Espermatozoides/fisiologia , Espermatozoides/metabolismoRESUMO
Quantum interference (QI) in single molecular junctions shows a promising perspective for realizing conceptual nanoelectronics. However, controlling and modulating the QI remains a big challenge. Herein, two-type substituents at different positions ofmeta-linked benzene, namely electron-donating methoxy (-OMe) and electron-withdrawing nitryl (-NO2), are designed and synthesized to investigate the substituent effects on QI. The calculated transmission coefficientsT(E) indicates that -OMe and -NO2could remove the antiresonance and destructive quantum interference (DQI)-induced transmission dips at position 2. -OMe could raise the antiresonance energy at position 4 while -NO2groups removes the DQI features. For substituents at position 5, both of them are nonactive for tuning QI. The conductance measurements by scanning tunneling microscopy break junction show a good agreement with the theoretical prediction. More than two order of magnitude single-molecule conductance on/off ratio could be achieved at the different positions of -NO2substituent groups at room temperature. The present work proves chemical substituents can be used for tuning QI features in single molecular junctions, which provides a feasible way toward realization of high-performance molecular devices.
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Clarifying interfacial electronic effects on molecular adsorption is significant in many chemical and biochemical processes. Here, we used STM breaking junction and shell-isolated nanoparticle-enhanced Raman spectroscopy to probe electron transport and adsorption geometries of 4,4'-bipyridine (4,4'-BPY) at Au(111). Modifying the surface with 1-butyl-3-methylimidazolium cation-containing ionic liquids (ILs) decreases surface electron density and stabilizes a vertical orientation of pyridine through nitrogen atom σ-bond interactions, resulting in uniform adsorption configurations for forming molecular junctions. Modulation from vertical, tilted, to flat, is achieved on adding water to ILs, leading to a new peak ascribed to CC stretching of adsorbed pyridyl ring and 316 % modulation of single-molecule conductance. The dihedral angle between adsorbed pyridyl ring and surface decreases with increasing surface electronic density, enhancing electron donation from surface to pyridyl ring.
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It is vital to understand the oxygen reduction reaction (ORR) mechanism at the molecular level for the rational design and synthesis of high activity fuel-cell catalysts. Surface enhanced Raman spectroscopy (SERS) is a powerful technique capable of detecting the bond vibrations of surface species in the low wavenumber range, however, using it to probe practical nanocatalysts remains extremely challenging. Herein, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was used to investigate ORR processes on the surface of bimetallic Pt3 Co nanocatalyst structures. Direct spectroscopic evidence of *OOH suggests that ORR undergoes an associative mechanism on Pt3 Co in both acidic and basic environments. Density functional theory (DFT) calculations show that the weak *O adsorption arise from electronic effect on the Pt3 Co surface accounts for enhanced ORR activity. This work shows SHINERS is a promising technique for the real-time observation of catalytic processes.
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Heterogeneous metal interfaces play a key role in determining the mechanism and performance of catalysts. However, inâ situ characterization of such interfaces at the molecular level is challenging. Herein, two model interfaces, Pd and Pt overlayers on Au single crystals, were constructed. The electronic structures of these interfaces as well as effects of crystallographic orientation on them were analyzed by shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) using phenyl isocyanide (PIC) as a probe molecule. A clear red shift in the frequency of the C≡N stretch (νNC ) was observed, which is consistent with X-ray photoelectron spectroscopy (XPS) data and indicates that the ultrathin Pt and Pd layers donate their free electrons to the Au substrates. Furthermore, inâ situ electrochemical SHINERS studies showed that the electronic effects weaken Pt-C/Pd-C bonds, leading to improved surface activity towards CO electrooxidation.
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Insightful understanding of how interfacial structures and properties affect catalytic processes is one of the most challenging issues in heterogeneous catalysis. Here, the essential roles of Pt-Au and Pt-oxide-Au interfaces on the activation of H2 and the hydrogenation of para-nitrothiophenol (pNTP) were studied at molecular level by in situ surface-enhanced Raman spectroscopy (SERS) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). Pt-Au and Pt-oxide-Au interfaces were fabricated through the synthesis of Pt-on-Au and Pt-on-SHINs nanocomposites. Direct spectroscopic evidence demonstrates that the atomic hydrogen species generated on the Pt nanocatalysts can spill over from Pt to Au via the Pt-Au and Pt-TiO2-Au interfaces, but would be blocked at the Pt-SiO2-Au interfaces, leading to the different reaction pathways and product selectivity on Pt-on-Au and Pt-on-SHINs nanocomposites. Such findings have also been verified by the density functional theory calculation. In addition, it is found that nanocatalysts assembled on pinhole-free shell-isolated nanoparticles (Pt-on-pinhole-free-SHINs) can override the influence of the Au core on the reaction and can be applied as promising platforms for the in situ study of heterogeneous catalysis. This work offers a concrete example of how SERS/SHINERS elucidate details about in situ reaction and helps to dig out the fundamental role of interfaces in catalysis.
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For the first time, we used the electrochemical shell-isolated nanoparticle-enhanced Raman spectroscopy (EC-SHINERS) technique to in situ characterize the adsorption behaviour of four DNA bases (adenine, guanine, thymine, and cytosine) on atomically flat Au(111) electrode surfaces. The spectroscopic results of the various molecules reveal similar features, such as the adsorption-induced reconstruction of the Au(111) surface and the drastic Raman intensity reduction of the ring breathing modes after the lifting reconstruction. As a preliminary study of the photo-induced charge transfer (PICT) mechanism, the in situ spectroscopic results obtained on single crystal surfaces are excellently illustrated with electrochemical data.
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DNA/química , Ouro , Nanopartículas , Análise Espectral Raman , Adsorção , EletrodosRESUMO
Correction for 'Shell-isolated nanoparticle-enhanced Raman spectroscopy study of the adsorption behaviour of DNA bases on Au(111) electrode surfaces' by Bao-Ying Wen et al., Analyst, 2016, DOI: 10.1039/c6an00180g.