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1.
J Biomater Appl ; 39(1): 48-57, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38659361

RESUMO

Electrospinning technology has recently attracted increased attention in the biomedical field, and preparing various cellulose nanofibril membranes for periodontal tissue regeneration has unique advantages. However, the characteristics of using a single material tend to make it challenging to satisfy the requirements for a periodontal barrier film, and the production of composite fibrous membranes frequently impacts the quality of the final fiber membrane due to the influence of miscibility between different materials. In this study, nanofibrous membranes composed of polylactic acid (PLA) and polycaprolactone (PCL) fibers were fabricated using side-by-side electrospinning. Different concentrations of gelatin were added to the fiber membranes to improve their hydrophilic properties. The morphological structure of the different films as well as their composition, wettability and mechanical characteristics were examined. The results show that PCL/PLA dual-fibrous composite membranes with an appropriate amount of gelatin ensures sufficient mechanical strength while obtaining improved hydrophilic properties. The viability of L929 fibroblasts was evaluated using CCK-8 assays, and cell adhesion on the scaffolds was confirmed by scanning electron microscopy and by immunofluorescence assays. The results demonstrated that none of the fibrous membranes were toxic to cells and the addition of gelatin improved cell adhesion to those membranes. Based on our findings, adding 30% gelatin to the membrane may be the most appropriate content for periodontal tissue regeneration, considering the scaffold's mechanical qualities, hydrophilic properties and biocompatibility. In addition, the PCL-gelatin/PLA-gelatin dual-fibrous membranes prepared using side-by-side electrospinning technology have potential applications for tissue engineering.


Assuntos
Adesão Celular , Fibroblastos , Gelatina , Nanofibras , Poliésteres , Alicerces Teciduais , Poliésteres/química , Gelatina/química , Nanofibras/química , Animais , Camundongos , Alicerces Teciduais/química , Linhagem Celular , Fibroblastos/citologia , Membranas Artificiais , Engenharia Tecidual , Materiais Biocompatíveis/química , Sobrevivência Celular/efeitos dos fármacos , Regeneração Tecidual Guiada Periodontal/métodos , Teste de Materiais , Regeneração
2.
Food Res Int ; 184: 114274, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38609251

RESUMO

Thermal processing with salt ions is widely used for the production of food products (such as whole grain food) containing protein and anthocyanin. To date, it is largely unexplored how salt ion presence during thermal processing regulates the practical performance of protein/anthocyanin binary system. Here, rice albumin (RA) and black rice anthocyanins (BRA) were used to prepare RA/BRA composite systems as a function of temperature (60-100 °C) and NaCl concentration (10-40 mM) or CaCl2 concentration (20 mM). It was revealed that the spontaneous complexing reaction between RA and BRA was driven by hydrophobic interactions and hydrogen bonds and becomes easier and more favorable at a higher temperature (≤90 °C), excessive temperature (100 °C), however, may result in the degradation of BRA. Moreover, the salt ion presence during thermal processing may bind with RA and BRA, respectively, which could restrict the interaction between BRA and RA. Additionally, the inclusion of Na+ or Ca2+ at 20 mM endowed the binary system with strengthened DPPH radical scavenging capacity (0.95 for Na+ and 0.99 for Ca2+). Notably, Ca2+ performed a greater impact on the stability of the system than Na+.


Assuntos
Oryza , Antocianinas , Albuminas , Cloreto de Sódio , Cloreto de Sódio na Dieta , Grão Comestível , Íons
3.
Hepatology ; 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38377465

RESUMO

BACKGROUND AND AIMS: Lymph node metastasis is a significant risk factor for patients with cholangiocarcinoma, but the mechanisms underlying cholangiocarcinoma colonization in the lymph node microenvironment remain unclear. We aimed to determine whether metabolic reprogramming fueled the adaptation and remodeling of cholangiocarcinoma cells to the lymph node microenvironment. APPROACH AND RESULTS: Here, we applied single-cell RNA sequencing of primary tumor lesions and paired lymph node metastases from patients with cholangiocarcinoma and revealed significantly reduced intertumor heterogeneity and syntropic lipid metabolic reprogramming of cholangiocarcinoma after metastasis to lymph nodes, which was verified by pan-cancer single-cell RNA sequencing analysis, highlighting the essential role of lipid metabolism in tumor colonization in lymph nodes. Metabolomics and in vivo CRISPR/Cas9 screening identified PPARγ as a crucial regulator in fueling cholangiocarcinoma colonization in lymph nodes through the oleic acid-PPARγ-fatty acid-binding protein 4 positive feedback loop by upregulating fatty acid uptake and oxidation. Patient-derived organoids and animal models have demonstrated that blocking this loop impairs cholangiocarcinoma proliferation and colonization in the lymph node microenvironment and is superior to systemic inhibition of fatty acid oxidation. PPARγ-regulated fatty acid metabolic reprogramming in cholangiocarcinoma also contributes to the immune-suppressive niche in lymph node metastases by producing kynurenine and was found to be associated with tumor relapse, immune-suppressive lymph node microenvironment, and poor immune checkpoint blockade response. CONCLUSIONS: Our results reveal the role of the oleic acid-PPARγ-fatty acid-binding protein 4 loop in fueling cholangiocarcinoma colonization in lymph nodes and demonstrate that PPARγ-regulated lipid metabolic reprogramming is a promising therapeutic target for relieving cholangiocarcinoma lymph node metastasis burden and reducing further progression.

4.
Front Cell Dev Biol ; 12: 1360137, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38380338
5.
Food Res Int ; 180: 114069, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38395558

RESUMO

While brown rice (BR) has numerous nutritional properties, the consumption potential of which is seriously restricted since the poor cooking quality and undesirable flavor. Here, edible oils (pork lard and corn oil, 1-5 wt%) were incorporated during the cooking of BR following heat moisture treatment. Incorporating corn oil rather than lard significantly ameliorated the texture properties (e.g. hardness, cohesiveness, and chewiness) and sensory properties of cooked BR. Both lard- and corn oil-incorporated cooked BR showed obvious structural changes accompanied by the formation of amylose-lipid complexes during cooking. It was confirmed that the incorporation of lard and corn oil allowed a higher degree of short-range molecular order, more V-type starch crystallites, and elevated nano-structural arrangements. Additionally, a decreased hardness (from 559.04 g to 424.18 g and 385.91 g, respectively) and enriched resistant starch (RS) were also observed, the highest RS content (15.95 % and 16.32 %, respectively) was observed when 1 wt% of lard and corn oil were incorporated.


Assuntos
Oryza , Oryza/química , Óleo de Milho , Temperatura Alta , Culinária , Amido/química
6.
BMC Geriatr ; 23(1): 612, 2023 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-37773113

RESUMO

BACKGROUND: This study aims to identify the current status and factors influencing self-management of knee discomfort in middle-aged and elderly people in China. METHODS: A stratified multistage cluster sampling method was used to select participants from communities in China from January 15 to May 31, 2020. A cross-sectional survey was conducted using the general information questionnaire and the Knee Joint Discomfort Self-management Scale. Univariate analysis and a generalized linear model were used to analyze the factors influencing self-management. RESULTS: The prevalence of knee discomfort was 77%. Moderate to severe discomfort accounted for 30.5%. The average item score of self-management in 9640 participants was 1.98 ± 0.76. The highest and lowest levels were: 'daily life management' and 'information management'. Gender, ethnicity, education level, economic source, chronic disease, knee pain in the past month, and the degree of self-reported knee discomfort were significant predictors of self-management. CONCLUSION: The self-management of knee discomfort in middle-aged and elderly people is poor, and the degree of discomfort is a significant predictor. Healthcare providers should consider socioeconomic demographic and clinical characteristics to help these individuals improve their self-management skills. Attention should also be given to improving their ability to access health information and making them aware of disease risks.


Assuntos
Autogestão , Idoso , Humanos , Pessoa de Meia-Idade , Estudos Transversais , Articulação do Joelho , Dor , Inquéritos e Questionários , China/epidemiologia
7.
J Hum Genet ; 68(10): 681-688, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37308564

RESUMO

Transposable elements (TEs) are mobile DNA sequences that can replicate themselves and play significant roles in embryo development and chromosomal structure remodeling. In this study, we investigated the variation of TEs in blastocysts with different parental genetic backgrounds. We analyzed the proportions of 1137 TEs subfamilies from six classes at the DNA level using Bowtie2 and PopoolationTE2 in 196 blastocysts with abnormal parental chromosomal diseases. Our findings revealed that the parental karyotype was the dominant factor influencing TEs frequencies. Out of the 1116 subfamilies, different frequencies were observed in blastocysts with varying parental karyotypes. The development stage of blastocysts was the second most crucial factor influencing TEs proportions. A total of 614 subfamilies exhibited different proportions at distinct blastocyst stages. Notably, subfamily members belonging to the Alu family showed a high proportion at stage 6, while those from the LINE class exhibited a high proportion at stage 3 and a low proportion at stage 6. Moreover, the proportions of some TEs subfamilies also varied depending on blastocyst karyotype, inner cell mass status, and outer trophectoderm status. We found that 48 subfamilies displayed different proportions between balanced and unbalanced blastocysts. Additionally, 19 subfamilies demonstrated varying proportions among different inner cell mass scores, and 43 subfamilies exhibited different proportions among outer trophectoderm scores. This study suggests that the composition of TEs subfamilies may be influenced by various factors and undergoes dynamic modulation during embryo development.


Assuntos
Transtornos Cromossômicos , Diagnóstico Pré-Implantação , Gravidez , Feminino , Humanos , Elementos de DNA Transponíveis/genética , Aneuploidia , Blastocisto
8.
Front Endocrinol (Lausanne) ; 14: 1098576, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37361538

RESUMO

Purpose: This randomised clinical pilot study evaluated the effect of the mid-luteal additional single dose of gonadotropin-releasing hormone agonist (GnRH-a) on the clinical outcome of the females subjected to artificial cycle frozen-thawed embryo transfer (AC-FET). Methods: A total of 129 females were randomised into two groups (70 in the control group and 59 in the intervention group). Both groups received standard luteal support. The intervention group was given an extra dose of 0.1 mg GnRH-a in the luteal phase. The live birth rate served as the primary endpoint. The secondary endpoints were the positivity of pregnancy tests, the clinical pregnancy rate, the miscarriage rate, the implantation rate, and the multiple pregnancy rate. Results: There were more positive pregnancy tests, clinical pregnancies, live births, and twinning pregnancies, and fewer miscarriages observed in the intervention arm compared to the controls, though no statistical significance was concluded. No difference was found in the number of macrosomia in the two groups. There was no congenital abnormality newborn. Conclusion: Overall, the difference of 12.1 percentage points in the live births rate (40.7% vs 28.6%) between the two groups, however, is statistically insignificant. the improvement of the pregnancy outcome supports the non-inferiority of GnRH-a added during the luteal phase in AC-FET. Larger-scale clinical trials are required to further establish the positive benefits.


Assuntos
Transferência Embrionária , Hormônio Liberador de Gonadotropina , Resultado da Gravidez , Feminino , Humanos , Recém-Nascido , Gravidez , Implantação do Embrião , Hormônio Liberador de Gonadotropina/agonistas , Fase Luteal , Projetos Piloto
9.
J Gastrointest Oncol ; 13(4): 1571-1578, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36092316

RESUMO

Background: In China, esophageal squamous cell carcinoma (ESCC) accounts for more than 90% of all esophageal cancer cases. Interleukin 13 (IL-13) was widely reported to play a key role in tumor progression. Our previous study reported that IL-13 was a favorable predictive marker for the overall survival of esophageal squamous cell carcinoma (ESCC) patients, but how IL-13 contributes to ESCC progression remains unknown. This study aims to explore the role of IL-13 and its underlying downstream molecular mechanisms in ESCC progression. Methods: Tissue microarrays including 262 primary ESCC tumor tissues were collected and analyzed. The expression of IL-13 in ESCC tumor tissue was detected with immunohistochemistry staining (IHC). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to qualify the expressions of KRT13, KRT4 and 15-lipoxygenase-1 (15-LOX-1) in cultured ESCC cell lines with recombinant IL-13 treatment. Results: IL-13 was expressed in the esophageal epithelium cells and ESCC tumor cells. High IL-13 expression in ESCC tumor cells predicted a good prognosis for patients. Recombinant human IL-13 raised KRT13 and 15-LOX-1 mRNA levels, but lowered KRT4 mRNA level 15-LOX-1 in ESCC cells in vitro. Conclusions: In summary, our study suggests that IL-13 might improve the prognosis of ESCC by promoting the terminal differentiation of ESCC cells. This may offer potential new therapeutic target for early treatment of ESCC.

10.
Comput Intell Neurosci ; 2022: 2897672, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35875775

RESUMO

To effectively diagnose and monitor the vertical collusion in construction project bidding, this paper developed a comprehensive evaluation model with deep neural network and transfer learning. By this model, the collusion characteristics of bidders, tenderers, and bid evaluation experts were mined from limited data set hidden and collusion tendency was evaluated. Firstly, 18 evaluation indicators were established from literature review, court file summarization, typical case analysis, and expert consultation. Then, a comprehensive evaluation model was developed with the deep neural network and transfer learning. Finally, the model was trained and tested with the collected data set. The test results showed that the developed model achieved 87.3% identification accuracy in collusion tendency evaluation of different subjects.


Assuntos
Aprendizado Profundo , Humanos , Aprendizagem , Redes Neurais de Computação
11.
Sci Adv ; 8(26): eabm9390, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35767609

RESUMO

Retroviruses and long terminal repeat retrotransposons rely on integrase (IN) to insert their complementary DNA (cDNA) into the genome of host cells. Nevertheless, in the absence of IN, retroelements can retain notable levels of insertion activity. We have characterized the IN-independent pathway of Tf1 and found that insertion sites had homology to the primers of reverse transcription, which form single-stranded DNAs at the termini of the cDNA. In the absence of IN activity, a similar bias was observed with HIV-1. Our studies showed that the Tf1 insertions result from single-strand annealing, a noncanonical form of homologous recombination mediated by Rad52. By expanding our analysis of insertions to include repeat sequences, we found most formed tandem elements by inserting at preexisting copies of a related transposable element. Unexpectedly, we found that wild-type Tf1 uses the IN-independent pathway as an alternative mode of insertion.

12.
Nucleic Acids Res ; 50(6): 3456-3474, 2022 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-35244719

RESUMO

Chromosome rearrangement plays important roles in development, carcinogenesis and evolution. However, its mechanism and subsequent effects are not fully understood. Large-scale chromosome rearrangement has been performed in the simple eukaryote, wine yeast, but the relative research in mammalian cells remains at the level of individual chromosome rearrangement due to technical limitations. In this study, we used CRISPR-Cas9 to target the highly repetitive human endogenous retrotransposons, LINE-1 and Alu, resulting in a large number of DNA double-strand breaks in the chromosomes. While this operation killed the majority of the cells, we eventually obtained live cell groups. Karyotype analysis and genome re-sequencing proved that we have achieved global chromosome rearrangement (GCR) in human cells. The copy number variations of the GCR genomes showed typical patterns observed in tumor genomes. The ATAC-seq and RNA-seq further revealed that the epigenetic and transcriptomic landscapes were deeply reshaped by GCR. Gene expressions related to p53 pathway, DNA repair, cell cycle and apoptosis were greatly altered to facilitate the cell survival. Our study provided a new application of CRISPR-Cas9 and a practical approach for GCR in complex mammalian genomes.


Assuntos
Edição de Genes , Transcriptoma , Sistemas CRISPR-Cas , Cromossomos/metabolismo , Variações do Número de Cópias de DNA , Edição de Genes/métodos , Genoma Humano , Humanos , RNA Guia de Cinetoplastídeos/genética
13.
Virology ; 565: 52-57, 2022 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-34736160

RESUMO

Transposons are mobile DNAs that can move to different locations in host genomes. The integration site selection of transposons is critical for both themselves and host cells. Studies on the integration of retrotransposons and retroviruses have focused more on the global preference than on the local preference. The local preferences of retrotransposons are usually weak and of large diversity. Here, we analyzed hundreds of thousands of independent integration events of the Tf1 retrotransposon in Schizosaccharomyces pombe. The consensus sequence at the Tf1 integration sites shows a palindromic pattern, which can be divided into four sections, each of them contains one or more CGnTA units with a period of 10 base pairs, indicating interaction with subunits of the integrase oligomer in the pre-integration complex. Moreover, the analysis on the nucleosome occupancy flanking Tf1 target sites shows that Tf1 integration favors regions with one entire nucleosome depletion.


Assuntos
Elementos de DNA Transponíveis , Nucleossomos/metabolismo , Recombinação Genética , Retroelementos , Retroviridae/genética , Schizosaccharomyces/genética , Sequência Consenso , DNA Fúngico , Integrases/metabolismo , Sequências Repetidas Invertidas , Schizosaccharomyces/metabolismo
14.
J Nanobiotechnology ; 19(1): 303, 2021 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-34600532

RESUMO

BACKGROUND: Long noncoding RNAs (lncRNAs) play important roles in many physiological and pathological processes, this indicates that lncRNAs can serve as potential targets for gene therapy. Stable expression is a fundamental technology in the study of lncRNAs. The lentivirus is one of the most widely used delivery systems for stable expression. However, it was initially designed for mRNAs, and the applicability of lentiviral vectors for lncRNAs is largely unknown. RESULTS: We found that the lentiviral vector produces lncRNAs with improper termination, appending an extra fragment of ~ 2 kb to the 3'-end. Consequently, the secondary structures were changed, the RNA-protein interactions were blocked, and the functions were impaired in certain lncRNAs, which indicated that lentiviral vectors are not ideal delivery systems of lncRNAs. Here, we developed a novel lncRNA delivery method called the Expression of LncRNAs with Endogenous Characteristics using the Transposon System (ELECTS). By inserting a termination signal after the lncRNA sequence, ELECTS produces transcripts without 3'-flanking sequences and retains the native features and function of lncRNAs, which cannot be achieved by lentiviral vectors. Moreover, ELECTS presents no potential risk of infection for the operators and it takes much less time. ELECTS provides a reliable, convenient, safe, and efficient delivery method for stable expression of lncRNAs. CONCLUSIONS: Our study demonstrated that improper transcriptional termination from lentiviral vectors have fundamental effects on molecular action and cellular function of lncRNAs. The ELECTS system developed in this study will provide a convenient and reliable method for the lncRNA study.


Assuntos
Técnicas de Transferência de Genes , Lentivirus/genética , RNA Longo não Codificante , Lentivirus/metabolismo , RNA Longo não Codificante/química , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , Terminação da Transcrição Genética
15.
Carbohydr Polym ; 270: 118358, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34364603

RESUMO

Encapsulation systems have gained significant interest in designing innovative foods, as they allow for the protection and delivery of food ingredients that have health benefits but are unstable during processing, storage and in the upper gastrointestinal tract. Starch is widely available, cheap, biodegradable, edible, and easy to be modified, thus highly suitable for the development of encapsulants. Much efforts have been made to fabricate various types of porous starch and starch particles using different techniques (e.g. enzymatic hydrolysis, aggregation, emulsification, electrohydrodynamic process, supercritical fluid process, and post-processing drying). Such starch-based systems can load, protect, and deliver various food ingredients (e.g. fatty acids, phenolic compounds, carotenoids, flavors, essential oils, irons, vitamins, probiotics, bacteriocins, co-enzymes, and caffeine), exhibiting great potentials in developing foods with tailored flavor, nutrition, sensory properties, and shelf-life. This review surveys recent advances in different aspects of starch-based encapsulation systems including their forms, manufacturing techniques, and applications in foods.


Assuntos
Ingredientes de Alimentos , Tecnologia de Alimentos/métodos , Amido/química , Carotenoides/química , Técnicas Eletroquímicas/métodos , Emulsões , Alimentos Fortificados , Alimento Funcional , Humanos , Hidrólise , Probióticos/química , Vitaminas/química
16.
ACS Appl Mater Interfaces ; 13(16): 19406-19413, 2021 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-33856757

RESUMO

The development of stable and low-cost catalysts with high reactivity to replace Pt-based ones is the central focus but challenging for hydrogen evolution reaction (HER). The incorporation of single atoms into two-dimensional (2D) supports has been demonstrated as an effective strategy because of the highly active single atomic sites and extremely large surface area of two-dimensional materials. However, the doping of single atoms is normally performed on the surface suffering from low stability, especially in acidic media. Moreover, it is experimentally challenging to produce monolayered 2D materials with atomic doping. Here, we propose a strategy to incorporate single foreign Fe atoms to substitute W atoms in sandwiched two-dimensional WS2. Because of the charge transfer between the doped Fe atom and its neighboring S atoms on the surface, the proximate S atoms become active for HER. Our theoretical prediction is later verified experimentally, showing an enhanced catalytic reactivity of Fe-doped WS2 in HER with the Volmer-Heyrovsky mechanism involved. We refer to this strategy as proximity catalysis, which is expected to be extendable to more sandwiched two-dimensional materials as substrates and transition metals as dopants.

17.
Front Genet ; 12: 639125, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33777107

RESUMO

Recently, we proved that Sleeping Beauty (SB) transposon integrates into non-TA sites at a lower frequency. Here, we performed a further study on the non-TA integration of SB and showed that (1) SB can integrate into non-TA sites in HEK293T cells as well as in mouse cell lines; (2) Both the hyperactive transposase SB100X and the traditional SB11 catalyze integrations at non-TA sites; (3) The consensus sequence of the non-TA target sites only occurs at the opposite side of the sequenced junction between the transposon end and the genomic sequences, indicating that the integrations at non-TA sites are mainly aberrant integrations; and (4) The consensus sequence of the non-TA target sites is corresponding to the transposon end sequence. The consensus sequences changed following the changes of the transposon ends. This result indicated that the interaction between the SB transposon end and genomic DNA (gDNA) may be involved in the target site selection of the SB integrations at non-TA sites.

18.
Genomics ; 112(6): 5295-5304, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33065245

RESUMO

Beta satellite DNA (satDNA), also known as Sau3A sequences, are repetitive DNA sequences reported in human and primate genomes. It is previously thought that beta satDNAs originated in old world monkeys and bursted in great apes. In this study, we searched 7821 genome assemblies of 3767 eukaryotic species and found that beta satDNAs are widely distributed across eukaryotes. The four major branches of eukaryotes, animals, fungi, plants and Harosa/SAR, all have multiple clades containing beta satDNAs. These results were also confirmed by searching whole genome sequencing data (SRA) and PCR assay. Beta satDNA sequences were found in all the primate clades, as well as in Dermoptera and Scandentia, indicating that the beta satDNAs in primates might originate in the common ancestor of Primatomorpha or Euarchonta. In contrast, the widely patchy distribution of beta satDNAs across eukaryotes presents a typical scenario of multiple horizontal transfers.


Assuntos
DNA Satélite/química , Animais , Eucariotos/genética , Transferência Genética Horizontal , Variação Genética , Genoma , Genoma Arqueal , Genoma Bacteriano , Humanos , Reação em Cadeia da Polimerase , Primatas/genética , Sequenciamento Completo do Genoma
19.
ACS Nano ; 14(2): 1635-1644, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31994869

RESUMO

A molecule-confined two-dimensional (2D) hybrid superlattice is emerging for uncovering the chemical properties as well as distinctive physical phenomenon arising from the interface electronic states. An efficient and convenient synthetic method represents an important precondition to implementing the superlattice in terminal applications and functional devices. Herein, we develop an approach of spontaneous molecular intercalation to obtain a TaS2-N2H4 hybrid superlattice through simple solution immersion processing at room temperature. A cross-sectional high-angle annular dark field image verifies that the N2H4 molecules intercalate into the TaS2 lattice, and the interlayer spacing expands approximately 1.5 times. Combining electrical transport testing and theoretical calculations, electron transfer from N2H4 to the S-Ta-S lattice induces enhanced superconductivity and the suppression of the order of charge density waves. Moreover, electrical and Kelvin probe force microscope measurements reveal that intercalary N2H4 molecules ensure that the superlattice has higher conductivity and a lower surface work function at room temperature. A 2D hybrid superlattice-based on-chip electrocatalytic microdevice was fabricated through in situ molecular intercalation to directly evaluate the catalytic performance. Benefiting from electronic state regulation, the hybrid superlattice is more active. The presented intercalation method would aid in exploring efficient catalysts and discovering fundamental 2D physics.

20.
Chem Sci ; 12(8): 2876-2884, 2020 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-34164053

RESUMO

Top7 is a de novo designed protein with atomic level accuracy and shows a folded structure not found in nature. Previous studies showed that the folding of Top7 is not cooperative and involves various folding intermediate states. In addition, various fragments of Top7 were found to fold on their own in isolation. These features displayed by Top7 are distinct from those of naturally occurring proteins of a similar size and suggest a rough folding energy landscape. However, it remains unknown if and how the intra-polypeptide chain interactions among the neighboring sequences of Top7 affect the folding of these Top7 fragments. Here we used single-molecule optical tweezers to investigate the folding-unfolding pathways of full length Top7 as well as its C-terminal fragment (CFr) in different sequence environments. Our results showed that the mechanical folding of Top7 involves an intermediate state that likely involves non-native interactions/structure. More importantly, we found that the folding of CFr is entirely dependent upon its sequence context in which it is located. When in isolation, CFr indeed folds into a cooperative structure showing near-equilibrium unfolding-folding transitions at ∼6.5 pN in OT experiments. However, CFr loses its autonomous cooperative folding ability and displays a folding pathway that is dependent on its interactions with its neighboring sequence/structure. This context-dependent folding dynamics and pathway of CFr are distinct from those of naturally occurring proteins and highlight the critical importance of intra-chain interactions in shaping the overall energy landscape and the folding pathway of Top7. These new insights may have important implications on the de novo design of proteins.

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