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1.
Animals (Basel) ; 14(3)2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38338092

RESUMO

Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) is a flavonoid derived from Artemisia plants that has beneficial biological activities, such as anti-apoptotic, anti-oxidant, and anti-inflammatory activities. However, the protective effects of eupatilin against oxidative stress and endoplasmic reticulum stress in porcine oocyte maturation are still unclear. To investigate the effect of eupatilin on the development of porcine oocytes after in vitro maturation and parthenogenetic activation, we added different concentrations of eupatilin in the process of porcine oocyte maturation in vitro, and finally selected the optimal concentration following multiple comparisons and analysis of test results using SPSS (version 17.0; IBM, Chicago, IL, USA) software. The results showed that 0.1 µM eupatilin supplementation did not affect the expansion of porcine cumulus cells, but significantly increased the extrusion rate of porcine oocyte polar bodies, the subsequent blastocyst formation rate, and the quality of parthenogenetically activated porcine embryos. Additionally, it reduced the level of reactive oxygen species in cells and increased glutathione production. Further analysis revealed that eupatilin supplementation could reduce apoptosis, DNA double-strand breaks, and endoplasmic reticulum stress. In conclusion, supplementation with 0.1 µM eupatilin during in vitro maturation improved oocyte maturation and subsequent embryo development by reducing oxidative stress and endoplasmic reticulum stress.

2.
BMC Psychiatry ; 23(1): 931, 2023 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-38082243

RESUMO

OBJECTIVES: This study aims to examine the associations among fear of childbirth, psychological distress, resilience, and sleep quality among Chinese pregnant women. METHODS: A cross-sectional survey was carried out between January 2022 to March 2022 among pregnant women who met the inclusion criteria and sought healthcare services at The First Affiliated Hospital of Guangzhou University of Chinese Medicine in Guangdong Province, Southern China. Data was collected using a structured questionnaire that included sociodemographic characteristics, childbirth attitudes questionnaires (CAQ), hospital anxiety and depression scale (HADS), Connor-Davidson resilience scale (CD-RISC), and Pittsburgh sleep quality index (PSQI). A generalized additive model and moderated mediation analysis were employed for data analysis. RESULTS: A non-linear and negative association between fear of childbirth and sleep quality was found in the second trimester and antenatal period. Psychological distress significantly mediated the relationship between fear of childbirth and sleep quality (first trimester: ß = 0.044, 95%CI:0.022-0.071; second trimester: ß = 0.029, 95%CI:0.009-0.056; third trimester: ß = 0.064, 95%CI:0.046-0.088; antenatal period: ß = 0.050, 95%CI:0.037-0.063). The moderating role of resilience between fear of childbirth and sleep quality was significant (second trimester: ß=-0.006, 95%CI:-0.012-0.001, P = 0.025; antenatal period: ß=-0.004, 95%CI:-0.007--0.001, P = 0.014), as well as between fear of childbirth and psychological distress (first trimester: ß=-0.016, 95%CI:-0.026--0.005, P = 0.004; antenatal period: ß=-0.005, 95%CI:-0.009--0.001, P = 0.014). CONCLUSIONS: Fear of childbirth, psychological distress, and resilience are three important factors affecting sleep quality in Chinese pregnant women.


Assuntos
Gestantes , Qualidade do Sono , Feminino , Gravidez , Humanos , Gestantes/psicologia , Análise de Mediação , Estudos Transversais , Parto/psicologia , Medo , Inquéritos e Questionários
3.
Eur J Oncol Nurs ; 67: 102453, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37951070

RESUMO

PURPOSE: This study aims to identify the heterogeneity in the stigma experienced by patients with breast cancer and examine the mediation effect of resilience on the relation between stigma and sleep quality. METHOD: A total of 396 patients with breast cancer were enrolled from Be Resilient to Breast Cancer (BRBC) program between January and April 2023. Participants completed the Social Impact Scale, the 10-item Connor-Davidson Resilience Scale, and the Pittsburgh Sleep Quality Index Scale. Latent profile analysis (LPA) and mediation analysis were conducted to analyze the data. RESULTS: LPA categorized stigma into three subgroups, namely low-stigma (21.9%), moderate-stigma (64.9%), and high-stigma (13.2%). Mediation analysis revealed a fully mediated effect in the comparison between low-stigma and moderate-stigma groups (standard error [SE] = 0.13, 95%CI = 0.06,0.56), whereas a partially mediated effect was observed in the comparison between low-stigma and high-stigma groups (SE = 0.18, 95%CI = 0.39,1.10). CONCLUSIONS: Stigma is a significant factor to sleep quality in breast cancer and resilience could act as a robust buffer against stigma resulting in improved sleep quality. Resilience-based interventions might be helpful in this population.


Assuntos
Neoplasias da Mama , Qualidade do Sono , Humanos , Feminino , Análise de Mediação , Estigma Social
4.
Reprod Domest Anim ; 58(11): 1583-1594, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37696770

RESUMO

Notoginsenoside R1 (NGR1), derived from the Panax notoginseng root and rhizome, exhibits diverse pharmacological influences on the brain, neurons, and osteoblasts, such as antioxidant effects, mitochondrial function protection, energy metabolism regulation, and inhibition of oxygen radicals, apoptosis, and cellular autophagy. However, its effect on early porcine embryonic development remains unclear. Therefore, we investigated NGR1's effects on blastocyst quality, reactive oxygen species (ROS) levels, glutathione (GSH) levels, mitochondrial function, and embryonic development-related gene expression in porcine embryos by introducing NGR1 during the in vitro culture (IVC) of early porcine embryos. Our results indicate that an addition of 1 µM NGR1 significantly increased glutathione (GSH) levels, blastocyst formation rate, and total cell number and proliferation capacity; decreased ROS levels and apoptosis rates in orphan-activated porcine embryos; and improved intracellular mitochondrial distribution, enhanced membrane potential, and reduced autophagy. In addition, pluripotency-related factor levels were elevated (NANOG and octamer-binding transcription factor 4 [OCT4]), antioxidant-related genes were upregulated (nuclear factor-erythroid 2-related factor 2 [NRF2]), and apoptosis- (caspase 3 [CAS3]) and autophagy-related genes (light chain 3 [LC3B]) were downregulated. These results indicate that NGR1 can enhance early porcine embryonic development by protecting mitochondrial function.


Assuntos
Desenvolvimento Embrionário , Partenogênese , Suínos , Animais , Espécies Reativas de Oxigênio/metabolismo , Antioxidantes/farmacologia , Mitocôndrias/metabolismo , Blastocisto , Glutationa/metabolismo , Apoptose
5.
Animals (Basel) ; 13(16)2023 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-37627386

RESUMO

Imidacloprid (IMI) is an endogenous neonicotinoid insecticide widely used in agriculture and has attracted researchers' attention because of its risks to the environment and human health. Melatonin (MT) is an antioxidant hormone produced by the pineal gland of the brain. Studies have shown that it has a variety of physiological functions and plays a crucial role in the development of animal germ cells and embryos. The potential protective effects of MT against oocyte damage caused by neonicotinoid pesticide toxicity remain unclear. In this study, we report the toxicity of IMI against, and its effects on the quality of, porcine oocytes and the protective effect of MT on IMI-exposed oocytes. The results show that IMI exposure adversely affected oocyte maturation, while MT supplementation ameliorated its toxic effects. Specifically, IMI exposure increased oxidative stress (OS), endoplasmic reticulum stress (ERS), and apoptosis, which may affect polar body expulsion rates and blastocyst formation. Also, IMI exposure reduced oocyte cleavage rates and the number of cells in blastocysts. However, all of these toxic effects can be restored after a melatonin supplementation treatment. In conclusion, these results suggest that melatonin has a protective effect on IMI-induced defects during porcine oocyte maturation.

6.
Animals (Basel) ; 13(14)2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37508068

RESUMO

Widely used as a flame retardant, 2,2'4,4'-tetrabromodiphenyl ether (BDE-47) is a persistent environmental pollutant with toxicological effects, including hepatotoxicity, neurotoxicity, reproductive toxicity, and endocrine disruption. To investigate the toxicological effects of BDE-47 on early porcine embryogenesis in vitro, cultured porcine embryos were exposed to BDE-47 during early development. Exposure to 100 µM BDE-47 decreased the blastocyst rate and mRNA level of pluripotency genes but increased the level of LC3 and the expression of autophagy-related genes. After BDE-47 exposure, porcine embryos' antioxidant capability decreased; ROS levels increased, while glutathione (GSH) levels and the expression of antioxidant-related genes decreased. In addition, BDE-47 exposure reduced mitochondrial abundance and mitochondrial membrane potential levels, downregulated mitochondrial biogenesis-associated genes, decreased endoplasmic reticulum (ER) abundance, increased the levels of GRP78, a marker of ER stress (ERS), and upregulated the expression of ERS-related genes. However, ER damage and low embryo quality induced by BDE-47 exposure were reversed with the ERS inhibitor, the 4-phenylbutyric acid. In conclusion, BDE-47 inhibits the development of early porcine embryos in vitro by inducing mitochondrial dysfunction and ERS. This study sheds light on the mechanisms of BDE-47-induced embryonic toxicity.

7.
Reprod Biomed Online ; 47(2): 103211, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37246104

RESUMO

RESEARCH QUESTION: Does the addition of an antioxidant agent, xanthoangelol (XAG), to the culture medium improve in-vitro development of porcine embryos? DESIGN: Early porcine embryos were incubated in the presence of 0.5 µmol/l XAG in in-vitro culture (IVC) media and analysed using various techniques, including immunofluorescence staining, reactive oxygen species (ROS) detection, TdT-mediated dUTP nick-end labelling (TUNEL), and reverse transcription followed by quantitative polymerase chain reaction (RT-qPCR). RESULTS: The addition of 0.5 µmol/l XAG to IVC media increased the rate of blastocyst formation, total cell number, glutathione concentrations and proliferative capacity, while reducing reactive oxygen species concentrations, apoptosis and autophagy. In addition, upon XAG treatment, the abundance of mitochondria and mitochondrial membrane potential significantly increased (both P < 0.001), and the genes related to mitochondrial biogenesis (TFAM, NRF1 and NRF2) were significantly up-regulated (all P < 0.001). XAG treatment also significantly increased the endoplasmic reticulum abundance (P < 0.001) and reduced the concentrations of endoplasmic reticulum stress (ERS) marker GRP78 (P = 0.003) and expression of the ERS-related genes EIF2α, GRP78, CHOP, ATF6, ATF4, uXBP1 and sXBP 1 (all P < 0.001). CONCLUSION: XAG promotes early embryonic development in porcine embryos in vitro by reducing oxidative stress, enhancing mitochondrial function and relieving ERS.


Assuntos
Chaperona BiP do Retículo Endoplasmático , Estresse do Retículo Endoplasmático , Gravidez , Animais , Feminino , Suínos , Espécies Reativas de Oxigênio/metabolismo , Desenvolvimento Embrionário , Apoptose , Mitocôndrias/metabolismo , Estresse Oxidativo
8.
Vet Sci ; 10(2)2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36851447

RESUMO

Chrysoeriol (CHE) is a flavonoid substance that exists in many plants. It has various physiological and pharmacological effects, including anti-inflammatory, antioxidant, anti-tumor, and protective activity, especially for the cardiovascular system and liver. Among common livestock embryos, porcine embryos are often considered high-quality objects for studying the antioxidant mechanisms of oocytes. Because porcine embryos contain high levels of lipids, they are more vulnerable to external stimuli, which affect development. Our study explored the influence of CHE supplementation on oxidative stress in porcine oocytes and its possible mechanisms. Different concentrations of CHE (0, 0.1, 1, and 3 µM) were supplemented in the in vitro culture medium of the porcine oocytes. The results showed that supplementation with 1 µM CHE significantly increased the blastocyst rate and total cell number of embryos in vitro. After finding the beneficial effects of CHE, we measured reactive oxygen species (ROS), glutathione (GSH), and mitochondrial membrane potential (MMP) when the oocytes reached the 4-cell stage of development and determined the levels of apoptosis, cell proliferation, and autophagy at the blastocyst stage of development. The expression levels of some related genes were preliminarily detected by qRT-PCR. The results showed that the apoptosis of blastocysts in the CHE-treated culture also decreased compared with the untreated culture. Furthermore, CHE downregulated intracellular ROS and increased GSH in the embryos. CHE was also shown to improve the activity of mitochondria and inhibit the occurrence of autophagy. In addition, antioxidant-related genes (SOD1, SOD2, and CAT) and cell pluripotency-related genes (SOX2, OCT4, and NANOG) were upregulated. At the same time, apoptosis-related (Caspase 3) and autophagy-related (LC3B) genes showed a downward trend after supplementation with CHE. These results indicate that CHE improved the development of porcine embryos in vitro by reducing oxidative stress and autophagy levels.

9.
J Reprod Dev ; 69(1): 10-17, 2023 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-36403957

RESUMO

Dihydromyricetin (DHM), a dihydroflavonoid compound, exhibits a variety of biological activities, including antitumor activity. However, the effects of DHM on mammalian reproductive processes, especially during early embryonic development, remain unclear. In this study, we added DHM to porcine zygotic medium to explore the influence and underlying mechanisms of DHM on the developmental competence of parthenogenetically activated porcine embryos. Supplementation with 5 µM DHM during in vitro culture (IVC) significantly improved blastocyst formation rate and increased the total number of cells in porcine embryos. Further, DHM supplementation also improved glutathione levels and mitochondrial membrane potential; reduced natural reactive oxygen species levels in blastomeres and apoptosis rate; upregulated Nanog, Oct4, SOD1, SOD2, Sirt1, and Bcl2 expression; and downregulated Beclin1, ATG12, and Bax expression. Collectively, DHM supplementation regulated oxidative stress during IVC and could act as a potential antioxidant during in vitro porcine oocytes maturation.


Assuntos
Blastocisto , Oócitos , Feminino , Gravidez , Suínos , Animais , Oócitos/metabolismo , Blastocisto/metabolismo , Estresse Oxidativo , Técnicas de Maturação in Vitro de Oócitos/veterinária , Espécies Reativas de Oxigênio/metabolismo , Desenvolvimento Embrionário , Suplementos Nutricionais , Mamíferos/metabolismo
10.
PeerJ ; 10: e13766, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35910774

RESUMO

Wedelolactone (WDL) is a coumaryl ether compound extracted from the traditional Chinese medicinal plant, Eclipta prostrata L. It is a natural polyphenol that exhibits a variety of pharmacological activities, such as anti-inflammatory, anti-free radical, and antioxidant activities in the bone, brain, and ovary. However, its effect on embryonic development remains unknown. The present study explored the influence of WDL supplementation of porcine oocytes culture in vitro on embryonic development and the underlying mechanisms and its effect on the levels of Kelch-like ECH-associated protein 1/nuclear factor-erythroid 2-related factor 2/antioxidant response element (Keap1/Nrf2/ARE). The results showed that WDL (2.5 nM) significantly increased the blastocyst formation rate, mitochondrial activity, and proliferation ability while reducing the reactive oxygen species accumulation, apoptosis, and autophagy. These findings suggested that WDL can enhance the growth and development of early porcine embryos to alleviate oxidative stress and autophagy through regulating NRF2 and microtubule-associated protein 1 light chain 3 (MAP1LC3) gene expression levels.


Assuntos
Fator 2 Relacionado a NF-E2 , Estresse Oxidativo , Feminino , Animais , Suínos , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Fator 2 Relacionado a NF-E2/genética , Autofagia/genética
11.
Reprod Domest Anim ; 57(10): 1255-1266, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35780288

RESUMO

Oroxin A (OA) is a flavonoid isolated from Oroxylum indicum (L.) Kurz that has various biological activities, including antioxidant activities. This study aimed to examine the viability of using OA in an in vitro culture (IVC) medium for its antioxidant effects and related molecular mechanisms on porcine blastocyst development. In this study, we investigated the effects of OA on early porcine embryo development via terminal deoxynucleotidyl transferase dUTP nick-end labeling, 5-ethynyl-2'-deoxyuridine labeling, quantitative reverse transcription PCR, and immunocytochemistry. Embryos cultured in the IVC medium supplemented with 2.5 µM of OA had an increased blastocyst formation rate, total cell number, and proliferation capacity, along with a low apoptosis rate. OA supplementation decreased reactive oxygen species levels while increasing glutathione levels. OA-treated embryos exhibited an improved intracellular mitochondrial membrane potential and reduced autophagy. Moreover, levels of pluripotency- and antioxidant-related genes were upregulated, whereas those of apoptosis- and autophagy-related genes were downregulated by OA addition. In conclusion, OA improves preimplantation embryonic development by reducing oxidative stress and enhancing mitochondrial function.


Assuntos
Técnicas de Cultura Embrionária , Flavonas , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Apoptose , Autofagia , Blastocisto , DNA Nucleotidilexotransferase/metabolismo , DNA Nucleotidilexotransferase/farmacologia , Técnicas de Cultura Embrionária/veterinária , Desenvolvimento Embrionário , Flavonas/metabolismo , Flavonas/farmacologia , Glucosídeos , Glutationa/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Suínos
12.
BMJ Open ; 12(6): e059704, 2022 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-35697443

RESUMO

OBJECTIVES: The current study examines the mediating roles of resilience and self-efficacy and the moderating role of gender in the association between neuroticism and psychological distress in Chinese freshman nursing students (FNSs). METHODS: A total of 1220 FNSs were enrolled from the Be Resilient to Nursing Career (ChiCTR2000038693) Programme and the following instruments were administered to them: NEO Five-Factor Inventory, General Self-Efficacy Scale, Connor-Davidson Resilience Scale and Kessler Psychological Distress Scale. A moderated mediation analysis and a generalised additive model analysis were performed. RESULTS: The direct and indirect effects of neuroticism on psychological distress were significantly mediated by self-efficacy (B = 0.200, 95% CI 0.001 to 0.039), resilience (B = 0.021, 95% CI 0.007 to 0.038) and the interaction between self-efficacy and resilience (B = 0.016, 95% CI 0.005 to 0.028). The interactions between neuroticism and gender (ß = 0.102, 95% CI 0.001 to 0.203, p<0.05) and between resilience and gender were significant (ß = 0.160, 95% CI 0.045 to 0.275, p<0.01). A non-linear and positive association was confirmed between neuroticism and psychological distress. CONCLUSIONS: Self-efficacy and resilience significantly mediate the relationship between neuroticism and psychological distress. Gender moderates the relationships between neuroticism and resilience and between resilience and psychological distress.


Assuntos
Angústia Psicológica , Resiliência Psicológica , Estudantes de Enfermagem , China , Estudos Transversais , Humanos , Neuroticismo , Autoeficácia
13.
Front Psychiatry ; 13: 1091042, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36590638

RESUMO

Introduction: Prenatal psychological distress is prevalent during pregnancy. This study aimed to estimate the associations among fear of childbirth, resilience and psychological distress. Methods: A total of 1,060 Chinese pregnant women were enrolled from Be Resilient to Postpartum Depression (ChiCTR2100048465) and the following instruments were administered to them: Childbirth Attitudes Questionnaire, Connor-Davidson Resilience Scale, Perceived Social Support Scale, General Self-Efficacy Scale, Adverse Childhood Experience scale and Hospital Anxiety and Depression Scale. A dominance, a response surface analysis and a moderated mediation analysis were performed. Results: In terms of psychological distress, resilience and fear of childbirth could explain 41.6% (0.148/0.356) and 33.1% (0.118/0.356), respectively. Pregnant women with high resilience-low fear of childbirth had significantly lower levels of psychological distress than those with low resilience-high fear of childbirth. The indirect effects of fear of childbirth on psychological distress through resilience was significantly (B = 0.054, 95% CI 0.038 to 0.070). The interactions between fear of childbirth and adverse childhood experiences (ß = 0.114, 95% CI -0.002 to 0.231, p = 0.054) and between resilience and adverse childhood experiences (ß = -0.118, 95% CI -0.222 to -0.012, p < 0.05) were significant. Conclusion: Resilience, fear of childbirth and adverse childhood experiences may be three important factors to psychological distress in Chinese pregnant women.

14.
J Chem Phys ; 144(20): 204308, 2016 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-27250307

RESUMO

Clathrate hydrates are characterized by their water cages encapsulating various guest atoms or molecules. The polarization effect of these guest-cage complexes was studied with combined density functional theory and finite-field calculations. An addition rule was noted for these systems whose total polarizability is approximately equal to the polarizability sum of the guest and the cage. However, their distributional polarizability computed with Hirshfeld partitioning scheme indicates that the guest-cage interaction has considerable influence on their polarization response. The polarization of encapsulated guest is reduced while the polarization of water cage is enhanced. The counteraction of these two opposite effects leads to the almost unchanged total polarizability. Further analysis reveals that the reduced polarizability of encapsulated guest results from the shielding effect of water cage against the external field and the enhanced polarizability of water cage from the enhanced bonding of hydrogen bonds among water molecules. Although the charge transfer through the hydrogen bonds is rather small in the water cage, the polarization response of clathrate hydrates is sensitive to the changes of hydrogen bonding strength. The guest encapsulation strengthens the hydrogen bonding network and leads to enhanced polarizability.

15.
J Chem Phys ; 144(13): 134307, 2016 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-27059570

RESUMO

The structural, electronic, and optical properties of core-shell nanoclusters, (CdSe)(x)@(CdSe)(y) and their Zn-substituted complexes of x = 2-4 and y = 16-28, were studied with density functional theory calculations. The substitution was applied in the cores, the shells, and/or the whole clusters. All these clusters are characterized by their core-shell structures in which the core-shell interaction was found different from those in core or in shell, as reflected by their bondlengths, volumes, and binding energies. Moreover, the core and shell combine together to compose a new cluster with electronic and optical properties different from those of separated individuals, as reflected by their HOMO-LUMO gaps and optical absorptions. With the substitution of Cd by Zn, the structural, electronic, and optical properties of clusters change regularly. The binding energy increases with Zn content, attributed to the strong Zn-Se bonding. For the same core/shell, the structure with a CdSe shell/core has a narrower gap than that with a ZnSe shell/core. The optical absorption spectra also change accordingly with Zn substitution. The peaks blueshift with increasing Zn concentration, accompanying with shape variations in case large number of Cd atoms are substituted. Our calculations reveal the core-shell interaction and its influence on the electronic and optical properties of the core-shell clusters, suggesting a composition-structure-property relationship for the design of core-shell CdSe and ZnSe nanoclusters.

16.
Phys Chem Chem Phys ; 17(27): 17864-71, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-26090584

RESUMO

The introduction of multiple carbon rings is one of the common ways for graphene modification. Starting from warped C80H30 nanographene, which consists of a number of six- and seven-membered carbon rings (C6 and C7) centering at a five-membered carbon ring (C5), we explored the structure and property variations of its derivatives in which their C7 rings were gradually replaced with C6 rings. With reducing number of C7 rings, their curved boundary with the C6 rings becomes flat until a bowl-like structure is formed when all the C7 rings disappear. The optical absorption spectra vary accordingly. Both the α-bands and the maximum absorption bands in the visible region are related to the number and location of the C7 rings. Further analysis of the excited states of the C80H30 derivatives, as well as on the designed model systems, revealed that the C7 rings affect the electron excitations in two ways. In addition to their participation in electronic transitions, they control the composition of molecular orbitals that are involved in the excitations. The highest occupied molecular orbitals are mainly contributed by atoms on the C6 and C7 rings, while the lowest unoccupied molecular orbitals by atoms on the C5 and C6 rings. Our study sheds some light on how the multiple carbon rings affect the optical absorption of nanographenes and provides information for the preparation of nanographenes with tunable structural and optical properties.

17.
Phys Chem Chem Phys ; 17(14): 9222-30, 2015 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-25761258

RESUMO

Understanding the size-dependent structures and properties of ligand-capped nanoclusters in solvent is of particular interest for the design, synthesis and application of II-VI colloidal QDs. Using DFT and TDDFT calculations, we studied the structure and optical property evolution of the cysteine-capped (CdSe)N clusters of N = 1-10, 13, 16 and 19 in gas, toluene, water and alkaline aqueous solution, and made a comparison with their corresponding bare clusters. The cysteine binds with (CdSe)Nvia several patterns depending on the medium they exist in, affecting the cluster structures and in consequence their optical absorption. In general, the absorption bands of (CdSe)N blueshift when cysteine is added, and the shift varies with the interaction strength between the cluster and the ligand, and the dielectric constant of the solvent. However, bare clusters retain their size sensitivity, in particular the redshift trend with increasing cluster size, and some similarity was noted for the optical absorption of the bare and ligated clusters regardless of the gas or solvent media. Population analysis reveals that the excitations are mainly from orbitals distributing on the (CdSe)N part, while the ligand is negligibly involved in the excitations. This is an important feature for the II-VI QDs as biosensors with which the information of biomolecules is detected from the size dependent optical absorption or emission of the QDs other than the biomolecules.


Assuntos
Compostos de Cádmio/química , Cisteína/química , Modelos Teóricos , Nanoestruturas/química , Nanotecnologia , Fenômenos Ópticos , Pontos Quânticos , Compostos de Selênio/química , Ligantes , Solventes , Água/química
18.
Angew Chem Int Ed Engl ; 53(27): 6898-904, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24855040

RESUMO

Primary alkyl amines (RNH2) have been empirically used to engineer various colloidal semiconductor nanocrystals (NCs). Here, we present a general mechanism in which the amine acts as a hydrogen/proton donor in the precursor conversion to nanocrystals at low temperature, which was assisted by the presence of a secondary phosphine. Our findings introduce the strategy of using a secondary phosphine together with a primary amine as new routes to prepare high-quality NCs at low reaction temperatures but with high particle yields and reproducibility and thus, potentially, low production costs.

19.
Angew Chem Int Ed Engl ; 52(42): 11034-9, 2013 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-24006135

RESUMO

One thing in common: The formation of binary colloidal semiconductor nanocrystals from single- (M(EEPPh2 )n ) and dual-source precursors (metal carboxylates M(OOCR)n and phosphine chalcogenides such as E=PHPh2 ) is found to proceed through a common mechanism. For CdSe as a model system (31) P NMR spectroscopy and DFT calculations support a reaction mechanism which includes numerous metathesis equilibriums and Se exchange reactions.

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