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1.
Breast Cancer Res Treat ; 181(2): 465-473, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32318955

RESUMO

PURPOSE: Limited studies have been conducted to evaluate pathogenetic mutations in breast cancer predisposition genes among Chinese women. To fully characterize germline mutations of these genes in this population, we used the whole-exome sequencing data in a population-based case-control study conducted in Shanghai, China. METHODS: We evaluated exonic, splicing, and copy number variants in 11 established and 14 candidate breast cancer predisposition genes in 831 invasive breast cancer cases and 839 controls. We identified 55 pathogenic variants, including 15 newly identified in this study. RESULTS: Approximately 8% of the cases and 0.6% of the cancer-free controls carried these pathogenetic variants (P = 3.05 × 10-15). Among cases, 3.7% had a BRCA2 pathogenic variant and 1.6% had a BRCA1 pathogenic variant, while 2.5% had a pathogenic variant in other genes including ATM, CHEK2, NBN, NF1, CDH1, PALB2, PTEN, TP53 as well as BARD1, BRIP, and RAD51D. Patients with BRCA1/2 pathogenic variants were more likely to have a family history of breast cancer and hormone receptor negative tumors compared with patients without pathogenic variants. CONCLUSIONS: This study highlighted the importance of hereditary breast cancer genes in the breast cancer etiology in this understudied population. Together with previous studies in East Asian women, this study suggested a relatively more prominent role of BRCA2 compared to BRCA1. This study also provides additional evidence to design cost-efficient genetic testing among Chinese women for risk assessment and early detection of breast cancer.


Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Biomarcadores Tumorais/genética , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Adulto , Idoso , Neoplasias da Mama/genética , Estudos de Casos e Controles , Quinase do Ponto de Checagem 2/genética , China/epidemiologia , Proteína do Grupo de Complementação N da Anemia de Fanconi/genética , Feminino , Seguimentos , Testes Genéticos , Humanos , Pessoa de Meia-Idade , Prognóstico , Receptor ErbB-2/metabolismo , Receptores Estrogênicos/metabolismo , Receptores de Progesterona/metabolismo
2.
Int J Cancer ; 146(8): 2175-2181, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-31837001

RESUMO

The missing heritability of breast cancer could be partially attributed to rare variants (MAF < 0.5%). To identify breast cancer-associated rare coding variants, we conducted whole-exome sequencing (~50×) in genomic DNA samples obtained from 831 breast cancer cases and 839 controls of Chinese females. Using burden tests for each gene that included rare missense or predicted deleterious variants, we identified 29 genes showing promising associations with breast cancer risk. We replicated the association for two genes, OGDHL and BRCA2, at a Bonferroni-corrected p < 0.05, by genotyping an independent set of samples from 1,628 breast cancer cases and 1,943 controls. The association for OGDHL was primarily driven by three predicted deleterious variants (p.Val827Met, p.Pro839Leu, p.Phe836Ser; p < 0.01 for all). For BRCA2, we characterized a total of 27 disruptive variants, including 18 nonsense, six frameshift and three splicing variants, whereas they were only detected in cases, but none of the controls. All of these variants were either very rare (AF < 0.1%) or not detected in >4,500 East Asian women from the genome Aggregation database (gnomAD), providing additional support to our findings. Our study revealed a potential novel gene and multiple disruptive variants of BRCA2 for breast cancer risk, which may identify high-risk women in Chinese populations.


Assuntos
Proteína BRCA2/genética , Neoplasias da Mama/genética , Complexo Cetoglutarato Desidrogenase/genética , Adulto , Idoso , Estudos de Casos e Controles , China , Bases de Dados Genéticas , Feminino , Frequência do Gene , Predisposição Genética para Doença , Humanos , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Sequenciamento Completo do Exoma
3.
J Am Chem Soc ; 141(50): 19754-19764, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31809035

RESUMO

The evolution of the optical properties of gold nanoclusters (NCs) versus size is of great importance because it not only reveals the nature of quantum confinement in NCs, but also helps to understand how the molecular-like Au NCs transit to plasmonic nanoparticles. While some work has been done in studying the optical properties of NCs of certain individual sizes, the global picture remains unclear, such as the detailed relationship between size/structure and properties. Here, we investigate the grand evolution of the optical properties by comparing the steady-state absorption, bandgap, transient absorption, as well as carrier dynamics of a series of thiolate-protected gold NCs ranging from tens to hundreds of gold atoms. We find that, on the basis of their optical behaviors, gold NCs can be classified into three groups: (i) ultrasmall NCs (ca. <50 Au atoms) are nonscalable as their optical properties are strongly dependent on the structure rather than size; (ii) medium-sized NCs (about 50-100 Au atoms) show both size- and structure-dependent optical properties; and (iii) large-sized gold NCs (ca. >100 Au atoms) exhibit optical properties solely dependent on size, and the structure effect fades out. Unraveling the grand evolution from nonscalable to scalable optical properties and their mechanisms will greatly deepen scientific understanding of the nature of quantum-sized gold NCs and will also provide implications for plasmonic NPs.

4.
J Am Med Inform Assoc ; 26(12): 1437-1447, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31609419

RESUMO

OBJECTIVE: The Phenotype Risk Score (PheRS) is a method to detect Mendelian disease patterns using phenotypes from the electronic health record (EHR). We compared the performance of different approaches mapping EHR phenotypes to Mendelian disease features. MATERIALS AND METHODS: PheRS utilizes Mendelian diseases descriptions annotated with Human Phenotype Ontology (HPO) terms. In previous work, we presented a map linking phecodes (based on International Classification of Diseases [ICD]-Ninth Revision) to HPO terms. For this study, we integrated ICD-Tenth Revision codes and lab data. We also created a new map between HPO terms using customized groupings of ICD codes. We compared the performance with cases and controls for 16 Mendelian diseases using 2.5 million de-identified medical records. RESULTS: PheRS effectively distinguished cases from controls for all 15 positive controls and all approaches tested (P < 4 × 1016). Adding lab data led to a statistically significant improvement for 4 of 14 diseases. The custom ICD groupings improved specificity, leading to an average 8% increase for precision at 100 (-2% to 22%). Eight of 10 adults with cystic fibrosis tested had PheRS in the 95th percentile prio to diagnosis. DISCUSSION: Both phecodes and custom ICD groupings were able to detect differences between affected cases and controls at the population level. The ICD map showed better precision for the highest scoring individuals. Adding lab data improved performance at detecting population-level differences. CONCLUSIONS: PheRS is a scalable method to study Mendelian disease at the population level using electronic health record data and can potentially be used to find patients with undiagnosed Mendelian disease.

5.
J Am Chem Soc ; 141(38): 15145-15152, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31496238

RESUMO

The synthesis of colloidal III-V quantum dots (QDs), particularly of the arsenides and antimonides, has been limited by the lack of stable and available group V precursors. In this work, we exploit accessible InCl3- and pnictogen chloride-oleylamine as precursors to synthesize III-V QDs. Through coreduction reactions of the precursors, we achieve size- and stoichiometry-tunable binary InAs and InSb as well as ternary alloy InAs1-xSbx QDs. On the basis of structural, analytical, optical, and electrical characterization of the QDs and their thin-film assemblies, we study the effects of alloying on their particle formation and optoelectronic properties. We introduce a hydrazine-free hybrid ligand-exchange process to improve carrier transport in III-V QD thin films and realize InAs QD field-effect transistors with electron mobility > 5 cm2/(V s). We demonstrate that III-V QD thin films are promising candidate materials for infrared devices and show InAs1-xSbx QD photoconductors with superior short-wavelength infrared (SWIR) photoresponse than those of the binary QD devices.

6.
Nanomaterials (Basel) ; 9(7)2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31261666

RESUMO

Recent advances in the determination of crystal structures and studies of optical properties of gold nanoclusters in the size range from tens to hundreds of gold atoms have started to reveal the grand evolution from gold complexes to nanoclusters and further to plasmonic nanoparticles. However, a detailed comparison of their photophysical properties is still lacking. Here, we compared the excited state behaviors of gold complexes, nanolcusters, and plasmonic nanoparticles, as well as small organic molecules by choosing four typical examples including the Au10 complex, Au25 nanocluster (1 nm metal core), 13 diameter Au nanoparticles, and Rhodamine B. To compare their photophysical behaviors, we performed steady-state absorption, photoluminescence, and femtosecond transient absorption spectroscopic measurements. It was found that gold nanoclusters behave somewhat like small molecules, showing both rapid internal conversion (<1 ps) and long-lived excited state lifetime (about 100 ns). Unlike the nanocluster form in which metal-metal transitions dominate, gold complexes showed significant charge transfer between metal atoms and surface ligands. Plasmonic gold nanoparticles, on the other hand, had electrons being heated and cooled (~100 ps time scale) after photo-excitation, and the relaxation was dominated by electron-electron scattering, electron-phonon coupling, and energy dissipation. In both nanoclusters and plasmonic nanoparticles, one can observe coherent oscillations of the metal core, but with different fundamental origins. Overall, this work provides some benchmarking features for organic dye molecules, organometallic complexes, metal nanoclusters, and plasmonic nanoparticles.

7.
Cancer Epidemiol Biomarkers Prev ; 28(8): 1308-1315, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31160347

RESUMO

BACKGROUND: Pathogenic variants in susceptibility genes lead to increased breast cancer risk. METHODS: To identify coding variants associated with breast cancer risk, we conducted whole-exome sequencing in genomic DNA samples from 831 breast cancer cases and 839 controls of Chinese women. We also genotyped samples, including 4,580 breast cancer cases and 6,695 controls, using whole exome-chip arrays. We further performed a replication study using a Multi-Ethnic Global Array in samples from 1,793 breast cases and 2,059 controls. A single marker analysis was performed using the Fisher exact test. RESULTS: We identified a missense variant (rs139379666, P2974L; AF = 0.09% for breast cancer cases, but none for controls) in the ATM gene for breast cancer risk using combing data from 7,204 breast cancer cases and 9,593 controls (P = 1.7 × 10-5). To investigate the functionality of the variant, we first silenced ATM and then transfected the overexpression vectors of ATM containing the risk alleles (TT) or reference alleles (CC) of the variant in U2OS and breast cancer SK-BR3 cells, respectively. Our results showed that compared with the reference allele, the risk allele significantly disrupts the activity of homologous recombination-mediated double-strand breaks repair efficiency. Our results further showed that the risk allele may play a defected regulation role in the activity of the ATM structure. CONCLUSIONS: Our findings identified a novel mutation that disrupts ATM function, conferring to breast cancer risk. IMPACT: Functional investigation of genetic association findings is necessary to discover a pathogenic variant for breast cancer risk.


Assuntos
Proteínas Mutadas de Ataxia Telangiectasia/genética , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Mutação de Sentido Incorreto , Reparo de DNA por Recombinação , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Estudos de Casos e Controles , China/epidemiologia , Estudos de Coortes , Feminino , Genótipo , Humanos , Fatores de Risco , Células Tumorais Cultivadas , Sequenciamento Completo do Exoma/métodos
8.
Chem Sci ; 10(42): 9684-9691, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-32015802

RESUMO

The transition from the discrete, excitonic state to the continuous, metallic state in thiolate-protected gold nanoclusters is of fundamental interest and has attracted significant efforts in recent research. Compared with optical and electronic transition behavior, the transition in magnetism from the atomic gold paramagnetism (Au 6s1) to the band behavior is less studied. In this work, the magnetic properties of 1.7 nm [Au133(TBBT)52]0 nanoclusters (where TBBT = 4-tert-butylbenzenethiolate) with 81 nominal "valence electrons" are investigated by electron paramagnetic resonance (EPR) spectroscopy. Quantitative EPR analysis shows that each cluster possesses one unpaired electron (spin), indicating that the electrons fill into discrete orbitals instead of a continuous band, for that one electron in the band would give a much smaller magnetic moment. Therefore, [Au133(TBBT)52]0 possesses a nonmetallic electronic structure. Furthermore, we demonstrate that the unpaired spin can be removed by oxidizing [Au133(TBBT)52]0 to [Au133(TBBT)52]+ and the nanocluster transforms from paramagnetism to diamagnetism accordingly. The UV-vis absorption spectra remain the same in the process of single-electron loss or addition. Nuclear magnetic resonance (NMR) is applied to probe the charge and magnetic states of Au133(TBBT)52, and the chemical shifts of 52 surface TBBT ligands are found to be affected by the spin in the gold core. The NMR spectrum of Au133(TBBT)52 shows a 13-fold splitting with 4-fold degeneracy of 52 TBBT ligands, which are correlated to the quasi-D 2 symmetry of the ligand shell. Overall, this work provides important insights into the electronic structure of Au133(TBBT)52 by combining EPR, optical and NMR studies, which will pave the way for further understanding of the transition behavior in metal nanoclusters.

9.
Gastroenterology ; 156(5): 1455-1466, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30529582

RESUMO

BACKGROUND & AIMS: Genome-wide association studies (GWASs) have associated approximately 50 loci with risk of colorectal cancer (CRC)-nearly one third of these loci were initially associated with CRC in studies conducted in East Asian populations. We conducted a GWAS of East Asians to identify CRC risk loci and evaluate the generalizability of findings from GWASs of European populations to Asian populations. METHODS: We analyzed genetic data from 22,775 patients with CRC (cases) and 47,731 individuals without cancer (controls) from 14 studies in the Asia Colorectal Cancer Consortium. First, we performed a meta-analysis of 7 GWASs (10,625 cases and 34,595 controls) and identified 46,554 promising risk variants for replication by adding them to the Multi-Ethnic Global Array (MEGA) for genotype analysis in 6445 cases and 7175 controls. These data were analyzed, along with data from an additional 5705 cases and 5961 controls genotyped using the OncoArray. We also obtained data from 57,976 cases and 67,242 controls of European descent. Variants at identified risk loci were functionally annotated and evaluated in correlation with gene expression levels. RESULTS: A meta-analyses of all samples from people of Asian descent identified 13 loci and 1 new variant at a known locus (10q24.2) associated with risk of CRC at the genome-wide significance level of P < 5 × 10-8. We did not perform experiments to replicate these associations in additional individuals of Asian ancestry. However, the lead risk variant in 6 of these loci was also significantly associated with risk of CRC in European descendants. A strong association (44%-75% increase in risk per allele) was found for 2 low-frequency variants: rs201395236 at 1q44 (minor allele frequency, 1.34%) and rs77969132 at 12p11.21 (minor allele frequency, 1.53%). For 8 of the 13 associated loci, the variants with the highest levels of significant association were located inside or near the protein-coding genes L1TD1, EFCAB2, PPP1R21, SLCO2A1, HLA-G, NOTCH4, DENND5B, and GNAS. For other intergenic loci, we provided evidence for the possible involvement of the genes ALDH7A1, PRICKLE1, KLF5, WWOX, and GLP2R. We replicated findings for 41 of 52 previously reported risk loci. CONCLUSIONS: We showed that most of the risk loci previously associated with CRC risk in individuals of European descent were also associated with CRC risk in East Asians. Furthermore, we identified 13 loci significantly associated with risk for CRC in Asians. Many of these loci contained genes that regulate the immune response, Wnt signaling to ß-catenin, prostaglandin E2 catabolism, and cell pluripotency and proliferation. Further analyses of these genes and their variants is warranted, particularly for the 8 loci for which the lead CRC risk variants were not replicated in persons of European descent.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Biomarcadores Tumorais/genética , Neoplasias Colorretais/genética , Loci Gênicos , Polimorfismo de Nucleotídeo Único , Ásia/epidemiologia , Estudos de Casos e Controles , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/etnologia , Neoplasias Colorretais/imunologia , Frequência do Gene , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Fenótipo , Medição de Risco , Fatores de Risco
10.
Nat Genet ; 50(7): 968-978, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29915430

RESUMO

The breast cancer risk variants identified in genome-wide association studies explain only a small fraction of the familial relative risk, and the genes responsible for these associations remain largely unknown. To identify novel risk loci and likely causal genes, we performed a transcriptome-wide association study evaluating associations of genetically predicted gene expression with breast cancer risk in 122,977 cases and 105,974 controls of European ancestry. We used data from the Genotype-Tissue Expression Project to establish genetic models to predict gene expression in breast tissue and evaluated model performance using data from The Cancer Genome Atlas. Of the 8,597 genes evaluated, significant associations were identified for 48 at a Bonferroni-corrected threshold of P < 5.82 × 10-6, including 14 genes at loci not yet reported for breast cancer. We silenced 13 genes and showed an effect for 11 on cell proliferation and/or colony-forming efficiency. Our study provides new insights into breast cancer genetics and biology.


Assuntos
Neoplasias da Mama/genética , Estudos de Casos e Controles , Feminino , Expressão Gênica , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla/métodos , Humanos , Polimorfismo de Nucleotídeo Único , Risco , Transcriptoma
11.
Angew Chem Int Ed Engl ; 56(51): 16257-16261, 2017 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-29098757

RESUMO

The transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.

12.
J Phys Chem Lett ; 8(17): 4023-4030, 2017 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-28796513

RESUMO

Understanding the correlation between the atomic structure and optical properties of gold nanoclusters is essential for exploration of their functionalities and applications involving light harvesting and electron transfer. We report the femto-nanosecond excited state dynamics of a periodic series of face-centered cubic (FCC) gold nanoclusters (including Au28, Au36, Au44, and Au52), which exhibit a set of unique features compared with other similar sized clusters. Molecular-like ultrafast Sn → S1 internal conversions (i.e., radiationless electronic transitions) are observed in the relaxation dynamics of FCC periodic series. Excited-state dynamics with near-HOMO-LUMO gap excitation lacks ultrafast decay component, and only the structural relaxation dominates in the dynamical process, which proves the absence of core-shell relaxation. Interestingly, both the relaxation of the hot carriers and the band-edge carrier recombination become slower as the size increases. The evolution in excited-state properties of this FCC series offers new insight into the structure-dependent properties of metal nanoclusters, which will benefit their optical energy harvesting and photocatalytic applications.

13.
Chem Asian J ; 12(15): 1839-1850, 2017 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-28653468

RESUMO

Chiral nanomaterials have received wide interest in many areas, but the exact origin of chirality at the atomic level remains elusive in many cases. With recent significant progress in atomically precise gold nanoclusters (e.g., thiolate-protected Aun (SR)m ), several origins of chirality have been unveiled based upon atomic structures determined by using single-crystal X-ray crystallography. The reported chiral Aun (SR)m structures explicitly reveal a predominant origin of chirality that arises from the Au-S chiral patterns at the metal-ligand interface, as opposed to the chiral arrangement of metal atoms in the inner core (i.e. kernel). In addition, chirality can also be introduced by a chiral ligand, manifested in the circular dichroism response from metal-based electronic transitions other than the ligand's own transition(s). Lastly, the chiral arrangement of carbon tails of the ligands has also been discovered in a very recent work on chiral Au133 (SR)52 and Au246 (SR)80 nanoclusters. Overall, the origins of chirality discovered in Aun (SR)m nanoclusters may provide models for the understanding of chirality origins in other types of nanomaterials and also constitute the basis for the development of various applications of chiral nanoparticles.

14.
J Phys Chem Lett ; 8(4): 866-870, 2017 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-28145114

RESUMO

Here we report an oxidation-induced transformation of [Au23(S-c-C6H11)16]-TOA+ (S-c-C6H11: cyclohexanethiolate; TOA: tetraoctylammonium) to the [Au28(S-c-C6H11)20]0 nanocluster by H2O2 treatment under ambient conditions. This is the first example of oxidation-induced transformation of one stable size to another with atomic precision. The product was crystallized and analyzed by X-ray crystallography. Further insights into the transformation process were obtained by monitoring the process with optical spectroscopy and also by electrochemical analysis. This work adds a new dimension to the recently established transformation chemistry of nanoclusters that involves size and structure transformations.

15.
J Am Chem Soc ; 139(3): 1077-1080, 2017 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-28068082

RESUMO

Electrocatalytic water splitting to produce hydrogen comprises the hydrogen and oxygen evolution half reactions (HER and OER), with the latter as the bottleneck process. Thus, enhancing the OER performance and understanding the mechanism are critically important. Herein, we report a strategy for OER enhancement by utilizing gold nanoclusters to form cluster/CoSe2 composites; the latter exhibit largely enhanced OER activity in alkaline solutions. The Au25/CoSe2 composite affords a current density of 10 mA cm-2 at small overpotential of ∼0.43 V (cf. CoSe2: ∼0.52 V). The ligand and gold cluster size can also tune the catalytic performance of the composites. Based upon XPS analysis and DFT simulations, we attribute the activity enhancement to electronic interactions between nanocluster and CoSe2, which favors the formation of the important intermediate (OOH) as well as the desorption of oxygen molecules over Aun/CoSe2 composites in the process of water oxidation. Such an atomic level understanding may provide some guidelines for design of OER catalysts.

16.
Science ; 354(6319): 1580-1584, 2016 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-28008066

RESUMO

We demonstrate that nanoparticle self-assembly can reach the same level of hierarchy, complexity, and accuracy as biomolecules. The precise assembly structures of gold nanoparticles (246 gold core atoms with 80 p-methylbenzenethiolate surface ligands) at the atomic, molecular, and nanoscale levels were determined from x-ray diffraction studies. We identified the driving forces and rules that guide the multiscale assembly behavior. The protecting ligands self-organize into rotational and parallel patterns on the nanoparticle surface via C-H⋅⋅⋅π interaction, and the symmetry and density of surface patterns dictate directional packing of nanoparticles into crystals with orientational, rotational, and translational orders. Through hierarchical interactions and symmetry matching, the simple building blocks evolve into complex structures, representing an emergent phenomenon in the nanoparticle system.

17.
Nat Commun ; 7: 13240, 2016 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-27775036

RESUMO

The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1-3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au25, Au38, Au144, Au333, Au∼520 and Au∼940 nanoparticles. Our results clearly map out three distinct states: metallic (size larger than Au333, that is, larger than 2.3 nm), transition regime (between Au333 and Au144, that is, 2.3-1.7 nm) and non-metallic or excitonic state (smaller than Au144, that is, smaller than 1.7 nm). The transition also impacts the catalytic properties as demonstrated in both carbon monoxide oxidation and electrocatalytic oxidation of alcohol.

18.
Chem Rev ; 116(18): 10346-413, 2016 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-27585252

RESUMO

Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1-3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal-ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles.

19.
J Am Chem Soc ; 138(37): 12045-8, 2016 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-27593173

RESUMO

Crystalline 3-D materials bearing interlinked domains of differential porosity and functionality offer the potential for organizing and shuttling molecular and nanoscale matter to specific locations within 3-D space. Here, we present methods for creating prototype MOF materials that have such structural features. Specifically, the process of pore expansion via ligand exchange was studied for an isoreticular series of mesoporous MOFs based on bMOF-100. It was found that pore expansion occurs incrementally in small steps and that it proceeds gradually in an "outside→in" fashion within individual crystals. The ligand exchange reaction can be terminated prior to complete crystal conversion to yield intermediate product MOFs, denoted bMOF-100/102 and bMOF-102/106, which bear descending porosity gradients from the crystal periphery to the crystal core. As a proof of concept, size-sensitive incorporation of a gold-thiolate nanocluster, Au133(SR)52, selectively in the bMOF-102/106 crystal periphery region was accomplished via cation exchange. These new methods open up the possibility of controlling molecular organization and transport within porous MOF materials.

20.
Br J Cancer ; 115(5): 624-31, 2016 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-27490808

RESUMO

BACKGROUND: Prostate cancer is a common cancer worldwide with no established modifiable lifestyle factors to guide prevention. The associations between polyunsaturated fatty acids (PUFAs) and prostate cancer risk have been inconsistent. Using Mendelian randomisation, we evaluated associations between PUFAs and prostate cancer risk. METHODS: We used individual-level data from a consortium of 22 721 cases and 23 034 controls of European ancestry. Externally-weighted PUFA-specific polygenic risk scores (wPRSs), with explanatory variation ranging from 0.65 to 33.07%, were constructed and used to evaluate associations with prostate cancer risk per one standard deviation (s.d.) increase in genetically-predicted plasma PUFA levels using multivariable-adjusted unconditional logistic regression. RESULTS: No overall association was observed between the genetically-predicted PUFAs evaluated in this study and prostate cancer risk. However, risk reductions were observed for short-chain PUFAs, linoleic (ORLA=0.95, 95%CI=0.92, 0.98) and α-linolenic acids (ORALA=0.96, 95%CI=0.93, 0.98), among men <62 years; whereas increased risk was found among men ⩾62 years for LA (ORLA=1.04, 95%CI=1.01, 1.07). For long-chain PUFAs (i.e., arachidonic, eicosapentaenoic, and docosapentaenoic acids), increased risks were observed among men <62 years (ORAA=1.05, 95%CI=1.02, 1.08; OREPA=1.04, 95%CI=1.01, 1.06; ORDPA=1.05, 95%CI=1.02, 1.08). CONCLUSION: Results from this study suggest that circulating ω-3 and ω-6 PUFAs may have a different role in the aetiology of early- and late-onset prostate cancer.


Assuntos
Ácidos Graxos Insaturados/metabolismo , Neoplasias da Próstata/metabolismo , Estudo de Associação Genômica Ampla , Humanos , Masculino , Neoplasias da Próstata/epidemiologia , Neoplasias da Próstata/genética , Fatores de Risco
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