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1.
Inorg Chem ; 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32578989

RESUMO

Reaction of the Cu(I) sources, [Cu5](Mes)5 and [(iDipp)CuOtBu] (Mes = mesityl; iDipp = 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene) with the Zn(I) complex [Zn2](Cp*)2 leads to a mixture of intermetallic Cu/Zn clusters with a distribution of species that is dependent on the stoichiometric ratio of the reactants, the reaction time, as well as the temperature. Systematic and careful investigation of the product mixtures rendered the isolation of two new clusters possible, i.e., the Zn-rich, red cluster 1, [CuZn10](Cp*)7 = [Cu(ZnZnCp*)3(ZnCp*)4], as well as the Cu-rich, dark-green cluster 2 [Cu10Zn2](Mes)6(Cp*)2. Structure and bonding of these two species was rationalized with the help of density functional theory calculations. Whereas 1 can be viewed as an 18-electron Cu center coordinated to four ZnCp* and three ZnZnCp* one-electron ligands (with some interligand bonding interaction), compound 2 is better to be described as a six-electron superatom cluster. This unusual electron count is associated with a prolate distortion from a spherical superatom structure. This unexpected situation is likely to be associated with the ZnCp* capping units that offer the possibility to strongly bind to the top and the bottom of the cluster in addition to the bridging mesityl ligands stabilizing the Cu core of the cluster.

2.
Dalton Trans ; 48(44): 16615-16625, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31657405

RESUMO

The synthesis and characterization of a novel macrocyclic Au(iii) N-heterocyclic carbene (NHC) imidazolyl complex, a novel macrocyclic tetra-NHC benzimidazole ligand, and the corresponding Ag(i) and Au(i) complexes are presented. Single-crystal X-ray diffraction analysis of the Au(i) benzimidazolyl complex 3 reveals an unusual structure, differing from the respective Au(i) imidazolyl complex 4. Both complexes have a Au4L2 composition; however, 3 has two C-Au(i)-C units acting as a connection between the two ligands with two Au(i) atoms being linearly coordinated inside the cavity of the macrocyclic ligand. In the case of complex 4, the structure shows a box-type coordination with all four Au(i) atoms being located between the two ligands. Stability studies in cell culture medium are performed for subsequent MTT assays and they show an unprecedented proton-to-deuterium exchange of the methylene bridge of the Au(iii) imidazolyl complex. In MTT assays, the tetranuclear acyclic Au(i) complex 5 displays the lowest IC50 values in MCF-7, PC3, and A2780cisR cells with a selective cytotoxicity for MCF-7 and A2780cisR cells.


Assuntos
Antineoplásicos/síntese química , Complexos de Coordenação/síntese química , Ouro/química , Compostos Heterocíclicos/química , Metano/análogos & derivados , Antineoplásicos/farmacologia , Benzimidazóis/química , Linhagem Celular Tumoral , Complexos de Coordenação/farmacologia , Estabilidade de Medicamentos , Humanos , Metano/química , Prata/química
3.
J Phys Chem A ; 123(26): 5574-5579, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31145614

RESUMO

More than 100 calculations of vibrational frequencies for cis-[Pt(NH3)2X2] (X = Cl-, Br-) and trans-[Pt(NH3)2Cl2] have been published over the past 25 years. The high-quality Raman spectra presented here have sufficient resolution in the crucial region of metal-ligand modes to permit an assessment of frequency calculations. The peaks for symmetric and antisymmetric Pt-Cl stretching modes νs and νa are resolved in the 312-333 cm-1 region. Frequency variations due to 35Cl and 37Cl isotopes are shown to be comparable in size to the differences between νs and νa. Peaks corresponding to the two Pt-Br stretching frequencies are observed at 213 and 218 cm-1 and Pt-N stretching frequencies for all compounds between 485 and 540 cm-1. The crystal structures of trans-[Pt(NH3)2Cl2] and cis-[Pt(NH3)2Br2] at 300 and 120 K are reported and complement the variable-temperature vibrational frequencies.

4.
Phys Chem Chem Phys ; 17(37): 24356-60, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26329892

RESUMO

A fast, generic, and suspension-based route to highly SERS-active assemblies of noble metal nanoparticles (Au, Ag) with small core-satellite gaps and single-particle Raman sensitivity is presented. Rationally designed, heterobifunctional Raman reporters serve as molecular linkers for electrostatic conjugation of the small satellites to the large core.

5.
Chem Asian J ; 9(8): 2219-24, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24996146

RESUMO

Silica-coated surface-enhanced Raman scattering (SERS) labels with a self-assembled monolayer (SAM) on the entire surface of the metal colloid combine high chemical and mechanical stability with bright and reproducible Raman signals due to the complete surface coverage and uniform molecular orientation within the SAM. Currently available chemical syntheses are either based on the direct encapsulation of covalently bound silane precursors or comprise several steps, such as the sequential addition of noncovalently bound polyelectrolytes to render the surface vitreophilic. Here, a generic approach for the direct and fast silica encapsulation of commercially available Raman reporter molecules with polar head groups by noncovalently bound silane precursors is reported. The formation of highly SERS-active silica-coated clusters during silica encapsulation is determined by several parameters, in particular the type of Raman reporter molecule, the solvent, and the type and amount of the silane precursor.

6.
Chem Commun (Camb) ; 50(21): 2711-4, 2014 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-24398564

RESUMO

Rapid parallel detection of two cytokines (IL-6 and IL-8) with femtogram sensitivity in a simple direct dot-blot assay is demonstrated. The microspectroscopic SERS acquisition scheme employs rationally designed, hydrophilically stabilized Au-Ag nanoshells as SERS labels, which are optimized for signal enhancement upon red laser excitation.


Assuntos
Ouro/química , Interleucina-6/análise , Interleucina-8/análise , Nanoconchas/química , Prata/química , Anticorpos/química , Anticorpos/imunologia , Antígenos/análise , Antígenos/imunologia , Interações Hidrofóbicas e Hidrofílicas , Immunoblotting , Interleucina-6/imunologia , Interleucina-8/imunologia , Soroalbumina Bovina , Análise Espectral Raman
7.
Analyst ; 138(6): 1764-71, 2013 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-23364184

RESUMO

Rationally designed gold/silver nanoshells (Au/Ag-NS) with plasmon resonances optimized for red laser excitation in order to minimize autofluorescence from clinical samples exhibit scattering cross-sections, which are ca. one order of magnitude larger compared with solid quasi-spherical gold nanoparticles (Au-NPs) of the same size. Hydrophilic stabilization and sterical accessibility for subsequent bioconjugation of Au/Ag-NS is achieved by coating their surface with a self-assembled monolayer (SAM) of rationally designed Raman reporter molecules comprising terminal mono- and tri-ethylene glycol (EG) spacers, respectively. The stability of the hydrophilically stabilized metal colloid was tested under different conditions. In contrast to metal colloids coated with a SAM without terminal EG spacers, the hydrophilically stabilized SERS particles do not aggregate under physiologically relevant conditions, i.e., buffer solutions with high ionic strength. Using these rationally designed SERS particles in conjunction with a microspectroscopic acquisition scheme, a sandwich immunoassay for the sensitive detection of interleukin-6 (IL-6) was developed. Several control experiments demonstrate the high specificity of the assay towards IL-6, with a lowest detectable concentration of ca. 1 pg mL(-1). The signal strength of the Au/Ag-NS is at least one order of magnitude higher compared with hydrophilically stabilized, non-aggregated solid quasi-spherical Au-NPs of the same size.


Assuntos
Ouro/química , Interleucina-6/análise , Nanoconchas/química , Prata/química , Análise Espectral Raman/métodos , Anticorpos Imobilizados/química , Humanos , Imunoensaio/métodos , Nanoconchas/ultraestrutura , Sensibilidade e Especificidade
8.
Nanoscale ; 5(1): 110-3, 2013 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-23076725

RESUMO

Dimers of metal nanospheres are well-known for their characteristic anisotropic optical response. Here, we demonstrate in single-particle SERS experiments that individual gold trimers and 3D superstructures exhibit a polarization-independent SERS response. This optical behavior of single particle clusters provides constant SERS signals, independent of the mutual orientation of the incident laser polarization and the plasmonic nanostructure, which is desired or even required in many SERS applications.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Refratometria/métodos , Ressonância de Plasmônio de Superfície/métodos , Luz , Teste de Materiais , Tamanho da Partícula , Espalhamento de Radiação , Propriedades de Superfície
9.
Small ; 7(24): 3445-51, 2011 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-22058082

RESUMO

The synthesis of 3D self-assembled plasmonic superstructures of gold nanospheres as well as the characterization of their structural and optical properties at the single-particle level is presented. This experimental work is complemented by FEM (finite element method) simulations of elastic scattering spectra and the spatial |E|(4) distribution for establishing structure-activity correlations in these complex 3D nanoclusters.


Assuntos
Ouro/química , Nanosferas/química , Tamanho da Partícula , Análise de Elementos Finitos , Nanosferas/ultraestrutura , Análise Espectral Raman
10.
Anal Chem ; 83(18): 7081-5, 2011 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-21819074

RESUMO

Immunohistochemistry (IHC) is one of the most widely used staining techniques for diagnostic purposes. The selective localization of target proteins in tissue specimens by conventional IHC is achieved with dye- or enzyme-labeled antibodies in combination with light microscopy. In this contribution, we demonstrate the proof-of-principle for IHC based on surface-enhanced coherent Raman scattering for contrast generation. Specifically, antibody-labeled metallic nanoshells in conjunction with surface-enhanced coherent anti-Stokes Raman scattering (SECARS) microscopy are employed for the selective, sensitive, and rapid localization of the basal cell protein p63 in normal prostate tissue. Negative control experiments were performed in order to confirm the selective binding of the target-specific metal nanoprobes and to disentangle the role of plasmonic (metal) and molecular (Raman reporter) resonances in this plasmon-assisted four-wave mixing technique.


Assuntos
Nanopartículas Metálicas/química , Microscopia/métodos , Análise Espectral Raman/métodos , Anticorpos Imobilizados/química , Anticorpos Imobilizados/imunologia , Ouro/química , Humanos , Imuno-Histoquímica , Masculino , Próstata/metabolismo , Próstata/patologia , Prata/química , Fatores de Transcrição/análise , Fatores de Transcrição/imunologia , Proteínas Supressoras de Tumor/análise , Proteínas Supressoras de Tumor/imunologia
11.
Small ; 7(17): 2443-8, 2011 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-21710486

RESUMO

A multilayer quasi-continuous density gradient centrifugation method for separating 20-250 nm metal colloids with high size resolution while maintaining particle stability is presented. Colloidal mixtures containing monodisperse gold nanospheres and clusters thereof, in particular, gold dimers, are purified with yields up to 94%. The rapid method uses standard laboratory equipment.


Assuntos
Centrifugação com Gradiente de Concentração/métodos , Ouro , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Centrifugação com Gradiente de Concentração/economia , Coloides/química , Análise Custo-Benefício , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Dióxido de Silício , Fatores de Tempo
12.
Chem Commun (Camb) ; 47(14): 4216-8, 2011 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-21359379

RESUMO

A biocompatible, seed-mediated synthesis of monodisperse ~60 nm gold nanostars, followed by hydrophilic stabilization with ethylene glycol-modified Raman reporter molecules, is presented. Their application as SERS labels for imaging of the tumor suppressor p63 in prostate biopsies by immuno-SERS microscopy is demonstrated.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Próstata/patologia , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Anticorpos/imunologia , Etilenoglicol/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Masculino , Nanopartículas Metálicas/ultraestrutura , Microscopia Imunoeletrônica , Imagem Molecular , Análise Espectral Raman , Fatores de Transcrição/imunologia , Proteínas Supressoras de Tumor/imunologia
13.
J Biophotonics ; 4(6): 453-63, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21298811

RESUMO

The design and synthesis of Raman reporter molecules comprising olefin or alkyne moieties with strong and characteristic vibrational Raman bands is presented. Chemisorption onto the surface of colloidal Au/Ag shells yields a self-assembled monolayer. Hydrophilic stabilization of such SERS labels can be achieved by short terminal ethylene glycol units attached to the Raman reporter. Encapsulation by silica with subsequent functionalization of the glass surface allows the conjugation to biomolecules such as antibodies. We demonstrate the use of SERS-labeled antibodies for tissue imaging of the tumor suppressor p63 in prostate biopsies.


Assuntos
Próstata/patologia , Análise Espectral Raman/métodos , Alquinos/química , Anticorpos/química , Etilenoglicol/química , Ouro/química , Humanos , Masculino , Proteínas de Membrana/metabolismo , Nanopartículas Metálicas/química , Microscopia Eletrônica de Transmissão/métodos , Nanopartículas/química , Nanotecnologia/métodos , Dióxido de Silício/química , Prata/química
15.
Angew Chem Int Ed Engl ; 48(11): 1950-3, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19191355

RESUMO

In a glass house: Silica-encapsulated self-assembled monolayers (SAMs) on tunable gold/silver nanoshells were used as labels for surface-enhanced Raman scattering (SERS). This concept combines the spectroscopic advantages arising from maximum surface coverage and uniform molecular orientation of the Raman reporter molecules within the complete monolayer together with the high chemical and mechanical stability of the glass shell.


Assuntos
Ouro/química , Lasers , Nanopartículas Metálicas/química , Dióxido de Silício/química , Prata/química , Análise Espectral Raman , Enzimas Imobilizadas , Nanopartículas Metálicas/ultraestrutura , Microscopia Eletrônica de Varredura , Coloração e Rotulagem
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