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1.
Clin Chem Lab Med ; 56(5): 796-802, 2018 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-29220880

RESUMO

BACKGROUND: Apolipoprotein E (APOE) is a key player in lipid transport and metabolism and exists in three common isoforms: APOE2, APOE3 and APOE4. The presence of the E4 allelic variant is recognized as a major genetic risk factor for dementia and other chronic (neuro)degenerative diseases. The availability of a validated assay for rapid and reliable APOE4 classification is therefore advantageous. METHODS: Biochip array technology (BAT) was successfully applied to identify directly the APOE4 status from plasma within 3 h, through simultaneous immunoassay-based detection of both specific APOE4 and total APOE levels. RESULTS: Samples (n=432) were first genotyped by polymerase chain reaction (PCR), and thereafter, using BAT, the corresponding plasma was identified as null, heterozygous or homozygous for the E4 allele by calculating the ratio of APOE4 to total APOE protein. Two centers based in Austria and Ireland correctly classified 170 and 262 samples, respectively, and achieved 100% sensitivity and specificity. CONCLUSIONS: This chemiluminescent biochip-based sandwich immunoarray provides a novel platform to detect rapidly and accurately an individual's APOE4 status directly from plasma. The E4 genotype of individuals has been shown previously to affect presymptomatic risk, prognosis and treatment response for a variety of diseases, including Alzheimer's disease. The biochip's potential for being incorporated in quantitative protein biomarker arrays capable of analyzing disease stages makes it a superior alternative to PCR-based APOE genotyping and may deliver additional protein-specific information on a variety of diseases in the future.


Assuntos
Apolipoproteína E4/sangue , Imunoensaio , Medições Luminescentes , Idoso , Idoso de 80 Anos ou mais , Alelos , Apolipoproteína E4/genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase
2.
Phys Chem Chem Phys ; 19(46): 31274-31283, 2017 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-29148552

RESUMO

Symmetry breaking has been recently observed in the endofullerenes M@C60 (M = H2, HF, H2O), manifesting in the splittings of the three-fold degenerate ground states of the endohedral ortho-H2, ortho-H2O and the j = 1 level of HF. The nature of the interaction causing the symmetry breaking is established in this study. A fragment of the solid C60 is considered, comprised of the central C60 molecule surrounded by twelve nearest-neighbor (NN) C60 molecules. The fullerenes have either P (major) or H (minor) orientational orderings, and are assumed to be rigid with Ih symmetry. Only the central C60 is occupied by the guest molecule M, while the NN fullerenes are all empty. The key proposition of the study is that the electrostatic interactions between the charge densities on the NN C60 molecules and that on M inside the central C60 give rise to the symmetry breaking responsible for the measured level splittings. Using this model, the M@C60 level splittings of interest are calculated variationally and using perturbation theory, for both the P and H orientations. Those obtained for the dominant P orientation are in excellent agreement with the experimental results, with respect to the splitting magnitudes and patterns, for all three M@C60 systems considered, pointing strongly to the quadrupolar M-NN interactions as the main cause of the symmetry breaking. The level splittings calculated for the H orientation are about 30 times smaller than the ones in the P orientation.

3.
Langmuir ; 33(51): 14586-14591, 2017 12 26.
Artigo em Inglês | MEDLINE | ID: mdl-29148779

RESUMO

We examine the adsorption of hydrogen and deuterium into the nanoporous nickel phosphate, VSB-5. On the basis of gas sorption analysis, VSB-5 exhibits one of the highest measured H2 heats of adsorption (HOA) for hydrogen (16 kJ/mol) yet reported. This high HOA is consistent with an unusually large red shift in the Q(1) and Q(0) hydrogen vibrational modes as measured with in situ infrared spectroscopy. The HOA for D2 is measured to be 2 kJ/mol higher than that for H2. "Ideal adsorbed solution theory" analysis of H2 and D2 isotherms provides selectivities above 4 for deuterium at 140 K, suggesting that VSB-5 is a promising adsorbent for pressure-swing adsorption-type separations of hydrogen isotopes.

4.
J Am Chem Soc ; 138(32): 10143-50, 2016 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-27486905

RESUMO

The drug olsalazine (H4olz) was employed as a ligand to synthesize a new series of mesoporous metal-organic frameworks that are expanded analogues of the well-known M2(dobdc) materials (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate; M-MOF-74). The M2(olz) frameworks (M = Mg, Fe, Co, Ni, and Zn) exhibit high surface areas with large hexagonal pore apertures that are approximately 27 Å in diameter. Variable temperature H2 adsorption isotherms revealed strong adsorption at the open metal sites, and in situ infrared spectroscopy experiments on Mg2(olz) and Ni2(olz) were used to determine site-specific H2 binding enthalpies. In addition to its capabilities for gas sorption, the highly biocompatible Mg2(olz) framework was also evaluated as a platform for the delivery of olsalazine and other encapsulated therapeutics. The Mg2(olz) material (86 wt % olsalazine) was shown to release the therapeutic linker through dissolution of the framework under simulated physiological conditions. Furthermore, Mg2(olz) was used to encapsulate phenethylamine (PEA), a model drug for a broad class of bioactive compounds. Under simulated physiological conditions, Mg2(olz)(PEA)2 disassembled to release PEA from the pores and olsalazine from the framework itself, demonstrating that multiple therapeutic components can be delivered together at different rates. The low toxicity, high surface areas, and coordinatively unsaturated metal sites make these M2(olz) materials promising for a range of potential applications, including drug delivery in the treatment of gastrointestinal diseases.


Assuntos
Ácidos Aminossalicílicos/química , Materiais Biocompatíveis/química , Sistemas de Liberação de Medicamentos , Adsorção , Sítios de Ligação , Química Orgânica , Portadores de Fármacos , Gastroenteropatias/tratamento farmacológico , Humanos , Hidrogênio/química , Ligantes , Estruturas Metalorgânicas , Metais/química , Compostos Orgânicos/química , Fenetilaminas/química , Ácidos Ftálicos , Espectrofotometria Infravermelho , Propriedades de Superfície
5.
Chem Commun (Camb) ; 51(58): 11642-5, 2015 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-26099041

RESUMO

1,3,5-Tris(4-carboxyphenyl)benzene assembles into an intricate 8-fold polycatenated assembly of (6,3) hexagonal nets formed through hydrogen bonds and π-stacking. One polymorph features 56 independent molecules in the asymmetric unit, the largest Z' reported to date. The framework is permanently porous, with a BET surface area of 1095 m(2) g(-1) and readily adsorbs N2, H2 and CO2.

6.
J Am Chem Soc ; 136(34): 12119-29, 2014 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-25130365

RESUMO

The well-known frameworks of the type M2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) have numerous potential applications in gas storage and separations, owing to their exceptionally high concentration of coordinatively unsaturated metal surface sites, which can interact strongly with small gas molecules such as H2. Employing a related meta-functionalized linker that is readily obtained from resorcinol, we now report a family of structural isomers of this framework, M2(m-dobdc) (M = Mg, Mn, Fe, Co, Ni; m-dobdc(4-) = 4,6-dioxido-1,3-benzenedicarboxylate), featuring exposed M(2+) cation sites with a higher apparent charge density. The regioisomeric linker alters the symmetry of the ligand field at the metal sites, leading to increases of 0.4-1.5 kJ/mol in the H2 binding enthalpies relative to M2(dobdc). A variety of techniques, including powder X-ray and neutron diffraction, inelastic neutron scattering, infrared spectroscopy, and first-principles electronic structure calculations, are applied in elucidating how these subtle structural and electronic differences give rise to such increases. Importantly, similar enhancements can be anticipated for the gas storage and separation properties of this new family of robust and potentially inexpensive metal-organic frameworks.


Assuntos
Cobalto/química , Hidrogênio/química , Ferro/química , Magnésio/química , Manganês/química , Níquel/química , Compostos Organometálicos/síntese química , Ácidos Ftálicos/química , Adsorção , Sítios de Ligação , Estrutura Molecular , Compostos Organometálicos/química , Espectrofotometria Infravermelho , Termogravimetria , Difração de Raios X
7.
J Chem Phys ; 138(24): 244707, 2013 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-23822264

RESUMO

We report rigorous quantum five-dimensional (5D) calculations of the coupled translation-rotation (TR) energy levels and wave functions of an H2 molecule, in the ground (ν = 0) and vibrationally excited (ν = 1) states, confined inside the octahedral interstitial site of solid C60 with S6 symmetry. Translational and rotational excitations of H2 in this nanocavity have been measured by the inelastic neutron scattering (INS) and infrared (IR) spectroscopy, enabling direct comparison between theory and experiment. A pairwise additive 5D intermolecular potential energy surface (PES) was employed in the calculations. The quantum calculations cover the range of energies and types of translational and rotational excitations of the guest molecule which go substantially beyond those considered in the earlier theoretical investigations of this system, revealing new information about the TR energy level structure. The computed j = 1 and j = 2 rotational levels and their splittings, as well as the translational fundamental, are in semi-quantitative agreement with the available INS and IR data, indicating the need for a more accurate intermolecular PES. Our calculations reveal a strong dependence of the TR energy levels, in particular their splittings, on the setting angle which defines the orientation of the C60 molecules relative to their local threefold axes.


Assuntos
Fulerenos/química , Hidrogênio/química , Teoria Quântica , Rotação
8.
J Am Chem Soc ; 135(25): 9458-64, 2013 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-23711176

RESUMO

The quantum sieving effect between D2 and H2 is examined for a series of metal-organic frameworks (MOFs) over the temperature range 77-150 K. Isothermal adsorption measurements demonstrate a consistently larger isosteric heat of adsorption for D2 vs H2, with the largest difference being 1.4 kJ/mol in the case of Ni-MOF-74. This leads to a low-pressure selectivity for this material that increases from 1.5 at 150 K to 5.0 at 77 K. Idealized adsorption solution theory indicates that the selectivity decreases with increasing pressure, but remains well above unity at ambient pressure. Infrared measurements on different MOF materials show a strong correlation between selectivity and the frequency of the adsorbed H2 translational band. This confirms that the separation is predominantly due to the difference in the zero-point energies of the adsorbed isotopologues.


Assuntos
Deutério/química , Hidrogênio/química , Compostos Organometálicos/química , Teoria Quântica , Temperatura
9.
Biopreserv Biobank ; 11(6): 379-86, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24835368

RESUMO

INTRODUCTION: Biomarker discovery studies seldom report on pre-analytical effects. We used a novel multiplex protein biochip for colorectal cancer screening to investigate effects of different storage temperatures and repeated freeze-thaw cycles. METHODS: This biochip, composed of CEA, IL-8, VEGF, M-CSF, S100A11, C3adesArg, CD26, and CRP, was applied to twenty highly standardized preserved serum samples. RESULTS: Aliquot comparison of long-term storage at -80°C (n=20) versus -170°C (n=20) did not show significant differences for any of the eight markers. In contrast, three freeze-thaw cycles (3 × 20 aliquots) detected changes in the serum level for all markers (p<0.05) but S100A11 and CD26: levels of CEA, IL-8, C3adesArg, and CRP increased, while VEGF and M-CSF levels decreased. However, applying diagnostic thresholds for CEA, IL-8, and CRP revealed that freeze-thaw cycles did not affect diagnostic performance. In contrast, analysis of samples stored at -80°C compared to -170°C failed to detect one out of three detectable malignancies. CONCLUSION: We conclude that three freeze-thaw cycles modulated serum marker levels significantly, but do not compromise biochip diagnostic performance. For our marker panel, serum preservation at -80°C seems comparable to -170°C; however, storage at -80°C could lead to misdiagnosis. Our findings emphasize the need for standardized sample collection, processing, storage, and reporting.


Assuntos
Biomarcadores/sangue , Neoplasias Colorretais/sangue , Técnicas de Diagnóstico Molecular/métodos , Análise Serial de Proteínas/métodos , Manejo de Espécimes/métodos , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/diagnóstico , Feminino , Congelamento , Ensaios de Triagem em Larga Escala , Humanos , Masculino , Pessoa de Meia-Idade , Manejo de Espécimes/normas , Fatores de Tempo
10.
J Am Chem Soc ; 133(50): 20310-8, 2011 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-22074154

RESUMO

Diffuse reflectance infrared (IR) spectroscopy performed over a wide temperature range (35-298 K) is used to study the dynamics of H(2) adsorbed within the isostructural metal-organic frameworks M(2)L (M = Mg, Mn, Co, Ni and Zn; L = 2,5-dioxidobenzene-1,4-dicarboxylate) referred to as MOF-74 and CPO-27. Spectra collected at H(2) concentrations ranging from 0.1 to 3.0 H(2) per metal cation reveal that strongly red-shifted vibrational modes arise from isolated H(2) bound to the available metal coordination site. The red shift of the bands associated with this site correlate with reported isosteric enthalpies of adsorption (at small surface coverage), which in turn depend on the identity of M. In contrast, the bands assigned to H(2) adsorbed at positions >3 Å from the metal site exhibit only minor differences among the five materials. Our results are consistent with previous models based on neutron diffraction data and independent IR studies, but they do not support a recently proposed adsorption mechanism that invokes strong H(2)···H(2) interactions (Nijem et al. J. Am. Chem. Soc.2010, 132, 14834-14848). Room temperature IR spectra comparable to those on which the recently proposed adsorption mechanism was based were only reproduced after contaminating the adsorbent with ambient air. Our interpretation that the uncontaminated spectral features result from stepwise adsorption at discrete framework sites is reinforced by systematic red shifts of adsorbed H(2) isotopologues and consistencies among overtone bands that are well-described by the Buckingham model of molecular interactions in vibrational spectroscopy.

12.
J Immunoassay Immunochem ; 27(4): 363-78, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16981649

RESUMO

The semiautomated Evidence Investigator has been applied to the simultaneous specific measurement of soluble adhesion molecules: L-, P-, E- selectins, VCAM-1, ICAM-1 using a reduced volume of sample. The biochip is the solid support and vessel where the sandwich immunoassay takes place. Signal detection, imaging, data processing, and storage are fully automated. Calibration curves are generated simultaneously for each analyte, with automatic validation against supplied calibration data. These curves are used for the calculation of the concentrations in multi-analyte controls and human serum samples. Data from the evaluation parameters assessed indicate suitability of the Evidence Investigator system for the application.


Assuntos
Molécula 1 de Adesão Intercelular/sangue , Análise Serial de Proteínas/instrumentação , Análise Serial de Proteínas/métodos , Selectinas/sangue , Molécula 1 de Adesão de Célula Vascular/sangue , Biomarcadores/sangue , Biomarcadores/química , Calibragem , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Molécula 1 de Adesão Intercelular/química , Reprodutibilidade dos Testes , Selectinas/química , Sensibilidade e Especificidade , Molécula 1 de Adesão de Célula Vascular/química
13.
Clin Chem Lab Med ; 43(12): 1303-13, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16309365

RESUMO

BACKGROUND: Proteomics' requirement for simultaneous measurement of multiple markers is now possible with biochip array technology. Many laboratories utilise in-house, manual procedures for biochip fabrication and sample testing. Reproducibility and standardisation of biochip processes is vital to ensure quality of results and offer the best tool for elucidation of complex relationships between multiple proteins in diseased conditions. METHODS: Various novel control checks have been implemented in biochip fabrication, reagent manufacture, automation and imaging processes for the Evidence analyser. Reference spots enable location of discrete test regions on the surface of the biochip and simultaneous quantification of multiple markers. Performance and standardisation methods are presented. RESULTS: Formulation of dispense solution for discrete test regions had a direct effect on their shape, stability and integrity on the biochip surface. Assays for fertility hormones and drugs of abuse demonstrated excellent precision, stability and comparison with other commercial methods. CONCLUSION: Control processes employed in the manufacture and analysis of Evidence components ensure reproducibility of assays for a range of routine and novel markers.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas de Laboratório Clínico , Análise Serial de Proteínas/métodos , Controle de Qualidade , Animais , Autoanálise , Biomarcadores/análise , Citocinas/análise , Citocinas/normas , Fertilidade/efeitos dos fármacos , Fertilidade/fisiologia , Hormônios/metabolismo , Hormônios/farmacologia , Humanos , Proteômica/métodos , Reprodutibilidade dos Testes , Projetos de Pesquisa , Sensibilidade e Especificidade , Transtornos Relacionados ao Uso de Substâncias/metabolismo
14.
J Am Chem Soc ; 125(19): 5889-96, 2003 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-12733930

RESUMO

Infrared spectroscopy has been used to make the first experimental discrimination between molecules bound by physisorption on the exterior surface of carbon single-walled nanotubes (SWNTs) and molecules bound in the interior. In addition, the selective displacement of the internally bound molecules has been observed as a second adsorbate is added. SWNTs were opened by oxidative treatment with O(3) at room temperature, followed by heating in a vacuum to 873 K. It was found that, at 133 K and 0.033 Torr, CF(4) adsorbs on closed SWNTs, exhibiting its nu(3) asymmetric stretching mode at 1267 cm(-1) (red shift relative to the gas phase, 15 cm(-1)). Adsorption on the nanotube exterior is accompanied by adsorption in the interior in the case of opened SWNTs. Internally bound CF(4) exhibits its nu(3) mode at 1247 cm(-1) (red shift relative to the gas phase, 35 cm(-1)). It was shown that, at 133 K, Xe preferentially displaces internally bound CF(4) species, and this counterintuitive observation was confirmed by molecular simulations. The confinement of CF(4) inside (10,10) single-walled carbon nanotubes does not result in the production of lattice modes that are observed in large 3D ensembles of CF(4).

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