The Experts below are selected from a list of 156 Experts worldwide ranked by ideXlab platform
Zhijun Zhang - One of the best experts on this subject based on the ideXlab platform.
-
composites of aminodextran coated fe3o4 nanoparticles and graphene oxide for cellular magnetic resonance imaging
ACS Applied Materials & Interfaces, 2011Co-Authors: Weihong Chen, Yi Zhang, Liming Zhang, Zongwu Deng, Zhijun ZhangAbstract:Formation of composites of dextran-coated Fe3O4 nanoparticles (NPs) and graphene oxide (Fe3O4-GO) and their application as T2-weighted contrast agent for efficient cellular magnetic resonance imaging (MRI) are reported. Aminodextran (AMD) was first synthesized by coupling reaction of Carboxymethyldextran with butanediamine, which was then chemically conjugated to meso-2,3-dimercaptosuccinnic acid-modified Fe3O4 NPs. Next, the AMD-coated Fe3O4 NPs were anchored onto GO sheets via formation of amide bond in the presence of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC). It is found that the Fe3O4-GO composites possess good physiological stability and low cytotoxicity. Prussian Blue staining analysis indicates that the Fe3O4-GO nanocomposites can be internalized efficiently by HeLa cells, depending on the concentration of the composites incubated with the cells. Furthermore, compared with the isolated Fe3O4 NPs, the Fe3O4-GO composites show significantly enhanced cellular MRI, being capable of detecting...
Anda Preda - One of the best experts on this subject based on the ideXlab platform.
-
magnetic resonance characterization of tumor microvessels in experimental breast tumors using a slow clearance blood pool contrast agent Carboxymethyldextran a2 gd dota with histopathological correlation
European Radiology, 2005Co-Authors: Anda Preda, Viktor Novikov, Martina Moglich, Eugenia Floyd, Karl Turetschek, David M Shames, Timothy P L Roberts, Claire Corot, Wayne O CarterAbstract:Carboxymethyldextran (CMD)-A2-Gd-DOTA, a slow clearance blood pool contrast agent with a molecular weight of 52.1 kDa, designed to have intravascular residence for more than 1 h, was evaluated for its potential to characterize and differentiate the microvessels of malignant and benign breast tumors. Precontrast single-slice inversion-recovery snapshot FLASH and dynamic contrast-enhanced MRI using an axial T1-weighted three-dimensional spoiled gradient recalled sequence was performed in 30 Sprague-Dawley rats with chemically induced breast tumors. Endothelial transfer coefficient and fractional plasma volume of the breast tumors were estimated from MRI data acquired with CMD-A2-Gd-DOTA enhancement injected at a dose of 0.1 mmol Gd/kg body weight using a two-compartment bidirectional model of the tumor tissue. The correlation between MRI microvessel characteristics and histopathological tumor grade was determined using the Scarff-Bloom-Richardson method. Using CMD-A2-Gd-DOTA, no significant correlations were found between the MR-estimated endothelial transfer coefficient or plasma volumes with histological tumor grade. Analysis of CMD-A2-Gd-DOTA-enhanced MR kinetic data failed to demonstrate feasibility for the differentiation of benign from malignant tumors or for image-based tumor grading.
L Bjorck - One of the best experts on this subject based on the ideXlab platform.
-
determination of sulfamethazine residues in milk by a surface plasmon resonance based biosensor assay
Analytical Biochemistry, 1995Co-Authors: A Sternesjo, C Mellgren, L BjorckAbstract:The use of antibiotics and chemotherapeutics in animal husbandry has led to the occurrence of veterinary drug residues in all types of food of animal origin. Due to the specification of toxicologically based maximum residue levels for a large number of substances, existing control strategies need even faster and more sensitive methods to meet new and more rigorous regulations. The applicability of an immunosensor device for biospecific interaction analysis was investigated and the development of an assay for analysis of sulfamethazine (SMZ) in milk is described. SMZ was covalently immobilized to a Carboxymethyldextran-modified gold film. Spiked samples with known concentrations of SMZ were prepared in HBS buffer and skim and raw milk for construction of standard curves. Polyclonal antibodies against SMZ were added to the sample and the immobilized surface was used to determine the amount of free antibodies by surface plasmon resonance detection. After each measurement the surface was regenerated by NaOH and HCl. In milk, the mean relative standard deviation of the assay was approximately 2% and the limit of detection less than 1 ppb. By introduction of a secondary sheep anti-rabbit antibody, the use of specific antibody could be reduced. Milk samples from the individual cow, herd, and tanker levels were analyzed and the relative standard deviations within each sample category were 4.4, 2.4, and 2.2%, respectively. The effect of some potential interferences, e.g., high somatic cells, bacterial contamination, and preservatives, was investigated. The results were not influenced in such a way that the risk for so-called false-positive findings was obvious.
Masahiro Iwakura - One of the best experts on this subject based on the ideXlab platform.
-
detection of conformational changes in an immobilized protein using surface plasmon resonance
Analytical Chemistry, 1998Co-Authors: Hiroyuki Sota, Yukio Hasegawa, Masahiro IwakuraAbstract:Utilizing surface plasmon resonance (SPR), we have developed novel methodology for the detection of conformational change(s) in immobilized proteins. A genetically altered E. coli dihydrofolate reductase (DHFR-ASC) was attached to a Carboxymethyldextran matrix layer covering the sensor surface of an SPR biosensor through a disulfide linkage at the engineered protein's C-terminus. The DHFR-ASC-immobilized surface exhibited a larger response to acid treatment than reference surfaces lacking immobilized proteins. The SPR signal of the tethered protein and the molar ellipticity of DHFR-ASC in solution responded similarly to pH changes, consistent with the interpretation that changes in the SPR signal reflect conformational changes occurring during acid denaturation. A pH shift observed between the SPR signal and ellipticity changes may reflect a difference between surface and bulk pH. The tethered protein sensor surface was stable to repeated acid treatment using solutions in the pH range of 0.12−7.80 and yie...
Wayne O Carter - One of the best experts on this subject based on the ideXlab platform.
-
magnetic resonance characterization of tumor microvessels in experimental breast tumors using a slow clearance blood pool contrast agent Carboxymethyldextran a2 gd dota with histopathological correlation
European Radiology, 2005Co-Authors: Anda Preda, Viktor Novikov, Martina Moglich, Eugenia Floyd, Karl Turetschek, David M Shames, Timothy P L Roberts, Claire Corot, Wayne O CarterAbstract:Carboxymethyldextran (CMD)-A2-Gd-DOTA, a slow clearance blood pool contrast agent with a molecular weight of 52.1 kDa, designed to have intravascular residence for more than 1 h, was evaluated for its potential to characterize and differentiate the microvessels of malignant and benign breast tumors. Precontrast single-slice inversion-recovery snapshot FLASH and dynamic contrast-enhanced MRI using an axial T1-weighted three-dimensional spoiled gradient recalled sequence was performed in 30 Sprague-Dawley rats with chemically induced breast tumors. Endothelial transfer coefficient and fractional plasma volume of the breast tumors were estimated from MRI data acquired with CMD-A2-Gd-DOTA enhancement injected at a dose of 0.1 mmol Gd/kg body weight using a two-compartment bidirectional model of the tumor tissue. The correlation between MRI microvessel characteristics and histopathological tumor grade was determined using the Scarff-Bloom-Richardson method. Using CMD-A2-Gd-DOTA, no significant correlations were found between the MR-estimated endothelial transfer coefficient or plasma volumes with histological tumor grade. Analysis of CMD-A2-Gd-DOTA-enhanced MR kinetic data failed to demonstrate feasibility for the differentiation of benign from malignant tumors or for image-based tumor grading.