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Find video protocols related to scientific articles indexed in Pubmed.
Synthesis of superparamagnetic iron oxide nanoparticles coated with a DDNP-carboxyl derivative for in vitro magnetic resonance imaging of Alzheimer's disease.
Mater Sci Eng C Mater Biol Appl
PUBLISHED: 01-05-2014
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Superparamagnetic iron oxide nanoparticles (SPIONs) have been proposed for use in magnetic resonance imaging as versatile ultra-sensitive nanoprobes for Alzheimer's disease imaging. In this work, we synthetized an efficient contrast agent of Alzheimer's disease using 1,1-dicyano-2-[6-(dimethylamino)naphthalene-2-yl]propene (DDNP) carboxyl derivative to functionalize the surface of SPIONs. The DDNP-SPIONs are prepared by conjugating DDNP carboxyl derivative to oleic acid-treated SPIONs through ligand exchange. The structure, size distribution and magnetic property were identified by IR, TGA-DTA, XRD, TEM, Zetasizer Nano and VSM. TEM and Zetasizer Nano observations indicated that the DDNP-SPIONs are relatively mono-dispersed spherical distribution with an average size of 11.7nm. The DDNP-SPIONs were then further analyzed for their MRI relaxation properties using MR imaging and demonstrated high T2 relaxivity of 140.57s(-1)FemM(-1), and the vitro experiment that DDNP-SPIONs binding to ?-Amyloid aggregates were then investigated by fluorophotometry, the results showed that the combination had induced the fluorescence enhancement of the DDNP-SPIONs and displayed tremendous promise for use as a contrast agent of Alzheimer's disease in MRI.
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Discrimination of Chinese green tea according to varieties and grade levels using artificial nose and tongue based on colorimetric sensor arrays.
Food Chem
PUBLISHED: 05-16-2013
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Colorimetric artificial tongue and nose were used to discriminate nine Chinese green teas from different geographical origins and grade levels. Printing nanoporous porphyrin, dimeric metalloporphyrins, metallosalophen complexes and chemically responsive dyes on a hydrophobic membrane, the developed sensor array of artificial tongue and nose showed a unique pattern of colorimetric change upon exposure to green tea liquids or gases. All green tea samples, both in liquid and gas analysis, gave distinct patterns according to geographical origin and grade level, thus resulting in their facile identification. The good reproducibility of colorimetric artificial tongue and nose was proved. Data analysis was performed by chemometric techniques: hierarchical cluster analysis (HCA), and principal component analysis (PCA). Chinese green tea from the same geographical origin could cluster together in PCA score plot. No errors in classification by HCA were observed in 90 trials. The colorimetric artificial tongue and nose can be used to discriminate Chinese green tea according to geographical origin and grade level.
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Molecular interactions of dimethyl methylphosphonate (DMMP) with metalloporphyrins: determination of the binding mechanism by spectroscopic methods.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 04-29-2011
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The molecular interactions of 5,10,15,20-tetraphenylporphine zinc (ZnTPP) and 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II) (CoTPP) with dimethyl methylphosphonate (DMMP) have been investigated by absorption/absorption difference spectroscopy. The interactions between the metalloporphyrins and DMMP change the absorbance characteristics of the porphyrins resulted from the formation of the metalloporphyrin-DMMP complexes. According to the Benesi-Hildebrand (B-H) equation, the equilibrium constants and stoichiometries of the binding systems at four different temperatures (288, 293, 298 and 303 K) were obtained. Experimental results showed that both ZnTPP and CoTPP bind to DMMP via axial coordination, resulting in the formation of 1:1 metalloporphyrin-DMMP complexes. However, it was found that ZnTPP showed stronger binding capacity with the equilibrium constant (K) of 83.864 M(-1) at room temperature, while CoTPP exhibited weaker binding with K of 24.904 M(-1). The thermodynamic parameters, enthalpy change (?(r)H(m)(?)), entropy change (?(r)S(m)(?)) and free energy changes (?(r)G(m)(?)) were also studied for the interactions, indicating that the formation of the metalloporphyrins-DMMP complex was an exothermic reaction.
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Interaction of monosulfonate tetraphenyl porphyrin (H2TPPS1) with plant-esterase: determination of the binding mechanism by spectroscopic methods.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 01-14-2011
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The interaction of monosulfonate tetraphenyl porphyrin (H(2)TPPS(1)) with plant-esterase was investigated using fluorescence and UV-vis absorption spectroscopy. Fluorescence quenching, from which the binding parameters were evaluated, revealed that the quenching of the esterase by H(2)TPPS(1) resulted from the formation of a dye-esterase complex. According to the modified Stern-Volmer equation, the effective quenching constants (K(a)) between H(2)TPPS(1) and plant-esterase at four different temperatures (297 K, 300 K, 303 K, and 306 K) were obtained to be 14.132×10(5), 5.734×10(5), 2.907×10(5), and 2.291×10(5) M(-1), respectively. The thermodynamic parameters, enthalpy change (?H) and entropy change (?S) for the reaction were calculated to be -181.67 kJ M(-1) and -0.49 kJ M(-1)K(-1), indicating that van der Waals force and hydrogen bonds were the dominant intermolecular force in stabilizing the complex. Site marker competitive experiments showed that the binding of H(2)TPPS(1) to plant-esterase primarily took place in the active site. The binding distance (r) was obtained to be 5.99 nm according to Förster theory of non-radioactive energy transfer. The conformation of plant-esterase was investigated by synchronous fluorescence and UV-vis absorption spectroscopy, and the results confirmed some micro-environmental and conformational changes of plant-esterase molecules.
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Molecular interactions of monosulfonate tetraphenylporphyrin (TPPS1) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP).
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 02-04-2009
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The molecular interactions of monosulfonate tetraphenylporphyrin (TPPS(1)) and meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) with dimethyl methylphosphonate (DMMP) have been investigated by UV-vis and fluorescence spectroscopies. The association constants and interaction stoichiometries of the bindings were obtained through Benesi-Hildebrand (B-H) method. Particularly, both linear and nonlinear fitting procedures were performed to evaluate the possible 1:2 interactions. Experimental results showed that hydrogen-bonding interactions existed in both of the two systems, resulting in regular changes in the absorbance and fluorescence characteristics of the porphyrins. The association constants and stoichiometries determined from absorbance and fluorescence studies were in excellent agreement. Using a nonlinear fitting method, we demonstrated that the one-step 1:2 interaction took place in the TPPS(1)-DMMP system, and the association constants were determined to be 71.4 M(-1) by absorbance measurements and 70.92 M(-1) by fluorescence measurements. The interaction stoichiometry of the TPPS-DMMP system was 1:1, and the association constants were determined to be 16.06 M(-1) by absorbance measurements and 16.03 M(-1) by fluorescence measurements. It was concluded that the interaction between TPPS(1) and DMMP was stronger than that between TPPS and DMMP.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.