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Find video protocols related to scientific articles indexed in Pubmed.
The human SRCAP chromatin remodeling complex promotes DNA-end resection.
Curr. Biol.
PUBLISHED: 08-28-2014
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Repair of DNA double-strand breaks (DSBs) by homologous recombination requires 5'-3' resection of the DSB ends. In vertebrates, DSB resection is initiated by the collaborative action of CtIP and the MRE11-RAD50-NBS1 (MRN) complex. However, how this process occurs within the context of chromatin is still not well understood.
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High specific detection of osteopontin using a three-dimensional copolymer layer support based on electrochemical impedance spectroscopy.
Analyst
PUBLISHED: 07-04-2014
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Tumor marker detection is essential for the therapy efficiency of early stage tumors and the evaluation of disease progression. Osteopontin (OPN) is supposed to be closely related to several kinds of tumors. In the present study, we describe a label-free electrochemical detection of OPN based on a specific reaction between OPN and its relevant antibody. An artificial three-dimensional (3D) scaffold structure consisting of 11-mercaptoundecanoic acid/6-mercapto-1-hexanol, dextran amino and synthetic peptides was designed as a substrate for the immobilization of the antibody. This substrate was characterized using cyclic voltammetry, atomic force microscopy and Fourier transform infrared reflection spectroscopy. Antibody immobilization and OPN detection were conducted using electrochemical impedance spectroscopy (EIS). The low limit of detection was 0.17 nM. The concentration of cancer risk (5.77 nM) can be selectively detected with a high EIS signal. The fabricated 3D OPN sensor is proposed for application in clinical analysis.
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Dietary calcium intake and mortality risk from cardiovascular disease and all causes: a meta-analysis of prospective cohort studies.
BMC Med
PUBLISHED: 04-22-2014
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Considerable controversy exists regarding the association between dietary calcium intake and risk of mortality from cardiovascular disease and all causes. Therefore, we performed a meta-analysis of prospective cohort studies to examine the controversy.
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Detection of vascular endothelial growth factor based on rolling circle amplification as a means of signal enhancement in surface plasmon resonance.
Biosens Bioelectron
PUBLISHED: 03-12-2014
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Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis. It has been identified as an ideal biomarker for staging of many kinds of cancers, so more specific and intense signal is desirable for VEGF biosensors so that the sensors may have more valuable clinical application. Herein, we report a highly sensitive and selective surface plasmon resonance (SPR) sensor for VEGF detection by using two DNA aptamers which target different VEGF domains used as the capture and detection probe, respectively. Moreover, by making use of carboxyl-coated polystyrene microspheres, 3'-NH2 immobilized aptamer and 3'-NH2 modified primer DNA are loaded through amidation onto the sensing layer for further rolling circle amplification (RCA) process to amplify the SPR signal. With the well-designed sensing platform, VEGF can be determined in a linear range from 100 pg mL(-1) to 1 ?g mL(-1) with a detection limit of 100 pg mL(-1). Due to its high specificity and desirable sensitivity, this RCA assisted SPR method may be a useful tool for the assay of VEGF in the future. What is more, by replacing the sensing element, i.e., the aptamer of VEGF used in this work, more biosensors for sensitive detection of other biomarkers proteins can be fabricated based on the strategy proposed in this study.
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Synthesis and properties of a lacquer wax-based quarternary ammonium gemini surfactant.
Molecules
PUBLISHED: 03-11-2014
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Lacquer wax is an important fatty resource obtained from the mesocarp of the berries of Toxicodendron vernicifluum. In order to expand the applications of lacquer wax, we hydrolyzed it after establishing the best conditions for the acid-catalyzed hydrolysis using a Box-Behnken design. Then we synthesized a quarternary ammonium gemini surfactant by a three-step reaction. The surface properties of an aqueous solution of the final product were investigated. The optimum conditions were 9% catalyst, 100 °C of reaction temperature and 14 h of reaction time, while the maximum free fatty acids (FFA)% was 99.67%. From the gas chromatography, the main fatty acids of the lacquer wax were palmitic, oleic and octadecanoic acid. The lacquer wax gemini surfactant was synthesized, and its structure was confirmed by IR and NMR. The experiments showed that the critical micelle concentration (CMC) is 5 × 10?? mol·L?¹, the surface tension is 33.6 mN·m?¹. When the content of surfactant was 0.1%, the separation time of 5 mL water was 10 min.
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Synthesis of ?-amidine-functionalized dianionic ?-diketiminato lanthanide amides and trianionic ?-diketiminato Na/Sm heterobimetallic complexes and their reactivity in polymerization of L-lactide.
Dalton Trans
PUBLISHED: 02-20-2014
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The readily accessible dianionic ?-diketiminato lanthanide amido complexes LnLN(SiMe3)2(THF) (L = {(2,6-(i)Pr2C6H3)NC(CH2)CHC(CH3)N(2,6-(i)Pr2C6H3)}(2-)) show an unprecedented reactivity toward carbodiimides. The reaction with N,N'-dicyclohexylcarbodiimide (DCC) led via [4 + 2] cycloaddition to ?-amidine-functionalized dianionic ?-diketiminato lanthanide amido complexes, LnL(1)N(SiMe3)2 (L(1) = {[(NHC6H11)(NC6H11)C]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(2-), Ln = Sm(1), Yb(2), Y(3), Gd(4)). Conversion of a mixture of SmLN(SiMe3)2(THF) and NaN(SiMe3)2 with carbodiimide furnished the heterobimetallic complexes of Sm/Na with a novel amidinate-functionalized trianionic ?-diketiminate ligand, [Na(DME)2](?-L(2))[SmN(SiMe3)2] (L(2) = {[C(N(i)Pr)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-), DME = dimethoxyethane) (5) for N,N'-diisopropylcarbodiimide (DIC) and [Na(DME)3](+)[SmL(3)N(SiMe3)2](-) (L(3) = {[C(NCy)2]HC[C(CH2)N(2,6-(i)Pr2C6H3)]2}(3-)) (6) for DCC. Molecular structures of complexes 1-6 were determined by an X-ray single crystal structure analysis. Complexes 1-4 were found to be highly active initiators of the ring-opening polymerization (ROP) of L-lactide (L-LA). The activity depended on the central metal with the increasing sequence of Yb < Y < Gd < Sm. Notably, the binary 1/BnOH (benzyl alcohol) system exhibited an "immortal" nature and proved able to convert 2000 equivalents of L-LA with up to 100 equivalents of BnOH per initiator. All the polylactides (PLAs) obtained showed monomodal, narrow molar mass distributions (M(w)/M(n) = 1.08-1.13) with the M(n) (average number molar mass) decreasing with increasing amount of BnOH proportionally.
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Perchlorate exposure and thyroid function in ammonium perchlorate workers in Yicheng, China.
Int J Environ Res Public Health
PUBLISHED: 01-24-2014
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The impact of low level dust on the thyroid function of workers chronically exposed to ammonium perchlorate (AP) is uncertain and controversial. The aim of this study was to examine whether workers in China with long-term (>3 years) occupational exposure to low levels of AP dust had affected thyroid homeostasis. Mean occupational exposures to AP dust ranged from 0.43 to 1.17 mg/m3. Geometric means of post-shift urinary perchlorate levels were 20.5 µg/L for those exposed and 12.8 µg/L for the controls. No significant differences were found for thyroid function parameters of FT3, FT4, or log TSH or for TPO prevalence or thyroglobulin levels. Additionally, no differences in findings were observed for complete blood count (CBC), serum biochemical profile, or pulmonary function test. Median urinary iodine levels of 172 and 184 µg/L showed that the workers had sufficient iodine intake. This study found no effect on thyroid function from long term, low-level documented exposure to ammonium perchlorate. It is the first study to report both thyroid status parameters and urinary perchlorate, a biomarker of internal perchlorate exposure, in occupationally exposed workers in China.
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HSP27 as a biomarker for predicting skin irritation in human skin and reconstructed organotypic skin model.
Toxicol. Lett.
PUBLISHED: 01-18-2014
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In vitro alternative tests aiming at replacing the traditional animal test for predicting the irritant potential of chemicals have been developed, but the assessing parameters or endpoints are still not sufficient. To discover novel endpoints for skin irritation responses, 2DE-based proteomics was used to analyze the protein expression in human skin exposed to sodium lauryl sulfate (SLS) following the test protocol of the European Centre for the Validation of Alternative Methods (ECVAM) in the present study. HSP27 was up-regulated most significantly among the eight identified proteins, consistent with our previous reports. Acid and basic chemicals were applied on human skin for further validation and results showed that the up-regulated expression of HSP27 was induced in 24h after the exposure. Skin-equivalent constructed with fibroblasts, basement membrane and keratinocytes was used to investigate the potential of HSP27 as a biomarker or additional endpoint for the hazard assessment of skin irritation. Our skin-equivalent (Reconstructed Organotypic Skin Model, ROSM) had excellent epidermal differentiation and was suitable for the skin irritation test. HSP27 also displayed an up-regulated expression in the ROSM in 24h after the irritants exposure for 15min. All these results suggest that HSP27 may represent a potential marker or additional endpoint for the hazard assessment of skin irritation caused by chemical products.
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Phenolic extracts from Rhus verniciflua Stokes bark by decompressing inner ebullition and their antioxidant activities.
Nat. Prod. Res.
PUBLISHED: 01-17-2014
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Decompressing inner ebullition (DIE) can reduce the extraction liquid boiling point and polyphenols oxidation in the extraction process. The aim of this study is to optimise the phenolic extraction process by DIE and to examine the antioxidant activities. The extraction process parameters were observed by central composite design. The antioxidant activity was measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing power assays. The results showed that the optimal extraction condition is extract time of 90 min, temperature of 45°C, solid-liquid ratio of 1:20 g/mL, vacuum degree of - 0.08 MPa, ethanol concentration of 60%, while the phenolic content was 5.4%. The phenolic extracts from Rhus verniciflua Stokes bark had better antioxidant activities; the antioxidant activity (IC50) of the DIE was 20 ?g/mL by the DPPH method. The reducing power of the phenolic extracts was significantly related to their total phenolic content (R = 0.9903). The results presented show that the DIE method is an effective method for polyphenols extraction.
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Fabrication of calix[4]arene derivative monolayers to control orientation of antibody immobilization.
Int J Mol Sci
PUBLISHED: 01-15-2014
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Three calix[4]arene (Cal-4) derivatives which separately contain ethylester (1), carboxylic acid (2), and crownether (3) at the lower rim with a common reactive thiol at the upper rim were synthesized and constructed to self-assembled monolayers (SAMs) on Au films. After spectroscopic characterization of the monolayers, surface coverage and orientation of antibody immobilized on the Cal-4 derivative SAMs were studied by surface plasmon resonance (SPR) technique. Experimental results revealed that the antibody could be immobilized on the Cal-4 derivatives spontaneously. The orientation of absorbed antibody on the Cal-4 derivative SAMs is related to the SAM's dipole moment. The possible orientations of the antibody immobilized on the Cal-4 derivative 1 SAM are lying-on or side-on, while on the Cal-4 derivative 2 and Cal-4 derivative 3 head-on and end-on respectively. These experimental results demonstrate the surface dipole moment of Cal-4 derivative appears to be an important factor to antibody orientation. Cal-4 derivatives are useful in developing site direct protein chips.
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Structural basis of SOSS1 complex assembly and recognition of ssDNA.
Cell Rep
PUBLISHED: 01-03-2014
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The SOSS1 complex comprising SOSSA, SOSSB1, and SOSSC senses single-stranded DNA (ssDNA) and promotes repair of DNA double-strand breaks (DSBs). But how SOSS1 is assembled and recognizes ssDNA remains elusive. The crystal structure of the N-terminal half of SOSSA (SOSSAN) in complex with SOSSB1 and SOSSC showed that SOSSAN serves as a scaffold to bind both SOSSB1 and SOSSC for assembly of the SOSS1 complex. The structures of SOSSAN/B1 in complex with a 12 nt ssDNA and SOSSAN/B1/C in complex with a 35 nt ssDNA showed that SOSSB1 interacts with both SOSSAN and ssDNA via two distinct surfaces. Recognition of ssDNA with a length of up to nine nucleotides is mediated solely by SOSSB1, whereas neither SOSSC nor SOSSAN are critical for ssDNA binding. These results reveal the structural basis of SOSS1 assembly and provide a framework for further study of the mechanism governing longer ssDNA recognition by the SOSS1 complex during DSB repair.
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Dysregulation of JAM-A plays an important role in human tumor progression.
Int J Clin Exp Pathol
PUBLISHED: 01-01-2014
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Junctional adhesion molecule A (JAM-A) is a transmembrane protein that belongs to the immunoglobulin (Ig) superfamily. Evidence determines that JAM-A plays a role in numerous cellular processes, including tight junction assembly, leukocyte migration, platelet activation, angiogenesis and virus binding. Recent research suggests that JAM-A is dysregulated in various cancers and is vital for tumor progression. JAM-A is implicated in carcinogenesis via different signal pathways such as TGF-?1 signaling. Furthermore, JAM-A expression in cancers is usually associated with certain outcome of patients and might be a prognostic indicator. In this review, the correlation between JAM-A expression and human cancers will be described.
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Retinal injury thresholds for 532, 578, and 630?nm lasers in connection to photodynamic therapy for choroidal neovascularization.
Lasers Surg Med
PUBLISHED: 10-07-2013
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The purpose of this study was to explore the retinal injury thresholds in rabbits and evaluate the influence of retinal pigmentation on threshold irradiance at laser wavelengths of 532, 578, and 630?nm which might be involved in hypocrellin B (HB) and hematoporphyrin monomethyl ether (HMME) photodynamic therapy (PDT) for choroidal neovascularization (CNV).
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Fabrication of a protease sensor for caspase-3 activity detection based on surface plasmon resonance.
Analyst
PUBLISHED: 08-03-2013
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Diagnosis of apoptosis is essential to the early detection of therapy efficiency and the evaluation of disease progression. Caspase-3 is supposed to be closely related to cellular apoptosis. We describe here a label-free surface plasmon resonance (SPR) detection of apoptosis based on caspase-3 activity assay through enzyme digestion. An artificial peptide sequence was designed as a substrate of caspase-3 and immobilized on a gold disk through covalent binding. The 4Lys part at the end of the pentadecyl-peptide was designed to form a unique peptide array through electrostatic repulsion. The immobilization of the peptide on the gold surface was carefully characterized by SPR and atomic force microscopy. The catalytic conditions of caspase-3 were optimized with electrochemical impedance spectroscopy. The detection limit of caspase-3 was found at a concentration of 1 pg mL(-1). The activity of caspase-3 in apoptotic cells could also be measured sensitively by the one-step and intuitional SPR response decrease. The fabricated simple and convenient caspase-3 sensor is proposed for application in clinical analysis.
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Metabolic changes during the pu-erh tea pile-fermentation revealed by a liquid chromatography tandem mass-spectrometry-based metabolomics approach.
J. Food Sci.
PUBLISHED: 05-27-2013
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In the current study, liquid chromatography-mass spectrometry combined with multivariate statistical analyses was employed to investigate the time-varying biochemical changes during the pile-fermentation process with the emphasis on the active ingredients to clarify the manufacturing process of ripened pu-erh tea as a whole. The metabolite profiles of different manufacturing processes were unique and could be distinguished with the aid of principal component analysis. Furthermore, partial least-squares discriminant analysis revealed a pairwise discrimination between the raw material group and pile-fermentation process groups or the final product group, and 48 differential metabolites with variable importance in the projection value greater than 1 were identified, which was confirmed by the subsequent hierarchical cluster analysis. These results highlight our current understanding of the exact changing process of the bioactive compounds during the pile fermentation, and the global change of these bioactive compounds provides the special flavor, taste, and health promoting effects of ripened pu-erh tea.
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Pulmonary fibrosis effect of ammonium perchlorate exposure in rabbit.
Arch Environ Occup Health
PUBLISHED: 04-10-2013
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Ammonium perchlorate (AP) is a kind of inorganic chemical. To evaluate the potential pulmonary fibrosis caused by occupational exposure to this compound, 25 male rabbits were randomly allocated into 5 groups to receive AP or bleomycin or saline by intratracheal injection. All rabbits were sacrificed and lung tissues were removed to prepare hematoxylin and eosin (HE) staining for microscope observation and to perform electron microscopy examine. In microscope observation, AP-instilled lung tissue showed inflammatory infiltrates, alveolar collapse, subpleural thickening, and lymphocyte proliferation. Electron microscopy examination of lung tissue showed massive fibroblast accumulation, collagen fiber hyperplasia, and dense collagen deposition. The histopathological changes were considered as effective indicator linking to the development of pulmonary fibrosis. These results demonstrated that chronic instillation of AP can induce pulmonary fibrosis. And these results revealed that AP has pulmonary toxic effect.
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Scaffolding protein SPIDR/KIAA0146 connects the Bloom syndrome helicase with homologous recombination repair.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 03-18-2013
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The Bloom syndrome gene product, BLM, is a member of the highly conserved RecQ family. An emerging concept is the BLM helicase collaborates with the homologous recombination (HR) machinery to help avoid undesirable HR events and to achieve a high degree of fidelity during the HR reaction. However, exactly how such coordination occurs in vivo is poorly understood. Here, we identified a protein termed SPIDR (scaffolding protein involved in DNA repair) as the link between BLM and the HR machinery. SPIDR independently interacts with BLM and RAD51 and promotes the formation of a BLM/RAD51-containing complex of biological importance. Consistent with its role as a scaffolding protein for the assembly of BLM and RAD51 foci, cells depleted of SPIDR show increased rate of sister chromatid exchange and defects in HR. Moreover, SPIDR depletion leads to genome instability and causes hypersensitivity to DNA damaging agents. We propose that, through providing a scaffold for the cooperation of BLM and RAD51 in a multifunctional DNA-processing complex, SPIDR not only regulates the efficiency of HR, but also dictates the specific HR pathway.
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Prevalence studies of dementia in mainland china, Hong Kong and taiwan: a systematic review and meta-analysis.
PLoS ONE
PUBLISHED: 01-01-2013
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Many studies have considered the prevalence of dementia in mainland China, Hong Kong and Taiwan. However, area level estimates have not been produced. This study examines area differences across mainland China, Hong Kong and Taiwan adjusting for the effect of methodological factors with the aim of producing estimates of the numbers of people with dementia in these areas.
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RAD18-BRCTx interaction is required for efficient repair of UV-induced DNA damage.
DNA Repair (Amst.)
PUBLISHED: 10-28-2011
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BRCA1 carboxyl-terminal (BRCT) motifs are present in a number of proteins involved in DNA repair and/or DNA damage signaling pathways. The BRCT domain-containing protein BRCTx has been shown to interact physically with RAD18, an E3 ligase involved in postreplication repair and homologous recombination repair. However, the physiological relevance of the interaction between RAD18 and BRCTx is largely unknown. In this study, we showed that RAD18 interacts with BRCTx in a phosphorylation-dependent manner and that this interaction, mediated via highly conserved serine residues on the RAD18 C terminus, is required for BRCTx accumulation at DNA damage sites. Furthermore, we uncovered critical roles of the RAD18-BRCTx module in UV-induced DNA damage repair but not PCNA mono-ubiquitination or homologous recombination. Thus, our results suggest that RAD18 has an additional function in the surveillance of the UV-induced DNA damage response signal.
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Antimicrobial activities of phenethyl isothiocyanate isolated from horseradish.
Nat. Prod. Res.
PUBLISHED: 08-05-2011
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Phenethyl isothiocyanate (PEITC) was obtained from horseradish. The preparation procedure was as follows: the horseradish powder was hydrolysed in the water first, and then, after filtration, the residue was extracted by petroleum ether; finally, PEITC was isolated by silica gel column. The structure of PEITC was identified by IR, MS, ¹H-NMR and ¹³C-NMR chromatography methods. The inhibitory activities of PEITC against Gibberella zeae, Xanthomonas axonopodis pv . citri, Cytospora sp . and Phytophthora capsisi showed that PEITC had good inhibition effects. The EC?? values of G. zeae, X. axonopodis pv . citri, Cytospora sp . and P. capsisi were 13.92, 1.20, 0.73 and 3.69?µg?mL?¹, respectively.
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[Post-marketed re-evaluation of fleabane injection and Dengzhan Shengmai capsule study on treatment in patients with ischemic stroke].
Zhongguo Zhong Yao Za Zhi
PUBLISHED: 06-27-2011
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To verify the efficacy and safety of post-marketed fleabane injection combined with Dengzhan Shengmai capsules in the treatment of ischemic stroke (IS).
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A comparative study on ocular damage induced by 1319nm laser radiation.
Lasers Surg Med
PUBLISHED: 04-19-2011
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High energy loss of 1,319?nm laser due to pre-retinal water absorption makes the ocular axial length more critical, while the relative low absorbance of melanin makes retinal pigmented epithelium less contributing, to retinal damage threshold. However, both have never been illustrated experimentally. Here we determined and compared the retinal damage thresholds at this wavelength in three species with different axial lengths and retinal pigmentations. The corneal damage threshold was also determined for further comparative analysis.
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Molecular recognition of arginine by supramolecular complexation with calixarene crown ether based on surface plasmon resonance.
Int J Mol Sci
PUBLISHED: 02-10-2011
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Arginine plays an important role in cell division and the functioning of the immune system. We describe a novel method by which arginine can be identified using an artificial monolayer based on surface plasmon resonance (SPR). The affinity of arginine binding its recognition molecular was compared to that of lysine. In fabrication of an arginine sensing interface, a calix[4]crown ether monolayer was anchored onto a gold surface and then characterized by Fourier Transform infrared reflection absorption spectroscopy, atomic force microscopy, and cyclic voltammetry. The interaction between arginine and its host compound was investigated by SPR. The calix[4]crown ether was found to assemble as a monolayer on the gold surface. Recognition of calix[4]crown monolayer was assessed by the selective binding of arginine. Modification of the SPR chip with the calix[4]crown monolayer provides a reliable and simple experimental platform for investigation of arginine under aqueous conditions.
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[Correlation of powder properties and formability of traditional Chinese medicine pellets].
Zhongguo Zhong Yao Za Zhi
PUBLISHED: 09-27-2010
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To investigate the correlation of powder properties and formability of traditional Chinese medicine pellets prepared by extrusion/spheronization.
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Controlled synthesis of mononuclear or binuclear aryloxo ytterbium complexes supported by beta-diketiminate ligand and their activity for polymerization of epsilon-caprolactone and L-lactide.
Dalton Trans
PUBLISHED: 06-22-2010
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The reaction of monomeric [(DIPPh)(2)nacnac]YbCl(2)(THF)(2) ((DIPPh)(2)nacnac = N,N-diisopropylphenyl-2,4-pentanediimineanion) with NaOAr (OAr = 2,6-diisopropylphenoxide) in THF afforded the mononuclear complexes [(DIPPh)(2)nacnac]Yb(OAr)Cl(THF) 1 and [(DIPPh)(2)nacnac]Yb(OAr)(2) 2 depending on the molar ratio of dichloride to sodium salt, while the same reaction with NaOAr (OAr = 2,6-dimethylphenoxide) in toluene yielded the binuclear complex [{(DIPPh)(2)nacnac}Yb(OAr)](2)(mu-Cl)(2) 3. Treatment of [(DIPPh)(2)nacnac]Yb(THF)(mu-Cl)(3)Yb(Cl)[(DIPPh)(2)nacnac] with NaOAr and NaOAr, respectively, in toluene yielded selectively the corresponding binuclear complexes {[(DIPPh)(2)nacnac]Yb(OAr)(mu-Cl)(3)Yb[(DIPPh)(2)nacnac](THF)} 4 and {[(DIPPh)(2)nacnac]Yb(OAr)(mu-Cl)(3)Yb[(DIPPh)(2)nacnac](THF)} 5 in high yields. All complexes were structurally characterized. Complex 2 was found to be a highly active initiator for both polymerizations of epsilon-caprolactone (epsilon-CL) and L-lactide. All monoaryloxide complexes can initiate the polymerization of epsilon-CL in a controlled manner giving polymers with narrow molecular weight distributions (M(w)/M(n) around 1.06) with relatively low activity relative to complex 2.
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Phenylalanine sensing based on surface plasmon resonance.
J Nanosci Nanotechnol
PUBLISHED: 11-14-2009
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A phenylalanine sensing system was constructed with photochromic spiroxazine derivative via surface plasmon resonance (SPR). Recognition-functional spiroxazine monolayer was formed on Au surface by self-assembly. After spectroscopic characterizations of monolayer, various concentrations of d- and l-phenylalanine were employed as analytes on UV addressable ring-opened spiroxazine monolayer. The different SPR angle shift derived from interaction between d- and l-phenylalanine and spiroxazine monolayer can be explained by the different dipole moment of ionic complexes. Computer simulations using Molecular Orbital PACkage AM1 approximation reinforced the reliability of the experimental results. To confirm the long-time stability of spiroxazine monolayer, we measured SPR response of spiroxazine monolayer with repetitive UV-on and off. These experimental results suggest that it can be applicable to simple analysis of interaction between zwitterionic recognition-functional molecule and analyte.
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Surface plasmon resonance investigation of a copolymer containing spiroxazine.
J Nanosci Nanotechnol
PUBLISHED: 11-14-2009
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Spiroxazines are a class of photochromic compounds whose molecular structures are alterable upon exposure to UV/visible light. The typical reaction of spiroxazines is the conversion between the non-polar ring-closure form and polar ring-open form. In this work, copolymer of 1,6-heptadiyne derivatives containing a spiroxazine was used as photochromic material. Precise photochromic properties of the copolymers thin-film were evaluated through measuring dielectric constant, optical constant and thickness by surface plasmon resonance (SPR) with multi-solvent approach. The change in structure under UV-light irradiation is accompanied by increase of dielectric constant. However, dielectric constant and UV-induced thickness change of the photochromic polymer thin-film are independent of film thickness.
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Photoluminescence up-conversion of bioconjugated hybrids on CdTe and Au nanoparticles.
J Nanosci Nanotechnol
PUBLISHED: 11-14-2009
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Semiconductor nanomaterials have attracted considerable attention in the design of high efficiency PL up-conversion in heterojunctions or nanostructures at extremely low continuous wave (cw)-excitation intensity. In this study, bioconjugated hybrids were constructed using CdTe and Au nanoparticles (NPs), where two-fold PL enhancement was observed in the solution state. These results are in accordance with theoretical predictions of the local-field effects associated with the combined influence of strong localization of the collective plasmon modes in metallic-semiconducting hybrids and multi-photon absorption into its localized plasmon modes. The feasibility of the nanohybrids as sensors was demonstrated by breaking the bioconjugation through thermal stress, which induced a rapid decrease in luminescence intensity. It is believed that the phenomena is applicable to high-compacted optoelectronic devices and sensing systems that take advantage of both quantum confinement effects and nonlinear optical properties.
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A novel elsinochrome A derivative: a study of drug delivery and photodynamic activity.
Photochem. Photobiol. Sci.
PUBLISHED: 10-12-2009
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Elsinochrome A (EA) possesses the highest singlet-oxygen quantum yield (0.98) amongst the perilenoquinoid pigments and may be suitable as a phototherapeutic drug. However, there have been virtually no studies into its medicinal applications. Based on the analysis of chemical derivatives of hypocrellins (the same family as EA), 5-(3-mercapto-1-propanesulfonic acid)-substituted elsinochrome A (MPEA) with an amphiphilicity was designed and synthesized by considering drug delivery and biological activity requirements. MPEA possesses a water solubility of 5.1 mg mL(-1), which is just sufficient to enable dissolution at a clinically acceptable concentration, while its partition coefficient (n-octanol/phosphate buffered saline) of 7 guarantees affinity to biological targets. MPEA could photogenerate semiquinone anion radicals and reactive oxygen species, especially singlet oxygen, at a yield of 0.73, which approaches that for hypocrellin B. Biological tests confirmed that the photodynamic activity of MPEA was as high as 60% of that of its parent EA, which is significantly higher than that of most other photosensitizers.
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Binding capability of the enediyne-associated apoprotein to human tumors and constitution of a ligand oligopeptide-integrated protein.
J. Biotechnol.
PUBLISHED: 05-01-2009
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The molecule of lidamycin that belongs to the chromoprotein family of antitumor antibiotics is composed of an apoprotein (LDP) and an enediyne chromophore. The enediyne moiety of the molecule is responsible for the potent cytotoxicity; however, the biological function of the apoprotein moiety, particularly its interaction with cancer cells, remains unclear. In present study, the binding capability of LDP to human tumors was detected for the first time by tissue microarray. LDP bound to various human tumors with significant difference from the corresponding normal tissues. Positive correlation between binding activity and the overexpression of VEGF and EGFR was confirmed by lung carcinoma tissue microarray. A fusion protein LG-LDP that consists of LDP and a ligand oligopeptide to EGFR was constructed by DNA recombination. LG-LDP showed augmented binding to EGFR-overexpressing cancer cells. Furthermore, an energized fusion protein LG-LDP-AE was prepared by integrating the active enediyne (AE) into LG-LDP molecule. By MTT assay, LG-LDP-AE displayed extremely potent cytotoxicity to cancer cells with IC50 approximate to 0.01nM. The results indicate that LDP binds to various human tumors and it might serve as a delivery carrier by integration of ligand oligopeptide to manufacture motif-based, targeted fusion proteins for cancer.
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A novel hypocrellin B derivative designed and synthesized by taking consideration to both drug delivery and biological photodynamic activity.
J. Photochem. Photobiol. B, Biol.
PUBLISHED: 01-10-2009
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For making hypocrellins clinically applicable for phototherapy to vascular diseases, it is mainly focused onto finding a derivative which can be transported fluently in blood system but without serious loss of the inherent activity of its parents. Based on this consideration, a novel 17-3-amino-1-propane-sulfonic acid-HB Schiff-base (NSHB) was designed and synthesized in this work. As expected, NSHB is readily dissolved in phosphate buffered saline (PBS) or any other aqueous solvent in a concentration which is suitable for intravenous injection, while the quite higher partition coefficient (5:1) is beneficial to the affinity to biological targets. Based on EPR measurements, it is proved that the photosensitization activity of NSHB to photo-generate semiquinone anion radicals and superoxide anion radical (O*(2)(-)) is even higher than its parent HB, while the ability to generate singlet oxygen ((1)O(2)) is not seriously reduced. In addition, nearly comparable PDT activity to A549 cells for NSHB and HB confirms that the molecular design is successful and NSHB is readily delivered into target tissues via blood circulation after intravenous injection. Furthermore, the quantum yield of (1)O(2) for NSHB is as 12.5 times as that for HB under red light (600-700 nm), which is beneficial to phototherapy to solid tumors.
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Prediction of fatty acid composition in Camellia oleifera oil by near infrared transmittance spectroscopy (NITS).
Food Chem
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Under the serious circumstances of Camellia oleifera adulteration, the accurate examination for quality trait of C. oleifera oil is extremely urgent. For rapid determination of FA composition in C. oleifera oil, the feasibility of NITS was first studied. The quantitative models for FA were built based on PLS regression. NITS spectra is able to accurately predict for oleic, linoleic, and palmitic acids (R(cv)>0.844, R(2)>0.886). R(cv) are 0.91987, 0.95755, and 0.84447, and R(2) are 0.9424, 0.9682, 0.8862 for NITS models of oleic, linoleic, and palmitic acids, respectively. But models for stearic and unsaturated acids are less accurate, with values of R(cv) from 0.67440 to 0.69114, and R(2) from 0.6834 to 0.7587. These results indicate that NITS will have potential to be used in predicting FA composition of C. oleifera oil.
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