Determination of Alkylphosphonic Acids Using Micellar Electrokinetic Chromatography with Laser-induced Fluorescence Detection and High-salt Stacking

Journal of Chromatography. A. Aug, 2002  |  Pubmed ID: 12214700

Methyl-, ethyl- and propylphosphonic acids (MPA, EPA, and PPA, respectively) were derivatized with panacyl bromide in dry N,N-dimethylformamide (DMF). After mixing with a high-salt dilution buffer, the derivatives were separated by micellar electrokinetic chromatography in 35 min and detected by laser-induced fluorescence (He-Cd laser excitation at 325 nm and detection at 500 nm). Baseline resolution was achieved using a separation buffer containing 50 mM sodium cholate, 40% (v/v) of acetonitrile and 50 mM borate. Addition of 400 mM NaCl to the dilution buffer allowed the injection time to be increased to 30 s while still maintaining baseline resolution. Limits of detection for MPA, EPA, and PPA were 0.13 microM (12 ppb), 0.13 microM (14 ppb) and 0.14 microM (17 ppb) injected, respectively. The reproducibility of corrected peak area at 15 microM was 3.7 approximately 4.3%.

Capillary Sodium Dodecyl Sulfate-DALT Electrophoresis with Laser-induced Fluorescence Detection for Size-based Analysis of Proteins in Human Colon Cancer Cells

Electrophoresis. Sep, 2002  |  Pubmed ID: 12298085

Capillary sodium dodecyl sulfate (SDS)-DALT electrophoresis (SDS-DALT-CE) refers to CE separation of proteins based on their size; DALT is the abbreviation for Dalton, the unit used to describe molecular weight. In this work, seven proteins from 18 to 116 kDa were denatured by SDS, labeled by 3-(2-furoyl) quinoline-2-carboxaldehyde, separated by SDS-DALT-CE in polyethylene oxide sieving matrix, and detected by laser-induced fluorescence (LIF) in a sheath flow cuvette. This method was combined with detergent differential fractionation, which is a protein fractionation method using a series of detergent-containing buffers to sequentially extract protein fractions from cells, to analyze the proteins in HT29 human colon adenocarcinoma cells. In addition, on-column labeling was demonstrated for protein analysis by SDS-DALT-CE with LIF, and applied to analysis of proteins in a single HT29 cancer cell. Most proteins had molecular masses from 10 to 120 kDa. Similar protein profiles were obtained for single cells and protein extract of a large cell population.

[Re-survey on Epidemiological History of 1 091 Probable Cases with Severe Acute Respiratory Syndrome in Beijing]

Zhonghua Yu Fang Yi Xue Za Zhi [Chinese Journal of Preventive Medicine]. Mar, 2004  |  Pubmed ID: 15061911

To know their real epidemiological histories in 1,091 probale cases of severe acute respiratory syndrome (SARS) without definite history of contact with SARS patients in the first survey.

[Changes in Endothelin-1 and Calcitonin Gene-related Peptide in Myocardium After Severe Burn and Delayed Fluid Resuscitation in Rats at Different Altitudes on Plateau]

Zhongguo Wei Zhong Bing Ji Jiu Yi Xue = Chinese Critical Care Medicine = Zhongguo Weizhongbing Jijiuyixue. Jan, 2005  |  Pubmed ID: 15636712

To explore changes in endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP) in the myocardium after severe burn and delayed fluid resuscitation in rats at different altitudes.

Imaging Membrane Potential in Dendritic Spines

Proceedings of the National Academy of Sciences of the United States of America. Jan, 2006  |  Pubmed ID: 16407122

Dendritic spines mediate most excitatory inputs in the brain. Although it is clear that spines compartmentalize calcium, it is still unknown what role, if any, they play in integrating synaptic inputs. To investigate the electrical function of spines directly, we used second harmonic generation (SHG) imaging of membrane potential in pyramidal neurons from hippocampal cultures and neocortical brain slices. With FM 4-64 as an intracellular SHG chromophore, we imaged membrane potential in the soma, dendritic branches, and spines. The SHG response to voltage was linear and seemed based on an electro-optic mechanism. The SHG sensitivity of the chromophore in spines was similar to that of the parent dendritic shaft and the soma. Backpropagation of somatic action potentials generated SHG signals at spines with similar amplitude and kinetics to somatic ones. Our optical measurements of membrane potential from spines demonstrate directly that backpropagating action potentials invade the spines.

Mass Spectrometry Assisted Assignments of Binding and Cleavage Sites of Copper(II) and Platinum(II) Complexes Towards Oxidized Insulin B Chain

Journal of Mass Spectrometry : JMS. Aug, 2006  |  Pubmed ID: 16888713

Interaction of cis-[Pt(en)(H2O)2]2+ and [CuL(H2O)]2+, where L is 2-[bis(2-aminoethyl)amino]ethanol, with oxidized insulin B chain in molar ratio of 1 : 1, 1 : 2 and 1 : 3 at pH 2.5 and 40 degrees C has been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS). The results show that the binding sites of the two complexes with oxidized insulin B chain are terminal NH2, imidazole groups of His5 and His10. The hydrolytic cleavage studies show that the [CuL(H2O)]2+, upon a pendant hydroxyl group of the ligand, selectively cleaves the peptide bonds at Gly8-Ser9, Asn3-Gln4 and Phe1-Val2, and the cis-[Pt(en)(H2O)2]2+ only cleaves the peptide bond at His10-Leu11. This is the first report of cis-[Pt(en)(H2O)2]2+-promoted cleavage of His-X peptide bond.

The Spine Neck Filters Membrane Potentials

Proceedings of the National Academy of Sciences of the United States of America. Nov, 2006  |  Pubmed ID: 17093040

Dendritic spines receive most synaptic inputs in the forebrain. Their morphology, with a spine head isolated from the dendrite by a slender neck, indicates a potential role in isolating inputs. Indeed, biochemical compartmentalization occurs at spine heads because of the diffusional bottleneck created by the spine neck. Here we investigate whether the spine neck also isolates inputs electrically. Using two-photon uncaging of glutamate on spine heads from mouse layer-5 neocortical pyramidal cells, we find that the amplitude of uncaging potentials at the soma is inversely proportional to neck length. This effect is strong and independent of the position of the spine in the dendritic tree and size of the spine head. Moreover, spines with long necks are electrically silent at the soma, although their heads are activated by the uncaging event, as determined with calcium imaging. Finally, second harmonic measurements of membrane potential reveal an attenuation of somatic voltages into the spine head, an attenuation directly proportional to neck length. We conclude that the spine neck plays an electrical role in the transmission of membrane potentials, isolating synapses electrically.

[Soil Infiltration Characteristics Under Main Vegetation Types in Anji County of Zhejiang Province]

Ying Yong Sheng Tai Xue Bao = The Journal of Applied Ecology / Zhongguo Sheng Tai Xue Xue Hui, Zhongguo Ke Xue Yuan Shenyang Ying Yong Sheng Tai Yan Jiu Suo Zhu Ban. Mar, 2007  |  Pubmed ID: 17552181

The study on the soil infiltration under different main vegetation types in Anji County of Zhejiang Province showed that the characteristics of soil infiltration differed significantly with land use type, and the test eight vegetation types could be classified into four groups, based on soil infiltration capability. The first group, deciduous broadleaved forest, had the strongest soil infiltration capability, and the second group with a stronger soil infiltration capability was composed of grass, pine forest, shrub community and tea bush. Bamboo and evergreen broadleaved forest were classified into the third group with a relatively strong soil infiltration capability, while bare land belonged to the fourth group because of the bad soil structure and poorest soil infiltration capability. The comprehensive parameters of soil infiltration (alpha) and root (beta) were obtained by principal component analysis, and the regression model of alpha and beta could be described as alpha = 0. 1708ebeta -0. 3122. Soil infiltration capability was greatly affected by soil physical and chemical characteristics and root system. Fine roots (< or = 1 mm in diameter) played effective roles on the improvement of soil physical and chemical properties, and the increase of soil infiltration capability was closely related to the amount of the fine roots.

Second Harmonic Generation in Neurons: Electro-optic Mechanism of Membrane Potential Sensitivity

Biophysical Journal. Sep, 2007  |  Pubmed ID: 17604312

Second harmonic generation (SHG) from membrane-bound chromophores can be used to image membrane potential in neurons. We investigate the biophysical mechanism responsible for the SHG voltage sensitivity of the styryl dye FM 4-64 in pyramidal neurons from mouse neocortical slices. SHG signals are exquisitely sensitive to the polarization of the incident laser light. Using this polarization sensitivity in two complementary approaches, we estimate a approximately 36 degrees tilt angle of the chromophore to the membrane normal. Changes in membrane potential do not affect the polarization of the SHG signal. The voltage response of FM 4-64 is faster than 1 ms and does not reverse sign when imaged at either side of its absorption peak. We conclude that FM 4-64 senses membrane potential through an electro-optic mechanism, without significant chromophore membrane reorientation, redistribution, or spectral shift.

[Proper Time and Conditions of Aeromedical Transportation in Critically Burn Patients]

Zhonghua Shao Shang Za Zhi = Zhonghua Shaoshang Zazhi = Chinese Journal of Burns. Feb, 2007  |  Pubmed ID: 17605254

To analyze the opportunity and condition of aeromedical transportation in critically burn patients.

Determination of Glyphosate Using Off-line Ion Exchange Preconcentration and Capillary Electrophoresis-laser Induced Fluorescence Detection

Talanta. Apr, 2007  |  Pubmed ID: 19071590

An enrichment method for the herbicide glyphosate is presented based on ion exchange solid phase extraction (SPE) technique. A 200-mul micro-pipette tip packed with 50mg of Bio-Rad AG1-X8 anion exchanger beads was used for offline extraction of glyphosate from 50ml of spiked river water sample. The retained glyphosate was eluted with 10mM HCl and then converted quantitatively to the corresponding amine (glycine) using hypochlorite. Subsequent fluorescent labeling using naphthalene-2,3-dicarboxaldehyde (NDA)-cyanide allowed micellar electrokinetic chromatography (MEKC) separation and laser-induced fluorescence detection (LIF) with a violet diode laser. Optimization of the sample clean-up, extraction, elution, conversion and labeling steps enabled analysis of glyphosate in river water in the nanomolar range. Detection limits were 0.04nM glyphosate in standards and 1.6nM in spiked river.

Silicon-induced DNA Damage Pathway and Its Modulation by Titanium Plasma Immersion Ion Implantation

Biomaterials. Feb, 2008  |  Pubmed ID: 17980424

Micronuclei tests (MNT) using the Chinese Hamster Ovary (CHO) cells and Chinese Hamster Ovary Mutant cells (XRS5) have been conducted to evaluate the biocompatibility of silicon and titanium plasma-implanted silicon. Pure Si induces high MN ratios of the two cell lines and thus has poor biocompatibility. The MN ratio of CHO cells is higher than background by about 44% and the MN ratio of XRS5 cells is even higher by about 180%, suggesting that most of the cellular DNA damages on the Si wafer are DNA double-strand breaks (DSB) and are efficiently repaired by the nonhomologous end-joining (NHEJ) pathway. The surface biocompatibility of Si can be enhanced by Ti plasma immersion ion implantation (PIII). The altered oxidized species on the Ti plasma-implanted surface block cellular DSB repaired by the NHEJ pathway and decrease the MN ratio of XRS5 cells. By increasing the Ti implantation time and consequently the Ti implant fluence, the oxygen binding energy shifts toward a lower energy and the intensity of the Si peaks corresponding to SiO(2) continually diminishes and even disappear. At the same time, the MN ratios of the two cell lines decrease. Our results suggest that the rest of the DNA damages which cannot be repaired by the NHEJ pathway may be blocked because the surface bonding changes from predominantly Si-O on the 10 min Ti-implanted Si to Ti-O on the 120 min Ti-implanted Si. Our results also suggest that the genotoxicity of cell assay such as MNT and DSB is a valid method to investigate biocompatibility.

When and How to Perform Aeromedical Transport of Critically Burned Patients in Northwest China

Burns : Journal of the International Society for Burn Injuries. Jun, 2008  |  Pubmed ID: 17980969

To introduce the experience of aeromedical transport of critically burned patients in Northwest China and to explore the time and conditions of transport.

The Proteomes of Human Parotid and Submandibular/sublingual Gland Salivas Collected As the Ductal Secretions

Journal of Proteome Research. May, 2008  |  Pubmed ID: 18361515

Saliva is a body fluid with important functions in oral and general health. A consortium of three research groups catalogued the proteins in human saliva collected as the ductal secretions: 1166 identifications--914 in parotid and 917 in submandibular/sublingual saliva--were made. The results showed that a high proportion of proteins that are found in plasma and/or tears are also present in saliva along with unique components. The proteins identified are involved in numerous molecular processes ranging from structural functions to enzymatic/catalytic activities. As expected, the majority mapped to the extracellular and secretory compartments. An immunoblot approach was used to validate the presence in saliva of a subset of the proteins identified by mass spectrometric approaches. These experiments focused on novel constituents and proteins for which the peptide evidence was relatively weak. Ultimately, information derived from the work reported here and related published studies can be used to translate blood-based clinical laboratory tests into a format that utilizes saliva. Additionally, a catalogue of the salivary proteome of healthy individuals allows future analyses of salivary samples from individuals with oral and systemic diseases, with the goal of identifying biomarkers with diagnostic and/or prognostic value for these conditions; another possibility is the discovery of therapeutic targets.

Reverse Microemulsion-mediated Synthesis of Silica-coated Gold and Silver Nanoparticles

Langmuir : the ACS Journal of Surfaces and Colloids. Jun, 2008  |  Pubmed ID: 18465888

A reverse microemulsion method is reported for preparing monodispersed silica-coated gold (or silver) nanoparticles without the use of a silane coupling agent or polymer as the surface primer. This method enables a fine control of the silica shell thickness with nanometer precision. As compared to the Stöber method reported for direct silica coating, which can only coat large gold particles ( approximately 50 nm in diameter) at low concentrations (<1.5 x 10(10) particles/mL), this new approach is capable of coating gold particles of a wide range of sizes (from 10 to 50 nm) at a much higher concentration ( approximately 1.5 x 10(13) particles/mL). Moreover, it enables straightforward surface functionalization via co-condensation between tetraethyl orthosilicate and another silane with the desired functional groups. The functional groups introduced by this method are readily accessible and thus useful for various applications.

Ag and Ag/N2 Plasma Modification of Polyethylene for the Enhancement of Antibacterial Properties and Cell Growth/proliferation

Acta Biomaterialia. Nov, 2008  |  Pubmed ID: 18586586

Polyethylene (PE) is one of the most common materials used for medical implants. However, it usually possesses low biocompatibility and insufficient antibacterial properties. In the work described here, plasma immersion ion implantation (PIII) is employed to implant silver into PE to enhance both its antibacterial properties and its biocompatibility. Our results show that Ag PIII can give rise to excellent antibacterial properties and induces the formation of functional groups such as C-O and C=C. These C-O and C=C groups on the modified surface can trigger the growth of the human fetal osteoblastic cell line (hFOB). Furthermore, combining N(2) and Ag PIII prolongs the antibacterial effects, but nitrogen-containing functional groups such as C-N and C=N created by N(2) co-PIII negatively impact proliferation of hFOB on the surface. According to our experimental investigation on cell proliferation, functional groups such as C-N and C=N created by nitrogen PIII are disadvantageous to cell growth whereas the C-O and C=C groups benefit cell growth. Both the antibacterial activity and biocompatibility of PE can be enhanced by means of the proper plasma surface treatment.

[Cell Apoptosis and Expression of Hypoxia-inducible Transcription Factor-1 Alpha in Kidney Tissue After Severe Burn with Delayed Fluid Resuscitation in Rats in Areas of Different Altitude]

Zhongguo Wei Zhong Bing Ji Jiu Yi Xue = Chinese Critical Care Medicine = Zhongguo Weizhongbing Jijiuyixue. Jul, 2008  |  Pubmed ID: 18611336

To explore the relationship of cell apoptosis and expression regularity of hypoxia-inducible transcription factor (HIF)-1 alpha after severe burn with delayed fluid resuscitation in areas of different altitude.

3C-SiC Nanocrystals As Fluorescent Biological Labels

Small (Weinheim an Der Bergstrasse, Germany). Aug, 2008  |  Pubmed ID: 18618492

Quantification of Serum Proteins of Metastatic Oral Cancer Patients Using LC-MS/MS and ITRAQ Labeling

The Open Proteomics Journal. 2008  |  Pubmed ID: 20485468

Metastasis is a critical event in oral squamous cell carcinoma (OSCC) progression. In this study, we have performed quantitative analysis of serum proteins from non-metastatic (lymph-node metastasis free) and metastatic OSCC patients using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with iTRAQ labeling (isobaric tagging for relative and absolute quantitation). To eliminate highly abundant proteins, the serum samples were initially separated by SDS-PAGE and only low abundant protein bands were excised for subsequent in-gel tryptic digestion. The resulting peptides were then extracted from each sample gels and labeled with iTRAQ reagent 114 (control), 116 (non-metastatic) and 117 (metastatic), respectively. Afterwards, the labeled samples were combined and subjected to LC-MS/MS analysis using linear ion trap (LIT) MS with pulsed Q collision induced dissociation (PQD). A total of 64 proteins were identified and quantified by this approach. Our study showed that iTRAQ labeling and LIT-MS with PQD is a valuable approach to quantification of serum proteins. We also demonstrated the presence of differentially expressed serum proteins between non-metastatic and metastatic OSCCs that may be further validated as biomarkers for metastatic OSCC. However, in order to comprehensively quantify low abundant serum proteins, a more efficient approach is needed to deplete highly abundant proteins prior to quantitative serum proteome analysis of OSCC.

Salivary Proteomics for Oral Cancer Biomarker Discovery

Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Oct, 2008  |  Pubmed ID: 18829504

This study aims to explore the presence of informative protein biomarkers in the human saliva proteome and to evaluate their potential for detection of oral squamous cell carcinoma (OSCC).

Second-harmonic Generation Imaging of Membrane Potential with Photon Counting

Microscopy and Microanalysis : the Official Journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada. Dec, 2008  |  Pubmed ID: 18986606

Second-harmonic generation (SHG) can be used for imaging membrane potential in neurons, but poor signal-to-noise (S/N) limits accurate measurements of small voltage transients. We use photon counting to improve the S/N of weak SHG signal detection. Photon counting generates shot-noise limited and integrable signals, eliminates pulse-to-pulse variation, and built-in discriminators reduces the background to practically zero. In single trials, by using photon counting, we obtain a more than a twofold S/N increase over analog voltage detection. Trial-to-trial variability is also reduced by 50%. Finally, we show that, using photon counting, the kinetics of fast events such as action potentials can be recorded more accurately.

Host Mating System and the Spread of a Disease-resistant Allele in a Population

Theoretical Population Biology. Sep, 2008  |  Pubmed ID: 18662709

The model presented here modifies a susceptible-infected (SI) host-pathogen model to determine the influence of mating system on the outcome of a host-pathogen interaction. Both deterministic and stochastic (individual-based) versions of the model were used. This model considers the potential consequences of varying mating systems on the rate of spread of both the pathogen and resistance alleles within the population. We assumed that a single allele for disease resistance was sufficient to confer complete resistance in an individual, and that both homozygote and heterozygote resistant individuals had the same mean birth and death rates. When disease invaded a population with only an initial small fraction of resistant genes, inbreeding (selfing) tended to increase the probability that the disease would soon be eliminated from a small population rather than become endemic, while outcrossing greatly increased the probability that the population would become extinct due to the disease.

Biocompatibility and Bioactivity of Plasma-treated Biodegradable Poly(butylene Succinate)

Acta Biomaterialia. Jan, 2009  |  Pubmed ID: 18760682

Poly(butylene succinate) (PBSu), a novel biodegradable aliphatic polyester with excellent processability and mechanical properties, is a promising substance for bone and cartilage repair. However, it typically suffers from insufficient biocompatibility and bioactivity after implantation into the human body. In this work, H(2)O or NH(3) plasma immersion ion implantation (PIII) is conducted for the first time to modify the PBSu surface. Both the treated and control specimens are characterized by X-ray photoelectron spectroscopy, contact angle measurements and atomic force microscopy. The plasma treatments improve the hydrophilicity and roughness of PBSu significantly and the different PIII processes result in similar hydrophilicity and topography. C-OH and C-NH(2) functional groups emerge on the PBSu surface after H(2)O and NH(3) PIII, respectively. The biological results demonstrate that both osteoblast compatibility and apatite formability are enhanced after H(2)O and NH(3) PIII. Furthermore, our results suggest that H(2)O PIII is more effective in rendering PBSu suitable for bone-replacement implants compared to NH(3) PIII.

A Universal Pre-analytic Solution for Concurrent Stabilization of Salivary Proteins, RNA and DNA at Ambient Temperature

Archives of Oral Biology. Mar, 2009  |  Pubmed ID: 19047016

Saliva is a biofluid that can be obtained from individuals without supervision by health care providers. To maximize this clinical advantage, it is highly desirable to have a global salivary analyte stabilizer for proteins, RNA and DNA at ambient temperature.

Systems Biology Analysis of Sjögren's Syndrome and Mucosa-associated Lymphoid Tissue Lymphoma in Parotid Glands

Arthritis and Rheumatism. Jan, 2009  |  Pubmed ID: 19116902

To identify key target genes and activated signaling pathways associated with the pathogenesis of Sjögren's syndrome (SS) by conducting a systems analysis of parotid glands manifesting primary SS or primary SS/mucosa-associated lymphoid tissue (MALT) lymphoma phenotypes.

Intracellular Chromosome Breaks on Silicon Surface

Biomaterials. May, 2009  |  Pubmed ID: 19217155

The genotoxicity of silicon (Si) is investigated by soaking crystalline Si in a complete culture medium for 60 days and conducting micronuclei tests (MNTs) utilizing hamster ovary (CHO) cells and its Ku80 deficient CHO mutant (xrs5) cells (DNA double-strand breaks repair deficiency). The intracellular concentrations of reactive oxygen/nitrogen species (ROS/RNS) on Si are determined to elucidate the relationship between ROS/RNS and Si-induced genotoxicity by using CHO cells. The cells are treated with ROS scavenger (dimethyl sulfoxide) and MNT are performed. The results indicate that the intracellular concentration of ROS and nitrogen oxide (NO) on Si is higher than those on the control group by about 38% and 12%. ROS/RNS include superoxide (O(2)*(-)) anion, NO, and peroxynitrite (ONOO(-)) which can injure chromosomes and induce high cellular DNA double-strand breaks (DSBs).

Current Advances in Identification of Cancer Biomarkers in Saliva

Frontiers in Bioscience (Scholar Edition). 2009  |  Pubmed ID: 19482703

Saliva samples from certain disease patients harbor a wide spectrum of proteins, mRNAs, DNAs and other molecules that may be associated with the disease phenotype. If successfully discovered and validated, these informative molecules may serve as biomarkers, leading to the use of non-invasive biofluid for detecting and monitoring the diseases. This article summarizes the current advances in searching for potential biomarkers in saliva for human cancers, especially head and neck/oral cancers. With the new molecular profiling technologies such as microarray and proteomics, we are expecting to reveal highly discriminatory genomic and proteomic targets that can best detect the disease status.

Corrosion Resistance and Cytocompatibility of Biodegradable Surgical Magnesium Alloy Coated with Hydrogenated Amorphous Silicon

Journal of Biomedical Materials Research. Part A. Jun, 2009  |  Pubmed ID: 18449935

The fast degradation rates in the physiological environment constitute the main limitation for the applications of surgical magnesium alloys as biodegradable hard-tissue implants. In this work, a stable and dense hydrogenated amorphous silicon coating (a-Si:H) with desirable bioactivity is deposited on AZ91 magnesium alloy using magnetron sputtering deposition. Raman spectroscopy and Fourier transform infrared spectroscopy reveal that the coating is mainly composed of hydrogenated amorphous silicon. The hardness of the coated alloy is enhanced significantly and the coating is quite hydrophilic as well. Potentiodynamic polarization results show that the corrosion resistance of the coated alloy is enhanced dramatically. In addition, the deterioration process of the coating in simulated body fluids is systematically investigated by open circuit potential evolution and electrochemical impedance spectroscopy. The cytocompatibility of the coated Mg is evaluated for the first time using hFOB1.19 cells and favorable biocompatibility is observed.

A Unique Technology to Transform Inorganic Nanorods into Nano-networks

Nanotechnology. Jun, 2009  |  Pubmed ID: 19487799

An inorganic nano-network of attapulgite is formed from rigid nanorods using ion beam bombardment. The structure of the nano-networks depends on the ion beam fluence for the same ion energy. Scanning electron microscopy reveals that ion beam bombardment improves the dispersion of the attapulgite particles and the change in the shape of the rod-shaped attapulgite particles stems from the thermal stress induced by ion beam bombardment. This phenomenon is more obvious for higher ion fluences. The bent or twisted rod-shaped attapulgite particles cross-link to form a network structure, which is stable in water, and when the ion fluence is increased further, the cross-linked points are permanently sealed. The improved materials are more useful than clava attapulgite particles.

Magnetic PEDOT Hollow Capsules with Single Holes

Chemical Communications (Cambridge, England). May, 2009  |  Pubmed ID: 19532914

We demonstrate magnetic capsules with high uptake capacity by combining single-hole hydroxyl-functionalized PEDOT hollow spheres and Fe(3)O(4) nanoparticles; potential applications include pollutant removal and controlled drug delivery.

Structural and Emulsifying Properties of Soy Protein Isolate Subjected to Acid and Alkaline PH-shifting Processes

Journal of Agricultural and Food Chemistry. Aug, 2009  |  Pubmed ID: 19601630

Structural unfolding of soy protein isolate (SPI) as induced by holding (0, 0.5, 1, 2, and 4 h) in acidic (pH 1.5-3.5) and alkaline (pH 10.0-12.0) pH solutions, followed by refolding (1 h) at pH 7.0, was analyzed. Changes in emulsifying properties of treated SPI were then examined. The pH-shifting treatments resulted in a substantial increase in protein surface hydrophobicity, intrinsic tryptophan fluorescence intensity, and disulfide-mediated aggregation, along with the exposure of tyrosine. After the pH-shifting processes, soy protein adopted a molten globule-like conformation that largely maintained the original secondary structure and overall compactness but lost some tertiary structure. These structural modifications, consequently, led to markedly improved emulsifying activity of SPI as well as the emulsion stability.

Bioactive SrTiO(3) Nanotube Arrays: Strontium Delivery Platform on Ti-based Osteoporotic Bone Implants

ACS Nano. Oct, 2009  |  Pubmed ID: 19736918

Development of strontium releasing implants capable of stimulating bone formation and inhibiting bone resorption is a desirable solution for curing osteoporosis. In this work, well-ordered SrTiO(3) nanotube arrays capable of Sr release at a slow rate and for a long time are successfully fabricated on titanium by simple hydrothermal treatment of anodized titania nanotubes. This surface architecture combines the functions of nanoscaled topography and Sr release to enhance osseointegration while at the same time leaving space for loading of other functional substances. In vitro experiments reveal that the SrTiO(3) nanotube arrays possess good biocompatibility and can induce precipitation of hydroxyapatite from simulated body fluids (SBF). This Ti-based implant with SrTiO(3) nanotube arrays is an ideal candidate for osteoporotic bone implants. The proposed method can also be extended to load other biologically useful elements such as Mg and Zn.

Cationic Fluorine-containing Amphiphilic Graft Copolymers As DNA Carriers

Biomaterials. Mar, 2010  |  Pubmed ID: 20034666

A series of cationic fluorine-containing amphiphilic graft copolymers P(HFMA-St-MOTAC)-g-PEG comprising poly(hexafluorobutyl methacrylate) (PHFMA) poly(methacryl oxyethyl trimethylammonium chloride) (PMOTAC) polystyrene (PSt) backbones and poly(ethylene glycol) (PEG) side chains are synthesized as a type of non-viral gene vector. The copolymers self-assemble into spherical micelles in the aqueous media and turbidity and cytotoxicity measurements show that those micelles have excellent dispersive stability and low cytotoxicity. The interactions between the copolymers and calf-thymus DNA are studied by fluorescence spectroscopy and viscosity. The former discloses electrostatic interaction, hydrophobic interaction, and hydrogen bonding in the copolymer/DNA system, whereas the latter indicates that these graft copolymers can bind DNA via the electrostatic and classical intercalation modes. The DNA-binding capacity determined by the gel retardation assay and UV-visible spectrophotometry shows that the copolymers have good binding capacity to DNA and a high charge density or HFMA content in the copolymers bode well for DNA-binding. Transmission electron microscopy, photon correlation spectroscopy, and zeta potential data reveal that stable colloidal complexes (particles) can form easily between the copolymer micelles and DNA. Our results suggest that the copolymers are a promising non-viral vector in a gene delivery system.

Cysteine-functionalized Polyaspartic Acid: a Polymer for Coating and Bioconjugation of Nanoparticles and Quantum Dots

Langmuir : the ACS Journal of Surfaces and Colloids. May, 2010  |  Pubmed ID: 20112990

We have synthesized a biocompatible polyaspartic acid-based polymer (molecular weight approximately 15,000-25,000) with cysteine on its backbone for use as a capping ligand for functionalized Au, Ag, and CdSe@ZnS nanoparticles. Nearly monodisperse, hydrophobic Au and Ag nanoparticles and CdSe@ZnS quantum dots were first prepared in organic solvents via conventional synthesis and then ligand exchanged to derive polymer-coated water-soluble nanoparticles. Multiple thiol groups in the polymer backbone conferred excellent protection against aggregation of the nanoparticles, and the carboxylic acid groups in the polymer provided the possibility of covalent binding with antibodies. Compared to the conventional thiol-based ligands, this polymer coating led to superior colloidal stability under the experimental conditions involved in the bioconjugation and purification steps. Goat antihuman-IgG (anti-h-IgG) and antimouse epidermal growth factor receptor (anti-m-EGFR) antibodies were conjugated with the polymer-coated nanoparticles and successfully applied to protein detection. This polymer coating exhibited minimal nonspecific interaction with cells and could be broadly applied to cell labeling.

Fe(3)O(4)-Ag Nanocomposites for Optical Limiting:broad Temporal Response and Low Threshold

Optics Express. Mar, 2010  |  Pubmed ID: 20389641

We report the observation of optical limiting in Fe(3)O(4)-Ag nanocomposites in solution. With these nanocomposites, we demonstrate that broad temporal optical limiting can be accomplished with low limiting threshold. Due to the presence of Ag nanoparticles, nonlinear scattering gives rise to enhanced optical limiting responses to 532-nm nanosecond laser pulses, with a limiting threshold comparable to carbon nanotubes. As exposed to 780-nm femtosecond laser pulses, the largest value (approximately 10(-44) cm(4)s photon(-1) or 10(6) GM) for two-photon absorption cross-sections reported to date results in superior limiting responses with a limiting threshold as low as 0.04 J/cm(2) or 100 GW/cm(2) for Fe(3)O(4)-Ag (7nm) solution in 1 cm quartz cell. The limiting threshold can be further reduced by increasing Ag particle size through plasmon enhancement or taking advantage of self-defocusing.

PH Shifting Alters Solubility Characteristics and Thermal Stability of Soy Protein Isolate and Its Globulin Fractions in Different PH, Salt Concentration, and Temperature Conditions

Journal of Agricultural and Food Chemistry. Jul, 2010  |  Pubmed ID: 20524657

Soy protein isolate (SPI), beta-conglycinin (7S), and glycinin (11S) were subjected to pH-shifting treatments, that is, unfolding at pH 1.5 or 12.0 followed by refolding at pH 7.0, to induce molten globule structures. Treated samples were analyzed for protein solubility, thermal stability, and aggregation in 0, 0.1, and 0.6 M NaCl solutions at pH 2.0-8.0. The pH(12) shifting resulted in drastic increases (up to 2.5-fold) in SPI solubility in the pH 6.0-7.0 range, especially at 0 M NaCl. The pH(1.5) shifting had a generally lesser effect on solubility. 11S exhibited a solubility pattern similar to that of SPI, but the solubility of 7S was unaffected by pH shifting except at 0.6 M NaCl. The pH shifting, notably at pH 12.0, produced soluble, disulfide-linked polymers from 11S and reduced (P < 0.05) its enthalpy but not its temperature of denaturation. Soy proteins structurally altered by pH shifting had a reduced sensitivity to thermal aggregation.

High-sensitivity and Stable Cellular Fluorescence Imaging by Patterned Silver Nanocap Arrays

ACS Applied Materials & Interfaces. Aug, 2010  |  Pubmed ID: 20666434

Patterned silver nanocap arrays (PSNAs) prepared on porous anodic alumina templates by a simple coating technique yield enhanced sensitivity and stability in cellular fluorescence imaging. Microstructural analysis, surface-enhanced Raman scattering mapping, and finite difference time domain simulation indicate that the hot spots are evenly distributed on the substrate. Ag1522 or Chinese Hamster Ovary cells are labeled by phalloidin-fluorscein isothiocyanate (P-FITC) on the cytoskeletons and the fluorescence signals from the fluorophores bound on the cell cytoskeletons on the PSNAs are enhanced 8-fold compared to those on glass used in conventional imaging. In addition to the intensity enhancement, the photostability is improved dramatically. Spectral analysis suggests that the PSNAs can create more excitons in the light-emitting P-FITC because of plasmon resonance energy transfer from the silver nanocaps to the nearby P-FITC. They can also act as plasmonic antennae by converting a part of the nonradiative near-field emission from the fluorophores to the far field consequently enhancing the emission.

Mechanical and Biological Characteristics of Diamond-like Carbon Coated Poly Aryl-ether-ether-ketone

Biomaterials. Nov, 2010  |  Pubmed ID: 20692699

Poly aryl-ether-ether-ketone (PEEK) is an alternative to metal alloys in orthopedic applications. Although the polymer provides many significant advantages such as excellent mechanical properties and non-toxicity, it suffers from insufficient elasticity and biocompatibility. Since the elastic modulus of diamond-like carbon (DLC) is closer to that of cortical bone than PEEK, the DLC/PEEK combination is expected to enhance the stability and surface properties of PEEK in bone replacements. In this work, PEEK is coated with diamond-like carbon (DLC) by plasma immersion ion implantation and deposition (PIII&D) to enhance the surface properties. X-ray photoelectron spectrometry (XPS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy demonstrate successful deposition of the DLC film on PEEK without an obvious interface due to energetic ion bombardment. Atomic force microscopy (AFM) and contact angle measurements indicate changes in the surface roughness and hydrophilicity, and nanoindentation measurements reveal improved surface hardness on the DLC/PEEK. Cell viability assay, scanning electron microscopy (SEM), and real-time PCR analysis show that osteoblast attachment, proliferation, and differentiation are better on DLC/PEEK than PEEK. DLC/PEEK produced by PIII&D combines the advantages of DLC and PEEK and is more suitable for bone or cartilage replacements.

Proteomic Analysis of Saliva: 2D Gel Electrophoresis, LC-MS/MS, and Western Blotting

Methods in Molecular Biology (Clifton, N.J.). 2010  |  Pubmed ID: 20717776

Saliva harbors a wide spectrum of proteins that may reflect the health/disease status in the human body. Profiling of the proteins in saliva from a disease population can potentially yield valuable clinical parameters to be used for diagnosis and prognosis of the disease. Advances in proteomic technologies have enabled comprehensive profiling of protein expression in cells, tissue, and body fluids. When applied to readily accessible saliva samples from disease patients for biomarker study, such a global approach allows attaining the most discriminatory protein biomarkers that can best predict the disease status. In this chapter, we describe the protocols for proteomic analysis of saliva using 2D gel electrophoresis, Western blotting, and LC-MS/MS.

Activation of Mitogen-activated Protein Kinases Cellular Signal Transduction Pathway in Mammalian Cells Induced by Silicon Carbide Nanowires

Biomaterials. Nov, 2010  |  Pubmed ID: 20674003

Because of emerging biomedical applications of nanoscale materials, the behavior of cells in contact with nanoscale materials must be better understood. SiC nanostructures constitute a new class of biomaterials and have potential in many applications. In this study, the cellular signal transduction processes and toxicity mechanisms of silicon carbide nanowires (SiCNWs) are investigated. The Chinese hamster ovary (CHO) cells in contact with SiCNWs have significantly lower reproduction rates and genomic instability which may be the upstream event of cell apoptosis. Expression of the phosphorylated form of the mitogen-activated protein kinases (MAPKs) family including phosphorylated signal-regulated kinases (p-ERKs), phosphorylated c-Jun NH2-terminal kinases (p-JNKs), and phosphorylated p38-mitogen-activated protein kinases (p-p38) are observed at different time points during exposure to SiCNWs. Moreover, activation of the MAPKs family by phosphorylation which is an upstream event giving rise to expression of cyclooxygenase-2 (COX-2) is also observed. The specific inhibitors of the MAPKs family are found to restrain COX-2 high expression at some time points. Our results show that activation of the MAPKs cellular signaling pathway and over-expression of COX-2 are the main toxicity mechanisms in SiCNWs irritation.

Role of β-conglycinin and Glycinin Subunits in the PH-shifting-induced Structural and Physicochemical Changes of Soy Protein Isolate

Journal of Food Science. Mar, 2011  |  Pubmed ID: 21535749

Soy β-conglycinin (7S) and glycinin (11S) were incubated up to 4 h in acidic (pH 1.5 to 3.5) or alkaline (pH 10 to 12) solutions to induce protein structural unfolding followed by refolding 1 h at pH 7.0, a process known as pH-shifting. The pH-shifting markedly increased (P < 0.05) emulsifying activity of 11S and to a lesser extent 7S; the former also produced more uniform oil droplets. The emulsifying activity improvements were accompanied by a significant rise in protein surface hydrophobicity, slight loss of the secondary structure (circular dichroism), and substantial dissociation of disulfide-linked basic and acidic 11S subunits. The findings suggested that 11S globulins of soy protein isolate (SPI) were more responsive to pH-shifting treatments than were 7S globulins, and the resulting emulsifying activity enhancements of 11S, in parallel with that of SPI, were indicative of its determinant role in the overall emulsifying properties of pH-shifting-treated SPI. PRACTICAL APPLICATION: Extreme alkaline (pH 12) and acidic (pH 1.5) medium treatments can significantly modify the structure and enhance the emulsifying properties of both β-conglycinin and glycinin components of SPI. The functionality improvement by the pH processes is more remarkable for the glycinin protein fraction. Therefore, SPI enriched with glycinin seems to be particularly suitable for extreme acidic or alkaline processes to produce surface-active functional ingredients for food applications.

Chloridobis[N'-(2-meth-oxy-benzyl-idene)-4-nitro-benzohydrazidato-κO,N'](4-methyl-pyridine-κN)cobalt(III)

Acta Crystallographica. Section E, Structure Reports Online. 2011  |  Pubmed ID: 21522234

In the title complex, [Co(C(15)H(12)N(3)O(4))(2)Cl(C(6)H(7)N)], the Co(III) ion is coordinated by two N atoms and two O atoms from two deprotonated Schiff base ligands, one N atom from a 4-methyl-pyridine ligand and one Cl atom, forming a distorted octa-hedral geometry. The Co(III) ion is displaced by 0.038 (2) Å from the equatorial plane towards the axial Cl atom.

Use of Autologous Chondrocytes and Bioinert Perforated Chambers to Tissue Engineer Cartilage In Vivo

The Journal of Surgical Research. Mar, 2012  |  Pubmed ID: 22099592

To explore the potential applications of a chamber for in vivo tissue engineering, and to establish a novel model for in vivo tissue-engineered cartilage.