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1.
J Vet Intern Med ; 37(6): 2391-2401, 2023.
Article in English | MEDLINE | ID: mdl-37837297

ABSTRACT

BACKGROUND: Tumor biomarkers have used widely in clinical oncology in human medicine. Only a few studies have evaluated the clinical utility of tumor biomarkers for veterinary medicine. A test for fibrinogen and fibrin degradation products (DR-70) has been proposed as an ideal biomarker for tumors in humans. The clinical value of DR-70 for veterinary medicine however has yet to be determined. OBJECTIVES: Investigate the diagnostic value of DR-70 concentrations by comparing them between healthy dogs and dogs with tumors. ANIMALS: Two hundred sixty-three dogs with different types of tumors were included. Sixty healthy dogs also were recruited for comparison. METHODS: The DR-70 concentrations were measured in all recruited individuals by ELISA. Clinical conditions were categorized based on histopathology, cytology, ultrasound examination, radiology, clinical findings, and a combination of these tests. RESULTS: The median concentration of DR-70 was 2.130 ± 0.868 µg/mL in dogs with tumors, which was significantly higher than in healthy dogs (1.202 ± 0.610 µg/mL; P < .0001). With a cut-off of 1.514 µg/mL, the sensitivity and specificity of DR-70 were 84.03% and 78.33%, respectively. The area under curve was 0.883. The DR-70 concentration can be an effective tumor biomarker in veterinary medicine. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased DR-70 concentrations were not affected by tumor type, sex, age, or body weight. However, in dogs with metastatic mast cell tumors and oral malignant melanoma, DR-70 concentrations were significantly increased. Additional studies, including more dogs with nonneoplastic diseases, are needed to further evaluate the usefulness of DR-70 as a tumor biomarker.


Subject(s)
Biomarkers, Tumor , Dog Diseases , Fibrin Fibrinogen Degradation Products , Neoplasms , Animals , Dogs , Humans , Biomarkers, Tumor/blood , Dog Diseases/blood , Dog Diseases/diagnosis , Fibrin Fibrinogen Degradation Products/analysis , Fibrinogen/metabolism , Neoplasms/blood , Neoplasms/diagnosis , Neoplasms/veterinary , Sensitivity and Specificity
2.
Nature ; 602(7897): 437-441, 2022 02.
Article in English | MEDLINE | ID: mdl-35173345

ABSTRACT

Ever more stringent regulations on greenhouse gas emissions from transportation motivate efforts to revisit materials used for vehicles1. High-strength aluminium alloys often used in aircrafts could help reduce the weight of automobiles, but are susceptible to environmental degradation2,3. Hydrogen 'embrittlement' is often indicated as the main culprit4; however, the exact mechanisms underpinning failure are not precisely known: atomic-scale analysis of H inside an alloy remains a challenge, and this prevents deploying alloy design strategies to enhance the durability of the materials. Here we performed near-atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. Our insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design.

3.
Comb Chem High Throughput Screen ; 25(5): 895-905, 2022.
Article in English | MEDLINE | ID: mdl-33645476

ABSTRACT

BACKGROUND: Frankincense is a resin secreted by the Boswellia tree. It is used in perfumery, aromatherapy, skincare, and traditional Chinese medicine. However, all Boswellia species are under threat owing to habitat loss and overexploitation. As a result, the market is getting flooded with counterfeit frankincense products. OBJECTIVE: This study aims to establish a high-throughput method to screen and identify the authenticity of commercial frankincense products. We report, for the first time, a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based method for rapid and high-throughput screening of frankincense samples. METHODS: MALDI-TOF MS, HPLC, thin-layer chromatography (TLC), and in vitro antiinflammatory activity assay were used to examine the frankincense samples. RESULTS: Well-resolved peaks of frankincense triterpenoids in the spectra were observed in the crude extract of commercial samples, including α-boswellic acids (αBAs), ß-boswellic acids (ßBAs), 11-keto-ß-boswellic acids (KBAs), acetyl-11-keto-ß-boswellic acids (AKBAs), and their esters. These compounds can be used as indicators for determining the authenticity of frankincense. CONCLUSION: Unlike LC-MS, which is a time-consuming and expensive method, and TLC, which requires a reference sample, our inexpensive, rapid high-throughput identification method based on MALDI-TOF MS is ideal for large-scale screening of frankincense samples sold in the market.


Subject(s)
Boswellia , Frankincense , Anti-Inflammatory Agents , Boswellia/chemistry , Chromatography, High Pressure Liquid/methods , Mass Spectrometry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
4.
Biosensors (Basel) ; 11(12)2021 Dec 03.
Article in English | MEDLINE | ID: mdl-34940252

ABSTRACT

Effective bilateral hand training is desired in rehabilitation programs to restore hand function for people with unilateral hemiplegia, so that they can perform daily activities independently. However, owing to limited human resources, the hand function training available in current clinical settings is significantly less than the adequate amount needed to drive optimal neural reorganization. In this study, we designed a lightweight and portable hand exoskeleton with a hand-sensing glove for bilateral hand training and home-based rehabilitation. The hand-sensing glove measures the hand movement of the less-affected hand using a flex sensor. Thereafter, the affected hand is driven by the hand exoskeleton using the measured hand movements. Compared with the existing hand exoskeletons, our hand exoskeleton improves the flexible mechanism for the back of the hand for better wearing experience and the thumb mechanism to make the pinch gesture possible. We designed a virtual reality game to increase the willingness of repeated movement practice for rehabilitation. Our system not only facilitates bilateral hand training but also assists in activities of daily living. This system could be beneficial for patients with hemiplegia for starting correct and sufficient hand function training in the early stages to optimize their recovery.


Subject(s)
Exoskeleton Device , Activities of Daily Living , Hand , Hemiplegia , Humans , Movement
5.
Nat Mater ; 20(12): 1629-1634, 2021 12.
Article in English | MEDLINE | ID: mdl-34239084

ABSTRACT

The antagonism between strength and resistance to hydrogen embrittlement in metallic materials is an intrinsic obstacle to the design of lightweight yet reliable structural components operated in hydrogen-containing environments. Economical and scalable microstructural solutions to this challenge must be found. Here, we introduce a counterintuitive strategy to exploit the typically undesired chemical heterogeneity within the material's microstructure that enables local enhancement of crack resistance and local hydrogen trapping. We use this approach in a manganese-containing high-strength steel and produce a high dispersion of manganese-rich zones within the microstructure. These solute-rich buffer regions allow for local micro-tuning of the phase stability, arresting hydrogen-induced microcracks and thus interrupting the percolation of hydrogen-assisted damage. This results in a superior hydrogen embrittlement resistance (better by a factor of two) without sacrificing the material's strength and ductility. The strategy of exploiting chemical heterogeneities, rather than avoiding them, broadens the horizon for microstructure engineering via advanced thermomechanical processing.


Subject(s)
Hydrogen , Steel , Steel/chemistry , Tensile Strength
6.
Sci Technol Adv Mater ; 20(1): 1073-1089, 2019.
Article in English | MEDLINE | ID: mdl-31807219

ABSTRACT

Quantitative detection of hydrogen in metal is important in providing a better basis for fundamental investigations of hydrogen embrittlement and hydrogen-related corrosion phenomena. Thermal desorption spectroscopy (TDS) has long been used in characterizing different hydrogen traps inside materials. However, in TDS measurements, the diffusible hydrogen (hydrogen at interstitial sites and weakly bound hydrogen) is usually not detected. The Davanathan-Starchurski permeation technique can cover this shortage. However, for such experiments, the stability of the palladium at the exit side, i.e. in aqueous solution under high potential polarization is an important issue. Alternatively, a Kelvin probe-based (KP-based) potentiometric method developed a few years ago has shown to allow quantitative determination of hydrogen in metal. This method is based on measuring the hydrogen electrode potential on the Pd-coated surface. The aim of this work is to check the reliability of this method and to demonstrate its potential applications in determining the hydrogen amount distributed in both shallow and deep traps in steel. The results reveal that different crystallographic orientation, grain shapes and grain sizes of the deposited palladium film (in the range of variation in this work) do not cause relevant effects on the KP-based hydrogen detection. It is shown in this work that the time lag and permeation rate derived from the permeation curves obtained by this method show a very good reliability and the calculated hydrogen amount shows a good agreement with TDS results. 5 wt.% Ni ferritic steel is used as a model material in this work.

7.
Phytochem Anal ; 30(6): 720-726, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31313432

ABSTRACT

INTRODUCTION: Dragon blood is a deep-red plant resin which has been used as folk medicine for more than a thousand years. It can be produced from at least four entirely different plant families: Asparagaceae, Arecaceae, Chamaesyce, and Fabaceae. Current pharmacopeia states that the only "authentic" source of dragon blood is the palm tree, Daemonorops draco. OBJECTIVE: The present study aims to find a high-throughput method to screen and identify the plant sources of commercial dragon blood products. METHODOLOGY: A matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) based method for rapid screening of dracorhodin in commercial dragon blood samples was established in this study. RESULTS: Well-resolved peaks of dracorhodin in spectra were observed in the crude extracts of samples. Dragon blood samples from two other plant species, Dracaena cinnabari and Dracaena cochinchinensis, were also examined. Their indicator compounds, loureirin A and B, were detected in these plants. CONCLUSION: A MALDI-TOF based method for preliminarily examination of commercial dragon blood samples is reported here. In contrast to MALDI-TOF, liquid chromatography mass spectrometry (LC-MS) is a time-consuming and costly method, not ideal for routine and large-scale screening of commercial samples.


Subject(s)
Arecaceae/chemistry , Dracaena/chemistry , Plant Extracts/chemistry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Chromatography, High Pressure Liquid/methods
8.
Carbohydr Polym ; 111: 236-44, 2014 Oct 13.
Article in English | MEDLINE | ID: mdl-25037348

ABSTRACT

In this study we have developed a capillary zone electrophoresis (CZE) method for the determination of the degree of deacetylation (DDA) of chitosan. The electrophoretic mobilities of chitosans were measured by using the optimized CZE conditions. An internal standard, hexammine cobalt(III) chloride, was used to improve the precision of the electrophoretic mobility measurement. We have constructed a linear calibration curve between the CZE measured mobilities and the (1)H NMR determined DDAs ranging from 55.3% to 96.2%. Based on the established linear calibration equation and the CZE measured mobilities, we were able to obtain not only the average DDA values but also the DDA distribution profiles of the chitosan samples. Without prior sample treatment or purification, we have successfully employed the newly developed CZE method to characterize the reacetylation derivatives of chitosans and to detect the DDA variability in different lots of chitosan products.


Subject(s)
Chitosan/chemistry , Acetylation , Electrophoresis, Capillary/methods
9.
Fish Shellfish Immunol ; 35(5): 1483-500, 2013 Nov.
Article in English | MEDLINE | ID: mdl-23994281

ABSTRACT

Nitric oxide (NO) is a well known essential molecule that is involved in multiple functions such as neuron transduction, cardiac disease, immune responses, etc.; nitric oxide synthase (NOS) is a critical enzyme that catalyzes the synthesis of it. A very few crustacean NOS molecules were biochemically characterized so far. In the present study, we cloned and characterized a NOS cDNA from haemocytes of tiger shrimp (Penaeus monodon) (PmNOS). The full-length of PmNOS cDNA contained 3997 bp, including a 5'UTR of 249 bp, ORF of 3582 bp and a 3'UTR of 166 bp. The putative peptide was 1193 amino acid residues in length, with an estimated molecular weight of 134.7 kDa and pI 6.7. Structurally, PmNOS contained oxygenase and reductase domains at N-terminal and C-terminal, respectively, and connected with a calmodulin binding motif. The deduced amino acid sequence of PmNOS shared 98% identical to the Chinese shrimp (Fenneropenaeus chinensis) NOS. Phylogenetically, PmNOS clustered with invertebrate NOS, but not clustered with iNOS, eNOS or nNOS found in vertebrates. PmNOS mRNA was expressed in many tissues or organs including thoracic and ventral nerves, midgut, gill, eyestalk, haemocytes, subcuticular epithelium and heart, but not found in hepatopancreas, muscle and lymphoid organ. But there was no significant difference in PmNOS mRNA expression after stimulation with LPS either by different concentration or time course or against CpG-ODN 2006. The enzyme activities of rPmNOS or crude homogenates from different tissues were detected, and were shown its highest activity in thoracic and ventral nerves, moderate in midgut and haemocytes but the lowest activity were seen in muscle. The addition of NOS antibody against NADPH binding domain leads to less activity which suggested that NADPH was an essential cofactor for PmNOS catalytic activity. The calcium dependency of PmNOS was ascertained using calmodulin inhibitor, Trifluroperazine. To confirm the population of haemocyte which produce NOS, the florescence test was assayed, and it implicated that the production of NO was catalyzed by subset of granulocytic NOS. Since the MW range, inducible/noninducible transcript, calcium-dependent activity and tissue distribution, we suggest that PmNOS may recognize as an ancient NOS evolutionarily.


Subject(s)
Evolution, Molecular , Nitric Oxide Synthase/genetics , Penaeidae/enzymology , RNA, Messenger/metabolism , Amino Acid Sequence , Animals , Base Sequence , Calcium/metabolism , Cloning, Molecular , DNA, Complementary/genetics , Fluorescence , Gene Components/genetics , Gene Expression Profiling , Hemocytes/metabolism , Molecular Sequence Data , NADP/metabolism , Oligonucleotides/genetics , Penaeidae/genetics , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA , Sequence Homology , Species Specificity , Trifluoperazine
10.
Carbohydr Polym ; 92(2): 2141-8, 2013 Feb 15.
Article in English | MEDLINE | ID: mdl-23399269

ABSTRACT

The chitosanase and chitinase activity were revealed in the culture supernatant of Bacillus cereus TKU027 with shrimp head powder (SHP) as the sole carbon/nitrogen source. The chitosan with 60% degree of deacetylation (DD) was depolymerized by TKU027 crude enzyme. The low DP oligomers stimulated the growth of Lactobacillus paracasei BCRC12193 and Lactobacillus kefir BCRC14011 in a MRS broth supplemented with low DP oligomers for 12 h. Conversely, the high DP oligomers (0.1%) had potent inhibitory effects against L. paracasei BCRC12193 and L. kefir BCRC14011 for 48 h. Besides, the study also investigated the effects of B. cereus TKU027 on degradation of SHP and the survival conditions of bacteria in mangrove river sediment of Tamsui River. The 5 weeks-incubation sample of SHP and B. cereus TKU027-amended mangrove river sediment showed the highest amounts of biomass, reducing sugar and total sugar, and some variance of bacterial community compositions existed in the soils.


Subject(s)
Bacillus cereus/enzymology , Chitinases/metabolism , Glycoside Hydrolases/metabolism , Prebiotics , Soil Microbiology , Bacillus cereus/cytology , Chitosan/chemistry , Chitosan/metabolism , Dose-Response Relationship, Drug , Extracellular Space/enzymology , Geologic Sediments/microbiology , Hydrolysis , Lactobacillus/drug effects , Lactobacillus/growth & development , Oligosaccharides/chemistry , Oligosaccharides/pharmacology , Rivers/microbiology
11.
J Shoulder Elbow Surg ; 22(7): 932-9, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23312816

ABSTRACT

BACKGROUND: This study aims to clarify the effect of various designs of reverse shoulder prosthesis (RSP) on stress variation of its glenoid component using 2-dimensional (2D) finite element analysis (FEA). This FEA study provides future reference for the optimal design of glenoid component of RSP. MATERIALS AND METHODS: In this study, a 2D finite element (FE) model of human shoulder with implementation of RSP was developed by commercial FE software. The proper material properties were adopted in our model. Various design factors were simulated and all the mechanical profile data were investigated by FEA. RESULTS: Both distal placement and increased lateral offset of glenosphere induce higher stress over glenoid-baseplate junction. Increased thickness of graft, inferiorly tilting of the baseplate, and adoption of BIO-RSA (bony increased-offset reverse shoulder arthroplasty) incur higher stresses over glenoid screws. The inferior screw attains more stress than superior screw. Maximum stress occurs at the base of inferior screw. CONCLUSION: Increased eccentric offset and lateral offset of glenosphere, although being able to reduce notching, may pay the penalty of significant stress concentration over glenoid and its subsequent loosening. Maximum stress occurs at the base of inferior screw elucidate the direct contact failure mode at the middle of inferior screw. This study provides an alternative tool for the optimal design of glenoid component of RSP in the future.


Subject(s)
Arthroplasty, Replacement/methods , Finite Element Analysis , Joint Prosthesis , Shoulder Joint/surgery , Stress, Mechanical , Arthroplasty, Replacement/instrumentation , Biomechanical Phenomena , Bone Plates , Bone Screws , Humans , Models, Anatomic , Prosthesis Design , Sensitivity and Specificity
12.
Pediatr Neonatol ; 52(4): 232-6, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21835371

ABSTRACT

Misalignment of lung vessels (MLV) with or without alveolar capillary dysplasia (ACD) is a rare cause of idiopathic persistent pulmonary hypertension of the neonate. This report describes a full-term infant with severe and intractable pulmonary hypertension. The patient's condition progressively deteriorated despite high-frequency oscillatory ventilation, infusion of magnesium sulfate, dopamine, and dobutamine to control blood pressure, and nitric oxide inhalation therapy. The infant died at 5 days of age. The diagnosis of MLV with ACD was established by autopsy. Histopathologic analysis revealed a failure of formation and an ingrowth of alveolar capillaries, thickening of the alveolar walls, poor contact of capillaries with alveolar epithelium, small intra-acinar muscularized arterioles, and anomalous pulmonary veins within bronchovascular bundles. The low rate of diagnosis of MLV with or without ACD may be because of the early high mortality rate or patchy involvement in some cases. Increasing awareness of this clinical entity may prevent the use of costly, invasive, and probably ineffective procedures. Short-term improvement after inhalation of nitric oxide does not lead to long-term survival but merely provides time for potential lung transplantation.


Subject(s)
Lung/abnormalities , Lung/blood supply , Persistent Fetal Circulation Syndrome/pathology , Adult , Autopsy , Female , Humans , Infant, Newborn , Male , Persistent Fetal Circulation Syndrome/etiology , Pregnancy , Pulmonary Alveoli/abnormalities , Pulmonary Alveoli/pathology
13.
Opt Express ; 19(3): 2556-61, 2011 Jan 31.
Article in English | MEDLINE | ID: mdl-21369075

ABSTRACT

We demonstrate a reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals (DDPSBP-LC). At the voltage-off state, the dye molecules and liquid crystals form the structure of the double twist cylinders. As a result, the DDPSBP-LC is in dark state due to the combination of Bragg reflection and light absorption. At the voltage-on state, the blue phase structure is unwound locally. The DDPSBP-LC is then in bright state because of the small light absorption only. The applications of such a switch are shutter glass of 3D displays, and electronic papers.


Subject(s)
Coloring Agents/chemistry , Liquid Crystals/chemistry , Polymers/chemistry , Refractometry/instrumentation , Color , Equipment Design , Equipment Failure Analysis
14.
Chemistry ; 17(3): 792-9, 2011 Jan 17.
Article in English | MEDLINE | ID: mdl-21226093

ABSTRACT

Through molecular design and straightforward synthesis, incorporating an additional alkoxy chain onto various numbers of peripheral phenyls in nematogenic hexakis(4-alkoxyphenylethynyl)benzene was achieved to generate columnar phases with significantly expanded temperature ranges. For the compound with two decyloxy chains on every peripheral phenyl, scanning tunnelling microscopic studies indicate the molecule adopts a preferred molecular-swirl geometry by restricting the conformational arrangement of the alkoxy side chains. Cooperative packing of the molecular swirls by a lock-in mechanism among columns results in a stable helical column packing evidenced by powder X-ray diffraction.

15.
Peptides ; 31(7): 1374-82, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20381562

ABSTRACT

Neuropeptide FF (NPFF) exhibited anti-/pro-opioid effects when centrally injected. It was proved to bind to its own receptors, namely NPFF(1) and NPFF(2) receptors, but did not bind to opioid receptors. In our previous study, we found that i.c.v. injected NPFF suppressed morphine-induced conditioned place preference (CPP) in rats, which indicated that NPFF may play a role in the modulation of morphine-induced reward. In the present study, we further investigated the action site of NPFF to attenuate morphine-induced reward. Bilateral intra-VTA (ventral tegmental area) and intra-NAc (nucleus accumbens) injections of NPFF both blocked the CPP caused by morphine in rats. This suggests that NPFF may act at both VTA and NAc to inhibit the sensitization of the mesocorticolimbic dopaminergic pathway. Neurochemical analyses support that NPFF could be acting through the inhibition of the mesocorticolimbic dopaminergic activity increased by morphine. We also determined the distribution of NPFF receptors in rat brains. Our results showed that both NPFF receptors were abundantly expressed in VTA but with less content in NAc. In fluorescent immunohistochemical staining, our results revealed that NPFF(1) and NPFF(2) receptors could be expressed at the TH (tyrosine hydroxylase)- or GAD67 (glutamic acid decarboxylase-67)-positive neurons in VTA, whereas some of them were present in the negative neurons. This implied a possible function of NPFF to modulate dopaminergic neurons directly and a possible indirect action of NPFF on GABAergic neurons to modulate dopamine release. Taken together, our study should be helpful for clarifying the possible mechanisms of NPFF system to modulate morphine-induced reward.


Subject(s)
Brain/drug effects , Morphine/pharmacology , Receptors, Neuropeptide/metabolism , Reward , Analgesics, Opioid/metabolism , Analgesics, Opioid/pharmacology , Animals , Glutamate Decarboxylase/metabolism , Male , Morphine/metabolism , Neurons/metabolism , Rats , Rats, Sprague-Dawley , Ventral Tegmental Area/drug effects , Ventral Tegmental Area/metabolism
16.
FEMS Microbiol Lett ; 274(1): 148-53, 2007 Sep.
Article in English | MEDLINE | ID: mdl-17590222

ABSTRACT

Ornithine and lysine are degraded in quite a similar way in Clostridium sticklandii. Both pathways involve adenosylcobalamin-dependent enzymes, d-ornithine 4,5-aminomutase and lysine 5,6-aminomutase. According to previous reports, lysine 5,6-aminomutase is an ATP-dependent allosteric enzyme with many different activators and inhibitors. However, recent studies indicate that ATP does not have a regulatory effect on the recombinant enzyme. To monitor the activity of lysine aminomutase, a novel capillary electrophoresis-based assay method was developed. The present results demonstrate that the S subunit of d-ornithine aminomutase, OraS, is capable of forming a complex with KamDE of lysine 5,6-aminomutase and restores the enzyme's ATP-dependent allosteric regulation. Not only does ATP lower the K(m) of the KamDE-OraS complex for adenosylcobalamin and pyridoxal phosphate, but also OraS protein alone lowers the K(m) of KamDE for adenosylcobalamin and pyridoxal phosphate. The activity of reconstituted enzyme can also be activated by ammonium ion as reported by Morley and Stadtman.


Subject(s)
Clostridium sticklandii/enzymology , Intramolecular Transferases/metabolism , Intramolecular Transferases/physiology , Protein Subunits/physiology , Adenosine Triphosphate/metabolism , Allosteric Regulation , Cloning, Molecular , Enzyme Activation , Intramolecular Transferases/chemistry
17.
Langmuir ; 21(19): 8947-51, 2005 Sep 13.
Article in English | MEDLINE | ID: mdl-16142983

ABSTRACT

Gold nanoparticles prepared by chemical reduction in sodium dodecyl sulfate (SDS) solution are size-controlled with the addition of pyrene. Micellar electrokinetic capillary chromatography (MEKC) is applied to the system to examine the size and polydispersity of gold nanoparticles and to show that pyrene has the extraordinary effect in decreasing the size and narrowing the dispersity of gold nanoparticles. The MEKC electropherograms further suggest that pyrene could be oxidized by the aqueous Au(III) complexes first. All the reduced Au complexes were then solubilized in the pyrene-SDS micelles. The growth of gold nanoparticles beyond the embryonic stage was subsequently inhibited by the encapsulating SDS and electrophilic pyrene.

18.
J Biomed Opt ; 7(3): 498-506, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12175303

ABSTRACT

Polymeric microspheres containing a magnetic core have been used in cancer therapy for biophysical targeting of antitumor agents and in magnetic resonance imaging as contrasting agents. For the Human Genome Project, deoxyribose nucleic acid (DNA) capillary electrophoresis has become the most widely used analytical technique where a key component is the design of an effective separation medium. The synthesis and optical characterization of polymeric coated superparamagnetic nanoparticles and of (self-assembled) polymer networks by means of a range of physical techniques, including laser light scattering and laser-induced fluorescence detection, are presented. (1) Polymeric microspheres with a superparamagnetic core. A water-in-oil microemulsion approach has been used successfully to synthesize the superparamagnetic core and the polymeric microsphere in one continuous step. The synthesis permits us to control the magnetic nanoparticle size and the thickness of the hydrogel, ranging from 80 to 320 nm. Magnetite concentration in the microspheres, calculated by vibrating-sample magnetometry, was found to be up to 3.3 wt %. The internal structure of the microspheres, as observed by atomic force microscopy, confirmed a core-shell model. (2) Development of new separation media for DNA capillary electrophoresis. Block copolymers in selective solvents can self-assemble to form supramolecular structures in solution. The nanostructures can be characterized in the dilute concentration regime by means of laser light scattering. At semidilute concentrations, the mesh size, the supramolecular structure, and the surface morphology can be investigated by means of small angle x-ray scattering and atomic force microscopy. The structural knowledge and the information on chain dynamics can then be correlated with electrophoresis using laser-induced fluorescence detection to provide a deeper understanding for the development of new separation media.


Subject(s)
Optics and Photonics , Biophysical Phenomena , Biophysics , DNA/isolation & purification , Electrophoresis, Capillary , Humans , Magnetics , Microscopy, Atomic Force , Microspheres , Nanotechnology , Polymers , Scattering, Radiation , X-Rays
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