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Physical Methods (physical + methods)
Selected AbstractsPlasma facilitated delivery of DNA to skinBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Richard J. Connolly Abstract Non-viral delivery of cell-impermeant drugs and DNA in vivo has traditionally relied upon either chemical or physical stress applied directly to target tissues. Physical methods typically use contact between an applicator, or electrode, and the target tissue and may involve patient discomfort. To overcome contact-dependent limitations of such delivery methodologies, an atmospheric helium plasma source was developed to deposit plasma products onto localized treatment sites. Experiments performed in murine skin showed that samples injected with plasmid DNA encoding luciferase and treated with plasma demonstrated increased levels of expression relative to skin samples that received injections of DNA alone. Increased response relative to injection alone was observed when either positive or negative voltage was used to generate the helium plasma. Quantitative results over a 26-day follow-up period showed that luciferase levels as high as 19-fold greater than the levels obtained by DNA injection alone could be achieved. These findings indicate that plasmas may compete with other physical delivery methodologies when skin is the target tissue. Biotechnol. Bioeng. 2009; 104: 1034,1040. © 2009 Wiley Periodicals, Inc. [source] Aqueous Stabilization and Self-Assembly of Graphene Sheets into Layered Bio-Nanocomposites using DNAADVANCED MATERIALS, Issue 31 2009Avinash J. Patil Stabilization of aqueous suspensions of graphene single sheets by single-stranded DNA is demonstrated using a range of physical methods. The negatively charged bio-functionalized graphene sheets are spontaneously assembled into layered hybrid nanocomposites containing intercalated DNA molecules, or co-intercalated mixtures of DNA and the redox protein, cytochrome c. Small-molecule reducing agents readily access the intercalated proteins. [source] A brief introduction to cell-penetrating peptidesJOURNAL OF MOLECULAR RECOGNITION, Issue 5 2003Pontus Lundberg Abstract Cell membranes act as protective walls to exclude most molecules that are not actively imported by living cells. This is an efficient way for a cell to prevent uncontrolled influx or efflux of solutes, which otherwise would be harmful to it. Only compounds within a narrow range of molecular size, polarity and net charge are able to diffuse effectively through cell membranes. In order to overcome this barrier for effective delivery of membrane-impermeable molecules, several chemical and physical methods have been developed. These methods, e.g. electroporation, and more recent methods as cationic lipids/liposomes, have been shown to be effective for delivering hydrophobic macromolecules. The drawbacks of these harsh methods are, primarily, the unwanted cellular effects exerted by them, and, secondly, their limitation to in vitro applications. The last decade's discovery of cell-penetrating peptides translocating themselves across cell membranes of various cell lines, along with a cargo 100-fold their own size, via a seemingly energy-independent process, opens up the possibility for efficient delivery of DNA, antisense peptide nucleic acids, oligonucleotides, proteins and small molecules into cells both in vitro and in vivo. Copyright © 2003 John Wiley & Sons, Ltd. [source] Sedimentation behaviour and turbidity of carrot juices in relation to the characteristics of their cloud particlesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2003Martin Reiter Abstract The cloud stability of carrot juices was investigated using physical methods. In contrast to cloudy juices from fruits or other vegetables described so far, complete clarification of juice samples could not be achieved even after ultracentrifugation. Since the density of one particle fraction was almost equal to that of the continuous phase, this fraction was resistant to sedimentation by centrifugal forces up to 60 600 × g in an 8° Brix carrot juice. Cloud stability problems of carrot juices, therefore, are usually associated with bottom sediment formation, but not with visible loss of turbidity. Particle size and density were shown to be decisive for suspension stability, whilst both particle charge and serum viscosity did not show any effect on cloud stability. The reasons for the exceptional stability of the suspended particles are discussed. Based on three particle fractions, a new physical concept could be deduced according to particle size and density explaining the extraordinary suspension stability of carrot juices. Copyright © 2003 Society of Chemical Industry [source] Recent trends in non-viral vector-mediated gene deliveryBIOTECHNOLOGY JOURNAL, Issue 11 2009Atul Pathak Abstract Nucleic acids-based next generation biopharmaceuticals (i.e., pDNA, oligonucleotides, short interfering RNA) are potential pioneering materials to cope with various incurable diseases. However, several biological barriers present a challenge for efficient gene delivery. On the other hand, developments in nanotechnology now offer numerous non-viral vectors that have been fabricated and found capable of transmitting the biopharmaceuticals into the cell and even into specific subcellular compartments like mitochondria. This overview illustrates cellular barriers and current status of non-viral gene vectors, i.e., lipoplexes, liposomes, polyplexes, and nanoparticles, to relocate therapeutic DNA-based nanomedicine into the target cell. Despite the awesome impact of physical methods (i.e., ultrasound, electroporation), chemical methods have been shown to accomplish high-level and safe transgene expression. Further comprehension of barriers and the mechanism of cellular uptake will facilitate development of nucleic acids-based nanotherapy for alleviation of various disorders. [source] Optical, Redox, and NLO Properties of Tricyanovinyl Oligothiophenes: Comparisons between Symmetric and Asymmetric Substitution PatternsCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2006Juan Casado Dr. Abstract A series of tricyanovinyl (TCV)-substituted oligothiophenes was synthesized and investigated with a number of physical methods including UV/Vis, IR, and Raman spectroscopy, nonlinear optical (NLO) measurements, X-ray diffraction, and cyclic voltammetry. Mono- or disubstituted oligomers were prepared by the reaction of tetracyanoethylene with mono- or dilithiated oligomers. The comparative effects of the symmetric and asymmetric substitutions in the electronic and molecular properties have been addressed. These oligomers display dramatic reductions in both their optical and electrochemical band gaps in comparison with unsubstituted molecules. The analysis of the electronic properties of the molecules was assisted by density functional theory calculations, which are in excellent agreement with the experimental data. TCV substitution influences the energies of the frontier orbitals, especially with respect to the stabilization of LUMO orbitals. X-ray structural characterization of a monosubstituted oligomer exhibits ,-stacking with favorable intermolecular interactions. NLO results agree with the role of the intramolecular charge-transfer feature in the asymmetric samples. These results furthermore exalt the role of conformational flexibility in the disubstituted compounds and reveal an unexpected nonlinear optical activity for symmetric molecules. Regarding the electronic structure, the interpretation of the vibrational data reflects the balanced interplay between aromatic and quinoid forms, finely tuned by the chain length and substitution pattern. The electronic and structural properties are consistent with the semiconducting properties exhibited by these materials in thin film transistors (TFTs). [source] Hoop-Shaped Condensed Aromatic Systems: Synthesis and Structure of Iron, and Ruthenium,Hepta(organo)[60]fullerene ComplexesCHEMISTRY - AN ASIAN JOURNAL, Issue 8 2007Yutaka Matsuo Dr. Abstract Potassium reduction of iron, and ruthenium,penta(organo)[60]fullerene complexes, [M(,5 -C60R5)(,5 -Cp)] (1,a: M=Fe, R=Ph; 1,b: M=Fe, R=Me; 1,c: M=Ru, R=Ph; 1,d: M=Ru, R=Me; Cp=C5H5) gave mono- and dianions of these complexes. Treatment of the dianion 1,a with ,-bromodiphenylmethane gave three different iron,hepta(organo)[60]fullerenes, [Fe{,5 -C60Ph5(CHPh2)2}(,5 -Cp)], as a mixture of regioisomers. All three compounds were fully characterized by physical methods, including X-ray crystallography and electrochemical measurements. One of the three compounds contains a new hoop-shaped condensed aromatic system. [source] Detection Methods for Irradiated FoodsCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 1 2009Sulaxana Kumari Chauhan ABSTRACT:, Proper control of irradiation processing of food is very critical to facilitate international trade of irradiated foods and to enhance consumer confidence, consumer choice, and safety. Analytical detection of radiation-processing of food is very important to implement quality control at all levels. An ideal detection method should measure a specific radiation effect, which is proportional to the dose and should not be affected by processing parameters and storage conditions or the length of time between irradiation processing and analysis. The detection of irradiated foods is mainly based on radiolysis of lipids, modification of amino acids, modification of DNA, modification of carbohydrates, formation of free radicals, release of hydrogen gas, alterations in microbial load, measurement of biological difference, and other physical methods. [source] | |||||||||||||