Design and Development of Light-Sensitive Chitosan-Based Nanocarriers for Gene Delivery

2012 ◽  
Vol 86 ◽  
pp. 75-80 ◽  
Author(s):  
Nicolas Duceppe ◽  
Maryam Tabrizian
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Uv Light ◽  
Transfection Efficiency ◽  
Fluorescent Microscopy ◽  
Amide Bond ◽  
Microscopy Imaging ◽  
Hek 293 ◽  
Dna Release ◽  
Nuclear Magnetic

In this work, we report on the development of a multifunctional and photo-inducible nanoplex made of chitosan (Ch) and hyaluronic acid (HA) for delivery of nucleic acid. Self-assembled Ch/HA nanoparticles were attached to ortho-nitrobenzyl (o-NB) photo-labile molecules (PL)-gold nanoparticles via thiol groups and to QDs-conjugate ssDNA through amide bond linkage to form nanoplexes (Ch:HA:AuPL:QD-DNA). The composition of DNA nanocarriers was validated by nuclear magnetic resonance, transmission electronic microscopy, energy dispersive x-ray spectroscopy, gel electrophoresis and spectrophotometry. The change in zeta potential (34 ± 11 to -26 ± 11 mV) and the loss of the o-NB characteristic peaks in nuclear magnetic resonance spectra, after the exposure of the PL molecule to ultraviolet light, both confirmed the photo-labile properties of the system. The potential of the nanoplexes to induce high cell transfection was assessed by flow cytometry and fluorescent microscopy imaging. Over 30% transfection of HEK-293 was obtained with the nanoplexes after a one-minute exposure of cells to UV light. This corresponds to a 15% increase in the transfection efficiency compared to unexposed Ch:HA:AuPL:QD-DNA nanocarriers. This high transfection efficiency was associated with the unique design of the carrier system and its photo-responsiveness feature for facilitating the DNA release.

Peptide Conformations. I. Nuclear Magnetic Resonance Study of the Carbamate Reaction of Amino Acids and Peptides

1971 ◽  
Vol 49 (5) ◽  
pp. 767-776 ◽  
Author(s):  
R. U. Lemieux ◽  
M. A. Barton
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Amide Bond ◽  
Resonance Spectroscopy ◽  
Peptide Conformations ◽  
End Distance ◽  
Phenylalanine Residue ◽  
Nuclear Magnetic

Nuclear magnetic resonance spectroscopy has been applied to the study of carbamate formation in solutions of amino acids and peptides in a carbonate-bicarbonate system. The possible conformations of these carbamates are discussed in terms of the n.m.r. data obtained. The n.m.r. parameters are reported for the diastereomers L-alanyl-L or D-phenylalanine and L-phenylalanyl-L or D-alanine and for the dipeptide glycyl-L-phenylalanine and their carbamates. The results are interpreted in terms of preferred rotamers about the Cα—Cβ bond of the phenylalanine residue and a β-type conformation of the peptide chain, wherein the two α-protons lie in the plane of the amide bond. All observations are in agreement with a shorter end to end distance in L,D- compared with L,L-dipeptides.

scholarly journals A 1H Nuclear Magnetic Resonance Spectroscopic Study of Hindered Rotation about the Amide Bond in Some N-Formyl-2-indolinols.

1969 ◽  
Vol 23 ◽  
pp. 1155-1167 ◽  
Author(s):  
Ole Buchardt ◽  
Philip L. Kumler ◽  
Christian Lohse ◽  
Kurt Andersson ◽  
Alf A. Lindberg ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Spectroscopic Study ◽  
Amide Bond ◽  
Hindered Rotation ◽  
1H Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

The Effect of UV Stabilizer on the Photo Degradation of Perfluoropolyether Lubricants Used in Hard Disk

2007 ◽  
Author(s):  
Jihye Lee ◽  
Sang-Wook Chun ◽  
Ho-Jong Kang ◽  
Frank E. Talke
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Physical Properties ◽  
Main Chain ◽  
Uv Light ◽  
Light Exposure ◽  
Hard Disk ◽  
Photo Degradation ◽  
Pfpe Lubricants ◽  
Nuclear Magnetic

Ultraviolet (UV) light exposure can lead to photo degradation of perfluoropolyether (PFPE) lubricants, resulting in a change of their physical properties. In this paper, 2,3,4,5,6-pentafluorobenzophenone was used as ultraviolet stabilizer (UVS) to slow down the photo degradation of PFPE. PFPE/UVS mixtures were exposed to UV light and the mechanism of photo degradation was studied with nuclear magnetic resonance (NMR). Small amounts of UVS (less than 0.3 wt%) were found to effectively stabilize both UV photo degradation at the main chain and the end chain of PFPE.

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

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