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Article: The charge structure function in electrolytes and polyelectrolytes.

Jannink, G / van der Maarel, J R

2006 Volume 41, Issue 1, Page(s) 15–22

Abstract: The relation between charge and dielectric structure functions is examined in the case of electrolytes and polyelectrolytes. When the coupling constant is larger than unity, characteristic features should be observed on the dielectric structure function, ...

Abstract	The relation between charge and dielectric structure functions is examined in the case of electrolytes and polyelectrolytes. When the coupling constant is larger than unity, characteristic features should be observed on the dielectric structure function, in addition to the classical screening effect. We point our the existence of experimental conditions which provide direct information of the dielectric structure at shorter wavelength (lambda 1 nm). They correspond to zero average contrast in scattering experiments.
Language	English
Publishing date	2006-09-01
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	185052-0
ISSN	1873-4200 ; 0301-4622
ISSN (online)	1873-4200
ISSN	0301-4622
DOI	10.1016/0301-4622(91)87205-j
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Article: Effect of spatial inhomogeneity in dielectric permittivity on DNA double layer formation.

van der Maarel, J R

Biophysical journal

1999 Volume 76, Issue 5, Page(s) 2673–2678

Abstract: In solutions of tetramethylammonium (TMA+) DNA (double stranded) without added low-molecular-weight salt, the counterion radial density is calculated using the cylindrical Poisson-Boltzmann equation with a distance-dependent quasimacroscopic dielectric ... ...

Abstract	In solutions of tetramethylammonium (TMA+) DNA (double stranded) without added low-molecular-weight salt, the counterion radial density is calculated using the cylindrical Poisson-Boltzmann equation with a distance-dependent quasimacroscopic dielectric permittivity. Comparisons with small-angle neutron scattering data indicate that any inhomogeneity in dielectric permittivity is confined to one or two solvent layers from the DNA surface. At least for TMA+, which may be too large to penetrate the grooves of DNA to any significant extent, dielectric inhomogeneity modeled in this way has no detectable effect on the radial distribution.
MeSH term(s)	Biophysical Phenomena ; Biophysics ; DNA/chemistry ; Ions ; Models, Chemical ; Neutrons ; Quaternary Ammonium Compounds ; Scattering, Radiation ; Solutions ; Static Electricity
Chemical Substances	Ions ; Quaternary Ammonium Compounds ; Solutions ; DNA (9007-49-2) ; tetramethylammonium (H0W55235FC)
Language	English
Publishing date	1999-05
Publishing country	United States
Document type	Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	218078-9
ISSN	1542-0086 ; 0006-3495
ISSN (online)	1542-0086
ISSN	0006-3495
DOI	10.1016/S0006-3495(99)77419-9
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Article: Plasmid DNA encapsulation within cationic diblock copolymer vesicles for gene delivery.

Korobko, A V / Backendorf, C / van der Maarel, J R C

The journal of physical chemistry. B

2006 Volume 110, Issue 30, Page(s) 14550–14556

Abstract: We report the design and structural characterization of cationic diblock copolymer vesicles loaded with plasmid DNA based on a single emulsion technique. For this purpose, a DNA solution was emulsified in an organic solvent and stabilized by an ... ...

Abstract	We report the design and structural characterization of cationic diblock copolymer vesicles loaded with plasmid DNA based on a single emulsion technique. For this purpose, a DNA solution was emulsified in an organic solvent and stabilized by an amphiphilic diblock copolymer. The neutral block forms an interfacial brush, whereas the cationic attachment complexes with DNA. A subsequent change of the quality of the organic solvent results in the collapse of the brush and the formation of a capsule. The capsules are subsequently dispersed in aqueous medium to form vesicles and stabilized with an osmotic agent in the external phase. Inside the vesicles, the plasmid is compacted in a liquid-crystalline fashion as shown by the appearance of birefringent textures under crossed polarizers and the increase in fluorescence intensity of labeled DNA. The compaction efficiency and the size distribution of the vesicles were determined by light and electron microscopy, and the integrity of the DNA after encapsulation and subsequent release was confirmed by gel electrophoresis. We demonstrate reverse transfection of in vitro cultured HeLa cancer cells growing on plasmid-copolymer vesicles deposited on a glass substrate.
MeSH term(s)	Cations ; Cell Membrane Permeability ; DNA/administration & dosage ; DNA/chemistry ; DNA/genetics ; Drug Stability ; Emulsions ; Gene Transfer Techniques ; Green Fluorescent Proteins/genetics ; HeLa Cells ; Humans ; Microscopy, Electron, Scanning ; Microscopy, Phase-Contrast ; Microscopy, Polarization ; Plasmids/administration & dosage ; Plasmids/chemistry ; Plasmids/genetics ; Polyvinyls/chemistry ; Transfection
Chemical Substances	Cations ; Emulsions ; Polyvinyls ; enhanced green fluorescent protein ; poly(butadiene-b-N-methyl-4-vinylpyridinium iodide) ; Green Fluorescent Proteins (147336-22-9) ; DNA (9007-49-2)
Language	English
Publishing date	2006-08-03
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ISSN	1520-6106
ISSN	1520-6106
DOI	10.1021/jp057363b
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Article: Encapsulation of DNA by cationic diblock copolymer vesicles.

Korobko, A V / Jesse, W / van der Maarel, J R C

Langmuir : the ACS journal of surfaces and colloids

2005 Volume 21, Issue 1, Page(s) 34–42

Abstract: Encapsulation of dsDNA fragments (contour length 54 nm) by the cationic diblock copolymer poly(butadiene-b-N-methyl-4-vinyl pyridinium) [PBd-b-P4VPQ] has been studied with phase contrast, polarized light, and fluorescence microscopies, as well as ... ...

Abstract	Encapsulation of dsDNA fragments (contour length 54 nm) by the cationic diblock copolymer poly(butadiene-b-N-methyl-4-vinyl pyridinium) [PBd-b-P4VPQ] has been studied with phase contrast, polarized light, and fluorescence microscopies, as well as scanning electron microscopy. Encapsulation was achieved with a single emulsion technique. For this purpose, an aqueous DNA solution is emulsified in an organic solvent (toluene) and stabilized by the amphiphilic diblock copolymer. The PBd block forms an interfacial brush, whereas the cationic P4VPQ block complexes with DNA. A subsequent change of the quality of the organic solvent results in a collapse of the PBd brush and the formation of a capsule. Inside the capsules, the DNA is compacted as shown by the appearance of birefringent textures under crossed polarizers and the increase in fluorescence intensity of labeled DNA. The capsules can also be dispersed in an aqueous medium to form vesicles, provided they are stabilized with an osmotic agent [poly(ethylene glycol)] in the external phase. It is shown that the DNA is released from the vesicles once the osmotic pressure drops below 10(5) N/m(2) or if the ionic strength of the supporting medium exceeds 0.1 M. The method has also proven to be efficient to encapsulate pUC18 plasmid in submicrometer-sized vesicles, and the general applicability of the method has been demonstrated by the preparation of the charge inverse system: cationic poly(ethylene imine) encapsulated by the anionic diblock poly(styrene-b-acrylic acid).
Language	English
Publishing date	2005-01-04
Publishing country	United States
Document type	Journal Article
ZDB-ID	2005937-1
ISSN	1520-5827 ; 0743-7463
ISSN (online)	1520-5827
ISSN	0743-7463
DOI	10.1021/la047967r
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Article: Counter-ion dynamics in crosslinked poly(styrene sulfonate) systems studied by NMR.

Tromp, R H / van der Maarel, J R / de Bleijser, J / Leyte, J C

Biophysical chemistry

2006 Volume 41, Issue 1, Page(s) 81–100

Abstract: The field dependence of the longitudinal and transverse nuclear magnetic relaxation rates of 23Na+ in aqueous crosslinked Na-poly(styrene sulfonate) (PSS) systems (ion exchange resins) has been obtained as a function of the degree of crosslinking. The ... ...

Abstract	The field dependence of the longitudinal and transverse nuclear magnetic relaxation rates of 23Na+ in aqueous crosslinked Na-poly(styrene sulfonate) (PSS) systems (ion exchange resins) has been obtained as a function of the degree of crosslinking. The relaxation is considerably enhanced relative to solutions of non-crosslinked NaPSS at equal ionizable group concentration. This is due to the dynamic constraints of the polymer chains, which render the averaging of the counter-ion chain interaction less efficient. The field dependence of the relaxation rates in the crosslinked NaPSS systems reveals two processes that are out of the extreme narrowing limit. This is in contrast to the relaxation behavior found in non-crosslinked NaPSS systems. To characterize these processes their correlation times were combined with constants of selfdiffusion to estimate the distances diffused by an ion in order to average the electric field gradient at its nucleus. These two distances are interpreted as characteristic length scales in the network. At all degrees of crosslinking it was found that the smallest of these length scales is roughly equal to the distance between two neighbouring crosslinks. The largest characteristic distance extends over several crosslinks and reflects inhomogeneities in the crosslink concentration. These conclusions were also reached from similar experiments on 7Li+ in LiPSS systems.
Language	English
Publishing date	2006-09-01
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	185052-0
ISSN	1873-4200 ; 0301-4622
ISSN (online)	1873-4200
ISSN	0301-4622
DOI	10.1016/0301-4622(91)87212-n
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Article: Structure of strongly interacting polyelectrolyte diblock copolymer micelles.

Korobko, A V / Jesse, W / Lapp, A / Egelhaaf, S U / van der Maarel, J R C

The Journal of chemical physics

2005 Volume 122, Issue 2, Page(s) 24902

Abstract: The structure of spherical micelles of the diblock poly(styrene-block-acrylic acid) [PS-b-PA] copolymer in water was investigated up to concentrations where the polyelectrolyte coronal layers have to shrink and/or interpenetrate in order to accommodate ... ...

Abstract	The structure of spherical micelles of the diblock poly(styrene-block-acrylic acid) [PS-b-PA] copolymer in water was investigated up to concentrations where the polyelectrolyte coronal layers have to shrink and/or interpenetrate in order to accommodate the micelles in the increasingly crowded volume. We obtained the partial structure factors pertaining to the core and corona density correlations with small angle neutron scattering and contrast matching in the water. The counterion structure factor was obtained with small angle x-ray scattering (SAXS) with a synchrotron radiation source. Furthermore, we have measured the flow curves and dynamic visco-elastic moduli. The functionality of the micelles is fixed with a 9 nm diameter PS core and a corona formed by around 100 PA arms. As shown by the SAXS intensities, the counterions are distributed in the coronal layer with the same density profile as the corona forming segments. Irrespective ionic strength and micelle charge, the corona shrinks with increasing packing fraction. At high charge and minimal screening conditions, the polyelectrolyte chains remain almost fully stretched and they interdigitate once the volume fraction exceeds the critical value 0.53+/-0.02. Interpenetration of the polyelectrolyte brushes also controls the fluid rheology: The viscosity increases by three orders of magnitude and the parallel frequency scaling behavior of the dynamic moduli suggests the formation of a physical gel. In excess salt, the coronal layers are less extended and they do not interpenetrate in the present concentration range.
Language	English
Publishing date	2005-01-08
Publishing country	United States
Document type	Journal Article
ZDB-ID	3113-6
ISSN	1089-7690 ; 0021-9606
ISSN (online)	1089-7690
ISSN	0021-9606
DOI	10.1063/1.1829039
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Article: A model for the dynamics of spins 3/2 in biological media: signal loss during radiofrequency excitation in triple-quantum-filtered sodium MRI.

Hancu, I / van der Maarel, J R / Boada, F E

Journal of magnetic resonance (San Diego, Calif. : 1997)

2000 Volume 147, Issue 2, Page(s) 179–191

Abstract: We have derived the differential equations that describe the dynamics of spin-3/2 nuclei in the presence of radiofrequency (RF) fields and both static and fluctuating quadrupolar interactions. The formalism presented was used to predict the sodium triple- ...

Abstract	We have derived the differential equations that describe the dynamics of spin-3/2 nuclei in the presence of radiofrequency (RF) fields and both static and fluctuating quadrupolar interactions. The formalism presented was used to predict the sodium triple-quantum-filtered (TQ-filtered) signal loss in a whole-body scanner, where the widths of the hard 90 degrees RF pulses are on the same order of magnitude as the transverse relaxation times. A small piece of bovine nasal cartilage, known for exhibiting residual quadrupolar splittings, was used to test the theory. The sample was modeled as consisting of small domains, each characterized by a static quadrupolar interaction constant, with an overall Gaussian distribution across the sample. An increase of about 15% in the TQ-filtered signal strength, as the 90 degrees RF pulse width was decreased from 500 to 100 micros, was predicted and demonstrated experimentally for this particular sample.
MeSH term(s)	Animals ; Cartilage/chemistry ; Cattle ; Magnetic Resonance Spectroscopy/methods ; Mathematics ; Radio Waves ; Sodium/chemistry
Chemical Substances	Sodium (9NEZ333N27)
Language	English
Publishing date	2000-12
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	1469665-4
ISSN	1096-0856 ; 1557-8968 ; 1090-7807 ; 0022-2364
ISSN (online)	1096-0856 ; 1557-8968
ISSN	1090-7807 ; 0022-2364
DOI	10.1006/jmre.2000.2177
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Article: Do spherical polyelectrolyte brushes interdigitate?

Korobko, A V / Jesse, W / Egelhaaf, S U / Lapp, A / van der Maarel, J R C

Physical review letters

2004 Volume 93, Issue 17, Page(s) 177801

Abstract: The structure of spherical micelles of the diblock copolymer poly(styrene-block-acrylic acid) in water was investigated with small angle neutron scattering and contrast matching. We have monitored intermicelle correlation and the extension of the ... ...

Abstract	The structure of spherical micelles of the diblock copolymer poly(styrene-block-acrylic acid) in water was investigated with small angle neutron scattering and contrast matching. We have monitored intermicelle correlation and the extension of the polyelectrolyte chains in the coronal layer through the overlap concentration. Irrespective of ionic strength, the corona shrinks with increasing packing fraction. Furthermore, at high charge and minimal screening conditions, the corona layers interpenetrate once the volume fraction exceeds the critical value 0.53+/-0.02.
Language	English
Publishing date	2004-10-22
Publishing country	United States
Document type	Journal Article
ZDB-ID	208853-8
ISSN	1079-7114 ; 0031-9007
ISSN (online)	1079-7114
ISSN	0031-9007
DOI	10.1103/PhysRevLett.93.177801
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Article: Dynamics of spin I=3/2 under spin-locking conditions in an ordered environment.

van der Maarel, J R / Jesse, W / Hancu, I / Woessner, D E

Journal of magnetic resonance (San Diego, Calif. : 1997)

2001 Volume 151, Issue 2, Page(s) 298–313

Abstract: We have derived approximate analytic solutions to the master equation describing the evolution of the spin I=3/2 density operator in the presence of a radio-frequency (RF) field and both static and fluctuating quadrupolar interactions. Spectra resulting ... ...

Abstract	We have derived approximate analytic solutions to the master equation describing the evolution of the spin I=3/2 density operator in the presence of a radio-frequency (RF) field and both static and fluctuating quadrupolar interactions. Spectra resulting from Fourier transformation of the evolutions of the on-resonance spin-locked magnetization into the various coherences display two satellite pairs and, in some cases, a central line. The central line is generally trimodal, consisting of a narrow component related to a slowly relaxing mode and two broad components pertaining to two faster relaxing modes. The rates of the fast modes are sensitive to slow molecular motion. Neither the amplitude nor the width of the narrow component is affected by the magnitude of the static coupling, whereas the corresponding features of the broad components depend in a rather complicated manner on the spin-lock field strength and static quadrupolar interaction. Under certain experimental conditions, the dependencies of the amplitudes on the dynamics are seen to vanish and the relaxation rates reduce to relatively simple expressions. One of the promising emerging features is the fact that the evolutions into the selectively detected quadrupolar spin polarization order and the rank-two double-quantum coherence do not exhibit a slowly relaxing mode and are particularly sensitive to slow molecular motion. Furthermore, these coherences can only be excited in the presence of a static coupling and this makes it possible to discern nuclei in anisotropic from those in isotropic environment. The feasibility of the spin-lock pulse sequences with limited RF power and a nonvanishing average electric field gradient has been demonstrated through experiments on sodium in a dense lyotropic DNA liquid crystal.
MeSH term(s)	Crystallization ; DNA/chemistry ; Magnetic Resonance Spectroscopy ; Mathematics ; Signal Processing, Computer-Assisted
Chemical Substances	DNA (9007-49-2)
Language	English
Publishing date	2001-08
Publishing country	United States
Document type	Journal Article
ZDB-ID	1469665-4
ISSN	1096-0856 ; 1557-8968 ; 1090-7807 ; 0022-2364
ISSN (online)	1096-0856 ; 1557-8968
ISSN	1090-7807 ; 0022-2364
DOI	10.1006/jmre.2001.2382
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Article: Liquid crystal formation in DNA fragment solutions.

Kassapidou, K / Jesse, W / van Dijk, J A / van der Maarel, J R

Biopolymers

1998 Volume 46, Issue 1, Page(s) 31–37

Abstract: The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic ... ...

Abstract	The critical volume fractions pertaining to the formation of DNA liquid crystals were obtained from polarization microscopy, 31P-nmr, and phase separation experiments. The DNA length (approximately one to two times the persistence length 50 nm), ionic strength, and counterion variety dependencies are reported. The cholesteric-isotropic transition is interpreted in terms of the coexistence equations, which are derived from the solution free energy including orientational entropy and excluded volume effects. With the wormlike chain as reference system, the electrostatic contribution to the free energy is evaluated as a thermodynamic perturbation in the second virial approximation with a Debye-Hückel potential of mean force. The hard core contribution has been evaluated with scaled particle theory and/or a simple generalization of the Carnahan-Starling equation of state for hard spheres. For sufficiently high ionic strengths, the agreement is almost quantitative. At lower amounts of added salt deviations are observed, which are tentatively attributed to counterion screening effects. The contour length dependence agrees with a DNA persistence length 50 nm.
MeSH term(s)	Crystallization ; DNA Fragmentation ; Microscopy, Polarization
Language	English
Publishing date	1998-07
Publishing country	United States
Document type	Journal Article
ZDB-ID	1123-x
ISSN	1097-0282 ; 0006-3525
ISSN (online)	1097-0282
ISSN	0006-3525
DOI	10.1002/(SICI)1097-0282(199807)46:1<31::AID-BIP3>3.0.CO;2-Z
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