Advances in molecular medicine related to the treatment of genetic disorders and cancer require f... more Advances in molecular medicine related to the treatment of genetic disorders and cancer require finding new pathways for gene transfer. Nonviral delivery methods rely on the application of polymers, liposomes and cationic lipid systems used as vehicle. Among these systems, there is increasing interest in surfactants, which, due to their ability to complex with nucleic acids can deliver into cell DNA or RNA molecules of almost any size, which is unattainable with viral gene delivery systems.The main aim of this study was to determine the effect of the concentration of lactose-based surfactants (zwitterionic derivatives of sulfobetaine with carbohydrate moieties) on the structure of DNA/RNA as well as to explore their abilities of nucleic acid complexation. Structural studies of DNA or RNA in complexes with surfactants of two types at various concentrations were conducted using circular dichroism (CD) spectroscopy, gel electrophoresis (GE) and synchrotron radiation small angle X-ray s...
ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA ... more ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA and polyethylene oxide (PEO) arms was studied by means of Broadband Dielectric Spectroscopy (BDS) and Nuclear Magnetic Resonance (NMR) methods. The spectroscopic studies were performed for three types of copolymers differing in the composition, namely materials containing 76%, 46% and 16% molar fraction of PBA arms. The local processes, described by the Arrhenius law (e.g. the anisotropic rotation of methyl groups and the anisotropic local motions in the PEO chain), were observed for the studied systems below the glass transition temperature. It was found that the investigated PBA/PEO miktoarm star copolymers are characterized by single glass transition, which may result from similar values of glass transition temperatures of the PBA and PEO polymers. The segmental dynamics in the studied systems was quantitatively described by using the Vogel-Fulcher-Tammann (VFT) relation applied to combined NMR and BDS data. Moreover, above the glass transition temperature the interfacial polarization and conductivity phenomena were detected with the BDS method for all systems under study.
ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction ... more ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction of poly(n-butyl acrylate) and poly(ethylene oxide) (PBA and PEO) arms were under investigation. Structural characteristics of copolymers was obtained on the basis of Small Angle X-Ray Scattering (SAXS) investigations. The phase separated nanoscale morphology of the miktoarm star copolymer with a high fraction of PEO arms was confirmed by Scanning Probe Microscopy (SPM) studies. The modified Avrami approach was used to obtain the information on the non-isothermal crystallization kinetics of the studied systems. It was observed that the crystallization in the system with a higher content of PBA, occurring at higher undercooling, was characterized by a higher crystallization rate. It was also found that increase in PBA arms fraction leads to the reduction in the size of PEO domains. The activation energy of the crystallization process, estimated with Kissinger's method, is lower for miktoarm star copolymer with higher PBA content, which results from facilitation of the transport of PEO chains in the direction of the growing crystal due to the presence of mobile PBA arms. The self-diffusion studies of miktoarm star copolymers melts, carried out with the Pulsed-Gradient STimulated-Echo (PGSTE) Nuclear Magnetic Resonance (NMR) technique, reveals the existence of at least two types of diffusion mechanisms in these systems.
Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below ... more Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below its glass transition point by a few techniques based on the NMR phenomenon. Temperature dependencies of proton spin-lattice relaxation times T1 (at 200MHz and at 30.2MHz), proton spin-lattice relaxation time in the rotating frame T1ρ (at 68kHz) and frequency dispersion of proton spin-lattice off-resonance relaxation times in the rotating frame T1ρ(off) were determined for the copolymer. Analysis of (1)H NMR relaxation data permitted characterization of local motions occurring in the copolymer i.e. rotation of methyl groups around C3 axes, reorientations of methylene groups and motions of segments of polymer chains including norbornene groups.
Advances in molecular medicine related to the treatment of genetic disorders and cancer require f... more Advances in molecular medicine related to the treatment of genetic disorders and cancer require finding new pathways for gene transfer. Nonviral delivery methods rely on the application of polymers, liposomes and cationic lipid systems used as vehicle. Among these systems, there is increasing interest in surfactants, which, due to their ability to complex with nucleic acids can deliver into cell DNA or RNA molecules of almost any size, which is unattainable with viral gene delivery systems.The main aim of this study was to determine the effect of the concentration of lactose-based surfactants (zwitterionic derivatives of sulfobetaine with carbohydrate moieties) on the structure of DNA/RNA as well as to explore their abilities of nucleic acid complexation. Structural studies of DNA or RNA in complexes with surfactants of two types at various concentrations were conducted using circular dichroism (CD) spectroscopy, gel electrophoresis (GE) and synchrotron radiation small angle X-ray s...
ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA ... more ABSTRACT Molecular dynamics of miktoarm star copolymers consisting of poly(n-butyl acrylate) PBA and polyethylene oxide (PEO) arms was studied by means of Broadband Dielectric Spectroscopy (BDS) and Nuclear Magnetic Resonance (NMR) methods. The spectroscopic studies were performed for three types of copolymers differing in the composition, namely materials containing 76%, 46% and 16% molar fraction of PBA arms. The local processes, described by the Arrhenius law (e.g. the anisotropic rotation of methyl groups and the anisotropic local motions in the PEO chain), were observed for the studied systems below the glass transition temperature. It was found that the investigated PBA/PEO miktoarm star copolymers are characterized by single glass transition, which may result from similar values of glass transition temperatures of the PBA and PEO polymers. The segmental dynamics in the studied systems was quantitatively described by using the Vogel-Fulcher-Tammann (VFT) relation applied to combined NMR and BDS data. Moreover, above the glass transition temperature the interfacial polarization and conductivity phenomena were detected with the BDS method for all systems under study.
ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction ... more ABSTRACT Morphology and NMR self-diffusion of two miktoarm star copolymers differing in fraction of poly(n-butyl acrylate) and poly(ethylene oxide) (PBA and PEO) arms were under investigation. Structural characteristics of copolymers was obtained on the basis of Small Angle X-Ray Scattering (SAXS) investigations. The phase separated nanoscale morphology of the miktoarm star copolymer with a high fraction of PEO arms was confirmed by Scanning Probe Microscopy (SPM) studies. The modified Avrami approach was used to obtain the information on the non-isothermal crystallization kinetics of the studied systems. It was observed that the crystallization in the system with a higher content of PBA, occurring at higher undercooling, was characterized by a higher crystallization rate. It was also found that increase in PBA arms fraction leads to the reduction in the size of PEO domains. The activation energy of the crystallization process, estimated with Kissinger's method, is lower for miktoarm star copolymer with higher PBA content, which results from facilitation of the transport of PEO chains in the direction of the growing crystal due to the presence of mobile PBA arms. The self-diffusion studies of miktoarm star copolymers melts, carried out with the Pulsed-Gradient STimulated-Echo (PGSTE) Nuclear Magnetic Resonance (NMR) technique, reveals the existence of at least two types of diffusion mechanisms in these systems.
Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below ... more Molecular motions in poly(ethylene-co-norbornene) were studied in a temperature range well below its glass transition point by a few techniques based on the NMR phenomenon. Temperature dependencies of proton spin-lattice relaxation times T1 (at 200MHz and at 30.2MHz), proton spin-lattice relaxation time in the rotating frame T1ρ (at 68kHz) and frequency dispersion of proton spin-lattice off-resonance relaxation times in the rotating frame T1ρ(off) were determined for the copolymer. Analysis of (1)H NMR relaxation data permitted characterization of local motions occurring in the copolymer i.e. rotation of methyl groups around C3 axes, reorientations of methylene groups and motions of segments of polymer chains including norbornene groups.
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