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od 2020-09-20 |
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1. |
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Clear distinction between CAC and CMC revealed by high-resolution NMR diffusometry for a series of bis-imidazolium gemini surfactants in aqueous solutions The aggregation behavior in the transition region was studied for a series of dicationic surfactants 3,3'-[alpha,omega-(dioxaalkane)]bis(1-dodecylimidazolium)dichlorides with varied spacer length from two to twelve carbon atoms. We employed Nuclear Magnetic Resonance diffusometry and Bayesian DOSY analysis to obtain the aggregate size distribution in the transition region. The critical concentrations CC were independently obtained from surface tension, electric conductivity, UV-Vis and NMR methods. The micelle aggregation numbers were estimated from the self-diffusion coefficients and were independently confirmed using steady-state fluorescence quenching. The morphology of the aggregates was characterized by small-angle scattering of synchrotron radiation and molecular dynamics simulations. The obtained CC values are identified as critical aggregation concentrations CAC. A broad transition region was observed, and stable micelles were obtained at much higher concentrations than CAC. The accurate CMC values could not be identified for the systems in the study. We indicated that the distribution of aggregate size becomes small and the system becomes homogeneous at much larger concentrations than CAC (typically 15-20 mM). The existence of a slow exchange between two environments, an aggregate and aqueous environment, was confirmed by H-1 NMR and 2D HSQC NMR spectroscopy.
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RSC Advances, 8(67), 38470-38482, (2018) |
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Disruptive effect of tocopherol oxalate on DPPC liposome structure: DSC, SAXS, and fluorescence anisotropy studies alpha-Tocopherol oxalate (TO), a tocopherol ester derivative, was investigated for its effect on the structural changes of fully hydrated 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes, as a function of concentration and temperature, by applying differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and DPH fluorescence anisotropy methods. The DSC and DPH anisotropy data indicated that TO embedded into DPPC membrane lowered the enthalpy (Delta H-m) and temperature (T-m) of the main phase transition as well its cooperativity. Fluidization of the membrane at a lowered temperature was accompanied by formation of mixed structures of tocopherol-enriched domains. SAXS studies showed the formation of various ordered structures in DPPC gel-phase during incorporation of TO into the bilayer, as evidenced by the existence of lamellar phases with repeat distances (d) of 6.13 and 6.87 nm, assigned to TO-enriched domains and a lamellar, liquid-ordered DPPC phase with d = 8.45 nm at increasing TO concentrations with lowering and broadening of the Bragg peaks, and diffuse scattering, characteristic of a fluid L-alpha phase, were observed. In DPPC fluid-phase, the increasing presence of TO at low concentrations resulted in the appearance of a liquid-ordered phase with repeat d = 6.9 nm coexistent with a lamellar structure with d = 9.2 nm, assigned to liquid-disordered structures. An increasing repeat distance observed with raising the TO amount in the DPPC bilayer evolved from an increasing interlamellar water layer of increasing thickness. Presence of TO facilitated penetration of water molecules into the acyl chain region which decreased van der Waals interactions in the bilayer. The DSC, SAXS, and fluorescence anisotropy data established that TO exhibited pronounced disruptive activity in DPPC membranes compared to a-tocopherol. The driving force of the observed action was attributed to electrostatic and dipole interactions of the acidic moiety with the polar head group of phospholipids in the interface region of the bilayer.
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Chemistry and Physics of Lipids, 216, 104-113, (2018) |
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Enhanced pharmacological efficacy of sumatriptan due to modification of its physicochemical properties by inclusion in selected cyclodextrins The study focused on the pharmacological action of sumatriptan, in particular its antiallodynic and antihyperalgesic properties, as an effect of cyclodextrinic inclusion of sumatriptan, resulting in changes of its physicochemical qualities such as dissolution and permeability through artificial biological membranes, which had previously been examined in vitro in a gastro-intestinal model. The inclusion of sumatriptan into beta-cyclodextrin and 2-hydroxylpropylo-beta-cyclodextrin by kneading was confirmed with the use of spectral (fourier-transform infrared spectroscopy (FT-IR); solid state nuclear magnetic resonance spectroscopy with magic angle spinning condition, H-1 and C-13 MAS NMR) and thermal (differential scanning calorimetry (DSC)) methods. A precise indication of the domains of sumatriptan responsible for its interaction with cyclodextrin cavities was possible due to a theoretical approach to the analysis of experimental spectra. A high-performance liquid chromatography with a diode-array detector method (HPLC-DAD) was employed to determine changes in the concentration of sumatriptan during dissolution and permeability experiments. The inclusion of sumatriptan in complex with cyclodextrins was found to significantly modify its dissolution profiles by increasing the concentration of sumatriptan in complexed form in an acceptor solution compared to in its free form. Following complexation, sumatriptan manifested an enhanced ability to permeate through artificial biological membranes in a gastro-intestinal model for both cyclodextrins at all pH values. As a consequence of the greater permeability of sumatriptan and its increased dissolution from the complexes, an improved pharmacological response was observed when cyclodextrin complexes were applied.
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Scientific Reports, 8, 16184, (2018) |
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Tetrapyrazinoporphyrazine with eight peripheral adamantanylsulfanyl units - Synthesis and physicochemical study A novel, (1-adamantylsulfanyl)-octasubstituted tetrapyrazinoporphyrazine has been synthesized and analyzed for its key physicochemical properties. Also, two 1-adamantylsulfanyl-substituted pyrazine derivatives were compared, and their crystallographic structures as well as chemical reactivity were assessed and discussed. Porphyrazine macrocycle showed good fluorescence and singlet oxygen generation properties as well as photostability. In addition, studied adamantylsulfanyl porphyrazine, despite its hydrophobic nature, revealed good solubility in polar solvents. Electrochemical studies revealed that the macrocycle underwent oxidation by one one-electron process and reduction with two one-electron processes.
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Synthetic Metals, 244, 66-72, (2018) |
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Experimental and theoretical studies of the physicochemical and mechanical properties of multi-layered TiN/SiC films: Temperature effects on the nanocomposite structure Nanoscale multilayered TiN/SiC films are of great importance in many electronic and industrial fields. The careful control over the structure of the laminates, nanocrystalline or amorphous, is crucial for their further applicability and study. However, several limitations in their fabrication have revealed important gaps in the understanding of this system. Here, we study influence of temperature on the physico-chemical and functional properties of TiN/SiC multilayers. We will show the clear increment on hardness of the samples, while the nanocomposite structure of the layers is maintained with no increment in crystal size. We will investigate the interstitial effects and rearrangements, between the TIN/SiC phases and their role in the enhanced mechanical response. Our experiments will dearly show a change in the modulation period of the samples, pointing to interfacial reactions, diffusion of ions or crystallization of new phases. Full Investigations of the film properties were carried out using several methods of analysis: XRD, XPS, FTIR, HR-TEM and SIMS Additionally, results were combined with First Principles MD computations of TiN/SiC heterostructures.
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Composites: part B - Engineering, 142, 85-94, (2018) |
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Cyclic trimer of human cystatin C, an amyloidogenic protein - molecular dynamics and experimental studies Human cystatin C (HCC) is a cysteine protease inhibitor that takes a series of oligomeric forms in solution (e.g., dimers, trimers, tetramers, decamers, dodecamers, and other higher oligomers). The best-known form of cystatin C is the dimer, which arises as a result of a domain swapping mechanism. The formation of the HCC oligomeric forms, which is most likely due to this domain swapping mechanism, is associated with the aggregation of HCC into amyloid fibrils and deposits. To investigate the structure of a specific HCC oligomer, we developed a covalently stabilized trimer of HCC. An atomic model of this HCC trimer was proposed on the basis of molecular docking and molecular dynamics simulations. The most stable model of the HCC trimer obtained from the molecular dynamics simulations is characterized by a well-preserved secondary structure. The molecular size and structural parameters of the HCC trimer in solution were also confirmed by Small Angle Neutron Scattering and Nuclear Magnetic Resonance Diffusometry. Published by AIP Publishing.
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Journal of Applied Physics, 123(17), Article Number: 174701, (2018) |
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7. |
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Photophysical properties and photocytotoxicity of free and liposome-entrapped diazepinoporphyrazines on LNCaP cells under normoxic and hypoxic conditions 5,7-Diaryl-substituted symmetrical diazepinoporphyrazine and tribenzodiazepinoporphyrazine were synthesized and characterized using UV-Vis, MS MALDI, and various NMR techniques. The expected photosensitizing potentials of these porphyrazines were evaluated by measuring their abilities to generate singlet oxygen in organic solvents and by comparing them with that of the recently obtained dendrimeric G1-type diazepinoporhyrazine. Absorbance and fluorescence measurements were performed to study the aggregation properties of the novel macrocycles. The photocytotoxicity of tribenzodiazepinoporphyrazine towards LNCaP cells in its free form and after its incorporation into liposomes was examined using MTT assay under normoxic and hypoxic conditions. It is interesting that all tested liposome formulations maintained their phototoxic activity in hypoxia. Also, tribenzodiazepinoporphyrazine incorporated into liposomes revealed better photocytotoxic effect (IC50 values of 0.600 +/- 0.357 mu M and 0378 +/- 0.002 mu M) than its free form (IC50 values of 3.135 +/- 0.156 mu M). Following the in vitro experiments, the most promising liposomal formulation containing L-alpha-phosphatidyl-DL-glycerol for tribenzodiazepinoporphyrazine was found. Moreover, tribenzodiazepinoporphyrazine incorporated into liposomes containing 1,2-dioleoyl-3-trimethylammonium-propane (chloride salt) revealed moderate phototoxicity at 5 x 10(-5) mu M for antibacterial photodynamic therapy. It was established that an irradiation of planktonic bacterial strains significantly reduced CFU5 of Staphylococcus aureus ATCC 25923 in comparison to tribenzodiazepinoporphyrazine containing L-alpha-phosphatidyl-DL-glycerol liposomes.
(C) 2018 Elsevier Masson SAS. All rights reserved. |
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European Journal of Medicinal Chemistry, 150, 64-73, (2018) |
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8. |
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Adaptive Modulation Amplitude in 2D Spectral-Spatial EPR Imagine A study concerning the image quality in Electron Paramagnetic Resonance Imaging (EPRI) in 2D spectralspatial (2D SSI) experiments is presented. The aim of the measurements is to improve the signal to noise ratio (SNR) of the projections by applying a more consciously selected modulation amplitude parameter. Data is gathered by applying three constant and one adaptive modulation amplitude. The three fixed modulation amplitudes values are leading to undermodulated (0.01 G), partially overmodulated (0.15 G) and fully overmodulated (0.65 G) projections. The study demonstrates the advantages of the adaptive method, which involves selecting different and dependent on cosine function modulation amplitudes for each projection. The study is performed on a phantom containing four tubes of LiPc and TCNQ, characterized by a different peak to peak linewidth and spin concentration
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Acta Physica Polonica A, 133(3), 710-712, (2018) |
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9. |
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Amyloid beta peptide aggregation process in the presence of sugar-based surfactants- conformational and structural studies The progression of Alzheimer's Disease (AD) is caused by aggregation process of amyloid β peptide (Aβ) [1]. The aggregation mechanism of Aβ peptides is still under discussion, because the process of Aβ oligomerization is relatively fast and it can be affected by many variables [2]. The control of Aβ aggregation is very hard to achieve, but use of selected specific surfactants may contribute to a better understanding of this process. The aim of this study was characterization of the structure and conformational changes in β-amyloid peptides induced by the presence of zwitterionic, sugar-based surfactants comprising a lactose moiety. Several different variants of β-amyloid peptides were selected for the study. The effect of surfactant concentration in solution was tested on Aβ1-42 peptide and its shorter variants. Selected solutions of tested β-amyloid peptides with surfactants were subjected to a series of solution scattering experiments using the synchrotron radiation (SR-SAXS). The SAXS data for these surfactants were collected on P12 beam line of EMBL (DESY). SR-SAXS studies exhibited the structure of various mixed (peptide-surfactant) assemblies. In our study we analyzed also the secondary structure of Aβ peptide in solutions with different concentrations of surfactant, using FTIR spectroscopy and circular dichroism (CD) methods. Atomic force microscopy (AFM) was used to characterize the morphology of Aβ assemblies. Particular attention was paid to analysis of small soluble oligomers that are currently believed to initiate development of brain disfunction in AD.
[1] J. Hardy and D. J. Selkoe, Science, 2002. [2] J. A. Loureiro, S. Rocha, and M. do C. Pereira, J. Pept. Sci. Off. Publ. Eur. Pept. Soc., 2013. Acknowledgments: The study was supported by research grant, Grant Diamentowy’’ from Ministry of Science and Higher Education (Poland) - DEC: 0011/DIA2015/44. |
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Biophysical Journal, 114(3) S1, 221A, (2018) |
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10. |
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Structural analysis of mtEXO mitochondrial RNA degradosome reveals tight coupling of nuclease and helicase components Nuclease and helicase activities play pivotal roles in various aspects of RNA processing and degradation. These two activities are often present in multi-subunit complexes from nucleic acid metabolism. In the mitochondrial exoribonuclease complex (mtEXO) both enzymatic activities are tightly coupled making it an excellent minimal system to study helicase-exoribonuclease coordination. mtEXO is composed of Dss1 3'-to-5' exoribonuclease and Suv3 helicase. It is the master regulator of mitochondrial gene expression in yeast. Here, we present the structure of mtEXO and a description of its mechanism of action. The crystal structure of Dss1 reveals domains that are responsible for interactions with Suv3. Importantly, these interactions are compatible with the conformational changes of Suv3 domains during the helicase cycle. We demonstrate that mtEXO is an intimate complex which forms an RNA-binding channel spanning its entire structure, with Suv3 helicase feeding the 3' end of the RNA toward the active site of Dss1.
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Nature Communications, 9, 97, (2018) |
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11. |
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Silver and ultrasmall iron oxides nanoparticles in hydrocolloids: effect of magnetic field and temperature on self-organization Micro/nanostructures, which are assembled from various nanosized building blocks are of great scientific interests due to their combined features in the micro- and nanometer scale. This study for the first time demonstrates that ultrasmall superparamagnetic iron oxide nanoparticles can change the microstructure of their hydrocolloids under the action of external magnetic field. We aimed also at the establishment of the physiological temperature (39°C) influence on the self-organization of silver and ultrasmall iron oxides nanoparticles (NPs) in hydrocolloids. Consequences of such induced changes were further investigated in terms of their potential effect on the biological activity in vitro. Physicochemical characterization included X-ray diffraction (XRD), optical microscopies (SEM, cryo-SEM, TEM, fluorescence), dynamic light scattering (DLS) techniques, energy dispersive (EDS), Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopies, zeta-potential and magnetic measurements. The results showed that magnetic field affected the hydrocolloids microstructure uniformity, fluorescence properties and photodynamic activity. Likewise, increased temperature caused changes in NPs hydrodynamic size distribution and in hydrocolloids microstructure. Magnetic field significantly improved photodynamic activity that was attributed to enhanced generation of reactive oxygen species due to reorganization of the microstructure.
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Scientific Reports, 8, 4041, (2018) |
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12. |
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Theranostic liposomes as a bimodal carrier for magnetic resonance imaging contrast agent and photosensitizer The present study is focused on the development of liposomes bearing gadolinium chelate (GdLip) providing two functionalities for magnetic resonance imaging (MRI) and photodynamic therapy of cancer. A lipid derivative of gadolinium(III) diethylenetriamine pentaacetic acid salt (GdDTPA1) was inserted in the liposomal membrane and served as MRI contrast agent whereas a zinc phthalocyanine (ZnPc) was used as a model photosensitizer. In addition to conventional liposomes, pegylated lipids were used for the preparation of "stealth" liposomes. The characterization of different GdLip formulations involved evaluation of the liposomes size by nanoparticle tracking analysis, thermal phase behavior by differential scanning calorimetry and ZnPc-mediated singlet oxygen production. Furthermore, relaxivity measurements were performed as well as cytotoxicity and photodynamic activity against cancerous and normal cell lines was studied. Size and thermal behavior were only slightly influenced by GdLip composition, however it distinctly affected singlet oxygen production of ZnPc-loaded GdLip. The quantum yields of singlet oxygen generation by zinc phthalocyanine incorporated in GdLip containing cationic or/and pegylated lipids were smaller than those obtained for non-pegylated carriers with l-alpha-phosphatidylglycerol. In general, all formulations of GdLip, irrespectively of composition, were characterized by relaxivities higher than those of commercially used contrast agents (e.g. Magnevist). NMR study has shown that the incorporation of ZnPc into the formulations of GdLip increases the relaxation parameters r1 and r2, compared to the values for the non-loaded vesicles. GdDTPA1 did not influence the photodynamic activity of ZnPc against HeLa cells.
Copyright © 2017 Elsevier Inc. All rights reserved.
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Journal of Inorganic Biochemistry, 180, 1-14, (2018) |
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13. |
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The influence of ligand charge and length on the assembly of Brome mosaic virus derived virus-like particles with magnetic core Virus-like particles (VLPs) have sparked a great interest in the field of nanobiotechnology and nanomedicine. The introduction of superparamagnetic nanoparticles (SPI-ONs) as a core, provides potential use of VLPs in the hyperthermia therapy, MRI contrast agents and magnetically-powered delivery agents. Magnetite NPs also provide a significant improvement in terms of VLPs stability. Moreover employing viral structural proteins as self-assembling units has opened a new paths for targeted therapy, drug delivery systems, vaccines design, and many more. In many cases, the self-assembly of a virus strongly depends on electrostatic interactions between positively charged groups of the capsid proteins and negatively charged nucleic acid. This phenomenon imposes the negative net charge as a key requirement for the core nanoparticle. In our experiments, Brome mosaic virus (BMV) capsid proteins isolated from infected plants Hordeum vulgare were used. Superparamagnetic iron oxide nanoparticles (Fe3O4) with 15 nm in diameter were synthesized by thermal decomposition and functionalized with COOH-PEG-PL polymer or dihexadecylphosphate (DHP) in order to provide water solubility and negative charge required for the assembly. Nanoparticles were characterized by Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Zeta Potential, Fourier Transformed Infrared Spectroscopy (FTIR) and Superconducting Quantum Interference Device (SQUID) magnetometry. TEM and DLS study were conducted to verify VLPs creation. This study demonstrates that the increase of negative surface charge is not a sufficient factor determining successful assembly. Additional steric interactions provided by longer ligands are crucial for the assembly of BMV SPION VLPs and may enhance the colloidal stability.
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AIP Advances, 8(3), 035005, (2018) |
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14. |
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Bioengineering the spider silk sequence to modify its affinity for drugs Background: Silk is a biocompatible and biodegradable material, able to self-assemble into different morphological structures. Silk structures may be used for many biomedical applications, including carriers for drug delivery. The authors designed a new bioengineered spider silk protein, EMS2, and examined its property as a carrier of chemotherapeutics.
Materials and methods: To obtain EMS protein, the MS2 silk monomer (that was based on the MaSp2 spidroin of Nephila clavipes) was modified by the addition of a glutamic acid residue. Both bioengineered silks were produced in an Escherichia coli expression system and purified by thermal method. The silk spheres were produced by mixing with potassium phosphate buffer. The physical properties of the particles were characterized using scanning electron microscopy, atomic force microscopy, Fourier-transform infrared spectroscopy, and zeta potential measurements. The MTT assay was used to examine the cytotoxicity of spheres. The loading and release profiles of drugs were studied spectrophotometrically.
Results: The bioengineered silk variant, EMS2, was constructed, produced, and purified. The EMS2 silk retained the self-assembly property and formed spheres. The spheres made of EMS2 and MS2 silks were not cytotoxic and had a similar secondary structure content but differed in morphology and zeta potential values; EMS2 particles were more negatively charged than MS2 particles. Independently of the loading method (pre- or post-loading), the loading of drugs into EMS2 spheres was more efficient than the loading into MS2 spheres. The advantageous loading efficiency and release rate made EMS2 spheres a good choice to deliver neutral etoposide (ETP). Despite the high loading efficiency of positively charged mitoxantrone (MTX) into EMS2 particles, the fast release rate made EMS2 unsuitable for the delivery of this drug. A faster release rate from EMS2 particles compared to MS2 particles was observed for positively charged doxorubicin (DOX).
Conclusion: By modifying its sequence, silk affinity for drugs can be controlled.
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International Journal of Nanomedicine, 13, 4247-4261, (2018) |
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15. |
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Anchoring Fe3O4 nanoparticles in a reduced graphene oxide aerogel matrix via polydopamine coating Reduced graphene oxide-magnetite hybrid aerogels attract great interest thanks to their potential applications, e.g., as magnetic actuators. However, the tendency of magnetite particles to migrate within the matrix and, ultimately, escape from the aerogel structure, remains a technological challenge. In this article we show that coating magnetite particles with polydopamine anchors them on graphene oxide defects, immobilizing the particles in the matrix and, at the same time, improving the aerogel structure. Polydopamine coating does not affect the magnetic properties of magnetite particles, making the fabricated materials promising for industrial applications.
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Beilstein Journal of Nanotechnology, 9, 591-601, (2018) |
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16. |
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Cilostazol-loaded poly(epsilon-caprolactone) electrospun drug delivery system for cardiovascular applications Purpose The study discusses the value of electrospun cilostazol-loaded (CIL) polymer structures for potential vascular implant applications.
Methods Biodegradable polycaprolactone (PCL) fibers were produced by electrospinning on a rotating drum collector. Three different concentrations of CIL: 6.25%, 12.50% and 18.75% based on the amount of polymer, were incorporated into the fibers. The fibers were characterized by their size, shape and orientation. Materials characterization was carried out by Fourier Transformed Infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In vitro drug release study was conducted using flow-through cell apparatus (USP 4).
Results Three-dimensional structures characterized by fibers diameter ranging from 0.81 to 2.48 mu m were in the range required for cardiovascular application. DSC and XRD confirmed the presence of CIL in the electrospun fibers. FTIR and Raman spectra confirmed CIL polymorphic form. Elastic modulus values for PCL and the CIL-loaded PCL fibers were in the range from 0.6 to 1.1 GPa. The in vitro release studies were conducted and revealed drug dissolution in combination with diffusion and polymer relaxation as mechanisms for CIL release from the polymer matrix.
Conclusions The release profile of CIL and nanomechanical properties of all formulations of PCL fibers demonstrate that the cilostazol loaded PCL fibers are an efficient delivery system for vascular implant application.
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Pharmaceutical Research, 35(2), UNSP 32, (2018) |
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17. |
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Selected polycationic surfactants as siRNA carriers for gene therapy So far many drug delivery systems for transfer of nucleic acids in gene therapy have been proposed but there is no universal system for transfer of genetic material into cells. The largest problem in the design of new nucleic acids delivery vehicles is finding a carrier which fulfill such criteria as: stability in complexes with nucleic acids, non-toxicity, non-immunogenicity, ability to safe degradation and easy preparation protocol.
A certain group of polycationic surfactants are able to meet these requirements. Their amphiphilic nature, structure flexibility and the ability to bind to siRNA or DNA oligomers are just some of the advantages. Our past research on selected dicationic compounds as DNA or siRNA delivery systems, indicated that an increase in the number of surfactant subunits is a promised direction to develop new efficient carriers of short nucleic acids. In this work we present results of the studies of the complexes based on selected novel polycationic surfactants (eg. oligomeric imidazolium derivatives) with a model system - double stranded 21-bp siRNA oligomer. By the use of biophysical methods (electrophoresis, circular dichroism, small angle scattering of synchtorton radiation and cryo-transmission electron microscopy) we examined their complexation capacity, nanostructure of lipoplexes, conformational changes in bound siRNA oligomers and micromorphology of complexes. Our studies have shown the formation of stable systems with promising transfection properties. These systems exhibit various morphologies in frozen state. Acknowledgments: The study was supported by research grant “PRELUDIUM” from National Science Center (Poland) - UMO-2016/23/N/ST4/01637. |
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Biophysical Journal, 114(3) S1, 438A, (2018) |
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18. |
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Analytical, thermodynamical and kinetic characteristics of photoluminescence immunosensor for the determination of Ochratoxin A Ochratoxin A (OTA) is one of the most widespread and dangerous food contaminants. Therefore, rapid, label free and precise detection of low OTA concentrations requires novel gensing elements with advanced bioanalytical properties. In the present paper we report photoluminescence (PL) based immunosensor for the detection of OTA. During the development of immunosensor photoluminescent ZnO nanorods (ZnO-NRs) were deposited on glass substrate. Then the ZnO-NRs were silanized and covalently modified by Protein-A (Glass/ ZnO-NRs/Protein-A). The latest structure was modified by antibodies against OTA (Anti-OTA) in order to form OTA-selective layer (Glass/ZnO-NRs/Protein-A/Anti-OTA). In order to improve immunosensors selectivity the surface of Glass/ZnO-NRs/Protein-A/Anti-OTA was additionally blocked by BSA. Formed Glass/ZnO-NRs/ Protein-A/BSA &Anti-OTA structures were integrated within portable fiber optic detection system, what is important for the development of low cost and portable immunosensors. The immunosensor has been tested in a wide range of OTA concentrations from 10(-4) ng/ml until 20 ng/ml. Interaction isotherms were derived from atialytical signals of immunosensor. Association constant and Gibbs free energy for the interaction of Glass/ ZnO-NRs/Protein-A/Anti-OTA with OTA were calculated, analyzed and compared with some other related results. Sensitivity range and limit of detection were determined as 0.1-1 ng/ml and 10(-2) ng/ml, respectively. Interaction kinetics of ZnO-NRs with OTA was evaluated. Response time of the immunosensor toward OTA was in the range of 500-800 s. Some insights related to the mechanism of PL-signal generation are proposed and discussed.
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Biosensors & Bioelectronics, 99, 237-243, (2018) |
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19. |
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Structural and dynamical study of PDMS and PS based block copolymers Block copolymers represent an interesting class of materials, combining properties of individual components and capable of developing nanoscopic domain morphologies. Copolymers which comprise polystyrene and poly(dimethylsiloxane) attract special attention due to their effective segregation and the highly contrasting thermal properties of individual blocks. This work covers structural studies of copolymeric domain architecture and investigates the molecular dynamics observed in bulk PDMS, diblock PS-PDMS and triblock PS-PDMS-PS. Utilization of atomic force microscopy and NMR spin diffusion provide a thorough picture of phase separated systems. Dielectric spectroscopy reveals the dynamic heterogeneity of PDMS amorphous phase. Two distinct structural relaxations, namely α and αc, were observed and attributed correspondingly to PDMS mobile amorphous fraction and PDMS rigid amorphous fraction. Unexpectedly, the segmental reorientations observed in the case of copolymers were faster that that observed for bulk PDMS.
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European Polymer Journal, 98, 384-393, (2018) |
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Zaktualizowano: podstrony 2021-06-21 / bazę danych: 2024-11-02 by Webmaster: Zbigniew Fojud