PnBA-b-PNIPAM-b-PDMAEA Thermo-Responsive Triblock Terpolymers and Their Quaternized Analogs as Gene and Drug Delivery Vectors

In this work, the ability of thermo-responsive poly [butyl acrylate-b-N-isopropylacrylamide-b-2-(dimethylamino) ethyl acrylate] (PnBA-b-PNIPAM-b-PDMAEA) triblock terpolymer self-assemblies, as well as of their quaternized analogs (PnBA-b-PNIPAM-b-QPDMAEA), to form polyplexes with DNA through electrostatic interactions was examined. Terpolymer/DNA polyplexes were prepared in three different amine over phosphate group ratios (N/P), and linear DNA with a 2000 base pair length was used. In aqueous solutions, the terpolymers formed aggregates of micelles with mixed PNIPAM/(Q)PDMAEA coronas and PnBA cores. The PnBA-b-PNIPAM-b-PDMAEA terpolymers’ micellar aggregates were also examined as carriers for the model hydrophobic drug curcumin (CUR). The complexation ability of the terpolymer with DNA was studied by UV–Vis spectroscopy and fluorescence spectroscopy by investigating ethidium bromide quenching. Fluorescence was also used for the determination of the intrinsic fluorescence of the CUR-loaded micellar aggregates. The structural characteristics of the polyplexes and the CUR-loaded aggregates were investigated by dynamic and electrophoretic light scattering techniques. Polyplexes were found to structurally respond to changes in solution temperature and ionic strength, while the intrinsic fluorescence of encapsulated CUR was increased at temperatures above ambient.

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Physicochemical Evaluation of Insulin Complexes with QPDMAEMA-b-PLMA-b-POEGMA Cationic Amphiphlic Triblock Terpolymer Micelles

Polymers ◽

10.3390/polym12020309 ◽

2020 ◽

Vol 12 (2) ◽

pp. 309 ◽

Cited By ~ 2

Author(s):

Athanasios Skandalis ◽

Anastasiia Murmiliuk ◽

Miroslav Štěpánek ◽

Stergios Pispas

Keyword(s):

Ionic Strength ◽

Surface Charge ◽

Electrostatic Interactions ◽

Protein Complexes ◽

Force Microscopy ◽

Atomic Force ◽

Cationic Micelles ◽

Micellar Aggregates ◽

Physicochemical Evaluation ◽

Triblock Terpolymers

Herein, poly[quaternized 2-(dimethylamino)ethyl methacrylate-b-lauryl methacrylate-b-(oligo ethylene glycol)methacrylate] (QPDMAEMA-b-PLMA-b-POEGMA) cationic amphiphilic triblock terpolymers were used as vehicles for the complexation/encapsulation of insulin (INS). The terpolymers self-assemble in spherical micelles with PLMA cores and mixed QPDMAEMA/POEGMA coronas in aqueous solutions. The cationic micelles were complexed via electrostatic interactions with INS, which contains anionic charges at pH 7. The solutions were colloidally stable in all INS ratios used. Light-scattering techniques were used for investigation of the complexation ability and the size and surface charge of the terpolymer/INS complexes. The results showed that the size of the complexes increases as INS ratio increases, while at the same time the surface charge remains positive, indicating the formation of clusters of micelles/INS complexes in the solution. Fluorescence spectroscopy measurements revealed that the conformation of the protein is not affected after the complexation with the terpolymer micellar aggregates. It was observed that as the solution ionic strength increases, the size of the QPDMAEMA-b-PLMA-b-POEGMA/INS complexes initially decreases and then remains practically constant at higher ionic strength, indicating further aggregation of the complexes. atomic force microscopy (AFM) measurements showed the existence of both clusters and isolated nanoparticulate terpolymer/protein complexes.

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Comparative Study of the Adsorption of Acid Blue 40 on Polyaniline, Magnetic Oxide and Their Composites: Synthesis, Characterization and Application

Materials ◽

10.3390/ma12182854 ◽

2019 ◽

Vol 12 (18) ◽

pp. 2854 ◽

Cited By ~ 5

Author(s):

Muhammad ◽

Shah ◽

Bilal

Keyword(s):

Free Energy ◽

Comparative Study ◽

Gibbs Free Energy ◽

Electrostatic Interactions ◽

Solution Temperature ◽

Maximum Adsorption Capacity ◽

Aqueous Environment ◽

Magnetic Oxide ◽

Vis Spectroscopy ◽

Acid Blue

Conducting polymers (CPs), especially polyaniline (PANI) based hybrid materials have emerged as very interesting materials for the adsorption of heavy metals and dyes from an aqueous environment due to their electrical transport properties, fascinating doping/de-doping chemistry and porous surface texture. Acid Blue 40 (AB40) is one of the common dyes present in the industrial effluents. We have performed a comparative study on the removal of AB40 from water through the application of PANI, magnetic oxide (Fe3O4) and their composites. Prior to this study, PANI and its composites with magnetic oxide were synthesized through our previously reported chemical oxidative synthesis route. The adsorption of AB40 on the synthesized materials was investigated with UV-Vis spectroscopy and resulting data were analyzed by fitting into Tempkin, Freundlich, Dubinin–Radushkevich (D–R) and Langmuir isotherm models. The Freundlich isotherm model fits more closely to the adsorptions data with R2 values of 0.933, 0.971 and 0.941 for Fe3O4, PANI and composites, respectively. The maximum adsorption capacity of Fe3O4, PANI and composites was, respectively, 130.5, 264.9 and 216.9 mg g−1. Comparatively good adsorption capability of PANI in the present case is attributed to electrostatic interactions and a greater number of H-bonding. Effect of pH of solution, temperature, initial concentration of AB40, contact time, ionic strength and dose of adsorbent were also investigated. Adsorption followed pseudo-second-order kinetics. The activation energy of adsorption of AB40 on Fe3O4, PANI and composites were 30.12, 22.09 and 26.13 kJmol−1 respectively. Enthalpy change, entropy change and Gibbs free energy changes are −6.077, −0.026 and −11.93 kJ mol−1 for adsorption of AB40 on Fe3O4. These values are −8.993, −0.032 and −19.87 kJ mol−1 for PANI and −10.62, −0.054 and −19.75 kJ mol−1 for adsorption of AB40 on PANI/Fe3O4 composites. The negative sign of entropy, enthalpy and Gibbs free energy changes indicate spontaneous and exothermic nature of adsorption.

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DETERMINATION OF GLYCOL CONTAMINATION IN ENGINE OIL BY INFRARED AND UV-VIS SPECTROSCOPY

Proceedings of the 73rd International Symposium on Molecular Spectroscopy ◽

10.15278/isms.2018.th10 ◽

2018 ◽

Author(s):

Torrey Holland ◽

Dennis Watson ◽

P Sivakumar ◽

Ali Abdul-Munaim ◽

Robinson Karunanithy

Keyword(s):

Engine Oil ◽

Vis Spectroscopy

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Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19791942 ◽

1979 ◽

Vol 44 (6) ◽

pp. 1942-1948 ◽

Cited By ~ 3

Author(s):

Jaroslav Hrouz ◽

Michal Ilavský ◽

Ivan Havlíček ◽

Karel Dušek

Keyword(s):

Methyl Acrylate ◽

Poisson Ratio ◽

Young Modulus ◽

Ethyl Acrylate ◽

Sample Volume ◽

Viscoelastic Behaviour ◽

Tensile Behaviour ◽

Temperature Superposition ◽

Main Transition

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.

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Influence of the Share of Renewable Energy Sources on the Level of Energy Security in EECCA Countries

Energies ◽

10.3390/en14040903 ◽

2021 ◽

Vol 14 (4) ◽

pp. 903 ◽

Cited By ~ 1

Author(s):

Ivan Trifonov ◽

Dmitry Trukhan ◽

Yury Koshlich ◽

Valeriy Prasolov ◽

Beata Ślusarczyk

Keyword(s):

Renewable Energy ◽

Energy Security ◽

Structural Characteristics ◽

Renewable Energy Sources ◽

Energy Resource ◽

Energy Sources ◽

Structural Content ◽

High Degree

In this study we aimed to determine the extent to which changes in the share of renewable energy sources, their structural complex, and the level of energy security in Eastern Europe, Caucasus and Central Asia (EECCA) countries in the medium- and long-term are interconnected. The study was performed through modeling and determination of the structural characteristics of energy security in the countries. The methodology of the approach to modeling was based on solving the problem of nonlinear optimization by selecting a certain scenario. For the study, the data of EECCA countries were used. The ability of EECCA countries to benefit from long-term indirect and induced advantages of the transformation period depends on the extent to which their domestic supply chains facilitate the deployment of energy transformation and induced economic activity. This study provides an opportunity to assess the degree of influence of renewable energy sources on the level of energy security of countries in the context of energy resource diversification. The high degree of influence of renewable energy sources on energy security in the EECCA countries has been proven in the implementation of the developed scenarios for its increase. Energy security is growing. At the same time, its level depends not only on an increase in the share of renewable sources but also on the structure of energy resources complex of countries, and the development of various renewable energy sources. Therefore, today the EECCA countries are forced not only to increase the share of renewable energy sources but also to attach strategic importance to the structural content of their energy complex.

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Voltammetric sensor based on long alkyl chain tetraalkylammonium ionic liquids comprising ascorbate anion for determination of nitrite

Microchimica Acta ◽

10.1007/s00604-021-04713-4 ◽

2021 ◽

Vol 188 (2) ◽

Author(s):

Tomasz Rębiś ◽

Michał Niemczak ◽

Patrycja Płócienniczak ◽

Juliusz Pernak ◽

Grzegorz Milczarek

Keyword(s):

Ionic Liquids ◽

Electrostatic Interactions ◽

Film Surface ◽

Modified Electrodes ◽

Voltammetric Sensor ◽

Nitrite Oxidation ◽

Alkyl Chains ◽

Modified Surface ◽

Influence Of Ph

AbstractAn electrochemical sensor was fabricated utilizing ionic liquids possessing cations with long alkyl chains such as trimethyl octadecylammonium and behenyl trimethylammonium and ascorbate anion. The ionic liquids were drop-coated onto the electrode. Thin modifying layers were prepared. Cyclic voltammetric investigations revealed electrostatic interactions between the electrochemical probes and the modified surface, proving that a positive charge was established at the film surface. Hence, negatively charged species such as nitrite can be pre-concentrated on the surface of presented modified electrodes. The fabricated electrodes have been used as a voltammetric sensor for nitrite. Due to the electrostatic accumulation properties of long alkyl cation, the assay exhibits a remarkable improvement in the voltammetric response toward nitrite oxidation. The influence of pH on the electrode response was thoroughly investigated, and the mechanism of the electrode was established. The developed sensor showed a linear electrochemical response in the range 1.0–50 μM with a detection limit of 0.1 μM. The electrode revealed good storage stability, reproducibility, and anti-interference ability. The determination of nitrite performed in curing salts brought satisfactory results. Graphical abstract

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Fabrication of Ultrathin MoS2 Nanosheets and Application on Adsorption of Organic Pollutants and Heavy Metals

Processes ◽

10.3390/pr8050504 ◽

2020 ◽

Vol 8 (5) ◽

pp. 504 ◽

Cited By ~ 1

Author(s):

Siyi Huang ◽

Ziyun You ◽

Yanting Jiang ◽

Fuxiang Zhang ◽

Kaiyang Liu ◽

...

Keyword(s):

Heavy Metals ◽

Electrostatic Interactions ◽

Large Scale ◽

Layer Structure ◽

Structural Characteristics ◽

Hexagonal Phase ◽

Two Dimensional ◽

Mos2 Nanosheets ◽

Hybrid Strategy ◽

Ultrathin Mos2 Nanosheets

Owing to their peculiar structural characteristics and potential applications in various fields, the ultrathin MoS2 nanosheets, a typical two-dimensional material, have attracted numerous attentions. In this paper, a hybrid strategy with combination of quenching process and liquid-based exfoliation was employed to fabricate the ultrathin MoS2 nanosheets (MoS2 NS). The obtained MoS2 NS still maintained hexagonal phase (2H-MoS2) and exhibited evident thin layer-structure (1–2 layers) with inconspicuous wrinkle. Besides, the MoS2 NS dispersion showed excellent stability (over 60 days) and high concentration (0.65 ± 0.04 mg mL−1). The MoS2 NS dispersion also displayed evident optical properties, with two characteristic peaks at 615 and 670 nm, and could be quantitatively analyzed with the absorbance at 615 nm in the range of 0.01–0.5 mg mL−1. The adsorption experiments showed that the as-prepared MoS2 NS also exhibited remarkable adsorption performance on the dyes (344.8 and 123.5 mg g−1 of qm for methylene blue and methyl orange, respectively) and heavy metals (185.2, 169.5, and 70.4 mg g−1 of qm for Cd2+, Cu2+, and Ag+). During the adsorption, the main adsorption mechanisms involved the synergism of physical hole-filling effects and electrostatic interactions. This work provided an effective way for the large-scale fabrication of the two-dimensional nanosheets of transition metal dichalcogenides (TMDs) by liquid exfoliation.

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Structural characteristics of plant cell wall elucidated by solution-state 2D NMR spectroscopy with an optimized procedure

Green Processing and Synthesis ◽

10.1515/gps-2020-0049 ◽

2020 ◽

Vol 9 (1) ◽

pp. 650-663

Author(s):

Wanwan Wang ◽

Jibao Cai ◽

Zhenyu Xu ◽

Yi Zhang ◽

Fanchao Niu ◽

...

Keyword(s):

Cell Wall ◽

Quantum Coherence ◽

Nmr Spectra ◽

Plant Cell Wall ◽

Milling Time ◽

Structural Characteristics ◽

2D Nmr ◽

2D Nmr Spectroscopy ◽

Complete Representation

AbstractA method was developed for rapid qualitative determination of lignocellulose in the tobacco cell wall by utilizing 2D heteronuclear single quantum coherence NMR spectra (2D HSQC NMR). Traditional methods for analyzing the structure of lignocellulose involve many steps of separation and extraction, which is labor-intensive. In this work, the whole cell wall was milled and dissolved in deuterium solvent. The solvent dimethylsulfoxide (DMSO-d6) containing hexamethylphosphoramide (HMPA-d18) enhanced swelling of the sample and gave high-resolution spectra. The tobacco samples are ball milled at different ball milling times, and the state of the particles is observed through an electron microscope, and then the probability of the particles being less than 5 µm is counted. Through the comparison of the abundance and integration of the peak signals in the spectra under different transmittances, it was determined that when the milling time was 6 h, the quality of the NMR spectra was the best. The optimum conditions of characterizing tobacco structure were DMSO-d6/HMPA-d18 solution and 6 h milling time. Under these conditions, complete representation of the structure of lignocellulose and simplified process could be achieved.

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