Display omitted
•Fluorine-containing block/branched cationic and nonionic polymers are synthesized.•Novel polyamphiphiles form micelles and intermolecular complexes with DNA and LYZ.•Morphology of ...micelles and bio-complexes depend on architecture of polyamphiphiles.•Natures of polyamphiphiles and biopolymers define mechanism of complex formation.•Polyamphiphiles provide delivery of DNA and LYZ and their controlled bio-activity.
Colloidal-chemical characteristics of block/branched cationic and non-ionic polyamphiphiles containing poly(fluorine-alkyl methacrylate) (poly(FMA)) block and their intermolecular complexes with biopolymers were studied. The dependences of their surface activity and micelle size on the length of hydrophobic and hydrophilic blocks, as well as the length of side fluorine-alkyl branches were established. Poly(FMA)-block-poly(DMAEMA) was used for formation of interpolyelectrolyte complexes with plasmid DNA (pDNA) via their electrostatic interaction. Novel non-viral polyplexes were tested as gene delivery systems for mammalian cells. The results of DLS, TEM and MALDI-ToF studies demonstrated disaggregation of lysozyme (LYZ) aggregates in the presence of poly(FMA)-block-poly(NVP) and formation of the polyamphiphile…LYS complex possessing antibacterial action.
The solubilisation of methylparaben (MP), an antimicrobial agent used as a food preservative and in cosmetics and personal-care products, in two poloxamines of different Hydrophilic-Lipophilic ...Balance (HLB), namely Tetronic® 904 (T904) and 1107 (T1107), has been studied. The influence of the preservative on the aggregation behaviour of both Tetronics has been analysed by dynamic light scattering (DLS) and small-angle neutron scattering (SANS), while the precise location of the molecule in the aggregates as well as the effects of the micellar solubilisation on the reactivity of the preservative have been elucidated by NMR and UV spectroscopies. The presence of MP reduces the critical micelle temperature (CMT) of any of the poloxamines and induces the formation of larger micelles at room temperature compared to the plain poloxamines; in addition, a remarkable temperature dependent effect on the structure of the micelles has been detected, which progressively evolve from core-shell spheres to rods as the temperature increases. The incorporation of the preservative into the micelles modifies its reactivity against alkaline hydrolysis, resulting in a decrease of its reaction rate constant in which the dominant factor for the reduction in the hydrolysis rate is the incorporation into the micelle core, with a little effect of the length of the hydrophilic polyethylene oxide (PEO) blocks.
•The presence of MP reduces the CMT of the poloxamines and induces the formation of larger micelles at room temperature.•The micelles containing MP evolve from spheres to rods and to wormlike micelles as the temperature increases.•The predominant location of MP in the PPO core of the micelles has been probed by 2D-NOESY experiments.•The incorporation of MP into the micelles results in a decrease of its alkaline hydrolysis rate constant.
The inverse-gelation of methylcellulose (MC) is statistically understood for the loop formation, in which trans and gauche conformation are simultaneous. The dynamic light scattering (DLS) studies ...are performed to understand the temperature-dependent multiple scattering for a dilute solution of MC in an aqueous medium. These conformations further grow to form an entangled network, with a scattered size of 1.7 µm (an average hydrodynamic size) at 75 °C. The area under the light scattered curves at various temperatures is measured to calculate the energies involved in the gelation process. In the view of Maxwell Boltzmann's statistical, the active spheres are the number of sites that interconnect with probability 'α' to form a gel. The 'α' is maximum at the gel point, where all Cayley spheres merged to create a 3D network. The computational studies reveal that entanglement depends on the orientation of MC molecules and non-neighboring intramolecular H bonding (hydrogen bonding). The periodic box of 32 Å and 24 MC surrounded by water molecules suggest a hydrodynamic length of 5.5 nm (diagonal of the periodic box).
Herein, polymethylmethacrylate (PMMA)/dextran(D) hybrid composites are prepared by reinforcement of various concentrations of in situ reduced gold nanoparticles (Au NPs). As-synthesised PMMA/D-Au ...nanocomposites are characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), high resolution transmission electron microscopy(HRTEM) and atomic force microscopy(AFM). It is found that, the average size of Au NPs is 30 nm. The size distributions of Au NPs are studied from dynamics light scattering studies (DLS). The incorporation of Au NPs enhances the oxygen barrier, thermal, and antimicrobial properties of the PMMA/D matrix, by which, the hybrid composites are suitable for packaging applications.
The goal of the present paper is to explore the properties of medium molecular-weight chitosan/polyvinyl alcohol blends mixed in volume ratios of 75:25, 50:50, and 25:75 obtained by solution casting. ...Cross-linked chitosan/poly(vinyl alcohol) nanostructures were obtained by treating these blends with 5% (v/v) glutaraldehyde. The prepared chitosan/polyvinyl alcohol films were characterized by attenuated total reflectance - Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, and cytotoxicity, while the nanostructured materials were examined by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Also, the removal of lead(II) ions from aqueous solution by adsorbents nanostructures was studied in the batch adsorption mode. The effects of adsorbent dosages, initial metal concentration, and contact time on the adsorption capacity were investigated. The FT-IR spectra indicated the interactions of polyvinyl alcohol with chitosan. DSC and TGA analyses revealed the loss of water up to 100 °C. The zeta potential and mobility of the prepared nanostructures were enhanced with the increasing ratio of the cationic polymer. The results showed that the 100% chitosan adsorbent provided the highest removal of Pb(II) during the first 15 min (̴94%). The chitosan100/polyvinyl alcohol0 and chitosan75/polyvinyl alcohol25 nanostructures fitted well with the Langmuir isotherm model. The maximum adsorption capacities for Pb(II) ions reached maxima of 7.36 and 7.67 mg/g, respectively. The Freundlich isotherm model best described the Pb(II) adsorption on the 50% chitosan/50% polyvinyl alcohol and 25% chitosan/75% polyvinyl alcohol adsorbents. Furthermore, (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay results demonstrated that chitosan/polyvinyl alcohol films are biocompatible with more than 90% cell viability.
Synthesis of pure (ligandless) titanium nanoparticles by EB-PVD method Kurapov, Yurii A.; Litvin, Stanislav Е.; Belyavina, Nadezhda N. ...
Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology,
2021/1, Volume:
23, Issue:
1
Journal Article
Pure (ligandless) nanoparticles of titanium (4–20 nm) in a porous NaCl matrix (29–43 nm) were synthesized by the method of electron beam physical vapor deposition (EB-PVD). Independent electron beams ...were used to preheat the compacted cylinder from NaCl salt and Ti ingot up to formation of liquid melts. Evaporation of the initial materials from the melt surface, vapor flow mixing, and deposition of the mixed vapor on the surface of the water-cooled copper substrate took place in vacuum. Deposited condensate composition was regulated by the intensity of the vapor flows of evaporated materials. Results of studying the structure (SEM) and element composition of the condensate (EDS), phase composition (XPA), and the size of the nanoparticles (TEM) and crystallites (XPA + Scherrer equation), as well as their thermal stability in NaCl–Ti–O system (TGA), are given. It is shown that the dimensions and phase composition of titanium nanoparticles can be further controlled by heat treatment of the initial NaCl–Ti condensate, produced at low condensation temperatures. Investigations of the kinetics of oxidation of NaCl–Ti condensates in air (TGA) show that breaking of the vacuum in the chamber titanium nanoparticles in the porous NaCl matrix demonstrates high adsorption ability to moisture and oxygen from the air. With temperature increase up to 250–400 °C, practically all the moisture is removed, and further heating activates the process of titanium nanoparticle oxidation. Obtained results are considered from the viewpoint of physical and chemical adsorption.
Graphical abstract
From the moment the Republic of Serbia declared a state of emergency in the summer semester of 2019/2020, higher education institutions (HEIs) used various teaching models from Distance Learning ...Systems (DLS), online platforms and modern information and communication technologies (ICT), to sending materials via student e-mails and notifications via faculty portals. Using survey research as a method, the paper describes the experiences of teachers and associates at HEIs in Serbia (780 respondents) regarding the efficiency of provided education services. In this article, we used the method of content analysis and participatory observation, as well. We analysed the attitudes of teachers and associates apropos the efficiency of providing educational services through the work from home (WFH) model and distance learning (DL) and other models used in response to COVID-19 epidemiological measures in education. During the WFH setup, we looked for factors that affect educational efficiency. When it comes to the statistical technique, factor analysis was selected. Technology, managerial support, and work–home conflict are all expected to impact process efficiency, so these were the first criteria considered when selecting potential factors. Principal Component Analysis (PCA) was used as the extraction method, and the Varimax rotation method was also used. We discarded all factors with eigenvalues below one. Four factors caught our attention: School management support, Family–work conflict, Home infrastructure, and Technology choice. The results showed that F1 (School management support) is positively correlated to F2 (Family–work conflict) and efficiency and negatively correlated to F3 (Home infrastructure). Conversely, F2 is negatively correlated to F3 and positively correlated to efficiency. The F4 factor shows no significant correlations to other factors.
A simple environmentally friendly method for the synthesis of different shaped gold nanoparticles (AuNPs) using silk fibroin (SF) as a reducing, shape tailoring, chapping and subsequent stabilizing ...agent is reported. In this study, neither external reducing agents nor high temperature are used for the synthesis of nanoparticles. The nanoparticles formed in SF solution was probed by considering the changes in position and intensity of the localized surface plasmon resonance (LSPR) peak using UV–Visible spectroscopy (UV–Vis). Nano crystalline structure and FCC crystal family was established by X-ray diffraction (XRD) measurement. The size and shape evolution of the nanoparticles was inspected using transmission electron microscope (TEM) which confirmed the formation of different shaped nanoparticles. The average particles size of AuNPs in colloidal solution was scrutinized using dynamic light scattering (DLS) experiment. Synthesized gold nanoparticles were sense as potential ammonia detector.
H NMR methods in combination with dynamic light scattering were applied to study temperature behavior of poly(2-isopropyl-2-oxazoline) (PIPOx) homopolymer as well as PIPOx-
...-poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx)-
-PMeOx diblock copolymers in aqueous solutions.
H NMR spectra showed a different way of phase transition for the main and side chains in PIPOx-based solutions. Additionally, the phase transition is irreversible for PIPOx homopolymer and partially reversible for PIPOx-
-PMeOx copolymer. As revealed by NMR, the phase transition in PEtOx-based copolymers solutions exists despite the absence of solution turbidity. It is very broad, virtually independent of the copolymer composition and reversible with some hysteresis. Two types of water molecules were detected in solutions of the diblock copolymers above the phase transition-"free" with long and "bound" with short spin-spin relaxation times
. NOESY spectra revealed information about conformational changes observed already in the pre-transition region of PIPOx-
-PMeOx copolymer solution.
PDF
