Poly Ethylene Terephthalate Track Membranes Research Articles

Developing tardigrade-inspired material: Track membranes functionalized with Dsup protein for cell-free DNA isolation.

When developing functionalized biomaterials, the proteins from extremophilic organisms, in particular unique tardigrade disordered proteins, are of great value. The damage suppressor protein (Dsup), initially discovered in the tardigrade Ramazzottius varieornatus and found to be an efficient DNA protector under oxidative and irradiation stress, has been hypothesized to possess a good potential for the development of the material, which can isolate cell-free DNA. With this in mind, DNA-nonadsorbing polyethylene terephthalate track membranes have been functionalized using the Dsup protein via covalent bonding with glutaraldehyde. The filtration experiments have verified the ability of track membranes with the immobilized Dsup protein to adsorb cell-free DNA, with an accumulation capacity of 70 ± 19 mg m-2. The resulting track membrane-based biomaterial might be used in various devices for filtration and separation of cell-free DNA molecules from biological solutions and environmental samples, and also for their accumulation, storage, and further manipulation.

Effect of Plasma Modification of Surface and Sterilization on Optical Characteristics of Polyethylene Terephthalate Track Membranes

Effect of plasma modification of surface and sterilization processes on optical characteristics of a polyethylene terephthalate (PET) track membrane (TM) is studied. The TMs are fabricated with the aid of irradiation of PET using 40Ar+8 ion beam and etching in a 1.5-M solution of NaOH. The TMs are modified using low temperature plasma and sterilized with the aid of autoclave treatment and gamma irradiation. The PET TMs exhibit low transmittance and refractivity due to formation of structural inhomogeneities and polymer crystal structure. The effect of plasma and sterilization leads to a decrease in the TM transmittance owing to an increase in the degree of crystallinity and formation of membrane artifacts.

Composite polyethylene terephthalate track membranes with thin teflon-like layers: Preparation and surface properties

In this work, we report on the synthesis and characteristics of composite membranes consisting of polymeric porous supports coated with thin films. Polyethylene terephthalate track etched membranes were used as porous substrates, while chemically-resistant polytetrafluoroethylene-like thin films were obtained by magnetron sputtering deposition. The effects of coating process on topside, backside and inside pores surfaces, leading to changes of morphology and chemical composition at surface were investigated upon the deposition time. Scanning Electron Microscopy (SEM) was used to reveal the morphological characteristics. The chemical composition of the initial support and resulted composite membranes was determined by means of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) measurements, where the chemical groups containing fluorine were used as indicators for plasma species penetration inside pores. Process conditions were identified which lead to membranes with contrast of properties on their sides, or completely coated with Teflon-like material on both sides and inside pores, thus with various wettability and liquid flow properties.

Ultrafast selective ionic transport through heat-treated polyethylene terephthalate track membranes with sub-nanometer pores

12-μm-thick polyethylene terephthalate (PET) track membranes with sub-nanometer pores fabricated with the newly developed track-UV technique without chemical etching showed ultrahigh selective ionic transport yet low permeability. We discovered that the permeability of these track membranes were irreversibly improved by two to three orders of magnitude via heat treatment. Meanwhile, these heat-treated track membranes maintained the high selectivity of ions. Our experimental results suggest heat treatment on the track membranes with sub-nanometer pores could provide a reliable and controllable way to enlarge nanopore size, and bring the track membrane to promising applications on ion separations, water purification, diaphragm material and so on.

FERROMAGNETIC NANOTUBES IN PORES OF TRACK MEMBRANES FOR THE FLEXIBLE ELECTRONIC ELEMENTS

In the paper the template synthesis of ferromagnetic (Fe, Co, Ni) nanotubes in the pores of track membranes were studied. The aim of this work was determination of nanotubes basic structural and magnetic parameters and demonstration of the possibility of application in the flexible electronics elements.By electrochemical deposition, ferromagnetic nanotubes with a diameter of 110 nm and an aspect ratio of 100 were formed in the pores of polyethylene terephthalate track membranes. The morphology of the obtained nanostructures were studied by scanning electron microscopy, the elemental composition was determined by the energy-dispersion analysis. Using the X-ray structural analysis, the main parameters of the crystal structure were established: lattice type, lattice parameter and average crystallite size. The magnetic properties were studied by the method of vibrational magnetometry.It was shown that in the selected conditions of synthesis without reference to the type of ferromagnetic metals nanotubes had the same dimensions – length, diameter and wall thickness. The produced nanotubes consisted of iron, cobalt and nickel, respectively without oxides impurities. Nanotubes had a polycrystalline structure of walls with a body-centered cubic (iron), face-centered cubic (cobalt and nickel) crystal lattice. According to the main magnetic parameters, nanotubes belonged to a group of soft magnetic materials. Also, the presence of magnetic anisotropy, which is caused by the features of crystalline structure and shape of the nanostructures.Based on the analysis of structural and magnetic characteristics of ferromagnetic nanotubes which were synthesized in the pores of track membranes, were proposed the main principles of their using in the elements’ of flexible electronics constructing (magnetic field direction sensors and magnetic memory elements).

Sterilization of Polyethylene Terephthalate Track Membranes Using Low-temperature Atmospheric-pressure Plasma

Currently, much attention is paid to low-temperature atmospheric-pressure plasma as an agent for gentle antimicrobial decontamination. In this work, data on the efficiency of low-temperature plasma for antimicrobial decontamination of polyethylene terephthalate track membranes used as corneal implants in keratoplasty are presented. The obtained results show that 30-, 60-, and 90-s exposure to low-temperature plasma has a gentle decontaminating effect on track membranes.

Energy transfer in rigid solutions with nonuniform distribution of components based on quantum dots and organic molecules

Energy transfer in hybrid structures based on colloidal quantum dots of CdSe/ZnS and molecules of tetra(p-trimethylamino)phenylporphin formed in polyethylene terephthalate track membranes is considered. A physical model for the formation of these hybrid structures is proposed, and the distribution of structure components in the near-surface layer of track membrane pores is estimated.

Influence of low-temperature plasma and γ radiation on the surface properties of PET track membranes

Physical and chemical properties of the surfaces of polyethylene-terephthalate (PET) track membranes (TMs) exposed to low-temperature atmospheric plasma and to γ radiation produced by 60Co isotopes are studied. It is established that the exposure to plasma leads to changes in the chemical composition of the surface and increases the number of polar (carbonyl and carboxyl) functional groups in a thin near-surface layer of a TM. The surface energy is also shown to grow owing to its polar component and surface reconstruction. The reconstruction consists in the growth of surface roughness owing to oxidation-reduction reactions, followed by the appearance of destructive areas. These changes promote a lyophilic behavior of the track-membrane surface. Subsequent γ irradiation of the surface is shown to reduce the plasma-modified TM undulation, while decreasing the number of destructive areas and bringing the material into a more equilibrium state.

Formation of microcrystalline structures in a flow of supersaturated HIO3 solution through the pores of track membranes

The formation of acicular microcrystals in the pores of a polyethylene terephthalate track membrane upon the filtration of a supersaturated aqueous HIO3 solution is studied. The transverse sizes and directions of preferred growth of the formed edged microcrystals are found to correspond to the configuration of pores of the track membrane.

Synthesis of bilayer composite nanomembranes with conductivity asymmetry

The structure and electrochemical properties of polyethylene terephthalate track membranes modified in acetylene plasma are studied. It is found that polymer deposition on the track membrane surface using acetylene polymerization in plasma results in the case of formation of a semipermeable layer covering pores in formation of a composite nanomembrane featuring asymmetry of conductivity in solutions of electrolytes: a rectifying effect similar to that of a p-n junction in semiconductors. It is shown that the observed effect of conductivity asymmetry is caused by a significant decrease in the diameter of pores in the plasma-deposited polymer layer and a change in the pore geometry, same as existence of an interface between the initial membrane and polymer layer that have a different concentration of carboxyl groups in the surface layer. The impedance spectroscopy method allowed obtaining information on ion transfer in the studied membranes.

Problems and prospects of development of nanomembrane technology

The latest Russian and foreign studies devoted to the theoretical and experimental investigation of the processes of formation of porous structure of track nanomembranes, the methods for studying their properties, and the application of track membranes to synthesis of nanostructures by a template method are reviewed. The results of the investigations carried out in these promising directions at the Department of Membrane Technologies of the Shubnikov Institute of Crystallography, Russian Academy of Sciences, are also presented. On the basis of the theoretical investigations of the mechanism of interaction of high-energy ions with a solid, it is shown that the theory of instantaneous explosion in a track region must be carefully verified. The results of the experimental investigation of the structure of tracks of high-energy ions in a polymer and the mechanism of pore formation in the stage of chemical etching of tracks showed that the track structure is inhomogeneous in the radial direction. It is shown that the surface of polyethylene terephthalate track membranes becomes negatively charged in neutral and alkaline solutions, and the value of this charge depends on the pore diameter. Good prospects of application of secondary metal structures formed on the basis of track membranes in mass spectroscopy are demonstrated experimentally.

Polyethyleneterephthalate track membranes with conical pores: Etching by water-alcohol alkali solutions

Etching by water-ethanol alkali (KOH) solutions and preparing polyethilene terephthalate track membranes with conical pores are described.