scholarly journals Radiation-Induced Graft Immobilization (RIGI): Covalent Binding of Non-Vinyl Compounds on Polymer Membranes

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1849
Author(s):  
Martin Schmidt ◽  
Stefan Zahn ◽  
Florian Gehlhaar ◽  
Andrea Prager ◽  
Jan Griebel ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Covalent Binding ◽  
Polymer Surface ◽  
Experimental Studies ◽  
Polymeric Materials ◽  
Covalent Attachment ◽  
Minor Role ◽  
Water Radiolysis ◽  
Radiation Induced

Radiation-induced graft immobilization (RIGI) is a novel method for the covalent binding of substances on polymeric materials without the use of additional chemicals. In contrast to the well-known radiation-induced graft polymerization (RIGP), RIGI can use non-vinyl compounds such as small and large functional molecules, hydrophilic polymers, or even enzymes. In a one-step electron-beam-based process, immobilization can be performed in a clean, fast, and continuous operation mode, as required for industrial applications. This study proposes a reaction mechanism using polyvinylidene fluoride (PVDF) and two small model molecules, glycine and taurine, in aqueous solution. Covalent coupling of single molecules is achieved by radical recombination and alkene addition reactions, with water radiolysis playing a crucial role in the formation of reactive solute species. Hydroxyl radicals contribute mainly to the immobilization, while solvated electrons and hydrogen radicals play a minor role. Release of fluoride is mainly induced by direct ionization of the polymer and supported by water. Hydrophobic chains attached to cations appear to enhance the covalent attachment of solutes to the polymer surface. Computational work is complemented by experimental studies, including X-ray photoelectron spectroscopy (XPS) and fluoride high-performance ion chromatography (HPIC).

scholarly journals Numerical Modeling of Bond Formation in Polymer Surface Metallization Using Cold Spray

2021 ◽  
Author(s):  
Asghar Heydari Astaraee ◽  
Chiara Colombo ◽  
Sara Bagherifard
Keyword(s):  
Numerical Modeling ◽  
Cold Spray ◽  
Particle Velocity ◽  
Spray Deposition ◽  
Polymer Surface ◽  
Experimental Studies ◽  
Polymeric Materials ◽  
Element Model ◽  
Mechanical Interlocking ◽  
Surface Metallization

AbstractSurface metallization of polymeric materials using cold spray technology has gained increasing attention in the past decade. Experimental studies have evidenced multiple challenges of this process regarding continuity and homogeneity of the metallic deposits on polymer substrates. Modeling and simulation tools could be very helpful to assess the efficiency of different strategies suggested for improved deposition at a considerably reduced cost; nevertheless, the efforts to use numerical modeling in this sector have been less successful. Here, we develop a detailed finite element model for the cold spray deposition of metal particles on polymeric substrates to shed light on the underlying deposition mechanisms. The simulation results are compared with the literature experiments to establish the effectiveness of the proposed model. The developed model is able to capture the key phenomena involved in the deposition mechanism particularly the particle and substrate mechanical interlocking and substrate local melting. It is shown that a particle velocity threshold value should be exceeded to achieve an effective mechanical interlocking. The substate thermal domain and melting as well as the effects of particle velocity and size on deformation and particle anchorage are discussed.

scholarly journals Structure Tuning and Electrical Properties of Mixed PVDF and Nylon Nanofibers

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6096
Author(s):  
Petr Černohorský ◽  
Tatiana Pisarenko ◽  
Nikola Papež ◽  
Dinara Sobola ◽  
Ştefan Ţălu ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Complex Analysis ◽  
Polymeric Materials ◽  
Sample Surface ◽  
Polyamide 6 ◽  
Scanning Calorimetry ◽  
Spinning Process ◽  
Ft Ir

The paper specifies the electrostatic spinning process of specific polymeric materials, such as polyvinylidene fluoride (PVDF), polyamide-6 (PA6, Nylon-6) and their combination PVDF/PA6. By combining nanofibers from two different materials during the spinning process, new structures with different mechanical, chemical, and physical properties can be created. The materials and their combinations were subjected to several measurements: scanning electron microscopy (SEM) to capture topography; contact angle of the liquid wettability on the sample surface to observe hydrophobicity and hydrophilicity; crystallization events were determined by differential scanning calorimetry (DSC); X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier-transform infrared spectroscopy (FT-IR) to describe properties and their changes at the chemical level. Furthermore, for the electrical properties of the sample, the dielectric characteristics and the piezoelectric coefficient were measured. The advantage of the addition of co-polymers was to control the properties of PVDF samples and understand the reasons for the changed functionality. The innovation point of this work is the complex analysis of PVDF modification caused by mixing with nylon PA6. Here we emphasize that the application of nylon during the spin influences the properties and structure (polarization, crystallization) of PVDF.

scholarly journals Non-Equilibrium Plasma Methods for Tailoring Surface Properties of Polyvinylidene Fluoride: Review and Challenges

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4243
Author(s):  
Alenka Vesel ◽  
Rok Zaplotnik ◽  
Gregor Primc ◽  
Miran Mozetič ◽  
Tadeja Katan ◽  
...  
Keyword(s):  
Surface Modification ◽  
Surface Properties ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Polymer Surface ◽  
Argon Plasma ◽  
Standard Technique ◽  
Water Contact ◽  
Plasma Methods ◽  
Non Equilibrium

Modification and functionalization of polymer surface properties is desired in numerous applications, and a standard technique is a treatment with non-equilibrium gaseous plasma. Fluorinated polymers exhibit specific properties and are regarded as difficult to functionalize with polar functional groups. Plasma methods for functionalization of polyvinylidene fluoride (PVDF) are reviewed and different mechanisms involved in the surface modification are presented and explained by the interaction of various reactive species and far ultraviolet radiation. Most authors used argon plasma but reported various results. The discrepancy between the reported results is explained by peculiarities of the experimental systems and illustrated by three mechanisms. More versatile reaction mechanisms were reported by authors who used oxygen plasma for surface modification of PVDF, while plasma sustained in other gases was rarely used. The results reported by various authors are analyzed, and correlations are drawn where feasible. The processing parameters reported by different authors were the gas pressure and purity, the discharge configuration and power, while the surface finish was predominantly determined by X-ray photoelectron spectroscopy (XPS) and static water contact angle (WCA). A reasonably good correlation was found between the surface wettability as probed by WCA and the oxygen concentration as probed by XPS, but there is hardly any correlation between the discharge parameters and the wettability.

scholarly journals Comparison of Different Oxidation Techniques for Biofunctionalization of Pyrolyzed Carbon

2014 ◽  
Vol 11 (1) ◽  
pp. 01-08 ◽  
Author(s):  
Varun Penmatsa ◽  
Hiroshi Kawarada ◽  
Yin Song ◽  
Chunlei Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Vacuum Ultraviolet ◽  
Covalent Binding ◽  
Covalent Attachment ◽  
Carbon Surface ◽  
Electrochemical Activation ◽  
Carbon Substrate ◽  
Carboxyl Group ◽  
Nano Structures ◽  
Pretreatment Time

Pyrolyzed carbon micro/nano-structures have great potential as functional units in biosensors where biofunctionalization of the carbon surface is a requisite. In this work, we present a comparison of four different oxidation pretreatments, i.e. vacuum ultraviolet (VUV), electrochemical activation (EA), oxygen reactive ion etching (RIE), and ultraviolet/ozone (UV/O3) pretreatments on pyrolyzed carbon surface. X-ray photoelectron spectroscopy (XPS) results indicated that all the oxidation techniques except UV/O3 pretreatment yielded identical oxidation levels. The percentage of the carboxyl group which is suitable for covalent attachment of amine terminated biomolecules increased with pretreatment time, and was highest in the case of VUV pretreatment (15%) followed by oxygen RIE (12.5%) and EA pretreatments (12.5%) and UV/O3 pretreatment showed significantly lower carboxyl group percentage at 6%. This study helps to optimize the surface functionalization conditions for covalent binding of bioreceptors on the pyrolyzed carbon substrate for biosensing applications.

New Method for Bonding Poly(Ethylene Oxide) PEO to Surfaces

1995 ◽  
Vol 414 ◽  
Author(s):  
S. J. S. Allgor ◽  
E.W. Merrill
Keyword(s):  
Electron Beam ◽  
Ethylene Oxide ◽  
Methacrylic Acid ◽  
Photoelectron Spectroscopy ◽  
Polymer Surface ◽  
New Method ◽  
Covalent Attachment ◽  
Basic Solution ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

AbstractA new method has been developed for the covalent attachment of poly(ethylene oxide) to various polymeric surfaces for use in biomedical applications. Methacrylic acid (MA) monomer was first grafted to low-density polyethylene (LDPE) or polystyrene (PS) sheets by placing them in a solution of 10–20% (v/v) methacrylic acid in water followed by electron beam irradiation of 2–4 megarads. The methacrylic acid was grafted to the surface and polymerized, resulting in the polymer surface being extremely hydrophilic. The MA-treated samples were placed in a solution of PEO in water (MW 8000 – lx106 g/mol, concentration 0.05–15 % w/v), where the PEO strongly hydrogen bonds to the MA on the surface. The pieces were either rinsed with water (monolayer formation) or drained of excess solution (multilayer formation), then placed under the electron beam for a dose of 2 megarads to graft the PEO to the MA-treated surface. The grafted PEO was stable on the surface, unable to be removed despite extensive washing with water, soaking in basic solution (which would break the hydrogen bonding of the PEO with the acid), or scraping of excess hydrogel from the surface. The monolayer thickness was found to have no dependence on the molecular weight or concentration of the PEO in solution, nor did it have any dependence on the time that the MA-treated samples were soaking in the PEO solution before the second irradiation. This indicates that the PEO molecules immediately lie flat on the surface with few loops or tails, with no exchange taking place after the initial adsorption. All surfaces were analyzed using X-ray photoelectron spectroscopy (XPS), with high resolution carbon Is scans being the principle means of MA and PEO detection in the top 50 angstroms of the surface.

scholarly journals Novel Pathway for Efficient Covalent Modification of Polyester Materials of Different Design to Prepare Biomimetic Surfaces

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1299 ◽  
Author(s):  
Viktor Korzhikov-Vlakh ◽  
Ilia Averianov ◽  
Ekaterina Sinitsyna ◽  
Yuliya Nashchekina ◽  
Dmitry Polyakov ◽  
...  
Keyword(s):  
Covalent Binding ◽  
Polymer Surface ◽  
Material Design ◽  
Covalent Modification ◽  
Covalent Attachment ◽  
Poly Lactic Acid ◽  
Elevated Concentration ◽  
The Novel ◽  
Biomimetic Surfaces ◽  
Reactive Groups

To form modern materials with biomimic surfaces, the novel pathway for surface functionalization with specific ligands of well-known and widely used polyester-based rigid media was developed and optimized. Two types of material bases, namely, poly(lactic acid) and poly(ε-caprolactone), as well as two types of material design, e.g., supermacroporous matrices and nanoparticles (NPs), were modified via covalent attachment of preliminary oxidized polyvinylsaccharide poly(2-deoxy-N-methacryloylamido-d-glucose) (PMAG). This polymer, being highly biocompatible and bioinspired, was used to enhance hydrophilicity of the polymer surface and to provide the elevated concentration of reactive groups required for covalent binding of bioligands of choice. The specialties of the interaction of PMAG and its preliminary formed bioconjugates with a chemically activated polyester surface were studied and thoroughly discussed. The supermacroporous materials modified with cell adhesion motifs and Arg-Gly-Asp-containing peptide (RGD-peptide) were tested in the experiments on bone tissue engineering. In turn, the NPs were modified with bioligands (“self-peptide” or camel antibodies) to control their phagocytosis that can be important, for example, for the preparation of drug delivery systems.

scholarly journals Molecular Hydrogen as a Potential Clinically Applicable Radioprotective Agent

2021 ◽  
Vol 22 (9) ◽  
pp. 4566
Author(s):  
Shin-ichi Hirano ◽  
Yusuke Ichikawa ◽  
Bunpei Sato ◽  
Haru Yamamoto ◽  
Yoshiyasu Takefuji ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Molecular Hydrogen ◽  
Regulation Of Gene Expression ◽  
Animal Experiments ◽  
Radiation Energy ◽  
Water Radiolysis ◽  
Low Dose Radiation ◽  
Oxidizing Power ◽  
Radiation Induced ◽  
Radioprotective Agent

Although ionizing radiation (radiation) is commonly used for medical diagnosis and cancer treatment, radiation-induced damages cannot be avoided. Such damages can be classified into direct and indirect damages, caused by the direct absorption of radiation energy into DNA and by free radicals, such as hydroxyl radicals (•OH), generated in the process of water radiolysis. More specifically, radiation damage concerns not only direct damages to DNA, but also secondary damages to non-DNA targets, because low-dose radiation damage is mainly caused by these indirect effects. Molecular hydrogen (H2) has the potential to be a radioprotective agent because it can selectively scavenge •OH, a reactive oxygen species with strong oxidizing power. Animal experiments and clinical trials have reported that H2 exhibits a highly safe radioprotective effect. This paper reviews previously reported radioprotective effects of H2 and discusses the mechanisms of H2, not only as an antioxidant, but also in intracellular responses including anti-inflammation, anti-apoptosis, and the regulation of gene expression. In doing so, we demonstrate the prospects of H2 as a novel and clinically applicable radioprotective agent.

scholarly journals In Vitro Effect of Replicated Porous Polymeric Nano-MicroStructured Biointerfaces Characteristics on Macrophages Behavior

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1913
Author(s):  
Luminita Nicoleta Dumitrescu ◽  
Madalina Icriverzi ◽  
Anca Bonciu ◽  
Anca Roșeanu ◽  
Antoniu Moldovan ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Photoelectron Spectroscopy ◽  
Polyvinylidene Fluoride ◽  
Surface Characteristics ◽  
Sem Analysis ◽  
Chemical Structures ◽  
Microstructured Surface ◽  
Inflammatory Conditions ◽  
Vitro Effect

In the last decades, optimizing implant properties in terms of materials and biointerface characteristics represents one of the main quests in biomedical research. Modifying and engineering polyvinylidene fluoride (PVDF) as scaffolds becomes more and more attractive to multiples areas of bio-applications (e.g., bone or cochlear implants). Nevertheless, the acceptance of an implant is affected by its inflammatory potency caused by surface-induced modification. Therefore, in this work, three types of nano-micro squared wells like PVDF structures (i.e., reversed pyramidal shape with depths from 0.8 to 2.5 microns) were obtained by replication, and the influence of their characteristics on the inflammatory response of human macrophages was investigated in vitro. FTIR and X-ray photoelectron spectroscopy analysis confirmed the maintaining chemical structures of the replicated surfaces, while the topographical surface characteristics were evaluated by AFM and SEM analysis. Contact angle and surface energy analysis indicated a modification from superhydrophobicity of casted materials to moderate hydrophobicity based on the structure’s depth change. The effects induced by PVDF casted and micron-sized reversed pyramidal replicas on macrophages behavior were evaluated in normal and inflammatory conditions (lipopolysaccharide treatment) using colorimetric, microscopy, and ELISA methods. Our results demonstrate that the depth of the microstructured surface affects the activity of macrophages and that the modification of topography could influence both the hydrophobicity of the surface and the inflammatory response.

scholarly journals Non-Covalent Binding of Tripeptides-Containing Tryptophan to Polynucleotides and Photochemical Deamination of Modified Tyrosine to Quinone Methide Leading to Covalent Attachment

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4315
Author(s):  
Antonija Erben ◽  
Igor Sviben ◽  
Branka Mihaljević ◽  
Ivo Piantanida ◽  
Nikola Basarić
Keyword(s):  
Quantum Yield ◽  
Photophysical Properties ◽  
Covalent Binding ◽  
Quinone Methide ◽  
Covalent Attachment ◽  
Dna And Rna ◽  
Pair Composition ◽  
Aqueous Solvent ◽  
Fluorometric Study ◽  
Spectral Responses

A series of tripeptides TrpTrpPhe (1), TrpTrpTyr (2), and TrpTrpTyr[CH2N(CH3)2] (3) were synthesized, and their photophysical properties and non-covalent binding to polynucleotides were investigated. Fluorescent Trp residues (quantum yield in aqueous solvent ΦF = 0.03–0.06), allowed for the fluorometric study of non-covalent binding to DNA and RNA. Moreover, high and similar affinities of 2×HCl and 3×HCl to all studied double stranded (ds)-polynucleotides were found (logKa = 6.0–6.8). However, the fluorescence spectral responses were strongly dependent on base pair composition: the GC-containing polynucleotides efficiently quenched Trp emission, at variance to AT- or AU-polynucleotides, which induced bisignate response. Namely, addition of AT(U) polynucleotides at excess over studied peptide induced the quenching (attributed to aggregation in the grooves of polynucleotides), whereas at excess of DNA/RNA over peptide the fluorescence increase of Trp was observed. The thermal denaturation and circular dichroism (CD) experiments supported peptides binding within the grooves of polynucleotides. The photogenerated quinone methide (QM) reacts with nucleophiles giving adducts, as demonstrated by the photomethanolysis (quantum yield ΦR = 0.11–0.13). Furthermore, we have demonstrated photoalkylation of AT oligonucleotides by QM, at variance to previous reports describing the highest reactivity of QMs with the GC reach regions of polynucleotides. Our investigations show a proof of principle that QM precursor can be imbedded into a peptide and used as a photochemical switch to enable alkylation of polynucleotides, enabling further applications in chemistry and biology.

New and safe experimental model of radiation-induced neurovascular histological changes for microsurgical research

2016 ◽  
Vol 51 (2) ◽  
pp. 124-137
Author(s):  
Sergi Barrera-Ochoa ◽  
Irene Gallardo-Calero ◽  
Andrea Sallent ◽  
Alba López-Fernández ◽  
Ramona Vergés ◽  
...  
Keyword(s):  
Side Effects ◽  
Experimental Model ◽  
Experimental Studies ◽  
Neurovascular Bundle ◽  
Control Group ◽  
Sprague Dawley ◽  
Histological Changes ◽  
Group I ◽  
Radiation Induced

The aim is to create a new and safe experimental model of radiation-induced neurovascular histological changes with reduced morbidity and mortality for use with experimental microsurgical techniques. Seventy-two Sprague–Dawley rats (250–300 g) were divided as follows: Group I: control group, 24 rats clinically evaluated during six weeks; Group II: evaluation of acute side-effects (two-week follow-up period), 24 irradiated (20 Gy) rats; and Group III: evaluation of subacute side-effects (six-week follow-up period), 24 irradiated (20 Gy) rats. Variables included clinical assessments, weight, vascular permeability (arterial and venous), mortality and histological studies. No significant differences were observed between groups with respect to the variables studied. Significant differences were observed between groups I vs II–III regarding survival rates and histological changes to arteries, veins and nerves. Rat body weights showed progressive increases in all groups, and the mortality rate of the present model is 10.4% compared with 30–40% in the previous models. In conclusion, the designed model induces selective changes by radiotherapy in the neurovascular bundle without histological changes affecting the surrounding tissues. This model allows therapeutic experimental studies to be conducted, including the viability of microvascular and microneural sutures post radiotherapy in the cervical neurovascular bundle.

Sign in / Sign up

Export Citation Format

Share Document