Pre-irradiation Dose Research Articles

Silicone Rubber Modified with Methacrylic Acid to Host Antiseptic Drugs

Silicone rubber (SR) was γ-ray grafted with poly(methacrylic acid) (PMAA) to improve its ability to host antimicrobial drugs. Dependence of grafting yield on monomer concentration, pre-irradiation dose, temperature and reaction time was evaluated. Modified SR films were characterized by means of FT-IR, DSC, TGA, SEM, contact angle measurements, and swelling studies. SR-g-MAA showed pH sensitivity (critical pH ∼6) and good cytocompatibility. Soaking of SR-g-MAA in benzalkonium chloride and vancomycin aqueous solutions led to high loadings; up to 5.8 and 15.2 mg cm-2, respectively. SR-g-MAA released 100% vancomycin after 24 h in buffer pH 7.4 at 37 °C, but only 20% benzalkonium chloride due to strong ionic interactions. Drug-loaded SR-g-MAA prevented in vitro growth of Staphylococcus aureus. Overall, grafting of PMAA may improve the performance of SR for biomedical applications.

Antimicrobial Protection of Pre-irradiated Cotton and Cotton/Polyester Fabrics Printed with Pigment Colours

The paper deals with the improvement of the antimicrobial properties of gamma pre-irradiated cotton and cotton/PET blend fabrics, by using of different metal oxides (ZnO and Al2O3) as antimicrobial agents, through the printing process. The antimicrobial properties of the fabrics were evaluated, in terms of the mechanical properties after burying in a soil reach with microorganisms. Moreover, the effect of antimicrobial finishing on the printing properties, in terms of colour strength was investigated. It was found that the antimicrobial properties were enhanced by addition of the metal oxides up to 1% to the pigment printing paste, under pre-irradiation of fabrics up to 5 (kGy) for cotton and blend fabrics. The colour strength (K/S) of printed fabrics was increased by addition of 0.5% of metal oxides and pre-irradiation dose up to 5 (kGy) for cotton fabric and up to (10 (kGy) for blend fabrics. The thermal stability of the printed fabrics was evaluated by thermogravimetric analysis (TGA) technique, which it showed a decreasing in the thermal stability by addition of the metal oxides, varying according to the types of fabrics and metal oxides used.

EFFECT OF PRE- γ-IRRADIATION DOSE ON THE DURABILITY OF THE SULFONATED ETFE-G-POLYSTYRENE CONDUCTING MEMBRANES

The influence of pre-g-irradiation dose on durability of the poly(ethylene-co-tetrafluoroethylene) (ETFE) film-based radiation-grafted polymer electrolyte membrane was investigated. The durability of membrane was found to be strongly influence by g-ray pre-irradiation dose. The durability was tested in a 3% H2O2 aqueous solution at 60°C. The durability of the polymer electrolyte membrane with a degree of grafting of about 30% prepared by lower pre-irradiation dose was more stable than that of the membrane prepared with higher pre-irradiation dose.

Study and Optimization on graft polymerization under normal pressure and air atmospheric conditions, and its application to metal adsorbent

Radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene (NWPE) fabric was achieved under normal pressure and air atmospheric conditions, without using unique apparatus such as glass ampoules or vacuum lines. To attain graft polymerization under normal pressure and air atmospheric conditions, the effects of the pre-irradiation dose, pre-irradiation atmosphere, pre-irradiation temperature, de-aeration of GMA-emulsion, grafting atmosphere in a reactor, and dissolved oxygen (DO) concentration in GMA-emulsion on the degree of grafting (Dg) were investigated in detail. It was found that the DO concentration had the strongest influence, the pre-irradiation dose, de-aeration of emulsion and grafting atmosphere had a relatively strong impact, and the pre-irradiation atmosphere and pre-irradiation temperature had the least effect on Dg. The optimum DO concentration before grafting was 2.0mg/L or less. When a polyethylene bottle was used as a reactor instead of a glass ampoule, graft polymerization under normal pressure and air atmospheric conditions could be achieved under the following conditions; the pre-irradiation dose was more than 50kGy, the volume ratio of GMA-emulsion to air was 50:1 or less, and the DO concentration in GMA-emulsion during grafting was below 2.0mg/L. Under these grafting conditions, Dg was controlled within a range of up to 362%. The prepared GMA–grafted NWPE (GMA–g-NWPE) fabric was modified with a phosphoric acid to obtain an adsorbent for heavy metal ions. In the column-mode adsorption tests of Pb(II), the adsorption performance of the produced phosphorylated GMA–g-NWPE fabric (fibrous metal adsorbent) was not essentially dependent on the flow rate of the feed. The breakthrough points of 200, 500, and 1000h−1 in space velocity were 483, 477 and 462 bed volumes, and the breakthrough capacities of the three flow rates were 1.16, 1.15 and 1.16mmol-Pb(II)/g-adsorbent.

Impact of reading pre-irradiation background signal on the post-irradiation glow curves of thermoluminescence dosimeters

Due to their sensitivity, signal reproducibility and stability, lithium fluoride thermoluminescence dosimeters are widely used in many applications. It was noticed that post-irradiation glow curves of LiF dosimeters that had undergone pre-irradiation background dose measurements dramatically differed from the curves of dosimeters irradiated without such preliminary measurements. Three types of dosimeters were studied in this respect, namely, TLD-700, TLD-600, and TLD-100. Impact of pre-irradiation background measurements on the glow curve areas, peak positions, and individual peak intensities were investigated using computerized glow curve analysis. Similarities in the behavior of the dosimeters of all three types were found. Areas of the glow peaks P 2a, P 3, P 4, P 5, and P 6 increased. Peak P 3 grew most significantly, followed by P 2, and P 5. Also, one of the common features was a shift of T max of P 5 to higher temperatures. Pre-irradiation background readings increase the total area of the glow curve in general and affect relative intensities and positions of specific peaks, which changes the shape of the glow curve. It is strongly recommended to perform pre-irradiation background measurements for all LiF-based dosimeters regardless of the values of the background doses relative to the radiation doses to be given.

Does Photofrin II Combined with a Radio-Adaptive Dose Lead to a Synergistic or Additive Effect after Ionising Irradiation <i>In Vitro</i>?

Background: The radiosensitizing effect of Photofrin II has been demonstrated in vitro and in animal models, even in tumor models known to be highly radioresistant, such as glioblastoma and bladder carcinoma. Radio-adaptive doses are also known to lead to an augmented cell or tissue reaction. The aim of this study was to investigate potential synergistic or additive effects when combining the two methods in vitro for an improved therapeutic concept in bladder cancer. Material and Methods: RT4 human bladder carcinoma cell line and HCV29 human bladder epithelium cells were seeded and incubated with various concentrations of Photofrin II. The cells were additionally irradiated with ionizing radiation (0.05 Gy/2 Gy/0.05 Gy + 2 Gy). Cells without Photofrin II incubation and irradiation served as controls. The cell survival was evaluated. Results: The survival rate of both cell lines, RT4 and HCV29, did not differ significantly when incubated with a non-toxic concentration of Photofrin II and exposed to a pre-irradiation dose of 0.05 Gy prior to the 2 Gy radiation fraction, compared to cells exposed to Photofrin II plus a 2 Gy ionizing radiation. Conclusion: The combination of both methods did neither demonstrate a synergistic or additive effect nor did it lead to a negative influence of both modulating factors in an in vitro setting.

Zero-bias operation of polycrystalline chemically vapour deposited diamond films for Intensity Modulated Radiation Therapy

A detailed investigation of the performance as a dosimeter of state-of-art polycrystalline CVD (pCVD) diamond detectors operated in photovoltaic regime for applications in clinical radiotherapy has been carried out with conventional 6–10–18 MV X-photons, as well as with a 10 MV photon Intensity Modulated Radiation Therapy (IMRT) beam from a linear accelerator. Our results show that the performances of a pCVD diamond dosimeter improves dramatically when operated in null-bias conditions. Main improvements with respect to operation with an external voltage applied are: a reduced pre-irradiation dose; an excellent time stability, characterised by standard deviations less than 0.5%; a rise-time comparable to that of commercial reference dosimeters; a linearity with dose proven over three decades; a reduced deviation from linearity of the current vs. dose–rate curve, output factors comparable to that of commercial reference dosimeters. These results represent a significant step towards clinical applications as IMRT with synthetic polycrystalline CVD diamond films.

Influence of electron beam pre-irradiation on the thermal behaviors of polyacrylonitrile

Thermal treatment of polyacrylonitrile pre-irradiated by electron beam was performed to investigate the radiation effects on thermally activated reactions. Thermal properties were characterized by differential scanning calorimetry and thermogravimetric analyses. Pre-irradiation lowers the onset temperature of reactions and alleviated the heat evolution process. Char yields (800 °C) of polyacrylonitrile increase significantly with increasing irradiation dose. FTIR was used to monitor the thermal reaction. The results reveal that the thermal reactions can be regulated by pre-irradiation dose. FTIR and UV–visible absorption spectra of pre-irradiation polyacrylonitrile illustrate the formation of –HC N–N CH– conjugation across the polymeric chains as a function of dose, which could improve the thermal behaviors of polyacrylonitrile.

Evaluation of the fullerene compound DF-1 as a radiation protector

BackgroundFullerene compounds are known to possess antioxidant properties, a common property of chemical radioprotectors. DF-1 is a dendrofullerene nanoparticle with antioxidant properties previously found to be radioprotective in a zebrafish model. The purpose of this study was to evaluate the radioprotective effects of DF-1 in a murine model of lethal total body irradiation and to assess for selective radioprotection of normal cells versus tumor cells.MethodsIn vitro radioresponse was evaluated with clonogenic assays with human tumor cells and fibroblast lines in the presence of varying concentrations of DF-1 or vehicle. DNA double strand break induction and repair was evaluated with immunocytochemistry for γH2AX. Lethal total body irradiation was delivered with 137Cs after intraperitoneal delivery of DF-1 or vehicle control. Bone marrow hypoxia was evaluated with piminidazole uptake assessed by flow cytometry.ResultsDF-1 provided modest radioprotection of human cancer cell lines and fibroblast cell lines when delivered prior to irradiation (dose modifying factor or 1.1). There was no evidence of selective protection of fibroblasts versus tumor cells. Cells treated with DF-1 at radioprotective doses were found to have fewer γH2AX foci at 1 and 6 hours after irradiation compared to vehicle treated controls. The LD50/30 for C57Bl6/Ncr mice treated with a single 300 mg/kg dose of DF-1 pre-irradiation was 10.09 Gy (95% CI 9.58-10.26) versus 8.29 Gy (95% CI, 8.21-8.32) for control mice. No protective effects were seen with a single 200 mg/kg dose. No increase in pimonidazole uptake was appreciated in bone marrow of mice treated with DF-1 compared to vehicle controls.ConclusionsDF-1 has modest activity as a radiation protector in vivo. There was no evidence of selective protection from irradiation of normal versus tumor cells with DF-1.

Radiation grafting of NIPAAm and acryloxysuccinimide onto PP films and sequent crosslinking with polylysine

N-isopropylacrylamide (NIPAAm) and N-acryloxysuccinimide (NAS) were grafted from their binary mixtures in tetrahydrofurane (THF) and toluene solutions onto polypropylene (PP) films by the pre-irradiation oxidative method in air. Effects of pre-irradiation dose, dose rate, and monomer concentrations (NAS/NIPAAm) were studied. The grafted copolymers exhibited the lower critical solution temperature (LCST) at around 31 °C. Based on its thermo-reversible behavior, this system has been used for immunoassay, drug delivery, separation processes and immobilization of enzymes. N-acryloxysuccinimide (NAS) has been used as an active ester to bind proteins through amide bond formation with lysine, and because of this property, the grafted copolymer has been crosslinked with polylysine. Techniques used to characterize the films included differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), infrared (FTIR-ATR) and elemental analysis. Results on thermo-sensitivity are presented. This new system could find applications in vesicle immobilizations.

Radiation-induced grafting of stimuli-responsive binary monomers: PDMAEMA/PEGMEMA onto PP films

Both poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) were radiation grafted onto polypropylene films (PP) using gamma radiation from a 60Co source. PP was pre-irradiated by gamma ray for modification following by grafted PDMAEMA and PEGMEMA by a one step method. Grafting was studied as a function of the pre-irradiation dose between 20 and 180 kGy, dose rate of 10.4 kGy/h, and monomer concentration 50% of PDMAEMA/PEGMEMA (1/1) in different solvents (toluene, acetone, and methanol). FTIR-ATR, TGA, and DSC were carried out in the characterization of the graft copolymer obtained. Stimuli-responsive behavior and critical pH point were studied by swelling in water. pH and thermo-responsive films of PE-g-(DMAEMA/PEGMEMA) presented a lower critical solution temperature (LCST) of 50 °C and critical pH point around 8.7.

Electron‐beam‐radiation‐induced grafting of acrylonitrile onto polypropylene fibers: Influence of the synthesis conditions

AbstractElectron‐beam‐radiation‐induced grafting of acrylonitrile onto polypropylene fibers was investigated with a pre‐irradiation method. Grafting conditions such as the solvents, additives, monomer concentration, radiation dose, and temperature were varied, and the effects on the degree of grafting were studied. The nature of the reaction medium and additives had a considerable influence on the degree of grafting. The dilution of acrylonitrile with N,N‐dimethylformamide significantly enhanced the degree of grafting in comparison with other solvents. The addition of sulfuric acid to the reaction mixture led to an increase in the degree of grafting and an acceleration of the rate of grafting. The order of dependence of the rate of grafting on the pre‐irradiation dose and monomer concentration was found to be 1.31 and 1.21, respectively, in the presence of sulfuric acid. The activation energy for grafting was calculated to be 21.9 kJ/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Biodegradable metal adsorbent synthesized by graft polymerization onto nonwoven cotton fabric

A fibrous adsorbent for Hg ions was synthesized by radiation-induced emulsion graft polymerization of glycidyl methacrylate (GMA) onto a nonwoven cotton fabric and subsequent chemical modification. The optimal pre-irradiation dose for initiation of the graft polymerization of GMA, which minimized the effects of radiation damage on the mechanical strength of the nonwoven cotton fabric, was found to be 10 kGy. The GMA-grafted nonwoven cotton fabric was subsequently modified with ethylenediamine (EDA) or diethylenetriamine (DETA) to obtain a Hg adsorbent. The resulting amine-type adsorbents were evaluated for batch and continuous adsorption of Hg. In batch adsorption, the distribution coefficients of Hg reached 1.9×10 5 and 1.0×10 5 for EDA- and DETA-type adsorbents, respectively. A column packed with EDA-type adsorbent removed Hg from 1.8 ppm Hg solution at a space velocity of 100 h −1, which corresponds to 16,000 times the volume of the packed adsorbent. The adsorbed Hg on the EDA-type adsorbent could be completely eluted by 1 M HCl solution. A microbial oxidative degradation test revealed that the EDA-type adsorbent is biodegradable.

Preparation and Characterization of Nonwoven Polypropylene Fabric Irradiation-grafted with Acrylic Acid as Weakly Acidic Cation Exchange Fiber

Graft polymerization of acrylic acid onto nonwoven polypropylene (PP) fabric was carried out by a preirradiation method using a 60Co gamma radiation source. Results showed that 2.2'-Azobisisobutyronitrile (AIBN), its concentration was 0.2%, was very important during the grafting polymerization without removal of polymerization inhibitor of AA. The most favorable grafting polymerization conditions were that the total preirradiation dose was under 60 kGy, the monomer concentration was lower than 30%, and the bath ratio was 1:200. FT-IR spectroscopy, surface morphology (SEM), wide angle X-ray diffraction (WAXD) spectra of the original PP and the grafted PP were also studied.

Preparation and Characterization of Melt Grafting 2-acrylamido-2-methyl-1-propanesulfonic Acid onto Pre-Irradiated Linear Low Density Polyethylene

Linear low density polyethylene (LLDPE) was functionalized with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) by using β -ray pre-irradiation in air in a twin-screw extruder. Fourier-transformed infrared spectroscopy (FT-IR) and electron spectroscopy for chemical analysis (ESCA) were used to characterize the formation of LLDPE-g-AMPS copolymers. The content of AMPS in LLDPE-g-AMPS was determined by using element analysis instrument. The effects of concentrations of monomer, reaction temperature and pre-irradiation dose on degree of grafting were investigated. The critical surface tension of LLDPE-g-AMPS was measured by using contact angle method. The influences of the degree of grafting on crystallization properties were studied by using DSC. Compared with neat LLDPE, the crystallization temperature increased about 4°C, and crystallinity decreased with increasing degree of grafting. Crystallization rates of grafted LLDPE were faster than that of plain LLDPE at the same crystallization temperature.

Surface modification by γ-ray-induced grafting of PDMAEMA/PEGMEMA onto PE films

Radiation grafting of poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) onto polyethylene (PE) films was synthesized using gamma radiation from a 60Co source. PE was modified by the PDMAEMA and PEGMEMA by pre-irradiation and one-step method. Grafting as a function of the pre-irradiation dose between 50 and 200 kGy, dose rate of 9 kGy h −1, and monomer concentration 50% of PDMAEMA/PEGMEMA (1/1) in toluene. The characterization of the graft copolymer obtained was carried out by FTIR-ATR, TGA, and DSC. Stimuli-responsive behavior and critical pH point were studied by swelling in water, pH and thermo-responsive films of PE-g-(DMAEMA/PEGMEMA) presented a lower critical solution temperature (LCST) of 55 °C and critical pH point around 8.5.

Radiation grafting of acrylic acid onto poly(ethylene terephthalate) fabric

AbstractRadiation grafting of acrylic acid onto poly(ethylene terephthalate) (PET) knittings was investigated by preirradiation technique. The influence of the grafting conditions, such as reaction time, ferrous sulfate concentration, preirradiation dose, organic additives, monomer concentration, and reaction temperature on the degree of grafting was investigated. Precise control over the degree of grafting was achieved by proper selection of the reaction conditions. The organic solvents such as methanol, acetone, isopropanol, THF, and MEK when used as sole medium do not allow the grafting to proceed, probably due to the inhibitory action. However, reasonable grafting proceeded when a mixture of water and organic solvent was used. Attenuated total reflectance‐FTIR spectroscopy analysis of the grafted knittings confirmed the existence of carboxylic acid groups in the knittings. The surface morphology, as studied by scanning electron microscopy (SEM), was significantly influenced by the addition of organic solvents in the reaction medium. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Preparation of cation-exchange membrane containing bi-functional groups by radiation induced grafting of acrylic acid and sodium styrene sulfonate onto HDPE: Influence of the synthesis conditions

Electron beam radiation induced grafting of acrylic acid (AA) and sodium styrene sulfonate (SSS) onto high-density polyethylene (HDPE) membranes was investigated by the pre-irradiation method, and a cation-exchange membrane containing bifunctional groups was synthesized. The effects of grafting conditions such as monomer concentration, radiation dose and temperature on grafting yield were studied. The dependence of grafting yield on pre-irradiation dose and monomer concentration was found to be 0.54 and 2.21, respectively. The activation energy for the grafting was calculated to be 22.2 kJ/mol. Infrared spectroscopy analysis of the grafted membrane confirmed the existence of sulfonate and carboxylic acid groups.

Preparation, structure and properties of PP-g-AA grafting copolymer

Polypropylene grafting with AA was prepared by reactive extrusion with pre-irradiated PP (rPP) as the homogeneous initiator. The effects of the pre-irradiated dose, the fraction of rPP and the concentration of acrylic acid on the grafting reaction were studied and the grafted PP was characterized by Fourier transition infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) and polarized light microscopy (PLM). The results show that the degradation of PP was suppressed efficiently with this novel method for preparing PP-g-AA copolymers, and the grafted copolymers with good mechanical properties were obtained. It was found that the product with higher graft degree (Gd)(0.19%) and relatively excellent mechanical properties can be produced if the mass ratio of PP/rPP/AA is 90:10:0.8, where the selected pre-irradiation dose of rPP is 4 kGy. Moreover, an adhesive strength of 4.88 kN/m was reached in the PP-g-AA/aluminum laminate.

Radiation-induced grafting of N-isopropylacrylamide and acrylic acid onto polypropylene films by two step method

Binary graft copolymerization of pH sensitive acrylic acid (AAc) and thermosensitive N-isopropylacrylamide (NIPAAm) monomers onto pre-irradiated polypropylene films (PP) was carried out by two individual steps using a Co 60 gamma radiation source. The influence of preparation conditions, such as pre-irradiation dose and reaction time on grafting yield was studied. The swelling behavior and FTIR-ATR study for PP films grafted films were investigated.