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Radiation techniques are used to modify the physical, chemical and biological properties of polymers. This induces crosslinking and degradation reactions of polymers by utilizing radicals generated through ionizing radiation. However, oxidation products (such as carbonyl) can be formed because oxidation occurs by chain scission in the presence of oxygen. Herein, we demonstrate the gamma-ray irradiation-induced oxidation with and without fluorine using polyethylene, polyvinylidene fluoride and polytetrafluoroethylene under the same conditions. In this study, changes in element-content and chemical-bond structures were analyzed before and after gamma-ray irradiation under air atmosphere. As a result, polytetrafluo-roethylene showed less oxidation and excellent thermal properties after the absorbed dose of 500 kGy. This can be attributed to the generation of stable perfluoroalkylperoxy radicals after gamma ray irradiation in the PTFE structure containing only CF2 groups, thereby hindering the oxidation reaction. [ABSTRACT FROM AUTHOR]

As a robust radioanalytical method for tracking carbonaceous particulates in vivo, polycyclic aromatic hydrocarbons from diesel exhaust were labeled with a radioactive-iodine-tagged pyrene analogue. Single-photon emission computed tomography and biodistribution studies showed high uptake and slow clearance of this matter in the respiratory system, which may underlie its severe toxicity. [ABSTRACT FROM AUTHOR]

In this report, we describe the radiosynthesis of a new thiol-targeting prosthetic group for efficient radioactive iodine labeling of biomolecules. Radioiodination using the precursor 3 was performed to obtain 125 I-labeled tetrazole 4b with high radiochemical yield (73%) and radiochemical purity. Using the radiolabeled 4b , a single free cysteine containing peptide and human serum albumin were labeled with 125 I in modest-to-good radiochemical yields (65–99%) under mildly reactive conditions. A biodistribution study of [ 125 I] 7 in normal ICR mice exhibited lower thyroid uptake values than those of 125 I-labeled human serum albumin prepared via a traditional radiolabeling method. Thus, [ 125 I] 7 could be employed as an effective radiotracer for molecular imaging and biodistribution studies. The results clearly demonstrate that 4b has the potential to be effectively implemented as a prosthetic group in the preparation of radiolabeled biomolecules. [ABSTRACT FROM AUTHOR]

To assess the risk posed by a toxic chemical to human health, it is essential to quantify its uptake in a living subject. This study aims to investigate the biological distribution of inhaled polyhexamethylene guanidine (PHMG) aerosol particle, which is known to cause severe pulmonary damage. By labeling with indium-111 ( 111 In), we quantified the uptake of PHMG for up to 7 days after inhalation exposure in rats. The data demonstrate that PHMG is only slowly cleared, with approximately 74% of inhaled particles persisting in the lungs after 168 h. Approximately 5.3% of inhaled particles were also translocated to the liver after 168 h, although the level of redistribution to other tissues, including the kidneys and spleen, was minimal. These observations suggest that large uptake and slow clearance may underlie the fatal inhalation toxicity of PHMG in humans. [ABSTRACT FROM AUTHOR]

In this report, we present a rapid and highly efficient method for radioactive iodine labeling of trans -cyclooctene group conjugated biomolecules using inverse-electron-demand Diels–Alder reaction. Radioiodination reaction of the tetrazine structure was carried out using the stannylated precursor 2 to give 125 I-labeled product ([ 125 I] 1 ) with high radiochemical yield (65 ± 8%) and radiochemical purity (>99%). For radiolabeling application of [ 125 I] 1 , trans -cyclooctene derived cRGD peptide and human serum albumin were prepared. These substrates were reacted with [ 125 I] 1 under mild condition to provide the radiolabeled products [ 125 I] 6 and [ 125 I] 8 , respectively, with excellent radiochemical yields. The biodistribution study of [ 125 I] 8 in normal ICR mice showed significantly lower thyroid uptake values than that of 125 I-labeled human serum albumin prepared by a traditional radiolabeling method. Therefore [ 125 I] 8 will be a useful radiolabeled tracer in various molecular imaging and biological studies. Those results clearly demonstrate that [ 125 I] 1 will be used as a valuable prosthetic group for radiolabeling of biomolecules. [ABSTRACT FROM AUTHOR]

Herein we report the radiosynthesis of a pyridine derived azide prosthetic group for iodine radioisotope labeling of dibenzocyclooctyne (DBCO) conjugated molecules. The radiolabeling of the stannylated precursor 2 was conducted using [ 125 I]NaI and chloramine-T to give 125 I-labeled azide ([ 125 I] 1 ) with high radiochemical yield (72 ± 8%, n = 4) and radiochemical purity (>99%). Using 125 I-labeled azide ([ 125 I] 1 ), cyclic RGD peptide and near infrared fluorescent molecule were efficiently labeled with modest to good radiochemical yields. The biodistribution study and SPECT/CT images showed that [ 125 I] 1 underwent rapid renal clearance. These results clearly demonstrated that [ 125 I] 1 could be used as an useful radiotracer for in vivo pre-targeted imaging as well as efficient in vitro radiolabeling of DBCO containing molecules. [ABSTRACT FROM AUTHOR]

The scission rates of polystyrene and fluorinated polystyrene irradiated in an irradiation facility with Co-60 γ-rays were determined using molecular dynamics simulation and gel permeation chromatography (GPC) molecular weight distributions. The prediction was based on the assumption that γ-ray energy is transferred to the initial velocity of the primary knock-on atom. We employed a molecular dynamics simulation procedure to compute the changes in bond length between the connections for selected values of the absorbed dose and compared the calculated values with measurements made on the irradiated samples. The samples were exposed to four different absorbed doses of 25, 50, 75, and 100 kGy. The scission process and scission ratio were simulated with LAMMPS with ReaxFF potential for each bond, and we compared the simulation results with the experimental data especially measuring average molecular weight to evaluate the effect of fluorination on radiation enhancement. [ABSTRACT FROM AUTHOR]

This paper describes a novel chromatographic method for efficient removal of anionic dyes from aqueous solutions. Chitosan-coated Fe3O4 nanoparticles can easily be immobilized on a dextran gel column. Single elution of Evans Blue (EB) solution to the nanoadsorbent-incorporated columns provides high removal efficiency with a maximum adsorption capacity of 243.9 mg/g. We also investigated the influence of initial concentration and solution pH on the removal efficiency of EB. The electrostatic interaction between the adsorbent surface and negatively charged sulfate groups on EB molecules promotes the efficient adsorption of dyes. The equilibrium data matched well with the Langmuir isotherm model, which indicated monolayer dye adsorption onto the adsorbent surface. To extend the application of the current method, we performed further adsorption experiments using other anionic dyes of different colors (Cy5.5, Acid Yellow 25, Acid Green 25, and Acid Red 1). All of these molecules can efficiently be captured under continuous flow conditions, with higher removal efficiency obtained with more negatively charged dyes. These findings clearly demonstrate that the present approach is a useful method for the removal of anionic dye contaminants in aqueous media by adsorption. [ABSTRACT FROM AUTHOR]

• A novel protein binder, termed 'Repebody', that specifically binds to human serum albumin with high affinity was developed. • The genetic fusion of GLP-1 to the repebody significantly improved the blood half-life of GLP-1. • The repebody-fused GLP-1 showed enhanced therapeutic efficacy in vivo. • The present approach can be effectively used for extending the blood half-life of small-sized therapeutic proteins. Many small-sized proteins and peptides, such as cytokines and hormones, are clinically used for the treatment of a variety of diseases. However, their short half-life in blood owing to fast renal clearance usually results in a low therapeutic efficacy and frequent dosing. Here we present the development of a human serum albumin (HSA)-specific protein binder with a binding affinity of 4.3 nM through a phage display selection and modular evolution approach to extend the blood half-life of a small-sized therapeutic protein. As a proof-of-concept, the protein binder composed of LRR (Leucine-rich repeat) modules was genetically fused to the N-terminus of Glucagon-like Peptide-1 (GLP-1). The fused GLP-1 was shown to have a significantly improved pharmacokinetic property: The terminal half-life of the fused GLP-1 increased to approximately 10 h, and the area under the curve was 5-times higher than that of the control. The utility and potential of our approach was demonstrated by the efficient control of the blood glucose level in type-2 diabetes mouse models using the HSA-specific protein binder-fused GLP-1 over a prolonged time period. The present approach can be effectively used in enhancing the efficacy of small-sized therapeutic proteins and peptides through an enhanced blood circulation time. [ABSTRACT FROM AUTHOR]

We herein report a new bioremediation method using a radiation-resistant bacterium. Biogenic gold nanomaterial-containing Deinococcus radiodurans R1 showed excellent capability for the removal of radioactive iodine (＞99%) in several aqueous solutions. These observations demonstrated that our remediation system would be efficiently applied to the treatment of radioactive wastes. [ABSTRACT FROM AUTHOR]

Herein we report an efficient method for iodine radioisotope labeling of cyclooctyne-containing molecules using copper-free click reaction. For this study, radioiodination using the tin precursor 2 was carried out at room temperature to give 125 I-labeled azide ([ 125 I] 1 ) with high radiochemical yield (85%) and excellent radiochemical purity. Dibenzocyclooctyne (DBCO) containing cRGD peptide and gold nanoparticle were labeled with [ 125 I] 1 at 37 °C for 30 min to give triazoles with good radiochemical yields (67–95%). We next carried out tissue biodistribution study of [ 125 I] 1 in normal ICR mice to investigate the level of organ accumulation which needs to be considered for pre-targeted in vivo imaging. Large amount of [ 125 I] 1 distributed rapidly in liver and kidney from bloodstream and underwent rapid renal and hepatobiliary clearance. Moreover [ 125 I] 1 was found to be highly stable (>92%) in mouse serum for 24 h. Therefore [ 125 I] 1 could be used as a potentially useful radiotracer for pre-targeted imaging. Those results clearly indicated that the present radiolabeling method using copper free click reaction would be quite useful for both in vitro and in vivo labeling of DBCO group containing molecules with iodine radioisotopes. [ABSTRACT FROM AUTHOR]

We herein report a convenient radiolabeling method capable of real-time in vivo imaging and biodistribution of bacteria in a living subject. Escherichia coli (E. coli), a model microorganism in this study, was incubated with technetium-99m (99mTc) tricarbonyl under physiological conditions provided radiolabeled bacterial cells. 99mTc-labeled bacterial cells were obtained in high yield (42%, n = 5) and purity (> 99%) within 30 min. In vitro radiolabeling study using cellular components revealed that 99mTc could be incorporated with cytosolic proteins and it was maintained stably in E. coli under several media including mouse serum, high salt solutions with varying pH. SPECT/CT images and organ biodistribution of 99mTc-labeled bacterial cells showed quantitative in vivo behavior and accumulation of E. coli in mice. The radiolabeling method demonstrated here will be a promising platform tool for in vivo tracking and biodistribution of infectious microorganism. [ABSTRACT FROM AUTHOR]