Low-energy ion beam bombardment of human cancer cells in vacuum to induce DNA transfection

A process of low-energy ion-beam-induced gene transfection in human cancer cells was developed for non-viral DNA transfection. The whole process included maintenance of the cells in vacuum, ion beam bombardment of the cells with optimized ion beam condition leading to a medium cell viability, and DNA transfer. A method of using a specially designed liquid-nitrogen cooled sample holder to house the cells and frozen medium to cover and protect the cells was adopted to maintain the cells viable in the vacuum condition during ion beam bombardment. Nitrogen ion beams with energy in the range 7–28 keV were used to bombard human cancer cells (HEp-2, the human laryngeal epitheloid cancer cell line) to fluence orders of 10¹⁵–10¹⁶ ions/cm². After ion beam bombardment, the cell viability was studied. The ion beam condition which resulted in a relatively medium viability of the cells was chosen to operate ion bombardment to induce gene transfection. To the viable cells, DNA transfection using plasmid DNA pEGFPN2 was carried out. The experiment demonstrated that under appropriately controlled ion beam conditions and freezing environment, the human cells could survive and be transfected with exogenous DNA. This technique could be used as an alternative of non-viral gene transfections with a promising efficiency.     

Rhenium‐188 Labeled Tungsten Disulfide Nanoflakes for Self‐Sensitized,Near‐Infrared Enhanced Radioisotope Therapy

Radioisotope therapy (RIT), in which radioactive agents are administered or implanted into the body to irradiate tumors from the inside, is a clinically adopted cancer treatment method but still needs improvement to enhance its performances. Herein, it is found that polyethylene glycol (PEG) modified tungsten disulfide (WS₂) nanoflakes can be easily labeled by ¹⁸⁸Re, a widely used radioisotope for RIT, upon simple mixing. Like other high‐Z elements acting as radiosensitizers, tungsten in the obtained ¹⁸⁸Re‐WS₂‐PEG would be able to absorb ionization radiation generated from ¹⁸⁸Re, enabling ‘‘self‐sensitization’’ to enhance the efficacy of RIT as demonstrated in carefully designed in vitro experiments of this study. In the meanwhile, the strong NIR absorbance of WS₂‐PEG could be utilized for NIR light‐induced photothermal therapy (PTT), which if applied on tumors would be able to greatly relieve their hypoxia state and help to overcome hypoxia‐associated radioresistance of tumors. Therefore, with ¹⁸⁸Re‐WS₂‐PEG as a multifunctional agent, which shows efficient passive tumor homing after intravenous injection, in vivo self‐sensitized, NIR‐enhanced RIT cancer treatment is realized, achieving excellent tumor killing efficacy in a mouse tumor model. This work presents a new concept of applying nanotechnology in RIT, by delivering radioisotopes into tumors, self‐sensitizing the irradiation‐induced cell damage, and modulating the tumor hypoxia state to further enhance the therapeutic outcomes.     

A Pirani gauge in a high-intensity proton accelerator

We have developed a Pirani-type vacuum gauge for monitoring the back pressure of a turbo-molecular pump (TMP), which is employed as the main pump for the 3-GeV Rapid Cycling Synchrotron (RCS) at the Japan Proton Accelerator Complex (J-PARC).As vacuum components are subjected to high levels of radiation in these devices, the TMP and the vacuum gauge used for monitoring the TMP’s back pressure should have high reliability and a long life so as to minimize exposure to radiation during maintenance. Moreover, to ascertain the vacuum conditions of the ring and to monitor the back pressure, the gauge should preferably be capable of measuring pressures from 0.1 Pa to 10³ Pa. To satisfy these requirements, the following measures were taken: All the components around the sensor head, including the connector and cables, were replaced with components that were guaranteed to perform satisfactorily even with a radiation dose greater than 30 MGy. Then, the semiconductor devices used in the measuring circuits were checked by using the four-point probe method and found to work satisfactorily at a distance of 150 m from the sensor. To measure higher pressures, the current control circuit was modified in such a way that the set value of the current increased in stages as the pressure increased. Further, it was ensured that the gauge showed high resistance to vibration and to an abrupt air intake as well as high radioactive resistance. The newly designed gauge head comprised a series of twelve Pt wires, each with a diameter of 100 μm. It was confirmed that pressures from 5 × 10⁻² Pa to atmospheric pressure were measurable with an accuracy of less than 30%.This Pt Pirani gauge has shown good performance in monitoring the back pressure of the TMP at the J-PARC RCS, where it has been in use since Oct. 2009.     

A Vacuum Infrared Standard Radiation Thermometer at the PTB

A thermal infrared radiation thermometer was jointly developed by the Physikalisch-Technische Bundesanstalt and Raytek GmbH for temperature measurements from − 150°C to 170°C under vacuum. The radiation thermometer is a purpose-built instrument to be operated with the PTB reduced-background infrared calibration facility. The instrument is a stand-alone system with an airtight housing that allows operation inside a vacuum chamber, attached to a vacuum chamber, and in air. The radiation thermometer will serve to calibrate thermal radiation sources, i.e., blackbody radiators, by comparing their radiance temperature to that of a variable-temperature reference blackbody inside the reduced-background calibration facility. Furthermore, since it can be operated under vacuum and in air, the instrument also allows the water- and ammonia-heat-pipe reference blackbodies of the PTB low-temperature calibration facility operated in air to be compared with the variable-temperature blackbody operated under vacuum. Finally, provided that sufficient long-term stability is achieved, the instrument shall be used as a transfer radiation thermometer to carry and compare the temperature scale of PTB by means of radiation thermometry to remote-sensing calibration facilities outside PTB. The mechanical, optical, and electrical designs of the instrument are reported. Results of investigations on the temperature resolution, size-of-source effect, and the reference function are given. The heat-pipe blackbodies operating in air are compared to the variable-temperature blackbody operated under vacuum by using the vacuum radiation thermometer. References to commercial products are provided for identification purposes only and constitute neither endorsement nor representation that the item identified is the best available for the stated purpose.     

Carbon fluoroxide nanoparticles as fluorescent labels and sonosensitizers for theranostic applications

Abstract

Carbon fluoroxide (CFO) nanoparticles (NPs) produced from silicon carbide wafers are used as both fluorescent probes and sonosensitizers for theranostic application. In vitro cell tests were carried out to investigate the feasibility of ultrasound-based therapy with the use of the CFO NPs. The NPs that penetrated inside the cells were shown to provoke cell destruction after application of an ultrasound treatment. No significant toxic effect was observed when the cells were treated with NP concentrations up to 0.5 mg ml^?1 without applying ultrasound treatment. The obtained results open a new way toward cancer therapy strategies.     

Carbon fluoroxide nanoparticles as fluorescent labels and sonosensitizers for theranostic applications

Carbon fluoroxide (CFO) nanoparticles (NPs) produced from silicon carbide wafers are used as both fluorescent probes and sonosensitizers for theranostic application. In vitro cell tests were carried out to investigate the feasibility of ultrasound-based therapy with the use of the CFO NPs. The NPs that penetrated inside the cells were shown to provoke cell destruction after application of an ultrasound treatment. No significant toxic effect was observed when the cells were treated with NP concentrations up to 0.5 mg ml⁻¹ without applying ultrasound treatment. The obtained results open a new way toward cancer therapy strategies.     

Synergistic Effects of Incubation in Rotating Bioreactors and Cumulative Low Dose 60Co γ-ray Irradiation on Human Immortal Lymphoblastoid Cells

The complex space environments can influence cell structure and function. The research results on space biology have shown that the major mutagenic factors in space are microgravity and ionizing radiation. In addition, possible synergistic effects of radiation and microgravity on human cells are not well understood. In this study, human immortal lymphoblastoid cells were established from human peripheral blood lymphocytes and the cells were treated with low dose (0.1, 0.15 and 0.2?Gy) cumulative ⁶⁰Co ??-irradiation and simulated weightlessness [obtained by culturing cells in the Rotating Cell Culture System (RCCS)]. The commonly used indexes of cell damage such as micronucleus rate, cell cycle and mitotic index were studied. Previous work has proved that Gadd45 (growth arrest and DNA-damage-inducible protein 45) gene increases with a dose-effect relationship, and will possibly be a new biological dosimeter to show irradiation damage. So Gadd45 expression is also detected in this study. The micronucleus rate and the expression of Gadd45?? gene increased with irradiation dose and were much higher after incubation in the rotating bioreactor than that in the static irradiation group, while the cell proliferation after incubation in the rotating bioreactor decreased at the same time. These results indicate synergetic effects of simulated weightlessness and low dose irradiation in human cells. The cell damage inflicted by ??-irradiation increased under simulated weightlessness. Our results suggest that during medium- and long-term flight, the human body can be damaged by cumulative low dose radiation, and the damage will even be increased by microgravity in space.     

Irradiation tests of thin substrate materials for nuclear targets

The resistance against alpha radiation of several thin plastic foils (formvar, parylene, polyimide, polypropylene, polysulfone, vyns), to be used as substrates for nuclear targets, was examined using alpha particles from an ²⁴¹Am source (in air and in vacuum) and from a cyclotron. The results depended on the experimental conditions, but the best results were always obtained using polyimide foils.     

Synergistic cytotoxicity of low-energy ultrasound and innovative mesoporous silica-based sensitive nanoagents

Low-energy ultrasound (LEUS) shows distinct potential as a safe therapeutic strategy for cancer treatment. Herein, mesoporous silica nanoparticles with closed-end cavities as sensitive nanoagents are prepared for effective cancer cell killing, when synergistically combined with mild LEUS (1 MHz, ≤1.0 W cm^?2). The closed-end cavities can entrap gas bubbles, and provide a large number of cavitation nucleation sites, which could lead to drastically amplify ultrasonic cavitation effect by responding to the mild LEUS (1 MHz, ≤1.0 W cm^?2). Significant killing effect against cancer cells is observed, when cells are treated by synergetic combination of mild LEUS and the nanoagents with closed-end cavities, showing distinct dose dependency on the nanoagents and irradiation intensity. Nevertheless, the killing effect is disappeared when the closed-end cavities are destructed. Moreover, no obvious cytotoxicity is observed when either the nanoagents or the LEUS is applied alone. The research may open up application opportunities of mild low-energy ultrasound for cancer therapy.     

Hollow ZnO Nanospheres Enhance Anticancer Immunity by Promoting CD4+ and CD8+ T Cell Populations In Vivo

Appropriate adjuvant aiding in generating robust anticancer immunity is crucial for cancer immunotherapy. Herein, hollow ZnO (HZnO) nanospheres are synthesized by a facile method using carbon nanospheres as the template. The HZnO nanospheres significantly promote the cellular uptake of a model antigen, and cytokine secretion by antigen‐presenting cells in vitro. HZnO loaded with ovalbumin and polyinosinic‐polycytidylic acid (poly(I:C)) inhibits cancer growth and metastasis to inguinal lymph node in a cancer cell challenge model. Moreover, HZnO loaded with autologous cancer antigens inhibits cancer cell growth in a cancer cell re‐challenge model. HZnO nanospheres significantly improve the CD4⁺ and/or CD8⁺ T cell population in splenocytes of mice in both cancer cell challenge model and re‐challenge model. The HZnO nanospheres can be used for cancer immunotherapy as adjuvant.     

Using nanoparticles to enable simultaneous radiation and photodynamic therapies for cancer treatment

This paper describes research into a new approach to cancer treatment through a combination of radiation and photodynamic therapies. The assumption is that supplementing conventional radiation therapy with photodynamic therapy (PDT) will enable the use of lower doses of radiation. Under this concept, scintillation or persistent luminescence nanoparticles with attached photosensitizers such as porphyrins are used as an in vivo agent for photodynamic therapy. The nanoparticle PDT agents are delivered to the treatment site. Upon exposure to ionizing radiation such as X-rays, the nanoparticles emit scintillation or persistent luminescence, which, in turn, activates the photosensitizers; as a consequence, singlet oxygen (1O2) is produced. Studies have shown that 1O2 can be effective in killing cancer cells. This is the conventional way in which PDT can augment the effectiveness of ionizing radiation. The innovation described in this study involves the use of in vivo luminescent nanoparticles so that an external light source is not required to support PDT. Consequently, application of the therapy can be more localized and the potential of damage to healthy cells is reduced. This new modality will provide an efficient, low-cost approach to PDT while still offering the benefits of augmented radiation therapy at lower doses.     

Performance of the SRS vacuum system

At the Daresbury Laboratory of the Science and Engineering Research Council is the SRS, the world's first dedicated high energy synchrotron radiation source. The SRS has been described elsewhere¹⁻³ and is essentially a 2 GeV electron storage ring of about 30 m diameter and designed for an ultimate beam current of 1 A. It is over seven years since commissioning of the SRS started, during which time nine out of a possible twelve beam lines have been built and scheduled experiments have been running for over six years. This paper will describe the general performance of the vacuum system and the specific experience gained on the performance of various types of vacuum pumps and gauges.     

Studies on certain wood-plastic-composites prepared by gamma irradiation

Wood-plastic-composites have been prepared using locally available soft wood and commercial monomers by vacuum impregnation of monomer in wood and subsequent polymerization by gamma irradiation. The irradiation was performed by means of a⁶⁰Co source of strength 50,000 Ci at 0·2 Mrad/h. The radiation dosage required for maximum conversion of monomer into polymer was less than 2 Mrad except styrene which required a much larger dose of about 10 Mrad. The impregnation efficiency was found to be more for wood with high pore volume. The impregnation efficiency also depended on the ambient pressure: the more the vacuum, the more was the impregnation efficiency. Mechanical strength of the composites was found to be enhanced and water absorption considerably reduced. X-ray diffraction studies showed that the crystallinity of the cellulose did not get affected by the radiation polymerization which suggested that grafting of polymer on to the cell wall took place only in the amorphous regions.     

Pulsed focused ultrasound can improve the anti-cancer effects of immune checkpoint inhibitors in murine pancreatic cancer

Pulsed high-intensity focused ultrasound (pHIFU) uses acoustic pressure to physically disrupt tumours. The aim of this study was to investigate whether pHIFU can be used in combination with immune checkpoint inhibitors (ICIs) to enhance survival of tumour-bearing animals. Murine orthotopic pancreatic KPC tumours were exposed both to a grid of pHIFU lesions (peak negative pressure = 17 MPa, frequency = 1.5 MHz, duty cycle = 1%, 1 pulse s⁻¹, duration = 25 s) and to anti-CTLA-4/anti-PD-1 antibodies. Acoustic cavitation was detected using a weakly focused passive sensor. Tumour dimensions were measured with B-mode ultrasound before treatment and with callipers post-mortem. Immune cell subtypes were quantified with immunohistochemistry and flow cytometry. pHIFU treatment of pancreatic tumours resulted in detectable acoustic cavitation and increased infiltration of CD8⁺ T cells in the tumours of pHIFU and pHIFU + ICI-treated subjects compared with sham-exposed subjects. Survival of subjects treated with pHIFU + ICI was extended relative to both control untreated subjects and those treated with either pHIFU or ICI alone. Subjects treated with pHIFU + ICI had increased levels of CD8⁺IFNγ⁺ T cells, increased ratios of CD8⁺IFNγ⁺ to CD3⁺CD4⁺FoxP3⁺ and CD11b⁺Ly6G⁺ cells, and decreased CD11c^high cells in their tumours compared with controls. These results provide evidence that pHIFU combined with ICI may have potential for use in pancreatic cancer therapy.     

Properties of radiation stable, low viscosity impregnating resin for cryogenic insulation system

Impregnating resins in fusion magnet technology are required to be radiation stable, low viscosity, long usable life and high toughness. To meet these objectives, we developed a new epoxy based composite which consists of triglycidyl-p-aminophenol (TGPAP) epoxy resin and isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether] (IPBE). The ratio of TGPAP to IPBE can be varied to achieve desired viscosity and working time. The boron-free glass fiber reinforced composites were prepared by vacuum pressure impregnation. The radiation resistance was evaluated by ⁶⁰Co γ-ray irradiation of 1 MGy at ambient temperature. The mechanical properties of the composites have been measured at room temperature and at 77 K.     

Biodegradable nanocarriers for small interfering ribonucleic acid (siRNA) co-delivery strategy increase the chemosensitivity of pancreatic cancer cells to gemcitabine

Ribonucleic acid (RNA) interference (RNAi) therapies are promising cancer treatment modalities that can specifically target abnormal proto-oncogenes, thus improving the therapeutic effect. For the treatment of pancreatic cancer, targeting one mutant proto-oncogene by RNAi usually does not yield the desired therapeutic efficiency. Both K-ras gene mutations and Notch1 overexpression are common symptoms in pancreatic cancer patients, and play a crucial role in pancreatic cancer cell drug resistance. In this study, biodegradable charged polyester-based vectors (BCPVs) were synthesized for the co-delivery of K-ras and Notch1 small interfering ribonucleic acid (siRNA) into MiaPaCa-2 cells (pancreatic cancer cell line) to overcome drug resistance to gemcitabine (GEM), a first-line chemotherapeutic drug used in the clinic. BCPVs could effectively absorb negative siRNA to form a capsule-like structure, prevent siRNA from nuclease digestion in the serum, and promote effective siRNA cell internalization and endosomal escape. Through K-ras and Notch1 gene silencing in MiaPaCa-2 cells, BCPV-siRNA^K-ras-siRNA^Notch1 nanocomplexes effectively reversed the epithelia-mesenchymal transition (EMT) in MiaPaCa-2 cells, thereby greatly enhancing the sensitivity of MiaPaCa-2 cells to GEM. MiaPaCa-2 cell proliferation, migration, and invasion were effectively inhibited, and cell apoptosis was also significantly enhanced by the synergistic antitumor effect of BCPV-siRNA^K-ras-siRNA^Notch1 nanocomplexes and GEM. These results suggest that this combination RNAi therapy can be used to improve cancer cell sensitivity to chemotherapeutic drugs. Specifically, this newly developed strategy has a great potential for treating pancreatic cancer.

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Polyphenols attached graphene nanosheets for high efficiency NIR mediated photodestruction of cancer cells

Green tea-reduced graphene oxide (GT-rGO) sheets have been exploited for high efficiency near infrared (NIR) photothermal therapy of HT29 and SW48 colon cancer cells. The biocompatibility of GT-rGO sheets was investigated by means of MTT assays. The polyphenol constituents of GT-rGO act as effective targeting ligands for the attachment of rGO to the surface of cancer cells, as confirmed by the cell granularity test in flow cytometry assays and also by scanning electron microscopy. The photo-thermal destruction of higher metastatic cancer cells (SW48) is found to be more than 20% higher than that of the lower metastatic one (HT29). The photo-destruction efficiency factor of the GT-rGO is found to be at least two orders of magnitude higher than other carbon-based nano-materials. Such excellent cancer cell destruction efficiency provided application of a low concentration of rGO (3 mg/L) and NIR laser power density (0.25 W/cm²) in our photo-thermal therapy of cancer cells.     

Soft vacuum processing of materials with electron beams

The use of soft vacuum (10^–3 to 1 Torr) rather than high vacuum (10^–5 to 10^–4 Torr) in connection with electron beam processing of materials is discussed. It is argued that practical, technical and economic advantages can be realized in a wide range of applications from heat-treatment, through welding and melting processes, to vapour deposition and gas processing. The new technology of glow discharge electron beam sources is especially suited to soft vacuum processes. While mainly developed so far for welding applications, it can be applied to this much wider field which presently employs thermionic guns working in high vacuum conditions.     

Thio-glucose bound gold nanoparticles enhance radio-cytotoxic targeting of ovarian cancer

The treatment of ovarian cancer has traditionally been intractable, and required novel approaches to improve therapeutic efficiency. This paper reports that thio-glucose bound gold nanoparticles (Glu-GNPs) can be used as a sensitizer to enhance ovarian cancer radiotherapy. The human ovarian cancer cells, SK-OV-3, were treated by gold nanoparticles (GNPs) alone, irradiation alone, or GNPs in addition to irradiation. Cell uptake was assayed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), while cytotoxicity induced by radiotherapy was measured using both 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide and clonogenic assays. The presence of reactive oxygen species (ROS) was determined using CM-H2-DCFDA confocal microscopy and cell apoptosis was determined by an Annexin V-FITC/propidium iodide (PI) kit with flow cytometry. The cells treated by Glu-GNPs resulted in an approximate 31% increase in nanoparticle uptake compared to naked GNPs (p < 0.005). Compared to the irradiation alone treatment, the intracellular uptake of Glu-GNPs resulted in increased inhibition of cell proliferation by 30.48% for 90 kVp and 26.88% for 6 MV irradiation. The interaction of x-ray radiation with GNPs induced elevated levels of ROS production, which is one of the mechanisms by which GNPs can enhance radiotherapy on ovarian cancer.