Gold nanoparticles have potential applications in biomedicine, but one of the important concerns is about their safety. Most toxicology data are derived from in vitro studies and may not reflect in vivo responses. Here, an animal toxicity study of 13.5 nm gold nanoparticles in mice is presented. Animal survival, weight, hematology, morphology, and organ index are characterized at different concentrations (137.5-2200 µg/kg) over 14-28 days. The results show that low concentrations of gold nanoparticles do not cause an obvious decrease in body weight or appreciable toxicity, even after their breakdown in vivo. High concentrations of gold nanoparticles induced decreases in body weight, red blood cells, and hematocrit. It was also found that gold nanoparticles administered orally caused significant decreases in body weight, spleen index, and red blood cells. Of the three administration routes, the oral and intraperitoneal routes showed the highest toxicity, and the tail vein injection showed the lowest toxicity. Combining the results of all of these studies, we suggest that targeted gold nanopartices by tail vein injection may be suitable for enhancement of radiotherapy, photothermal therapy, and related medical diagnostic procedures.

Gold nanoparticles are promising as a kind of novel radiosensitizer in radiotherapy. If gold nanoparticles are shown to have good irradiation stability and biocompatibility, they would play an important role in radiotherapy. In this work, we investigated irradiation effects of gold nanoparticles under 2–10 kR gamma irradiation and cytotoxicity of gold nanoparticles with human K562 cells by using Cell Titre-Glo™ luminescent cell viability assay. The results revealed that gamma irradiation had not induced any obvious instability and size variations in gold nanoparticles. We found that gold nanoparticles showed excellent radiation hardness with an absorbed dose conversation factor of 9.491 rad/R. Meanwhile, the surface plasmon resonance of gold nanoparticles was enhanced obviously after 2–10 kR gamma irradiation. Subsequently, cytotoxicity tests indicated that the extremely high concentration of gold nanoparticles could cause a sharp decrease in K562 cell viability, while the low concentration of gold nanoparticles had no obvious influence on the cell viability. Our results revealed that gold nanoparticles were stable under high-energy ray irradiation and showed concentration-dependent cytotoxicity.

The objective of this study was to estimate solid cancer risk attributable to long-term, fractionated occupational exposure to low-doses of ionizing radiation. Based on cancer incidence for the period 1950–1995 in a cohort of 27,011 Chinese medical diagnostic X-ray workers and a comparison cohort of 25,782 Chinese physicians who did not use X-ray equipment in their work, we used Poisson regression to fit excess relative risk (ERR) and excess absolute risk (EAR) dose-response models for incidence of all solid cancers combined. Radiation dose reconstruction was based on a previously published method that relied on simulating measurements for multiple X-ray machines, workplaces and working conditions, information about protective measures, including use of lead aprons, and work histories. The resulting model was used to estimate calendar year-specific badge dose calibrated as personal dose equivalent (Sv). To obtain calendar year-specific colon doses (Gy), we applied a standard organ conversion factor. 1643 cases of solid cancer were identified in 1.45 million person-years of follow-up. In both ERR and EAR models, a statistically significant radiation dose-response relationship was observed for solid cancers as a group. Averaged over both sexes, and using colon dose as the dose metric, the estimated ERR/Gy was 0.87 (95% CI: 0.48, 1.45), and the EAR was 22 per 104PY-Gy (95% CI: 14, 32) at age 50. We obtained estimates of the ERR and EAR of solid cancers per unit dose that are compatible with those derived from other populations chronically exposed to low dose-rate occupational or environmental radiation.

Data on occupational exposures from medical uses of radiation in China during 1986-2000 are presented. Individual dose monitoring results in the reports of monitoring centres in different provinces in China during 1986-2000 were collected as the basic data. These data were summarised and then analysed. From 1986 to 2000, in diagnostic radiology, nuclear medicine and radiotherapy, the annual collective effective doses varied within the range 122.4-206.6, 5.4-9.3 and 4.1-10.3 man Sv, respectively; the average annual effective dose in these categories varied within the range 1.5-2.2, 1.2-1.6 and 1.0-1.5 mSv, respectively. Almost all the average annual effective doses in medical uses of radiation were <3 mSv in 1986-2000, and no monitored workers were found to have received an occupational exposure >50 mSv in a single year or >100 mSv in a 5-y period. After 1990, the protection status of medical radiation workers in China was sufficient.

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Gold nanoclusters have the tunable optical absorption property, and are promising for cancer cell imaging, photothermal therapy and radiotherapy. First-principle is a very powerful tool for design of novel materials. In the present work, structural properties, band gap engineering and tunable optical properties of Ag-doped gold clusters have been calculated using density functional theory. The electronic structure of a stable Au20 cluster can be modulated by incorporating Ag, and the HOMO–LUMO gap of Au20−nAgn clusters is modulated due to the incorporation of Ag electronic states in the HOMO and LUMO. Furthermore, the results of the imaginary part of the dielectric function indicate that the optical transition of gold clusters is concentration-dependent and the optical transition between HOMO and LUMO shifts to the low energy range as the Ag atom increases. These calculated results are helpful for the design of gold cluster-based biomaterials, and will be of interest in the fields of radiation medicine, biophysics and nanoscience.

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Two rotations and one translation (2R1T) parallel kinematic machines (PKMs) are suitable for the machining of complex curved surfaces, which requires high speed and precision. To further improve rigidity, precision, and avoid singularity, actuation redundancy, and overconstrained PKMs with fixed actuators and limited-degrees of freedom (DOF) limbs are preferred. However, there are few 2R1T PKMs with these features. This paper introduces a new 2R1T overconstrained PKM with actuation redundancy, which is called Tex4. The Tex4 PKM consists of four limited-DOF limbs; that is, two PUR limbs and two 2PRU limbs (where P denotes an actuated prismatic joint, U denotes a universal joint, and R denotes a revolute joint). The kinematic model of the proposed 2PUR-2PRU machine is presented along with the results of mobility, inverse kinematics, and velocity analysis. By considering the motion/force transmissibility, the dimensional parameters of the Tex4 PKM were optimized to obtain an improved satisfactory transmission workspace without singular configurations. Finally, a prototype based on the optimized parameters was fabricated, and its feasibility and accuracy were validated by motion and position error experiments. The Tex4 PKM has the advantages of high rigidity, simple kinematic model, and zero singularity in the workspace, which suggests that it has potential for use in the high-speed machining of curved surfaces.