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Radiation-sensitive biomolecules are highly significant for studying biological effects of radiation and developing ionizing radiation detectors based on biomolecules. In this work, we selected hypoxanthine phosphoribosyl transferase gene fragments sensitive to gamma-ray irradiation as a sensing element for radiation detection. The end was modified with thiol groups. The thiol-modified oligonucleotide sequences were coupled to the surface of gold nanoparticles by Au-S covalent bonds. The DNA attached to the surface of gold nanoparticles forms a DNA-AuNPs assembly through base pairing. The assembly was irradiated by gamma rays. And its response to radiation was studied with ultraviolet-visible spectroscopy and surface-enhanced Raman scattering (SERS) spectroscopy techniques. SERS spectroscopy and ultraviolet spectroscopy can detect the response of the DNA-AuNPs assembly to gamma-ray irradiation below 100 and 100 - 250 Gy, respectively. The results indicated that it was feasible to develop a new approach of gamma-ray detectors using biomolecular assemblies of gold nanoparticles.

Radiotherapy is one of the main therapeutic methods for cancers, but radiation resistance of cancer cells still remains a serious concern. Searching for radiosensitizers to overcome such resistance is therefore urgently required. The goal of this study is to evaluate and compare the radiosensitizing efficacy of Fe 3 O 4 -OA, Ag and Fe 3 O 4 @Ag nanoparticles on U251 cells. The results show that Fe 3 O 4 @Ag nanoparticles have the highest ability of radiosensitization among the three nanoparticles. The underlying mechanism of Fe 3 O 4 @Ag nanoparticles' radiosensitivity enhancement is through decrease of the cytoprotective autophagy at the early stage, and increase of the calcium-dependent apoptosis at the later stage. These findings suggest the potential application of Fe 3 O 4 @Ag nanoparticles as a highly effective nano-radiosensitizer for the treatment of glioblastoma cells.

Herein, we constructed a novel sandwich surface plasmon resonance (SPR) detection assay for sensitive prion disease-associated isoform (PrP Sc ) detection, utilizing bare gold film and apatamer-graphene oxide (AGO). Due to the self-assembling behavior of PrP Sc on gold surface, the non-modified gold surface can be directly used as sensing surface for the quick detection, for the purpose to avoid the interference from the traditional, complex and changeable probe-modified sensing surface. And due to the highly specific affinity of AGO towards PrP Sc , the sandwich type SPR sensor exhibits excellent analytical performance towards the discrimination and quantitation of PrP Sc . A good linear relationship was obtained between SPR responses and the logarithm of PrP Sc concentrations over a range of 0.001-1ng/mL. The detection sensitivity for PrP Sc was improved by ∼156 orders of AGO compared with SPR direct detection format. Besides, morphological changes of the sensing film surfaces were investigated by high resolution AFM imaging, confirming the capture of PrP Sc molecules and their further specific recognition by AGO. The specificity of the present biosensor was also investigated by PrP C and other regents as controls. By compared with other reported methods, the AGO enhanced sandwich SPR assay was confirmed to be efficient, sensitive, and with wide working range., (Copyright © 2017 Elsevier B.V. All rights reserved.)

By in situ time-lapse AFM, we investigated early-stage aggregates of PrP formed at low concentration (100 ng/mL) on mica and Au(111) surfaces in acetate buffer (pH 4.5). Remarkably different PrP assemblies were observed. Oligomeric structures of PrP aggregates were observed on mica surface, which was in sharp contrast to the multi-layer PrP aggregates yielding parallel linear patterns observed Au(111) surface. Combining molecular dynamics and docking simulations, PrP monomers, dimers and trimers were revealed as the basic units of the observed aggregates. Besides, the mechanisms of the observed PrP aggregations and the corresponding molecular-substrate and intermolecular interactions were suggested. These interactions involved gold-sulfur interaction, electrostatic interaction, hydrophobic interaction, and hydrogen binding interaction. In contrast, the PrP aggregates observed in pH 7.2 PBS buffer demonstrated similar large ball-like structures on both mica and Au(111) surfaces. The results indicate that the pH of a solution and the surface of the system can have strong effects on supramolecular assemblies of prion proteins. This study provides in-depth understanding on the structural and mechanistic nature of PrP aggregation, and can be used to study the aggregation mechanisms of other proteins with similar misfolding properties., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The pencil-like ZnO hollow tubes with 9-12 μm in length, 350-700 nm in width, 200 nm in wall thickness coating with g-C3N4 have been prepared via a chemical deposition process. As compared with uncoated ZnO or g-C3N4, these g-C3N4/ZnO composites showed the enhanced photocatalytic activity which can be attributed to the heterojunction structure. Furthermore, it is worth pointing out that the weight ratios of g-C3N4 to ZnO (g-C3N4/ZnO) played a significantly influence on the photodegradable properties. With increasing the mass ratio, the photocatalytic activity increased firstly and then decreased after reaching to an optimal photocatalytic performance. It can be inferred that the appreciation of g-C3N4 on the ZnO surface can improve the contact area which resulted in high separation of electrons and holes. However, excessive g-C3N4 may hinder the electrons transferring from the g-C3N4 to ZnO, and thus worse its photocatalytic performance. In our study, the g-C3N4/ZnO sample prepared with 10 wt% of g-C3N4 exhibited the optimal photodegradable efficiency which 94% of Rhodamine B (RhB) has been degraded just in 2 h., (Copyright © 2015 Elsevier Inc. All rights reserved.)

An original solution phase approach was developed for the synthesis of single-crystal Au nanoprims with anisotropic structure of triangular, hexagonal and truncated triangular, nanometre or micrometer scale, and nanometer thickness. It has been confirmed that the Fe3O4 magnetite nanoparticles and (3-aminopropyl) triethoxysilane (APTES) coated on the magnetite nanoparticles play important roles in the formation of Au nanoplates. Significantly, such Au nanoplates exhibit remarkable optical properties, both the dipole plasmon resonance and the quadrupole plasmon resonance were observed. And the selected area electron diffraction (SAED) pattern shows the nanoplates obtained were single crystals with (111) plans as two basal surfaces. The growth of gold nanoplates in the solution with time had been monitored by microscopic and spectroscopic techniques to allow the detection of several key intermediates in the growth process. To our knowledge, this is the first report on the production of large planar gold nanostructures with gamma irradiation in combination of another nanocomposite materials (APTES-Fe3O4).