Flexible Lead-Free X-ray Detector from Metal-Organic Frameworks.

Semiconductive metal-organic frameworks (MOFs) obtained by specific host-guest interactions have attracted a large interest in the last two decades, promising development of next-generation electronic devices. Herein, we designed and presented flexible X-ray detectors using Ni-DABDT (DABDT = 2,5-diamino-1,4-benzenedithiol dihydrochloride) MOFs as the absorbing layer. The π-d coupling interactions of Ni-DABDT throughout the framework implement a conspicuous carrier transportation pathway. The detector that converts X-ray photons directly into carriers manifests an attractive achievement with high detection sensitivity of 98.6 µC Gyair-1 cm-2, with a low detection limit of 7.2 µGyair s-1 for the radiation robustness. This work provides insights for next-generation green and high-performance flexible sensor detectors by utilizing MOF materials with the benefits of a designable structure and tunable property, demonstrating a proof-of-concept in wearable X-ray detectors for radiation monitoring and imaging.

UV-enhanced cytotoxicity of CdTe quantum dots in PANC-1 cells depend on their size distribution and surface modification.

The cytotoxicity of quantum dots (QDs) under normal conditions has received more and more attention, but their cytotoxicity under light illumination has not been fully investigated. In this study, different sized CdTe QDs coated with mercaptopropionic acid (MPA) and N-acetylcysteine (NAC) were employed to investigate the influences of size distribution and surface modification on their UV-enhanced cytotoxicity and mechanism. The results indicated that different sized MPA-CdTe QDs exhibited distinct cytotoxicity under UV illumination and the smaller-sized QDs presented more obviously damages to cells than the larger-sized QDs. Comparing with MPA-CdTe QDs, NAC-CdTe QDs had better cellular metabolizability and lower cytotoxicity. The generation of reactive oxygen species (ROS) were also investigated. The results revealed that ROS in cells containing MPA-CdTe QD538 were about 1.7 times of NAC-CdTe QD538 under UV illumination. ROS might play an important role in the UV-enhanced cytotoxicity of QDs. By selecting appropriate surface modifications and particle sizes, the cytotoxicity of QDs under UV illumination could be controlled.

Magnetic nanoparticle decorated multi-walled carbon nanotubes for removing copper ammonia complex from water.

A kind of novel magnetic carbon nanotube composite was prepared and designed for wastewater treatment. Multi-walled carbon nanotubes were decorated with magnetic iron oxide nanoparticles, with an uniform distribution on the nanotube surface. The functionalized carbon nanotubes exhibit superparamagnetic behavior and can be easily and rapidly separated from the dispersion via a magnetic process. The carbon nanotube-iron oxide composites might serve as adsorbent for contaminant adsorption in water, especially for copper ammonia complex removal. The adsorption of copper ammonia complex to carbon nanotube-iron oxide composites is time dependent, and they can be quickly and efficiently removed together through a magnetic separation process. This novel magnetic composites might serve as an efficient and proper adsorbent in wastewater treatment applications.

Removal of cesium and strontium for radioactive wastewater by Prussian blue nanorods.

In this work, novel Prussian blue tetragonal nanorods were prepared by template-free solvothermal methods to remove radionuclide Cs and Sr. The as-prepared Prussian blue nanorods were identified and characterized by scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopic, thermogravimetric analysis, zeta potential, and surface analysis, and its sorption performance was tested by batch experiments. Our results suggest that Prussian blue nanorods exhibited better adsorption performance than co-precipitation PB or Prussian blue analogue composites. Thermodynamic analysis implied that the adsorption process was spontaneous and endothermic which was described well with the Langmuir isotherm and pseudo-second-order equation. The maximum adsorption capacity of PB nanorod was estimated to be 194.26 mg g-1 and 256.62 mg g-1 for Cs+ and Sr2+(adsorbate concentration at 500 mg L-1, the temperature at 298 k, pH at 7.0). Moreover, the experimental results showed that the Prussian blue nanorods have high crystallinity, few crystal defects, and good stability under alkaline conditions. The adsorption mechanism of Cs+ and Sr2+ was studied by X-ray photoelectron spectroscopy, X-ray diffraction, and 57Fe Mössbauer spectroscopy. The results revealed that Cs+ entered the PB crystal to generate a new phase, and most of Sr2+ was trapped in the internal crystal and the other exchanged Fe2+. Furthermore, the effect of co-existing ions and pH on PB adsorption process was also investigated. The results suggest that PB nanorods were an outstanding candidate for removing Cs+ and Sr2+ from radioactive wastewater.

Subcellular tracking of drug release from carbon nanotube vehicles in living cells.

The direct observation of drug release from carbon nanotube vehicles in living cells is realized through a unique two-dye labeling approach. Single-walled carbon nanotubes (SWNTs) are firstly marked with fluorescein isothiocyanate (FITC) to track their location and movement inside the cell. Then a fluorescent anticancer drug doxorubicin (DOX) is attached by means of π-stacking onto SWNTs. Delivered by SWNTs into cells, DOX will detach from the vehicle in an acidic environment due to the pH-dependent π-π stacking interaction between DOX and SWNTs. From observation of the two different kinds of fluorescence (green and red) that respectively represent the carrier SWNTs and drug DOX, the process of drug release inside the living cell can be monitored under a confocal microscope. Results show that the drug DOX detaches from SWNTs inside the lysosomes to yield free molecules and escape into the cytoplasm and finally into the nucleus, while the vehicle SWNTs are trapped inside the lysosomes, without entering the nucleus. The current observations confirm previously proposed mechanisms for drug/DOX release inside cells. The experimental establishment of drug-release mechanisms in living cells here might provide important insights for future design of new drug-delivery and release systems.

The combined influence of surface modification, size distribution, and interaction time on the cytotoxicity of CdTe quantum dots in PANC-1 cells.

Mercaptopropionic acid (MPA) and cysteamine (Cys) capped CdTe quantum dots (QDs) were successfully prepared and used to investigate the combined influence of surface modification, size distribution, and interaction time on their cytotoxicity in human pancreatic carcinoma (PANC-1) cells. Results indicated that the smaller the size of MPA-CdTe QDs, the higher the cytotoxicity, which could be partly due to the difference of their distribution inside cells. Comparing with MPA-CdTe QDs, Cys-CdTe QDs had better cellular metabolizability and lower cytotoxicity. These QDs' cellular distribution and cytotoxicity were closely related to their interaction time with cells. Their cytotoxicity was found to be significantly enhanced with the increase of incubation time in medium. After QD treatments, the influence of recover time on the final cell viability was also dependent on the concentration and surface modification of QDs used in pretreatment. The combined influence of these factors discussed here might provide useful information for understanding and reducing the cytotoxicity of QDs in future biomedical applications.

Ferroptosis, a new form of cell death defined after radiation exposure.

PURPOSE: Ferroptosis is an iron-dependent form of regulated cell death, driven by excessive lipid peroxidation and/or inactivation/depletion of protective molecules against lipid peroxidation. Ionizing radiation can induce ferroptosis in both normal tissues and tumor cells. Here, we reviewed the findings of ionizing radiation-induced ferroptosis. CONCLUSIONS: Ionizing radiation induces an increase in hydroxyl radicals, free iron, and lipid metabolic enzymes, which subsequently synergistically initiate a high level of lipid peroxidation, making ionizing radiation an exogenous inducer of ferroptosis. In addition, ferroptosis may be the primary form of cell death in the bone marrow under hematopoietic acute radiation syndrome. Ionizing radiation can also induce changes in iron metabolism, which may be a target for regulating ferroptosis. Finally, ionizing radiation-induced ferroptosis initiates from the cytoplasm and ends on the membrane, and is independent of DNA damage.

Recent Advancement of Emerging Nano Copper-Based Printable Flexible Hybrid Electronics.

Printed copper materials have been attracting significant attention prominently due to their electric, mechanical, and thermal properties. The emerging copper-based flexible electronics and energy-critical applications rely on the control of electric conductivity, current-carrying capacity, and reliability of copper nanostructures and their printable ink materials. In this review, we describe the growth of copper nanostructures as the building blocks for printable ink materials on which a variety of conductive features can be additively manufactured to achieve high electric conductivity and stability. Accordingly, the copper-based flexible hybrid electronics and energy-critical devices printed by different printing techniques are reviewed for emerging applications.

Response of HPRT Gene Fragment Functionalized Gold Nanoparticles to Gamma Ray Irradiation.

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.

Two-Dimensional Conductive π-d Frameworks with Multiple Sensory Capabilities.

Two-dimensional (2D) metal-molecule hybrid frameworks have attracted great attention due to their π-d interactions for the charge-spin-lattice coupling, promising for next-generation molecular electronics. However, a high electrical conductivity is indispensable to realize such potential. Herein, we design and assemble a conductive 2D conjugated coordination thin film through an interfacial reaction between the aqueous and organic phases. Its electronic conducting properties are derived from the π-d coupling interactions to achieve an electrical conductivity of 1.05 S/cm, while the stimulus-dependent π-d interactions induce multifunctional sensory capabilities. The Co-DABDT (DABDT = 2,5-diamino-1,4-benzenedithiol dihydrochloride) thin films demonstrate an excellent performance for sensing light, strain, temperature, and humidity, as well as robust mechanical stability. The 2D frameworks with multisensing properties for real-time static and dynamic monitoring are promising for smart wearable electronic systems.

Nanometer-Sized Boron Loaded Liposomes Containing Fe3O4 Magnetic Nanoparticles and Tributyl Borate and Anti-Albumin from Bovine Serum Antibody for Thermal Neutron Detection.

A shortage in the supply of 3He used for thermal neutron detector makes researchers to find 3He alternatives for developing new neutron detectors. Here, we prepared a neutron-sensitive composite liposome with tributyl borate and encapsulating with Fe3O4@oleic acid nanoparticles (Fe3O4@OA NPs), methylene blue (MB), or anti-albumin from bovine serum (anti-BSA). The tributyl borate compound was characterized by Fourier transform infrared spectroscopy (FT-IR). In addition, the morphology, element compositions, and magnetic properties of the composite liposome were investigated with transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and vibrating sample magnetometer (VSM), respectively. The results indicated that a typical ellipsoidal magnetic liposome structure was obtained, and the lengths of the minor axis and major axis were 49 ± 1 nm and 87 ± 3 nm, respectively. Under thermal neutron irradiation, the structure of composite liposome was destroyed, and encapsulated reporter molecules were released, which was detected by ultraviolet-visible (UV-vis) spectroscopy and surface plasmon resonance (SPR) technology. The response of this sensor based on a destructive assay shows a good correlation with neutron doses. Besides, the sensor has a neutron to gamma-ray rejection ratio of 1568 at a thermal neutron flux rate of 135.6 n/cm2·s, which makes it a promising alternative to 3He.

Low-Diffusion Fricke Gel Dosimeters with Core-Shell Structure Based on Spatial Confinement.

The diffusion of ferric ions is an important challenge to limit the application of Fricke gel dosimeters in accurate three-dimensional dose verification of modern radiotherapy. In this work, low-diffusion Fricke gel dosimeters, with a core-shell structure based on spatial confinement, were constructed by utilizing microdroplet ultrarapid freezing and coating technology. Polydimethylsiloxane (PDMS), with its excellent hydrophobicity, was coated on the surface of the pellets. The concentration gradient of the ferric ion was realized through shielding half of a Co-60 photon beam field size, and ion diffusion was measured by both ultraviolet-visible spectrophotometry and magnetic resonance imaging. No diffusion occurred between the core-shell pellets, even at 96 h after irradiation, and the diffusion length at the irradiation boundary was limited to the diameter (2-3 mm) of the pellets. Furthermore, Monte Carlo calculations were conducted to study dosimetric properties of the core-shell dosimeter, which indicated that a PDMS shell hardly affected the performance of the dosimeter.

Cu-based metal-organic frameworks for highly sensitive X-ray detectors.

Here, we constructed Pb-free Cu-DABDT-MOFs-based (DABDT = 2,5-diamino-1,4-benzenedithiol) X-ray detectors. Combined with the advantage of high activation energy, the Cu-DABDT-MOFs-based detector can effectively generate and capture electrons under X-ray exposure and presents a high mobility-lifetime (µτ) product of 6.49 × 10-4 cm2 V-1 and promising detection sensitivity of 78.7 µC Gyair-1 cm-2. As groundbreaking work, these discoveries have provided information for exploring MOF materials toward green and high-performance high-energy radiation detectors by exploiting the designable structure and tunable properties of the MOF family.

Smart Hydrogel Bilayers Prepared by Irradiation.

Environment-responsive hydrogel actuators have attracted tremendous attention due to their intriguing properties. Gamma radiation has been considered as a green cross-linking process for hydrogel synthesis, as toxic cross-linking agents and initiators were not required. In this work, chitosan/agar/P(N-isopropyl acrylamide-co-acrylamide) (CS/agar/P(NIPAM-co-AM)) and CS/agar/Montmorillonite (MMT)/PNIPAM temperature-sensitive hydrogel bilayers were synthesized via gamma radiation at room temperature. The mechanical properties and temperature sensitivity of hydrogels under different agar content and irradiation doses were explored. The enhancement of the mechanical properties of the composite hydrogel can be attributed to the presence of agar and MMT. Due to the different temperature sensitivities provided by the two layers of hydrogel, they can move autonomously and act as a flexible gripper as the temperature changes. Thanks to the antibacterial properties of the hydrogel, their storage time and service life may be improved. The as prepared hydrogel bilayers have potential applications in control devices, soft robots, artificial muscles and other fields.

Hematopoietic protection and mechanisms of ferrostatin-1 on hematopoietic acute radiation syndrome of mice.

PURPOSE: Baicalein (an anti-ferroptosis drug) was recently reported to synergistically improve the survival rate of mice following a high dose of total body irradiation with anti-apoptosis and anti-necroptosis drugs. At the same time, our group has demonstrated that ferrostatin-1, a ferroptosis inhibitor, improves the survival rate of a mouse model of hematopoietic acute radiation syndrome to 60% for 150 days (p < .001). These phenomena suggest that ferroptosis inhibition can mitigate radiation damage. In this study, we continued to study the mechanisms by which ferrostatin-1 alleviated radiation-induced ferroptosis and subsequent hematopoietic acute radiation syndrome. MATERIALS AND METHODS: Male ICR mice (8-10 weeks old) were exposed to doses of 0, 8, or 10 Gy irradiated from a 137Cs source. Ferrostatin-1 was intraperitoneally injected into mice 72 h post-irradiation. Bone marrow mononuclear cells (BMMCs) and peripheral blood cells were counted. The changes in iron-related parameters, lipid metabolic enzymes, lipid peroxidation repair molecules (glutathione peroxidase 4, glutathione, and coenzyme Q10), and inflammatory factors (TNF-α, IL-6, and IL-1ß) were evaluated using biochemical or antibody techniques. RESULTS: Ferrostatin-1 increased the number of red and white blood cells, lymphocytes, and monocytes in the peripheral blood after total body irradiation in mice by mitigating the ferroptosis of BMMCs. Total body irradiation induced ferroptosis in BMMCs by increasing the iron and lipid peroxidation levels and depleting the acyl-CoA synthetase long-chain family member 4 (ASCL4), lipoxygenase 15, glutathione peroxidase 4, and glutathione levels. Ferroptotic BMMCs did not release TNF-α, IL-6, or IL-1ß at the early stage of radiation exposure. Ferrostatin-1 mitigated the lipid peroxidation of radiation-induced ferroptosis by attenuating increases in levels of hemosiderin and liable iron pool and decreases in levels of ASCL4 and glutathione peroxidase 4. CONCLUSIONS: The onset of total body irradiation-induced ferroptosis in BMMCs involved changes in iron, lipid metabolic enzymes, and anti-lipid peroxidation molecules. Ferrostatin-1 could be a potential radiation mitigation agent by acting on these targets.

Highly Sensitive Gold Nanoparticles-DNA Nanosensor for γ-Radiation Detection.

It is very important to control the ionizing radiation dose in radiation therapy, which depends on the accurate and rapid measurement of radiation. Herein, a novel and highly sensitive nanosensor for γ-radiation detection is constructed using single-stranded DNA sequences as radiation-sensitive material and gold nanoparticles (AuNPs) as a signal reporter. Well-dispersed AuNPs gradually aggregated at high salt concentration when the sensor was irradiated, and this change was quantified by the visible spectra and surface plasmon resonance spectra. The radiation nanosensor has excellent linearity in the dose range of 0-100 Gy under optimal conditions. This method is simple and fast, which provides a new path for the γ-radiation dosimeter and has potential applications in the assessment of radiation-induced biological effects.

Ductile cooling phase change material.

Cooling represents a considerable fraction of energy consumption. However, it is indispensable to develop eco-friendly, biocompatible, and ductile cooling materials for personal applications. In this study, we demonstrate the ductile cooling ability with phase change of thermally passivated hydrogel composite materials with additive manufacturing ability. Thermal evaluation of such water-based composites indicates a superior cold retention capacity with a cooling comfort over 6 hours, while the composite displays a full recovery when strained up to 80% in uniaxial compression tests as a result of the intertwining between covalent and ionic bonds. A three-layered rectangular model was utilized to simulate the problem in a steady-state thermal analysis to study the cooling effect. Our findings indicate the potential of hydrogel as a cooling phase-change medium and its contribution towards ductile cooling applications.

Ionizing radiation induces ferroptosis in granulocyte-macrophage hematopoietic progenitor cells of murine bone marrow.

Purpose: To study whether radiation-induced bleeding in the bone marrow induced iron accumulation, and subsequently caused ferroptosis in granulocyte-macrophage hematopoietic progenitor cells.Materials and methods: Male mice were subjected to different doses (0, 4, 8, or 10 Gy) of gamma radiation from a 137Cs source. The changes in iron metabolism or ferroptosis-related parameters of irradiated bone marrow were accessed with biochemical, histopathological, and antibody methods. Hematocytes were detected with a hematology analyzer. The counts of granulocyte-macrophage hematopoietic progenitor cells were measured with the granulocyte-macrophage colony-forming unit.Results: Iron accumulation occurred in the bone marrow, which caused by radiation-induced hemorrhage. The iron accumulation triggered an iron regulatory protein-ferroportin 1 axis to increase serum iron levels. Using LDN193189, radiation-induced iron accumulation was demonstrated to decrease white blood cell counts at least partly through a decrease in the counts of granulocyte-macrophage hematopoietic progenitor cells. The reduction in the counts of granulocyte-macrophage hematopoietic progenitor cells was subsequently demonstrated to attribute to ferroptosis with the use of ferroptosis inhibitors and through the detection of ferroptosis related-parameters. The survival rate of irradiated mice was improved using Ferrostatin-1 or LDN193189.Conclusions: These findings suggest that radiation-induced hemorrhage in the bone marrow causes ferroptosis in granulocyte-macrophage hematopoietic progenitor cells, and anti-ferroptosis has the potential to be a radioprotective strategy to ameliorate radiation-induced hematopoietic injury.

Cancer-cell targeting and photoacoustic therapy using carbon nanotubes as "bomb" agents.

A unique approach using the large photoacoustic effect of single-walled carbon nanotubes (SWNTs) for targeting and selective destruction of cancer cells is demonstrated. SWNTs exhibit a large photoacoustic effect in suspension under the irradiation of a 1064-nm Q-switched millisecond pulsed laser and trigger a firecracker-like explosion at the nanoscale. By using such an explosion, a photoacoustic agent is developed by functionalizing the SWNTs with folate acid (FA) that can selectively bind to cancer cells overexpressing folate receptor on the surface of the cell membrane and kill them through SWNT explosion inside the cells under the excitation of millisecond pulsed laser. The uptake pathway of folate-conjugated SWNTs into cancer cells is investigated via fluorescence imaging and it is found that the FA-SWNTs can enter into cancer cells selectively with a high targeting capability of 17-28. Under the treatment of 1064-nm millisecond pulsed laser, 85% of cancer cells with SWNT uptake die within 20 s, while 90% of the normal cells remain alive due to the lack of SWNTs inside cells. Temperature changes during laser treatment are monitored and no temperature increases of more than +/- 3 degrees C are observed. With this approach, the laser power used for cancer killing is reduced 150-1500 times and the therapy efficiency is improved. The death mechanism of cancer cells caused by the photoacoustic explosion of SWNTs is also studied and discussed in detail. These discoveries provide a new way to use the photoacoustic properties of SWNTs for therapeutic applications.

Gamma-radiation synthesis of silk fibroin coated CdSe quantum dots and their biocompatibility and photostability in living cells.

Silk fibroin coated CdSe quantum dots (SF-CdSe QDs) were successfully synthesized via a one-step gamma-radiation route in an aqueous system at room temperature. The as prepared products were characterized by transmission electron microscope (TEM), energy dispersion spectrum (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence spectrum (PL). The SF-CdSe QDs were about 5 nm in diameter and exhibited excellent water-solubility and photoluminescence properties. The cellular distribution, photostability and cytotoxicity of SF-CdSe QDs with different amount of SF coatings were also investigated by laser scanning confocal microscope (LSCM) and MTT assays in human pancreatic carcinoma (PANC-1) cells. All the results reveal that these QDs could be easily internalized by cells and localized in cytoplasm around nuclei. Moreover, SF-CdSe QDs were proved to be low cytotoxicity (the concentration of QDs < 5 microg mL(-1)) and high photostability (the illumination energy density < 2 x 10(-5) W microm(-2)) within PANC-1 cells, which was mainly due to the biocompatible silk fibroin. The resulted SF-CdSe QDs might have many potential applications in tumor imaging and therapy. And the synthesis strategy could be easily extended to fabrication of other nanoparticles coated with silk fibroin.