Huan Huang

An organic–inorganic hybrid perovskite logic gate for better computing

A practicable means of significantly reducing the energy consumption and speeding up the operating rate of computer chips is to place the processor and memory into one device, which processes and stores information simultaneously like the human brain. Here we demonstrate a novel sandwich architecture where organic–inorganic hybrid perovskite materials could be used as building-block materials for non-volatile memristors, accompanied with photoresponsive performance. Owing to the distinct photo-response of the two resistance states of the memristor, it is feasible to utilize the device as a logic OR gate by employing an electrical field and light illumination as input sources. This study provides potential applications in logic circuits, optical digital computation and optical quantum information for beneficial supplementation of the von Neumann architecture, or even for computing beyond it.

Novel Carbon Nanohybrids As Highly Efficient Magnetic Resonance Imaging Contrast Agents

Novel carbon nanohybrids based on unmodified metallofullerenes have been successfully fabricated for use as a new magnetic resonance imaging (MRI) contrast agent. The nanohybrids showed higher R1 relaxivity and better brightening effect than Gd@C82(OH)X, in T1-weighted MR images in vivo. This is a result of the proton relaxivity from the original gadofullerenes, which retained a perfect carbon cage structure and so might completely avoid the release of Gd3+ ions. A “secondary spin-electron transfer” relaxation mechanism was proposed to explain how the encaged Gd3+ ions of carbon nanohybrids interact with the surrounding water molecules. This approach opens new opportunities for developing highly efficient and low toxicity MRI contrast agents.

Adaption of the structure of carbon nanohybrids toward high-relaxivity for a new MRI contrast agent

Water-soluble GO–Gd@C82 nanohybrids exhibit high relaxivities and could be explored as potential magnetic resonance imaging (MRI) contrast agents. To better understand the relaxation mechanism in the novel carbon nanohybrids, in the present paper, after layers of in-depth analysis and exploration, we propose that the structure and the physicochemical properties of the carbon nanohybrids contribute significantly to the enhanced relaxivity. Better electron transfer from Gd@C82 to the GO nanosheet, appropriate electric conductivity and size of the GO used, an increased number of H proton exchange sites and an adequate concentration of Gd3+ should result in optimal equilibrium for high relaxivity of the GO–Gd@C82. These results are important for constructing and optimizing novel nanoscale architectures with higher relaxivity.

Synthesis of a UCNPs@SiO2@gadofullerene nanocomposite and its application in UCL/MR bimodal imaging

Multimodal imaging provides more complementary information than single mode imaging. Herein, we have developed a novel bimodal imaging agent (GdF–UCNPs) through conjugating paramagnetic water-soluble polyhydroxy Gd@C82-PCBM with silica coated NaYF4:Yb,Er nanoparticles. In the new contrast agent, the stable silica shell and the carbon cage structure protect the encaged inner rare earth ions, which results in low toxicity. The resulting nanoconjugates exhibit strong luminescence and present efficient MRI contrast (r1 = 11.89 mM−1 s−1). Ex vivo and in vivo bimodal imagings were carried out in a mouse model. The results prove that the nanocomposites are useful as bimodal imaging agents for luminescence/MR imaging in biomedical research.

Eu3+:Y2O3@CNTs—a rare earth filled carbon nanotube nanomaterial with low toxicity and good photoluminescence properties

Red-emission phosphor europium-doped yttria (Eu3+:Y2O3) nanoparticles have been successfully filled into the nanocavity of carbon nanotubes (CNTs) via supercritical reaction and supercritical fluids followed by calcination. The existence of Eu3+:Y2O3 nanoparticles inside CNTs was characterized by TEM, EDS and XRD. The as-prepared nanomaterials (Eu3+:Y2O3@CNTs) exhibited strong red-emission at 610 nm, which corresponded to 5D0 → 7F2 transition within Eu3+ ions. It showed that the existence of the walls of the CNTs did not quench the luminescence of Eu3+:Y2O3. Due to the surface modification with Tween 80, Eu3+:Y2O3@CNTs had good water solubility. In vitro cytotoxicity studies showed that the as-prepared nanomaterials had low toxicity on HeLa cells at concentrations of 10–1000 μg mL−1. And their use as luminescence probes for live cell imaging was demonstrated by using inverted fluorescence microscopy. With the advantages of the easy dispersion in water, low toxicity, and good photoluminescence (PL) properties, the as-prepared Eu3+:Y2O3@CNTs could potentially be used as nanophosphors in bio-imaging.

Highly delocalized endohedral metal in Gd@C2v(9)-C82 metallofullerenes co-crystallized with α-S8

A new Gd@C2v(9)-C82·2.5(S8)·0.5(CS2) co-crystal was prepared for the first time and characterized by single-crystal X-ray diffraction (XRD). The analysis clearly showed that, even though the C2v(9)-C82 cage is fully ordered, the endohedral Gd atoms are highly disordered. This result indicates the presence of highly delocalized endohedral Gd atoms, which has never been reported before. Density functional theory (DFT) calculations were used to rationalize the XRD results. The calculations reveal the presence of two local energy minima, a and b, with the latter existing as four conformers b1–b4. Whereas the energy difference between the two minima is calculated only ∼ 10 kcal/mol, their interconversion is almost impossible due to a high energy barrier, of up to 35.98 kcal/mol. This suggests the existence of multiple low-energy positions for the endohedral Gd atom. In addition, a remarkable electron transfer from the C2v(9)-C82 cage to the S8 moieties was demonstrated, which might result in a modified endohedral environment and further contribute to the occurrence of delocalized endohedral Gd atoms.

Facile Synthesis of Ni-Based Catalysts by Adsorption and Conversion of Metal Ions on Graphene Oxide for Methanol Oxidation

AbstractControllable synthesis of highly dispersed non-precious nanocatalysts is an attractive strategy to prepare efficient electrocatalysts for fuel cell applications. In this study, a facile synthesis of Ni-based mono- and bimetallic nanocatalysts has been developed by adsorption and conversion of metal ions on graphene oxide. The morphology and composition of Ni catalyst are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical and electrocatalytic properties of Ni catalysts are studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopic techniques. The catalytic performance can be improved easily by increasing the adsorption and deposition cycles of metal ions and changing the composition of precursor metal ions solution. This work will be of general interest to design efficient nanostructured catalysts and find ideal electrocatalysts for application with high catalytic performance and low price. Graphical AbstractA facile synthesis of metallic nanocatalysts has been developed by adsorption and conversion of metal ions on graphene oxide

Fluorescent activatable gadofullerene nanoprobes as NIR-MR dual-modal in vivo imaging contrast agent

Dual mode imaging technology is widely developed to achieve the early-stage precision cancer diagnosis. Here we designed a dual-modal magnetic resonance/near infrared fluorescence optical imaging contrast agent (GdF-SS-NIR783) with the fluorescence activatable and safer gadofullerene. The nanoprobes were fabricated by conjugating the gadofullerene derivatives with a NIR fluorescence imaging agent (NIR783) via the disulfide bond. The obtained nanoprobes showed no fluorescence (OFF), but the fluorescence turned on when incubated within reduction environment such as GSH solution. The clear fluorescence signal in tumor site was observed obviously after their intratumor injection. The nanoprobes also revealed efficient MRI contrast enhancement both in vitro and in vivo. And they showed good biocompatibility and did not demonstrate any tissue toxicity in vivo. This work gave the new possibility in designing more efficient and safer nanoprobes for future medical diagnoses.