Polymer-assisted hydrothermal synthesis of Bi2S3 nanostructured flowers

Nanostructured Bi₂S₃ was hydrothermally produced from Bi₂O₃ and thiocarbohydrazide in acidic solutions containing PVA, PEG and PVP. By using XRD, SAED and Raman spectrometry, the products were orthorhombic Bi₂S₃, with four vibration modes at 139.6, 253.7, 310 and 968.9 cm⁻¹. The phase was also in accordance with the diffraction patterns obtained by simulation. SEM, TEM and HRTEM show that the products are clusters of nanorods produced in polymer-free solution, and nanostructured flowers of nanospears, nanorods and nanoplates in the respective PVA-, PEG- and PVP-added solutions, with their growths in the same direction of [0 0 1]. A formation mechanism was also proposed according to their phase and morphologies.     

Rational Design of [13C,D14]Tert‐butylbenzene as a Scaffold Structure for Designing Long‐lived Hyperpolarized 13C Probes

Dynamic nuclear polarization (DNP) is a technique to polarize the nuclear spin population. As a result of the hyperpolarization, the NMR sensitivity of the nuclei in molecules can be dramatically enhanced. Recent application of the hyperpolarization technique has led to advances in biochemical and molecular studies. A major problem is the short lifetime of the polarized nuclear spin state. Generally, in solution, the polarized nuclear spin state decays to a thermal spin equilibrium, resulting in loss of the enhanced NMR signal. This decay is correlated directly with the spin‐lattice relaxation time T₁. Here we report [¹³C,D₁₄]tert‐butylbenzene as a new scaffold structure for designing hyperpolarized ¹³C probes. Thanks to the minimized spin‐lattice relaxation (T₁) pathways, its water‐soluble derivative showed a remarkably long ¹³C T₁ value and long retention of the hyperpolarized spin state.     

Photochemical patterning of a self-assembled monolayer of 7-diazomethylcarbonyl-2,4,9-trithiaadmantane on gold films via Wolff rearrangement

Photolithographic attachment of functional organic molecules via ester or amide linkages to self-assembled monolayers (SAMs) on gold thin films was achieved by employing a novel photoreactive surface anchor, 7-diazomethylcarbonyl-2,4,9-trithiaadmantane. The photoreactive SAM was prepared by the spontaneous physical adsorption of the photoreactive surface anchor onto gold surfaces. The alpha-diazo ketone moiety of the SAM was found to display the classical Wolff rearrangement reactivity to produce a ketene intermediate on the exposed area. Organic molecules such as alcohols and amines can thus be attached to the gold surfaces selectively by the facile in situ formation of ester or amide linkages. The structure and reactivity of the photoreactive surface anchor were characterized by real-time FT-IR, fluorescence, and polarization modulation infrared reflectance absorption spectroscopy (PM-IRRAS). The Wolff rearrangement reactivity of the SAM suggested that a "surface-isolated" carbonylcarbene may be generated when the SAM was exposed to 255-nm irradiation.     

Zinc ferrite nanoparticles as MRI contrast agents

Mixed spinel hydrophobic ZnxFe1-xO x Fe2O3 (up to x = 0.34) nanoparticles encapsulated in polymeric micelles exhibited increased T2 relaxivity and sensitivity of detection over clinically used Feridex.     

Hydroxyethyl cellulose-assisted hydrothermal synthesis of Bi2S3 urchin-like colonies

Orthorhombic Bi₂S₃ with different morphologies was successfully synthesized by the acid-catalyst hydrothermal reactions of bismuth nitrate (Bi(NO₃)₃) and thiourea (NH₂CSNH₂) solutions containing different amounts of hydroxyethyl cellulose (HEC). Phase, morphologies, and optical properties were characterized by X-ray diffraction, selected area electron diffraction, scanning and transmission electron microscopy, and ultraviolet-visible spectroscopy. The products, hydrothermally synthesized in the HEC-free, 0.25 g HEC-added, 0.5 g HEC-added and 1.00 g HEC-added solutions, were respectively proved to be orthorhombic Bi₂S₃ irregular nanorods, complete urchin-like colonies of regular nanorods, incomplete urchin-like colonies of regular nanorods, and highly crystalline regular nanorods growing along the [001] direction. Tauc band gaps of the orthorhombic Bi₂S₃ nanorods, synthesized in the HEC-free, 0.25 g HEC-added, and 1.00 g HEC-added solutions were determined to be 3.0, 1.75 and 1.8 eV, respectively. Formation mechanism of orthorhombic Bi₂S₃ nanorods, synthesized in the HEC-free and HEC-added solutions, was also discussed at great detail.     

Off-resonance saturation MRI of superparamagnetic nanoprobes: theoretical models and experimental validations

Off-resonance saturation (ORS) is a new magnetic resonance imaging (MRI) method that has shown greatly improved contrast sensitivity for the detection of cancer-specific biomarkers by superparamagnetic nanoprobes in vivo. However, quantitative understanding of the ORS contrast mechanism and its dependence on the structural parameters of superparamagnetic nanoprobes are still lacking. Here we propose a quantitative model of ORS contrast and its experimental validation by superparamagnetic polymeric micelles (SPPM) with precisely controlled structural properties. Size selected, monodisperse Fe?O? nanoparticles (6.1 ± 0.2 nm) were used to form a series of SPPM nanoprobes with specifically controlled corona thickness using 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxypoly(ethylene glycol) (DSPE-PEG) with different PEG molecular weights. Transmission electron microscopy and dynamic light scattering showed that SPPM were uniform in size. The average hydrodynamic diameters of SPPM with PEG lengths of 0.55, 1, 2, and 5 kD were 16.6 ± 2.8, 18.4 ± 2.9, 24.1 ± 3.4, and 28.9 ± 3.4 nm, respectively. MRI experiments at 7 T determined that r? values of SPPM with 0.55, 1, 2, and 5 kD PEG as corona were 201 ± 3, 136 ± 8, 107 ± 5, and 108 ± 8 FemM?1s?1, respectively. ORS intensity from Z-spectra of SPPM showed a significant correlation with the inverse of T? relaxation rates (1/T?, s?1) of the SPPM nanoprobes regardless of the PEG corona thickness. These data provide the fundamental understanding of the structure-property relationships between the SPPM nanostructures and ORS sensitivity, which offers useful mechanistic insights for the future improvement of SPPM nanoprobes in cancer molecular imaging applications.     

Synthesis and catalytic activity of a poly(N,N-dialkylcarbodiimide)/palladium nanoparticle composite: a case in the Suzuki coupling reaction using microwave and conventional heating

Poly(N,N-dialkylcarbodiimide) was found to be an effective polymeric ligand system for preparing and stabilizing palladium nanoparticles (1-5 nm). The composite material prepared in situ was found to be a robust catalyst for the Suzuki coupling reaction under microwave or regular heating.     

Solvothermal synthesis of CdS nanorods using hydroxyethyl cellulose as a template

CdS nanorods were solvothermally produced from Cd(CH₃COO)₂ and S powder using ethylenediamine (en) as a solvent and hydroxyethyl cellulose (HEC) as a template. The phase with hexagonal structure was detected using XRD and SAED, which is in perfect accordance with the results obtained by simulation. SEM, TEM and HRTEM revealed the development of nanorods with a number of atoms arranged in crystal lattices. When the appropriate amount of HEC was used, the longest nanorods, with preferential growth in the [0 0 1] direction, were produced. Raman spectra showed the fundamental and overtone modes at the same wavenumbers of 301 and 599 cm⁻¹, respectively. Their relative intensities at each temperature were strongly influenced by the anisotropic geometry of the products. Photoluminescence caused by electron-hole recombination was detected at 470 nm, and by surface trapping induced emission at 575 nm. The formation mechanism of CdS nanorods was also proposed based on the experimental results.