A novel fluorescent indicator displacement assay for sensing the anticancer drug gefitinib

<p>Fluorescent indicator displacement assays have become popular for converting synthetic receptors into optical sensors. We have now shown that a 1:2 host–guest complex between cucurbit[8]uril (Q[8]) and proflavine (PF) can be used as a fluorescent indicator for sensing the anticancer drug gefitinib. The 2PF@Q[8] complex can be used to detect gefitinib with high selectivity using fluorescence spectrometry with a detection limit of 6.63 × 10⁻⁸ mol^−L. The proposed sensing mechanism was investigated using ¹H nuclear magnetic resonance spectroscopy (¹H NMR), isothermal titration calorimetry and electrospray ionisation mass spectrometry. The 2PF@Q[8] complex was shown to be suitable for imaging gefitinib in prostate cancer (PC3) cells, which may help to elucidate relevant biological processes at the molecular level. We have developed a novel F-IDA to detect the anticancer drug GEF with high selectivity. The new indicator has excellent selectivity and a low detection limit for GEF. We have also demonstrated that the F-IDA can be used for the practical determination of drugs in living cells.</p

Giant Magnetoelastic Effect at the Opening of a Spin-Gap in Ba₃BiIr₂O₉

As compared to 3d (first-row) transition metals, the 4d and 5d transition metals have much more diffuse valence orbitals. Quantum cooperative phenomena that arise due to changes in the way these orbitals overlap and interact, such as magnetoelasticity, are correspondingly rare in 4d and 5d compounds. Here, we show that the 6H-perovskite Ba₃BiIr₂O₉, which contains 5d Ir⁴⁺ (<i>S</i> = 1/2) dimerized into isolated face-sharing Ir₂O₉ bioctahedra, exhibits a giant magnetoelastic effect, the largest of any known 5d compound, associated with the opening of a spin-gap at <i>T</i>* = 74 K. The resulting first-order transition is characterized by a remarkable 4% increase in Ir–Ir distance and 1% negative thermal volume expansion. The transition is driven by a dramatic change in the interactions among Ir 5d orbitals, and represents a crossover between two very different, competing, ground states: one that optimizes direct Ir–Ir bonding (at high temperature), and one that optimizes Ir–O–Ir magnetic superexchange (at low temperature)

Giant Magnetoelastic Effect at the Opening of a Spin-Gap in Ba₃BiIr₂O₉

As compared to 3d (first-row) transition metals, the 4d and 5d transition metals have much more diffuse valence orbitals. Quantum cooperative phenomena that arise due to changes in the way these orbitals overlap and interact, such as magnetoelasticity, are correspondingly rare in 4d and 5d compounds. Here, we show that the 6H-perovskite Ba₃BiIr₂O₉, which contains 5d Ir⁴⁺ (<i>S</i> = 1/2) dimerized into isolated face-sharing Ir₂O₉ bioctahedra, exhibits a giant magnetoelastic effect, the largest of any known 5d compound, associated with the opening of a spin-gap at <i>T</i>* = 74 K. The resulting first-order transition is characterized by a remarkable 4% increase in Ir–Ir distance and 1% negative thermal volume expansion. The transition is driven by a dramatic change in the interactions among Ir 5d orbitals, and represents a crossover between two very different, competing, ground states: one that optimizes direct Ir–Ir bonding (at high temperature), and one that optimizes Ir–O–Ir magnetic superexchange (at low temperature)

Key Role of Bismuth in the Magnetoelastic Transitions of Ba₃BiIr₂O₉ and Ba₃BiRu₂O₉ As Revealed by Chemical Doping

The key role played by bismuth in an average intermediate oxidation state in the magnetoelastic spin-gap compounds Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉ has been confirmed by systematically replacing bismuth with La³⁺ and Ce⁴⁺. Through a combination of powder diffraction (neutron and synchrotron), X-ray absorption spectroscopy, and magnetic properties measurements, we show that Ru/Ir cations in Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉ have oxidation states between +4 and +4.5, suggesting that Bi cations exist in an unusual average oxidation state intermediate between the conventional +3 and +5 states (which is confirmed by the Bi L₃-edge spectrum of Ba₃BiRu₂O₉). Precise measurements of lattice parameters from synchrotron diffraction are consistent with the presence of intermediate oxidation state bismuth cations throughout the doping ranges. We find that relatively small amounts of doping (∼10 at%) on the bismuth site suppress and then completely eliminate the sharp structural and magnetic transitions observed in pure Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉, strongly suggesting that the unstable electronic state of bismuth plays a critical role in the behavior of these materials