01213nas a2200193 4500008004100000022001400041245011500055210006900170260011000239300001600349490000700365520042700372100001700799700001400816700002500830700001900855700002000874856012500894 2011 eng d a1359-734500aDesign and in situ synthesis of a Cu-based porous framework featuring isolated double chain magnetic character0 aDesign and in situ synthesis of a Cubased porous framework featu aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a11008-110100 v473 a

A Cu-based double chain MOF was synthesized in hydrothermal conditions using an in situ ligand formation method. This double chain MOF shows temperature dependent ferromagnetic (long range ordering) and antiferromagnetic (intra double chain) coupling. The magnetic behaviour originating from the individual double chain remains almost same even after structural collapse due to the removal of guest water molecules.

1 aDey, Chandan1 aDas, Raja1 aSaha, Binoy, Krishna1 aPoddar, Pankaj1 aBanerjee, Rahul uhttps://library.ncl.res.in/content/design-and-situ-synthesis-cu-based-porous-framework-featuring-isolated-double-chain-001989nas a2200181 4500008004100000022001400041245006800055210006800123260012500191300001100316490000800327520130000335100002001635700001401655700001701669700001901686856010201705 2011 eng d a0021-897900aDielectric and spin relaxation behaviour in DyFeO3 nanocrystals0 aDielectric and spin relaxation behaviour in DyFeO3 nanocrystals aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScDEC a1243010 v1103 a

We report the temperature and frequency dependent dielectric measurements and ac magnetic susceptibility of chemically synthesized DyFeO3 nanoparticles (size similar to 50-60 nm). The measurement of the dielectric properties was carried out in a broad temperature (20-325 K) and frequency (1-10(6) Hz) range. The non-Debye type dipolar relaxation phenomenon was observed in the DyFeO3 nanoparticles, as confirmed by the Cole-Cole plots. The higher values of epsilon' at the lower frequencies are explained on the basis of the Maxwell-Wagner model. The Cole-Cole analysis enabled us to separate the contribution of relaxation times, resistance and capacitance in grain and grain boundaries in DyFeO3 nanocrystals. We found that with increasing temperature, the contribution of grain boundary resistance increases in comparison to the grain resistance. We also performed spin relaxation studies in a broad temperature and frequency range. Both the in-phase (chi') and out-of-phase (chi `') components of the ac magnetic susceptibilities of the DyFeO3 nanoparticles show a clear evidence at spin reorientation transition around 70K and T-N (Dy) around 4K as reported by us in our earlier study using the dc magnetic behaviour. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3669154]

1 aJaiswal, Adhish1 aDas, Raja1 aMaity, Tuhin1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/dielectric-and-spin-relaxation-behaviour-dyfeo3-nanocrystals-003303nas a2200193 4500008004100000022001400041245025000055210006900305260011000374300001600484490000600500520237600506100001902882700001602901700002102917700002602938700001902964856012602983 2015 eng d a2040-336400aDoxorubicin-conjugated beta-NaYF4:Gd3+/Tb3+ multifunctional, phosphor nanorods: a multimodal, luminescent, magnetic probe for simultaneous optical and magnetic resonance imaging and an excellent pH-triggered anti-cancer drug delivery nanovehicle0 aDoxorubicinconjugated betaNaYF4Gd3Tb3 multifunctional phosphor n aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a19501-195180 v73 a

Herein, we report the fabrication of a multifunctional nanoprobe based on highly monodispersed, optically and magnetically active, biocompatible, PEI-functionalized, highly crystalline beta-NaYF4:Gd3+/Tb3+ nanorods as an excellent multi-modal optical/magnetic imaging tool and a pH-triggered intracellular drug delivery nanovehicle. The static and dynamic photoluminescence spectroscopy showed the presence of sharp emission peaks, with long lifetimes (similar to 3.5 milliseconds), suitable for optical imaging. The static magnetic susceptibility measurements at room temperature showed a strong paramagnetic signal (chi similar to 3.8 x 10(-5) emu g(-1) Oe(-1)). The nuclear magnetic resonance (NMR) measurements showed fair T-1 relaxivity (r(1) = 1.14 s(-1) mM(-1)) and magnetic resonance imaging gave enhanced T-1-weighted MRI images with increased concentrations of beta-NaYF4:Gd3+/Tb3+ making them suitable for simultaneous magnetic resonance imaging. In addition, an anticancer drug, doxorubicin (DOX) was conjugated to the amine-functionalized beta-NaYF4:Gd3+/Tb3+ nanorods via pH-sensitive hydrazone bond linkages enabling them as a pH-triggered, site-specific drug delivery nanovehicle for DOX release inside tumor cells. A comparison between in vitro DOX release studies undertaken in normal physiological (pH 7.4) and acidic (pH 5.0) environments showed an enhanced DOX dissociation (similar to 80%) at pH 5.0. The multifunctional material was also applied as an optical probe to confirm the conjugation of DOX and to monitor DOX release via a fluorescence resonance energy transfer (FRET) mechanism. The DOX-conjugated beta-NaYF4:Gd3+/Tb3+ nanorods exhibited a cytotoxic effect on MCF-7 breast cancer cells and their uptake by MCF-7 cells was demonstrated using confocal laser scanning microscopy and flow cytometry. The comparative cellular uptakes of free DOX and DOX-conjugated beta-NaYF4:Gd3+/Tb3+ nanorods were studied in tumor microenvironment conditions (pH 6.5) using confocal imaging, which showed an increased uptake of DOX-conjugated beta-NaYF4:Gd3+/Tb3+ nanorods. Thus, DOX-conjugated beta-NaYF4:Get(3+)/Tb3+ nanorods combining pH-triggered drug delivery, efficient luminescence and paramagnetic properties are promising for a potential multifunctional platform for cancer therapy, biodetection, and optical and magnetic resonance imaging.

1 aPadhye, Preeti1 aAlam, Aftab1 aGhorai, Suvankar1 aChattopadhyay, Sarnit1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/doxorubicin-conjugated-beta-nayf4gd3tb3-multifunctional-phosphor-nanorods-multimodal-004056nas a2200157 4500008004100000245009000041210006900131260000800200300001400208490000600222520349800228100001803726700001903744700001903763856011603782 2019 eng d00a Downconversion luminescence-based nanosensor for label-free detection of explosives 0 aDownconversion luminescencebased nanosensor for labelfree detect cFEB a4259-42680 v43 a

We report a selective and sensitive nanosensor probe based on polyethylenimine (PEI)-capped downconverting nanophosphors beta-NaYF4:Gd3+, Tb3+@PEI for the detection of 2,4,6-trinitrotoluene (TNT), both in water and buffer media. These downconverting phosphors were synthesized via a hydrothermal route and are known to show excellent chemical, thermal, and photostability. They emit sharp emission peaks centered at similar to 488, 544, 584, and 619 nm, among which the peak at similar to 544 nm was remarkably quenched (similar to 90%) by the addition of TNT without giving any new emission peak. The sensing mechanism is based on the formation of a Meisenheimer complex between the electron-rich amine-functionalized beta-NaYF4:Gd3+, Tb3+ nanophosphors and electron-deficient TNT molecule, which was prominently visualized by the change in the color of the solution from whitish to brownish yellow, enabling visual detection, followed by luminescence resonance energy transfer between the nanophosphors and the complex. A linear range for TNT detection was obtained from 0.1 to 300 mu M with a limit of detection as low as 119.9 nM. This method displayed excellent selectivity toward TNT over other nitroaromatic compounds, which had no influence on the detection. Moreover, various other classes of analytes, viz., amino acids, pesticides, and sugars, did not quench the luminescence intensity of the nanophosphors. This developed nanosensor probe possesses high, stable fluorescence brightness and capability for the selective and sensitive on-site recognition of TNT molecules in aqueous media, avoiding complicated strategies and instruments. Thus, this work promises to pave ways to many applications in the detection of ultratrace analytes.

1 aMalik, Monika1 aPadhye, Preeti1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/downconversion-luminescence-based-nanosensor-label-free-detection-explosives