01403nas a2200181 4500008004100000022001400041245008100055210006900136260007100205300002600276490000800302520072300310100001801033700001901051700001701070700001901087856011501106 2006 eng d a0002-786300aRoom-temperature biosynthesis of ferroelectric barium titanate nanoparticles0 aRoomtemperature biosynthesis of ferroelectric barium titanate na a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP aArticle No. JA063011M0 v1283 a

The syntheses of inorganic materials by biological systems is characterized by processes that occur close to ambient temperatures, pressures, and neutral pH, as is exemplified by biosilicification and biomineralization processes in nature. Conversely, laboratory-based syntheses of oxide materials often require extremes of temperature and pressure. We have shown here the extracellular, room-temperature biosynthesis of 4-5 nm ternary oxide nanoparticles such as barium titanate (BT) using a fungus-mediated approach. The tetragonality as well as a lowered Curie transition temperature in sub-10 nm particles was established, and the ferroelectricity in these particles was shown using Kelvin probe microscopy.

1 aBansal, Vipul1 aPoddar, Pankaj1 aAhmad, Absar1 aSastry, Murali uhttps://library.ncl.res.in/content/room-temperature-biosynthesis-ferroelectric-barium-titanate-nanoparticles-102954nas a2200169 4500008004100000022001400041245019800055210006900253260007100322300001400393490000800407520218600415100001702601700001902618700001902637856012802656 2009 eng d a1520-610600aReal-time nanomechanical and topographical mapping on live bacterial cells-brevibacterium casei under stress due to their exposure to Co2+ Ions during microbial synthesis of Co3O4 nanoparticles0 aRealtime nanomechanical and topographical mapping on live bacter a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN a7927-79330 v1133 a

The study of elastic properties of microbial and mammalian cells using atomic force microscopy, with force-sensitivity as high as pico-Newtons and spatial resolution of a few nanometers, is proving to be a great tool for the real-time observation of the effects of drugs, biomolecules, metal ions, and nanoparticles on cell physiology in their natural environment. It has been shown that the Young's modulus of the cell surfaces is extremely sensitive to the surrounding environment. Recently, a broad array of microbes have been used successfully to synthesize nanocrystals of several metal and metal oxides in a controlled manner at room temperature after exposing them to various metal ion precursors. However, so far there is no report on the fate of their elastic properties and cell topography etc. during and after their exposure to the metal ions during the microbial synthesis of nanomaterials. Additionally, this information is also found to be extremely relevant to areas such as bioremediation, bioleaching, and biomineralization, where it is important to study the direct influence on the cell physiology in the presence of metal ions. Here, we report, for the first time, the use of AFM force-distance curves on live cells, to directly monitor (in real time) the changes in the surface-topography, surface-adhesion, indentation-depth, and Young's modulus of a metal-tolerant marine bacterium, Brevibacterium casei, isolated from the coast of the Arabian Sea, after its exposure to the Co2+ ions during the process of biosynthesis of nanoparticles. We earlier reported that this bacterium is capable of using the cobalt acetate as a precursor to synthesize protein-functionalized Co3O4 nanoparticles with very high crystallinity. Our study indicates a significant change in the morphology as well as elastic and adhesive properties of the Brevibacterium casei, where we found an increase in the adhesive properties and the indentation depth of the bacterial surfaces and a decrease in the cell stiffness after several hours of exposure to the cobalt acetate. We have discussed both qualitative and quantitative analysis of the force-spectroscopy data in detail.

1 aKumar, Umesh1 aVivekanand, K.1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/real-time-nanomechanical-and-topographical-mapping-live-bacterial-cells-brevibacterium-001760nas a2200229 4500008004100000022001400041245010300055210006900158260009500227300001200322490000800334520089600342653003601238653001901274653000801293100002201301700002201323700001401345700001901359700002601378856012601404 2011 eng d a0022-459600aRoom temperature ferromagnetism in undoped and Fe doped ZnO nanorods: microwave-assisted synthesis0 aRoom temperature ferromagnetism in undoped and Fe doped ZnO nano a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcFEB a391-4000 v1843 a

One-dimensional (1D) undoped and Fe doped ZnO nanorods of average length similar to 1 mu m and diameter similar to 50 nm have been obtained using a microwave-assisted synthesis. The magnetization (M) and coercivity (H-c) value obtained for undoped ZnO nanorods at room temperature is similar to 5 X 10(-3) emu/g and similar to 150 Oe, respectively. The Fe doped ZnO samples show significant changes in M -H loop with increasing doping concentration. Both undoped and Fe doped ZnO nanorods exhibit a Curie transition temperature (T-c) above 390 K. Electron spin resonance and Mossbauer spectra indicate the presence of ferric ions. The origin of ferromagnetism in undoped ZnO nanorods is attributed to localized electron spin moments resulting from surface defects/vacancies, where as in Fe doped samples is explained by F center exchange mechanism. (C) 2010 Published by Elsevier Inc.

10aDiluted magnetic semiconductors10aNanostructures10aZnO1 aLimaye, Mukta, V.1 aSingh, Shashi, B.1 aDas, Raja1 aPoddar, Pankaj1 aKulkarni, Sulabha, K. uhttps://library.ncl.res.in/content/room-temperature-ferromagnetism-undoped-and-fe-doped-zno-nanorods-microwave-assisted-002421nas a2200157 4500008004100000245014700041210006900188260000800257520176200265100002302027700001602050700002302066700002502089700001902114856013002133 2018 eng d00aRetention of anticancer activity of curcumin after conjugation with fluorescent gold quantum clusters: an in vitro and in vivo xenograft study0 aRetention of anticancer activity of curcumin after conjugation w cMAY3 aGold nanoparticles (Au NPs) have been thoroughly investigated for anti-cancer therapy. However, their undesired high gold content remains a problem when injected into the body for drug delivery applications. In this report, we made an effort to conjugate the curcumin molecules on the surface of gold quantum clusters (Au QCs) by a novel in situ synthesis method which provides an alternative route to not only reduce the metallic content but also increase the water solubility of curcumin and the loading efficiency. Here, curcumin itself acts as a reducing and capping agent for the synthesis of Au QCs. The UV−vis absorption, fluorescence, transmission electron microscopy, and electrospray ionization mass spectrometry results confirmed the synthesis of fluorescent Au QCs. Curcumin-conjugated Au NPs (C-Au NPs) and glutathione (GSH)-conjugated Au QCs (GSH-Au QCs) were also synthesized to visualize the effect of particle size and the capping agent, respectively, on the cytotoxicity to normal and cancer cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that the curcumin-conjugated Au QCs (C-Au QCs) were less cytotoxic to normal cells while almost the same cytotoxic to cancer cells in comparison to curcumin itself, which indicates that curcumin preserves its anticancer property even after binding to the Au QCs. However, C-Au NPs and GSH-Au QCs did not show any cytotoxicity against the normal and cancer cells at the concentration used. The western blot assay indicated that C-Au QCs promote apoptosis in cancer cells. Further, the in vivo study on severe combined immunodeficiency mice showed that C-Au QCs also inhibited the tumor growth efficiently without showing significant toxicity to internal organs.1 aKhandelwal, Puneet1 aAlam, Aftab1 aChoksi, Arpankumar1 aChattopadhyay, Samit1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/retention-anticancer-activity-curcumin-after-conjugation-fluorescent-gold-quantum-clusters01873nas a2200169 4500008004100000022001400041245014100055210006900196260000800265300001400273490000700287520121800294100002601512700001801538700001901556856012801575 2021 eng d a1144-054600aRaman spectroscopy-based sensitive, fast and reversible vapour phase detection of explosives adsorbed on metal-organic frameworks UiO-670 aRaman spectroscopybased sensitive fast and reversible vapour pha cAPR a7145-71530 v453 a

In this work, we report highly sensitive, selective, rapid, and reversible detection of explosive molecules in the vapour phase, adsorbed on metal-organic frameworks (MOFs) under ambient laboratory conditions. The sensing is based on the quenching of the Raman intensity of a zirconium-based MOF, Zr6O4(OH)(4)(dcppy)(6) (MOF 1, UiO-67-dcppy; dcppy is 2-phenylpyridine-5,4'-dicarboxylate), where 50% of the signal quenches swiftly within similar to 5 s of its exposure to trinitrophenol (TNP) vapours, while 90% of the Raman signal was quenched in 30 s. The high surface area of porous MOFs provides increased adsorption of various nitro analytes. The quenching of Raman peaks resulted from the pi-pi interactions of the analytes with the benzene ring of the MOF. The sensors have also been proven to be reversible and stable by mild heat treatment (80 degrees C for 5 min). These notable results using Raman spectroscopy point to a new and important approach towards explosive sensing using metal-organic frameworks considering their vast versatility. This work emphasizes the importance of a non-invasive and non-destructive technique that can be used to develop handheld vapour phase explosive detectors.

1 aBishwas, Mousumi, Sen1 aMalik, Monika1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/raman-spectroscopy-based-sensitive-fast-and-reversible-vapour-phase-detection-explosives01683nas a2200157 4500008004100000022001400041245012500055210006900180260000800249300001400257490000800271520107600279100002101355700001901376856013001395 2022 eng d a1932-744700aRemarkable effect of Fe and Se composition on magnetic properties-comparative study of the Fe-Se system at the nanoscale0 aRemarkable effect of Fe and Se composition on magnetic propertie cMAR a4655-46630 v1263 a

Herein, for the first time, the correlation between the phase structure and the magnetic properties of the Fe-Se system has been presented for FexSey compounds-where x/y ranges from 1:2 to 1:1. These phases-orthorhombic (FeSe2), monoclinic (Fe3Se4), hexagonal (Fe7Se8), and tetragonal (beta-FeSe)-were synthesized using a one-pot thermal decomposition route at the nanoscale. The magnetic properties vary enormously with change in the Fe/Se ratio due to the change in the Fe2+/Fe3+ ratio, crystal field environment around the Fe ions, magnetocrystalline anisotropy, Fe vacancies, and so forth. Among the four Fe-Se phases studied, two of them, Fe3Se4 and Fe7Se8, are ferrimagnetic below similar to 300 K and show semihard magnetic properties. The other two phases FeSe2 and beta-FeSe exhibiting weaker magnetism are less known for their magnetic properties. All these phases are prone to surface oxidation despite surface passivation, and its effect on the magnetic moment will be pronounced for the phases with weak magnetization such as FeSe2 and beta-FeSe.

1 aGhalawat, Monika1 aPoddar, Pankaj uhttps://library.ncl.res.in/content/remarkable-effect-fe-and-se-composition-magnetic-properties-comparative-study-fe-se-system