Ferroelectric Polarization and Iron Substitution Synergistically Boost Electrocatalytic Oxygen Evolution Reaction in Bismuth Oxychloride Nanosheets.

Ferroelectric materials have gained significant interest in various kinds of water splitting, but the study of ferroelectric materials for electrocatalytic water splitting is in its infancy. Ferroelectric materials have spontaneous polarization below their Curie temperature due to dipolar alignment, which results in surface charges. In 2D ferroelectric materials, spontaneous polarization depends on thickness. Herein, we report that thickness-dependent ferroelectric polarization in 2D nanosheets can also accelerate the oxygen evolution reaction (OER) along with the tailored active surface area of exposed crystalline facets, which improves the electrocatalytic activity relatively. Iron-substituted BiOCl nanosheets of varying thickness are fabricated by varying the pH using a facile coprecipitation method. The substituted iron enhances polarization and electrochemical active sites on the surface. The findings in this study show that the exposed (001) facet and higher thickness of the nanosheets have high ferroelectric polarization and, in turn, superior electrocatalytic activity and remarkable stability, requiring low overpotentials (348 mV and 270 mV at 100 mA/cm2 and 10 mA/cm2) in alkaline (1.0 M KOH) electrolyte. As the thickness of the nanosheets is decreased from 140 to 34 nm, the electrocatalytic performance of iron-substituted BiOCl nanosheets starts to reduce due to the lower Coulomb-Coulomb interaction and the increasing depolarization.

Scalable Synthesis of Dodecanethiol-Capped Bismuth Nanoparticles by a Solvent-Free Solid-State Grinding Method for Reduction of 4-Nitrophenol to 4-Aminophenol.

Thiol-capped metal nanoparticles have two constituents: an inorganic metal and an organic molecule as a shell. Both characters are inbuilt in the structure of the metal thiolate. Herein, we have investigated bismuth dodecanethiolate as a precursor for the synthesis of dodecanethiol-capped bismuth nanoparticles (Bi NPs) by a solid-state grinding method. By using sodium borohydride and bismuth dodecanethiolate, crystalline bismuth nanoparticles are synthesized in a solvent-free environment at room temperature (24 ± 4 °C). Bi NPs are tested for catalytic activity by reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with an excess of NaBH4. Dodecanethiol-capped bismuth nanoparticles exhibit an efficient reduction of 4-NP to 4-AP within 12 min. Additionally, these nanoparticles remain catalytically active for up to three cycles.

Study of the Phase-Evolution Mechanism of an Fe-Se System at the Nanoscale: Optimization of Synthesis Conditions for the Isolation of Pure Phases and Their Controlled Growth.

The iron selenide (Fe-Se) family of nanoparticles (FexSey-where x/y ranges from 1:2 to 1:1) has been fabricated by a thermal decomposition method. The control over solution chemistry has been developed by intensively investigating the effect of reaction parameters by means of wide-angle X-ray scattering, leading to the rich insights into the phase-evolution mechanism of the Fe-Se system. The phase transformation followed the FeSe2 → Fe3Se4 → Fe7Se8 → FeSe sequence in the temperature range of 110-300 °C. The deep mechanistic insight helped in the identification of optimized conditions needed to crystallize the individual phase of the Fe-Se system as well as control of the morphology, crystalline phase purity, and thermal stability of the obtained Fe-Se nanoparticles.

Downconversion Luminescence-Based Nanosensor for Label-Free Detection of Explosives.

We report a selective and sensitive nanosensor probe based on polyethylenimine (PEI)-capped downconverting nanophosphors ß-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 ∼488, 544, 584, and 619 nm, among which the peak at ∼544 nm was remarkably quenched (∼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 ß-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 µM 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.

Retention of Anticancer Activity of Curcumin after Conjugation with Fluorescent Gold Quantum Clusters: An in Vitro and in Vivo Xenograft Study.

Gold 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.

Graphene Quantum Dots-Driven Multiform Morphologies of ß-NaYF4:Gd3+/Tb3+ Phosphors: The Underlying Mechanism and Their Optical Properties.

Dimension and shape tunable architectures of inorganic crystals are of extreme interest because of morphology-dependent modulation of the properties of the materials. Herein, for the first time, we present a novel impurity-driven strategy where we studied the influence of in situ incorporation of graphene quantum dots (GQDs) on the growth of ß-NaYF4:Gd3+/Tb3+ phosphor crystals via a hydrothermal route. The GQDs function as a nucleation site and by changing the concentration of GQDs, the morphology of ß-NaYF4:Gd3+/Tb3+ phosphors was changed from rod to flowerlike structure to disklike structure, without phase transformation. The influence of size and functionalization of GQDs on the size and shape of phosphor crystals were also systematically studied and discussed. Plausible mechanisms of formation of multiform morphologies are proposed based on the heterogeneous nucleation and growth. Most interestingly, the experimental results indicate that the photoluminescence properties of ß-NaYF4:Gd3+/Tb3+ phosphor crystals are strongly dependent on the crystallite size and morphology. This study would be suggestive for the precisely controlled growth of inorganic crystals; consequently, it will open new avenues and thus may possess potential applications in the field of materials and biological sciences.

Physical Mechanism Behind Enhanced Photoelectrochemical and Photocatalytic Properties of Superhydrophilic Assemblies of 3D-TiO2 Microspheres with Arrays of Oriented, Single-Crystalline TiO2 Nanowires as Building Blocks Deposited on Fluorine-Doped Tin Oxide.

In comparison to the one-dimensional (1D) semiconductor nanostructures, the hierarchical, three-dimensional (3D) microstructures, composed of the arrays of 1D nanostructures as building blocks, show quite unique physicochemical properties due to efficient photon capture and enhanced surface to volume ratio, which aid in advancing the performance of various optoelectronic devices. In this contribution, we report the fabrication of surfactant-free, radially assembled, 3D titania (rutile-phase) microsphere arrays (3D-TMSAs) composed of bundles of single-crystalline titania nanowires (NWs) directly on fluorine-doped conducting oxide (FTO) substrates with tunable architecture. The effects of growth parameters on the morphology of the 3D-TMSAs have been studied thoroughly. The 3D-TMSAs grown on the FTO-substrate showed superior photon-harvesting owing to the increase in light-scattering. The photocatalytic and photon to electron conversion efficiency of dye-sensitized solar cells (DSSC), where the optimized 3D-TMSAs were used as an anode, showed around 44% increase in the photoconversion efficiency compared to that of Degussa P-25 as a result of the synergistic effect of higher surface area and enhanced photon scattering probability. The TMSA film showed superhydrophilicity without any prior UV irradiation. In addition, the presence of bundles of almost parallel NWs led to the formation of arrays of microcapacitors, which showed stable dielectric performance. The fabrication of single-crystalline, oriented, self-assembled TMSAs with bundles of titania nanowires as their building blocks deposited on transparent conducting oxide (TCO) substrates has vast potential in the area of photoelectrochemical research.

Oxidant mediated one-step complete conversion of multi-walled carbon nanotubes to graphene quantum dots and their bioactivity against mammalian and bacterial cells.

It is essential for any antibacterial agent (for clinical applications) that it should have high and selective toxicity towards bacterial cells only, and should not affect the human cells at the concentration used. Graphene quantum dots (GQDs) have emerged as a potential candidate for biomedical applications. However, a simple, low cost, safe, easy to execute, one-step synthesis of uniform and monodispersed GQDs with selective toxicity towards bacterial cells rather than mammalian cells is difficult to achieve. Herein, we have reported a one-step, low-cost, aqueous-phase, simple approach for the complete conversion of multi-walled carbon nanotubes into water-dispersible GQDs with an average size of ∼3 nm using sodium bismuthate (NaBiO3) as a strong oxidant. The cyclic voltammetry and X-ray photoelectron spectroscopy results indicated that the as-synthesized GQDs suspension possess almost negligible amounts of metallic impurities. The cytotoxicity studies of GQDs against mammalian NIH 3T3 (mouse embryo fibroblast cells) and HEK 293T (human embryonic kidney cells) cells showed that the as-synthesized GQDs were non-cytotoxic up to the concentration of ∼200 µg mL-1. The antimicrobial study shows that the synthesized GQDs have high and selective toxicity towards bacterial cells with a minimum inhibitory concentration of ∼256 µg mL-1 for E. coli and B. subtilis and ∼512 µg mL-1 for P. aeruginosa and S. aureus. The scanning electron microscopy and atomic force microscopy images show extensive cell damage via the perturbation of bacterial cell walls, which was consistent with the enhancement of reactive oxygen species production by almost two times in the bacterial cells upon incubation with ∼256 µg mL-1 GQDs. Our study suggested that the as-synthesized GQDs can be used as a potential candidate for clinical applications as they possess high toxicity to bacterial cells and low toxicity to mammalian cells.

Fluorescent metal quantum clusters: an updated overview of the synthesis, properties, and biological applications.

Metal quantum clusters are evolving as excellent systems for a wide range of biological applications due to their small size (∼2 nm), tunable optical properties, including optical absorption, photoluminescence (UV to NIR), nonlinear optical properties (two-photon absorption, two-photon fluorescence, and second/third harmonic generation), ultrafast dynamics (relaxation kinetics, electron-phonon coupling, and radiative emission), and magnetism. These excellent properties have resulted in their use in a broad range of applications, including the sensing of ions (heavy metal ions, anions), biomolecules (proteins, DNA, miRNA, and enzymes), biological cells, diagnosis, and therapy. This article presents an introduction to metal quantum clusters, including a brief history of research in this system and an overview of the existing theories to understand their properties. We also discuss the synthesis methods, the various properties of quantum clusters and present a broad and updated overview of the applications of metal quantum clusters in biology.

Global Conformation of Tau Protein Mapped by Raman Spectroscopy.

Alzheimer's disease (AD) is one of the neurodegenerative disease characterized by progressive neuronal loss in the brain. Its two major hallmarks are extracellular senile plaques and intracellular neurofibrillary tangles (NFTs), formed by aggregation of amyloid ß-42 (Aß-42) and Tau protein respectively. Aß-42 is a transmembrane protein, which is produced after the sequential action of ß- and γ-secretases, thus obtained peptide is released extracellularly and gets deposited on the neuron forming senile plaques. NFTs are composed of microtubule-associated protein-Tau (MAPT). Tau protein's major function is to stabilize the microtubule that provides a track on which the cargo proteins are shuttled and the stabilized microtubule also maintains shape and integrity of the neuronal cell. Tau protein is subjected to various modifications such as phosphorylation, ubiquitination, glycation, acetylation, truncation, glycosylation, deamination, and oxidation; these modifications ultimately lead to its aggregation. Phosphorylation is the major modification and is extensively studied with respect to Tau protein. Tau protein, however, undergoes certain level of phosphorylation and dephosphorylation, which regulates its affinity for microtubule and ultimately leading to microtubule assembly and disassembly. Our main aim was to study the native state of longest isoform of Tau (hTau40WT-4R2N) and its shortest isoform, (hTau23WT-3R0N), at various temperatures such as 10, 25, and 37 °C. Raman spectroscopic results suggested that the proportion of random coils or unordered structure depends on the temperature of the protein environment. Upon increase in the temperature from 10 to 37 °C, the proportion of random coils or unordered structures increased in the case of hTau40WT. However, we did not find a significant effect of temperature on the structure of hTau23WT. This current approach enables one to analyze the global conformation of soluble Tau in solution.

Immobilization of multivalent glycoprobes on gold surfaces for sensing proteins and macrophages.

The multivalent display of carbohydrates on the cell surface provides cooperative binding to improve the specific biological events. In addition to multivalency, the spatial arrangement and orientation of sugars with respect to external stimuli also trigger carbohydrate-protein interactions. Herein, we report a non-covalent host-guest strategy to immobilize heptavalent glyco-ß-cyclodextrin on gold-coated glass slides to study multivalent carbohydrate-protein interactions. We have found that the localization of sugar entities on surfaces using ß-cyclodextrin (ß-CD) chemistry increased the avidity of carbohydrate-protein and carbohydrate-macrophage interactions compared to monovalent-ß-CD sugar coated surfaces. This platform is expected to be a promising tool to amplify the avidity of sugar-mediated interactions on surfaces and contribute to the development of next generation bio-medical products.

Study of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au8 quantum clusters for Hg(2+) ion sensing, cellular imaging and antibacterial applications.

Herein, we report a detailed experimental study supported by DFT calculations to understand the mechanism behind the synthesis of cefradine (CFD--an antibiotic) labeled gold nanoparticles (Au NPs) by employing CFD as both a mild reducing and capping agent. The analysis of the effect of growth conditions reveals that a higher concentration of HAuCl4 results in the formation of an increasing fraction of anisotropic structures, higher temperature leads to the formation of quasi-spherical particles instead of anisotropic ones, and larger pH leads to the formation of much smaller particles. The cyclic voltammetry (CV) results show that when the pH of the reaction medium increases from 4 to 6, the reduction potential of CFD increases which leads to the synthesis of nanoparticles (in a pH 4 reaction) to quantum clusters (in a pH 6 reaction). The MALDI-TOF mass spectrometry results of supernatant of the pH 6 reaction indicate the formation of [Au8(CFD)2S6] QCs which show fluorescence at ca. 432 nm with a Stokes shift of ca. 95 nm. The blue luminescence from Au8 QCs was applied for sensing of Hg(2+) ions on the basis of an aggregation-induced fluorescence quenching mechanism and offers good selectivity and a high sensitivity with a limit of detection ca. 2 nM which is lower than the detection requirement of 10 nM by the U.S. EPA and 30 nM by WHO for drinking water. We have also applied the sensing probe to detect Hg(2+) ions in bacterial samples. Further, we have investigated the antibacterial property of as-synthesized Au NPs using MIC, growth curve and cell survival assay. The results show that Au NPs could reduce the cell survival very efficiently rather than the cell growth in comparison to the antibiotic itself. The scanning electron microscopy study shows the degradation and blebbing of the bacterial cell wall upon exposure with Au NPs which was further supported by fluorescence microscopy results. These Au NPs did not show reactive oxygen species generation. We believe that the bacterial cytotoxicity is due to the direct contact of the Au NPs with bacterial cells.

Doxorubicin-conjugated ß-NaYF4:Gd(3+)/Tb(3+) multifunctional, phosphor nanorods: a multi-modal, luminescent, magnetic probe for simultaneous optical and magnetic resonance imaging and an excellent pH-triggered anti-cancer drug delivery nanovehicle.

Herein, we report the fabrication of a multifunctional nanoprobe based on highly monodispersed, optically and magnetically active, biocompatible, PEI-functionalized, highly crystalline ß-NaYF4:Gd(3+)/Tb(3+) 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 (∼3.5 milliseconds), suitable for optical imaging. The static magnetic susceptibility measurements at room temperature showed a strong paramagnetic signal (χ∼ 3.8 × 10(-5) emu g(-1) Oe(-1)). The nuclear magnetic resonance (NMR) measurements showed fair T1 relaxivity (r1 = 1.14 s(-1) mM(-1)) and magnetic resonance imaging gave enhanced T1-weighted MRI images with increased concentrations of ß-NaYF4:Gd(3+)/Tb(3+) making them suitable for simultaneous magnetic resonance imaging. In addition, an anticancer drug, doxorubicin (DOX) was conjugated to the amine-functionalized ß-NaYF4:Gd(3+)/Tb(3+) 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 (∼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 ß-NaYF4:Gd(3+)/Tb(3+) 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 ß-NaYF4:Gd(3+)/Tb(3+) nanorods were studied in tumor microenvironment conditions (pH 6.5) using confocal imaging, which showed an increased uptake of DOX-conjugated ß-NaYF4:Gd(3+)/Tb(3+) nanorods. Thus, DOX-conjugated ß-NaYF4:Gd(3+)/Tb(3+) 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.

Construction of Polynuclear Lanthanide (Ln = Dy(III), Tb(III), and Nd(III)) Cage Complexes Using Pyridine-Pyrazole-Based Ligands: Versatile Molecular Topologies and SMM Behavior.

Employment of two different pyridyl-pyrazolyl-based ligands afforded three octanuclear lanthanide(III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium(III) coordination cage, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semirigid pyridyl-pyrazolyl-based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centers. It is noteworthy here that construction of lanthanide complex itself is a challenging task in a ligand system as soft N-donor rich as pyridyl-pyrazol. We report herein some lanthanide complexes using ligand containing only one or two O-donors compare to five N-coordinating sites. The resultant multinuclear lanthanide complexes show interesting magnetic and spectroscopic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5 T direct current field, a typical characteristic feature of single-molecule magnet (SMM) behavior, indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behavior of the terbium complex, further confirmed by ac susceptibility measurement.

Temperature and magnetic field-assisted switching of magnetization and observation of exchange bias in YbCrO3 nanocrystals.

In this paper, we demonstrate an interesting feature in YbCrO3 (YCO) nanocrystals, in which the material shows temperature and external magnetic field-assisted switching (a complete sign reversal) of zero field cooled magnetization (MZFC) and observation of exchange bias (EB) as a result of competing spin interaction at low temperature. This feature can be applied in nonvolatile memories, where, simply by changing the magnitude of the Hext and T, the polarity of the magnetization can be switched between negative and positive. We also observed negative magnetization in YCO. Our results showed that, below its Nèel temperature (TN ≈ 119 K), the MZFC crosses over to negative sign for H < 1000 Oe. At 60 K, YCO showed a significant negative MZFC ≈ -0.05 emu/g (at 100 Oe) due to the competing effects of Yb(3+), Cr(3+) spins, thermal activation energy, and Hext. At further lower temperatures, the MZFC showed a crossover to positive values, and the crossover temperature showed the dependence on Hext (∼19 K for 100 Oe curve). The YCO also showed Hext and T-dependent HEB, which changed its sign with T. The observed T-dependent sign reversal in the EB was closely associated with the sign reversal of MZFC. The symmetric shift in field-cooled isothermal hysteresis curves confirmed that the observed EB was not due to the unsaturated minor loop. The training cycle further confirmed that the HEB value decreased to ∼2% of the initial value of observed EB, which was very small compared to the observed HEB in YCO, which indicated stable spin configuration at the locally formed ferromagnetic/antiferromagnetic interface.

Modification of crystal anisotropy and enhancement of magnetic moment of Co-doped SnO2 thin films annealed under magnetic field.

Co-doped SnO2 thin films were grown by sputtering technique on SiO2/Si(001) substrates at room temperature, and then, thermal treatments with and without an applied magnetic field (HTT) were performed in vacuum at 600°C for 20 min. HTT was applied parallel and perpendicular to the substrate surface. Magnetic M(H) measurements reveal the coexistence of a strong antiferromagnetic (AFM) signal and a ferromagnetic (FM) component. The AFM component has a Néel temperature higher than room temperature, the spin axis lies parallel to the substrate surface, and the highest magnetic moment m =7 µB/Co at. is obtained when HTT is applied parallel to the substrate surface. Our results show an enhancement of FM moment per Co(+2) from 0.06 to 0.42 µB/Co at. for the sample on which HTT was applied perpendicular to the surface. The FM order is attributed to the coupling of Co(+2) ions through electrons trapped at the site of oxygen vacancies, as described by the bound magnetic polaron model. Our results suggest that FM order is aligned along [101] direction of Co-doped SnO2 nanocrystals, which is proposed to be the easy magnetization axis.

Synthesis, characterization and in vitro study of biocompatible cinnamaldehyde functionalized magnetite nanoparticles (CPGF Nps) for hyperthermia and drug delivery applications in breast cancer.

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼ 20 nm. TGA data revealed the drug payload of ∼ 18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6 °C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.

Large magnetocaloric effect, moment, and coercivity enhancement after coating Ni nanoparticles with Ag.

We observe a large magnetocaloric effect in monodisperse Ni and Ni(core)Ag(shell) nanoparticles in the superparamagnetic region. The organically passivated Ni nanospheres show a large magnetic entropy change of 0.9 J kg(-1) K for a 3 T magnetic field change. In comparison to the surfactant-coated Ni nanoparticles, the Ni(core)Ag(shell) nanoparticles show an enhanced coercivity, magnetization, and magnetocaloric effect (1.3 kg K for a 3 T magnetic field change). The coercivity at 10 K increases from 360 Oe for Ni nanoparticles to nearly 610 Oe for Ni(core)Ag(shell) particles. This large enhancement is attributed to the enhanced inter-particle interaction, which is mediated by the metallic shell, over the relatively weaker dipolar interaction in the surfactant-coated Ni nanoparticles, and to modification of the surface spin structure.

Modulation of Reaction Kinetics for the Tuneable Synthesis of Gold Nanoparticles and Quantum Clusters: Application of Gold Quantum Clusters as "Turn-Off" Sensing Probe for Sn4+ Ions.

The syntheses of gold nanoparticles (Au NPs) and gold quantum clusters (Au QCs) that employ cefadroxil (CFX; an antibiotic) as both reducing and capping agents are reported. The HAuCl4 /CFX concentration, temperature, and pH are crucial factors in the modulation of the nucleation and growth kinetics of the reaction, and consequently, in guiding the size and morphology of as-synthesized Au NPs. Interesting results are observed if the reaction is performed under different pH conditions. TEM analysis of the Au NPs synthesized at pH 6 shows an average particle size of approximately 2 nm along with a relatively smaller population of bigger NPs (up to 6 nm). The Au QCs were isolated by high-speed centrifugation and showed fluorescence at λ≈460 nm. Furthermore, the as-synthesized Au QCs were applied as sensor for Sn4+ ions on the basis of an aggregation-induced fluorescence quenching mechanism. These Au QCs offer acceptable sensitivity, high selectivity, and a limit of detection of approximately 10 µM for the determination of Sn4+ ions.