Water-Dispersible Rhodamine B Hydrazide Loaded TiO2 Nanoparticles for "Turn On" Fluorimetric Detection and Imaging of Orthosilicic Acid Accumulation In-Vitro in Nephrotoxic Kidney Cells.

Silica (SiO2) is the inevitable form of silicon owing to its high affinity for oxygen, existing as a geogenic element perpetrating multifarious health problems when bioavailable via anthropogenic activities. The hydrated form of silica viz. orthosilicic acid (H4SiO4) excessively displays grave toxicity, attributed to prolonged exposure and incessant H+ ions generating capacity inflicting pulmonary toxicity and renal toxicity silica. The diverse deleterious potency of silica highlights the desirability of selective and sensitive detection of toxic species (mainly orthosilicic acid) bioaccumulation in affected living human cells. In this paper we have reported, the design of water-dispersible turn-on fluorimetric sensing material for the detection of orthosilicic acid in the aqueous phase and in live cells. The sensing material was prepared by adsorbing a suitable rhodamine derivative (i.e., Rhodamine B hydrazide (Rh1)) on water dispersible TiO2 nanoparticles. The function of the sensing system, which is composed of Rh1 and TiO2 (Rh1@TiO2), is accredited to H+ ion (from orthosilicic acid) induced spirolactam ring-opening of the rhodamine derivative generating orange fluorescence and bright pink colouration. The sensing system was efficiently utilized for fluorimetric detection and imaging of orthosilicic acid accumulation in-vitro in human kidney cells (HK cells). To the best of our knowledge, this is the first time this sensing system (Rh1@TiO2) is reported for detection of toxic silica species accumulation in-vitro in human kidney cells. The advantages, such as good water dispersibility, the absence of organic solvents during fluorimetric studies, quick turn-on type signal transduction, low-level imaging, which are offered by the synthesized sensing material (Rh1@TiO2), make it a potential candidate to fabricate medical tool for early identification of silicainduced nephrotoxicity, which can help to reduce the burden and risk of chronic kidney disease development.

Applications of Metal Nanoparticles as Catalysts in Cleaning Dyes Containing Industrial Effluents: A Review.

From the last few decades, water pollution due to the dye containing effluents, which are released from various dyeing industries, has become one of the major environmental problems. Continuous efforts are going on to effectively deal with industrial wastewater containing aromatic pollutants. Varieties of physical, biological and chemical methods have been developed for this purpose. Among these methods, recently the catalytic reduction of water soluble dyes over heterogeneous catalysts has gained immense attention for treatment of dye containing wastewater because it offers high efficiency. In this review article, the use of metal nanoparticles based catalysts for the catalytic reduction of water soluble dyes has been discussed. Various synthetic methods to prepare these nanocatalysts with typical examples, their advantages, as well as limitations, have also been discussed in details.

Barium Hexaferrite (BaFe12O19) Nanoparticles as Highly Active and Magnetically Recoverable Catalyst for Selective Epoxidation of Styrene to Styrene Oxide.

Herein, we are reporting the use of pure single phase barium hexaferrite (BaFe12O19) nanoparticles as an efficient catalyst for epoxidation of styrene. BaFe12O19 nanocatalysts exhibit high conversion of styrene with excellent selectivity of styrene oxide formation. Easy method of preparation, capability of catalyzing the epoxide reaction of styrene to styrene oxide with excellent styrene conversion (~91%) and high styrene oxide selectivity (~86.5%), easy magnetic separation and very good reusability make the synthesized BaFe12O19 nanocatalyst an excellent catalyst for this reaction. To the best of our knowledge, this is the first time the use of BaFe12O19 as catalyst for this reaction has been reported.

Synthesis of Various Ferrite (MFe2O4) Nanoparticles and Their Application as Efficient and Magnetically Separable Catalyst for Biginelli Reaction.

Herein, we reports the application of various spinel ferrite nanoparticles, MFe2O4 (M = Co, Ni, Cu, Zn), as efficient catalyst for Biginelli reaction. All ferrite nanoparticles were synthesized using a novel aqueous solution based method. It was observed that, the catalytic activity of the ferrite nanoparticles followed the decreasing order of CoFe2O4 > CuFe2O4 > NiFe2O4 > ZnFe2O4. The most important feature of these ferrite nanocatalysts is that, these nanoparticles can directly be used as catalyst and no surface modification or functionalization is required. These ferrite nanoparticles are easily separable from reaction mixture after reaction by using a magnet externally. Easy synthesis methodology, high catalytic activity, easy magnetic separation and good reusability make these ferrite nanoparticles attractive catalysts for Biginelli reaction.

A facile synthesis methodology for preparation of Ag-Ni-reduced graphene oxide: a magnetically separable versatile nanocatalyst for multiple organic reactions and density functional study of its electronic structures.

Here, we report a simple 'in situ' co-precipitation reduction synthesis method for the preparation of nanocatalysts composed of Ag, Ni nanoparticles, and reduced graphene oxide (RGO). First-principles calculations based on Density Functional Theory (DFT) were performed to obtain the electronic structures and properties of Ag-Ni-graphene superlattice and to understand the interfacial interactions which exist at the interface between Ag, Ni, and graphene. The catalytic performance of the synthesized catalysts (Ag x Ni(1-x)) y RGO(100-y) were evaluated for four reactions (i) reduction of 4-nitrophenol (4-NP) in the presence of excess NaBH4 in aqueous medium, (ii) A3 coupling reaction for the synthesis of propargylamines, (iii) epoxidation of styrene, and (iv) 'Click reaction' for the synthesis of 1,2,3-triazole derivatives. For all of these reactions the catalyst composed of Ag, Ni, and RGO, exhibited significantly higher catalytic activity than that of pure Ag, Ni, and RGO. Moreover, an easy magnetic recovery of this catalyst from the reaction mixture after completion of the catalytic reactions and the good reusability of the recovered catalyst is also reported here. To the best of our knowledge, this is the first time the demonstration of the versatile catalytic activity of (Ag x Ni(1-x)) y RGO(100-y) towards multiple reactions, and the DFT study of its electronic structure have been reported.

Development of a Ru Nanoparticle Loaded Thiol Functionalized Meso Porous Silica Modified Screen Printed Au Electrode for Electrochemical Detection and Estimation of Glucose.

Here we report the development of a glucose sensor based on electrochemical detection. The working electrode was a screen printed Au electrode, which was modified with Ru nanoparticle loaded thiol functionalized mesoporous silica. This sensor demonstrated its capability of detecting and estimating glucose concentration in aqueous medium over a wide range of concentration with high sensitivity, durability and reproducibility.

One-Pot Synthesis of (NiFe2O4)x-(SrFe12O19)1-x Nanocomposites and Their Microwave Absorption Properties.

In this paper, we report a simple but novel aqueous solution based 'one-pot' method for preparation of (NiFe2O4)x-(SrFe12O19)1-x nanocomposites consist of hard ferrite-soft ferrite phases. A physical mixing method has also been employed to prepare nanocomposites having same compositions. The effects of synthetic methodologies on the microstructures of the nanocomposites as well as their magnetic and microwave absorption properties have been evaluated. Crystal structures and microstructures of these composites have been investigated by using X-ray diffraction, transmission electron microscope and scanning electron microscope. In the nanocomposites, prepared by both methods, presence of nanocrystalline NiFe2O4 and SrFe12O19 phases was detected. However, nanocomposites, prepared by one-pot method, possessed better homogeneous distribution of hard and soft ferrite phases than the nanocomposites, prepared by physical mixing method. Nanocomposites, prepared by one-pot method, demonstrated significant spring exchange coupling interaction between hard and soft ferrite phases and exhibited magnetically single phase behaviour. The spring exchange coupling interaction enhanced the magnetic properties (high saturation magnetization and coercivity) and microwave absorption properties of the nanocomposites, prepared by one-pot method, in comparison with the nanocomposites prepared by physical mixing method as well as pure NiFe2O4 and SrFe12O19 nanoparticles. Minimum reflection loss of the composite was ~ -17 dB (i.e., 98% absorption) at 8.2 GHz for an absorber thickness of 3.2 mm.