Manganese cobalt-MOF@carbon nanofiber-based non-enzymatic histamine sensor for the determination of food freshness.

Early detection of histamine in foodstuffs/beverages could be useful in preventing various diseases. In this work, we have prepared a free-standing hybrid mat based on manganese cobalt (2-methylimodazole)-metal organic frameworks (Mn-Co(2-MeIm)MOF) and carbon nanofibers (CNFs) and explored as a non-enzymatic electrochemical sensor for determining the freshness of fish and bananas based on histamine estimation. As-developed hybrid mat possesses high porosity with a large specific surface area and excellent hydrophilicity those allow easy access of analyte molecules to the redox-active metal sites of MOF. Furthermore, the multiple functional groups of the MOF matrix can act as active adsorption sites for catalysis. The Mn-Co(2-MeIm)MOF@CNF mat-modified GC electrode demonstrated excellent electrocatalytic activities toward the oxidation of histamine under acidic conditions (pH = 5.0) with a faster electron transfer kinetics and superior fouling resistance. The Co(2-MeIm)MOF@CNF/GCE sensor exhibited a wide linear range from 10 to 1500 µM with a low limit of detection (LOD) of 89.6 nM and a high sensitivity of 107.3 µA mM-1 cm-2. Importantly, as-developed Nb(BTC)MOF@CNF/GCE sensor is enabled to detect histamine in fish and banana samples stored for different periods of time, which thus indicates its practical viability as analytical histamine detector.

Recent Advances in Gadolinium Based Contrast Agents for Bioimaging Applications.

Gadolinium (Gd) based contrast agents (CAs) (Gd-CAs) represent one of the most advanced developments in the application of Gd for magnetic resonance imaging (MRI). Current challenges with existing CAs generated an urgent requirement to develop multimodal CAs with good biocompatibility, low toxicity, and prolonged circulation time. This review discussed the Gd-CAs used in bioimaging applications, addressing their advantages and limitations. Future research is required to establish the safety, efficacy and theragnostic capabilities of Gd-CAs. Nevertheless, these Gd-CAs offer extraordinary potential as imaging CAs and promise to benefit bioimaging applications significantly.

Flexible nickel disulfide nanoparticles-anchored carbon nanofiber hybrid mat as a flexible binder-free cathode for solid-state asymmetric supercapacitors.

Nickel disulfide nanoparticles (NiS2NPs)-anchored carbon nanofibers (NiS2NPs@CNF) hybrid mats were fabricated via the sequential process of stabilization and carbonization of electrospun polyacrylonitrile-based fibers followed by hydrothermal growth of NiS2NPs on the porous surface of CNFs. The vertical growth of NiS2NPs on entire surfaces of porous CNFs appeared in the SEM images of hybrid mat. The hierarchical NiS2NPs@CNF core-shell hybrid nanofibers with 3D interconnected network architecture can endow continuous channels for easy and rapid ionic diffusion to access the electroactive NiS2NPs. The conductive and interconnected CNF core could facilitate electron transfer to the NiS2shell. Moreover, the porous CNF as a buffering matrix can resist volumetric deformation during the long-term charge-discharge process. The NiS2NPs@CNF electrode can yield high specific capacitance (916.3 F g-1at 0.5 A g-1) and reveal excellent cycling performances. The solid-state asymmetric supercapacitor (ASC) was fabricated with NiS2NPs@CNF mat as a binder-free positive electrode and activated carbon cloth as a negative electrode. As-assembled ASC not only produce high specific capacitance (364.8 F g-1at 0.5 A g-1) but also exhibit excellent cycling stability (∼92.8% after 5000 cycles). The ASC delivered a remarkably high energy density of 129.7 Wh kg-1at a power density of 610 W kg-1. These encouraging results could make this NiS2NPs@CNF hybrid mat a good choice of cathode material for the fabrication of flexible solid-state ASC for various flexible/wearable electronics.

Chitosan Oligosaccharide Lactate-Coated Ultrasmall Gadolinium Oxide Nanoparticles: Synthesis, In Vitro Cytotoxicity, and Relaxometric Properties.

In this study, hydrophilic and biocompatible chitosan oligosaccharide lactate (COL)-coated ultra-small gadolinium oxide nanoparticles (NPs) were synthesized through a one-pot polyol method and characterized by various experimental techniques. The In Vitro cellular cytotoxicity assay indicated that the COL-coated gadolinium oxide NPs were non-toxic up to 500 µM Gd. In addition, their water proton spin relaxivities (i.e., r1 and r2) were estimated to be 13.0 and 27.0 s-1mM-1, respectively, which are higher than those of commercial magnetic resonance imaging (MRI) contrast agents. The application potential of the solution sample as a T1 MRI contrast agent was demonstrated In Vitro by measuring map images in which dose-dependent contrast enhancements were observed.

Ex situ Synthesis and Characterization of High Strength Multipurpose Bacterial Cellulose-Aloe vera Hydrogels.

The innate structural and functional properties of bacterial cellulose (BC) have been greatly improved by developing its composites with other materials for its applications in different fields. In the present study, BC-Aloe vera (BCA) gel composite with high tensile strength was ex situ developed and characterized for its potential applications in environmental and medical fields. FE-SEM micrographs showed the impregnation of Aloe vera gel into the fibril network of BC. The dry weight analysis showed the addition of 40 wt.% Aloe vera contents into the BC matrix. The addition of Aloe vera resulted in a 3-fold increase in the mechanical strength of BCA composite. The critical strain or stress concentration points were accurately identified in the composite using a three-dimensional digital image correlation (3D-DIC) system. The BCA composite retained water for an extended period of up to 70 h. The BCA composite effectively adsorbed Cu, Co, Fe, and Zn metals. Moreover, the BCA composite supported the adhesion and proliferation of MC3T3-E1 cells. The findings of this study suggest that the developed BCA composite could find multipurpose applications in different fields.

Therapeutic Potential of Equol: A Comprehensive Review.

Equol (4',7-isoflavandiol), is a phytoestrogenic compound, which is synthesized from parent molecule diadzein by intestinal bacterial flora. It is among one of the most extensively researched molecule due to its high affinity towards estrogen receptors. Its enantiomeric form S-equol has been explored in the treatment of estrogen/androgen mediated diseases. Various therapeutic applications such as anti-cancer, cardioprotective, antidiabetic, antiosteoporosis, anti-ageing, and neuroprotective efficacy are attributed to it. This review explored major studies related to biochemistry and pharmacological applications of equol for human health.

In Vivo Positive Magnetic Resonance Imaging Applications of Poly(methyl vinyl ether-alt-maleic acid)-coated Ultra-small Paramagnetic Gadolinium Oxide Nanoparticles.

The study of ultra-small paramagnetic gadolinium oxide (Gd2O3) nanoparticles (NPs) as in vivo positive (T1) magnetic resonance imaging (MRI) contrast agents is one of the most attractive fields in nanomedicine. The performance of the Gd2O3 NP imaging agents depends on the surface-coating materials. In this study, poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was used as a surface-coating polymer. The PMVEMA-coated paramagnetic ultra-small Gd2O3 NPs with an average particle diameter of 1.9 nm were synthesized using the one-pot polyol method. They exhibited excellent colloidal stability in water and good biocompatibility. They also showed a very high longitudinal water proton spin relaxivity (r1) value of 36.2 s-1mM-1 (r2/r1 = 2.0; r2 = transverse water proton spin relaxivity) under a 3.0 tesla MR field which is approximately 10 times higher than the r1 values of commercial molecular contrast agents. High positive contrast enhancements were observed in in vivo T1 MR images after intravenous administration of the NP solution sample, demonstrating its potential as a T1 MRI contrast agent.

Effective Role of Magnetic Core-Shell Nanocomposites in Removing Organic Wastes from Water.

BACKGROUND: Affordable and efficient water treatment process to produce water free from various contaminants is a big challenge. The presence of toxic heavy metals, dyes, hazardous chemicals and other toxins cause contamination of water sources and our food chain and make them hazardous to living organisms. The current water treatment processes are no longer sustainable due to high cost and low efficiency. Due to advantageous properties, nanotechnology based materials can play a great role in increasing the efficiency of water treatment processes. Magnetic nanocomposites use nano as well as magnetic properties and have the potential to provide a sophisticated system to overcome most of the impurities present in water. There is diversity of magnetic nanocomposites, however presently we have focussed the core-shell magnetic nanocomposites because they have excellent magnetic and separation properties, stability, and good biocompatibility. METHODS: We collected systematically the bibliographic data bases for peer-reviewed research literature focusing on the theme of our review. The Quality of the included research papers are selected by standard tools. A conceptual frame work is designed to arrange the topics and extracted the interventions and findings of the included studies. RESULTS: The overall study was divided in sections and each section incorporated the most appropriate literature citation. Total one hundred and eight references were included of which 32 references were used for basic description/introduction of core-shell magnetic nanocomposites. One review paper containing the synthesis methods for core shell magnetic nanocomposites is included while majority (76) of the references are included for comprehensive description of applications of the core-shell nanocomposites among which 25 were for dyes removal, 27 for hazardous metals, 07 for hazardous chemicals, 12 for pesticides and biological contaminants removal and five other including patents were added as miscellaneous substances removal from water sources. This review identified the effective role of core-shell magnetic nanocomposites for environmental remediation in terms of removal of various hazardous substances from water resources. CONCLUSION: The outcomes of the present review confirms that the magnetic core-shell nanocomposites provide a cost effective and efficient way for the removal of various toxic substances including dyes, heavy metals, toxic organic chemicals, pesticides and some biological contaminants from water sources.

Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application.

A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd(3+) ((8)S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy(3+) ((6)H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd(3+) and Dy(3+) and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

Potential dual imaging nanoparticle: Gd2O3 nanoparticle.

Gadolinium (Gd) is a unique and powerful element in chemistry and biomedicine which can be applied simultaneously to magnetic resonance imaging (MRI), X-ray computed tomography (CT), and neutron capture therapy for cancers. This multifunctionality can be maximized using gadolinium oxide (Gd2O3) nanoparticles (GNPs) because of the large amount of Gd per GNP, making both diagnosis and therapy (i.e., theragnosis) for cancers possible using only GNPs. In this study, the T1 MRI and CT dual imaging capability of GNPs is explored by synthesizing various iodine compound (IC) coated GNPs (IC-GNPs). All the IC-GNP samples showed stronger X-ray absorption and larger longitudinal water proton relaxivities (r1 = 26-38 s(-1) mM(-1) and r2/r1 = 1.4-1.9) than the respective commercial contrast agents. In vivo T1 MR and CT images of mice were also acquired, supporting that the GNP is a potential dual imaging agent.

Synthesis of nanoparticle CT contrast agents: in vitro and in vivo studies.

Water-soluble and biocompatible D-glucuronic acid coated Na2WO4 and BaCO3 nanoparticles were synthesized for the first time to be used as x-ray computed tomography (CT) contrast agents. Their average particle diameters were 3.2 ± 0.1 and 2.8 ± 0.1 nm for D-glucuronic acid coated Na2WO4 and BaCO3 nanoparticles, respectively. All the nanoparticles exhibited a strong x-ray attenuation. In vivo CT images were obtained after intravenous injection of an aqueous sample suspension of D-glucuronic acid coated Na2WO4 nanoparticles, and positive contrast enhancements in the kidney were clearly shown. These findings indicate that the nanoparticles reported in this study may be promising CT contrast agents.

Stereoselective synthesis of 3,7-diarylaminocholestanes by titanium-mediated reductive amination.

An efficient method for the synthesis of aryl aminocholestanes, using a chlorotriisopropoxytitanium(IV)-mediated reductive amination reaction of 5α-cholestane-3,7-dione, is reported. A series of 3,7-diarylaminocholestane derivatives were prepared according to this methodology in up to 98% yield. These compounds were primarily characterized by (1)H NMR, (13)C NMR, and mass spectrometry.