Green Luminescent CdTe Quantum Dot Based Fluorescence Nano-Sensor for Sensitive Detection of Arsenic (III)

Arsenic (As³⁺) is a hazardous and ubiquitous element; hence the quantitative detection of arsenic in various kinds of environmental sample is an important issue. Herein, we reported L-cysteine capped CdTe Quantum dot based optical sensor for the fluorometric detection of arsenic (III) in real water sample. The method is based on the fluorescence quenching of QDs with the addition of arsenic solution that caused the reduction in fluorescence intensity due to strong interaction between As³⁺ and L-cysteine to form As(Cys)₃. The calibration curve was linear over 2.0 nM-0.5 μM arsenic with limit of detection (LOD) of 2.0 nM, correlation coefficient (r²) of 0.9698, and relative standard deviation (RSD %) of 5.2%. The Stern-Volmer constant for the quenching of CdTe QDs with As³⁺ at optimized condition was evaluated to be 1.17 × 10⁸ L mol^?1 s^?1. The feasibility of the sensor has been analyzed by checking the inference of common metal ions available in the water such as K⁺, Na⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Al³⁺, Co²⁺, Cr²⁺, Fe³⁺ and its higher oxidation state As⁵⁺.

Open image in new window

Graphical Abstract Schematic representation of As³⁺ detection by L-Cysteine capped CdTe QDs

     

Ab-initio study of electronic,optical, thermal,and transport properties of Cr4AlB6

Theoretical investigation of different physical parameters of Cr₄AlB₆ have been done within the framework of density functional theory. Cr₄AlB₆ is a no band gap material. Its Cr-3d states contributes the most at the Fermi level. Thermal properties are investigated using quasi-harmonic Debye model as implemented in Gibbs code for different values of pressure and temperature. Study of transport property suggests that its electrical conductivity increases nonlinearly with increase in temperature but the relative change in its value is very low whereas its thermal conductivity increases linearly with the increase in temperature and relative increase in thermal conductivity is very high. The behavior of Cr₄AlB₆ is anisotropic and property is ceramic. It has potential applications in making ceramic capacitors. Its reflectivity is high in low energy region. It suggests that material can be used as coating material for far-infrared radiation. Study of the transport property suggests that because of very high value of thermal conductivity, it can be used for heat sink applications.     

Design,synthesis and in vitro bioactivity of mixed ligand Ru(II) complexes bearing the fluoroquinolone antibacterial agents

Transition Metal Chemistry - Mixed ligand Ru(II) phenanthroline complexes of the type [Ru(1,10-phen)2Flq]ClO4 (RPFlq-1-3) and “piano-stool”-type Ru(II) arene complexes...     

Synthesis,characterization, and biological activity of organophosphates derived from substituted benzoxazole

The reaction of phosphorus oxychlo‐ ride/phosphorus thiochloride with 2‐(2′‐mercapto‐ phenyl)benzoxazole in 1:1, 1:2, and 1:3 molar ratio in the presence of stoichiometric amounts of triethyl‐ amine has afforded a series of organophosphates. These organophosphates have been characterized by elemental analyses, infrared, ¹H NMR, ³¹P NMR, and mass spectral studies. The antifungal activity of these organophosphates has been evaluated against pathogenic fungi Aspergillus niger and Fusarium oxysporium. The antifungal screening data reveal that these compounds are more fungitoxic than 2‐(2′‐mercaptophenyl) benzoxazole. These organophosphates were also found to be insecticidal when tested against Periplenata americana.© 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:309–315, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20551     

A review on stabilization of carbon nanotube nanofluid

Journal of Thermal Analysis and Calorimetry - CNT nanoparticles have high tensile strength, excellent thermal transfer properties, and optimal chemical and physical stability. The lack of CNT...     

All-oxide-based and metallic electrode-free artificial synapses for transparent neuromorphic computing

The extraordinary abilities of the human brain rely on the functioning of biological synapses in the nervous system. Emulating human brain activity for neuromorphic computing has been an alluring prospect in artificial intelligence, and this would become possible with the development of an efficient artificial synapse. The human brain assimilates most information through visual perception. Therefore, optoelectronic synapses can be considered an important keystone of neuromorphic computing due to their efficient ability to process optoelectronic input signals. In this work, a metallic electrode-free, all-oxide-based optoelectronic synapse was developed that demonstrated efficient and repeatable electronic and photonic synaptic plasticity behaviour. A unique artificial synapse with an n–n heterostructure was developed using ZnO and V₂O₅. This artificial synapse structure has high optical transparency and does not require a metallic electrode for data acquisition. The device exhibits resistive switching memory behaviour, along with electronic and photonic synaptic behaviour. The storing and erasing of information, as well as learning-experience behaviour, was also successfully demonstrated in the V₂O₅/ZnO artificial synapse. This work could therefore be beneficial to the development of artificial intelligence when transparent and metallic electrode-free synaptic devices are considered necessary.     

Characterization of nucleobases in sea buckthorn leaves: An HPTLC approach

The present study aims to establish a high-performance thin layer chromatography (HPTLC)-based comparative analysis, directed toward characterization of nucleobases in aqueous and alcoholic extracts of sea buckthorn leaves from three different varieties: Hippophae salicifolia, Hippophae rhamnoides mongolica, and Hippophae rhamnoides turkestanica. The alcoholic and aqueous leaf extracts from these sea buckthorn varieties were prepared using accelerated solvent extraction technique. A novel HPTLC method for separating and identifying six nucleobases, namely, guanosine, guanine, cytosine, adenine, uracil, and thymine were adopted. HPTLC analysis indicated the presence of one or more of these nucleobases in a total of six leaf extracts evaluated, their quantities varying from 0.23 to 7.76?µg nucleobase per mg of extract. Though a typical trend could not be observed in the values obtained, the extracts were found to be considerably rich with respect to nucleobase contents. The results acquired from HPTLC were subsequently validated by hyphenation with mass spectrometry and also by applying chemometric tools in form of heat maps, hierarchical cluster dendrograms, and principal component analysis. The presence of nucleobases in the leaf extracts was confirmed by HPLC as well but HPTLC proved to be a better approach for characterization of nucleobases in plant extracts, than high performance liquid chromatography (HPLC).     

Rapid fingerprinting of a highly glycosylated fusion protein by microfluidic chip-based capillary electrophoresis–mass spectrometry

Protein glycosylation can impact the efficacy, safety, and pharmacokinetics of therapeutic proteins. Achieving uniform and consistent protein glycosylation is an important requirement for product quality control at all stages of therapeutic protein drug discovery and development. The development of a new microfluidic CE device compatible with MS offers a fast and sensitive orthogonal mode of high-resolution separation with MS characterization. Here, we describe a fast and robust chip-based CE-MS method for intact glycosylation fingerprinting of a therapeutic fusion protein with complex sialylated N and O-linked glycoforms. The method effectively separates multiple sialylated glycoforms and offers a rapid detection of changes in glycosylation profile in 6 min.     

Enhancement in the stability of alginate gels prepared with mixed solution of divalent ions using a diffusion through dialysis tube (DTDT) approach

In this work, calcium alginate hydrogels have been prepared by a new technique, called ‘diffusion through dialysis tube’ (DTDT) which involved transfer of crosslinking ions into alginate solution via a dialysis tube with a molecular weight cutoff of 8 k Da. The various hydrogels, prepared with varying degree of crosslinking, were characterized by FTIR, XRD and TG analysis. We also investigated their dynamic water absorbency in phosphate buffer saline (PBS) of pH 7.4 and the data were interpreted in terms of various kinetic models. The equilibrium water uptake data was used to determine network parameters of hydrogels. Finally, the stability and water absorbency of these hydrogels were enhanced to a desired level by using crosslinker solutions, composed of Ba⁺⁺/Ca ⁺⁺and Zn⁺⁺ / Ca⁺⁺ ions.