Anees A. Ansari

Bio: Anees A. Ansari is an academic researcher from King Saud University. The author has contributed to research in topics: Nanoparticle & Fourier transform infrared spectroscopy. The author has an hindex of 36, co-authored 157 publications receiving 4506 citations. Previous affiliations of Anees A. Ansari include National Physical Laboratory.

Iron oxide-chitosan nanobiocomposite for urea sensor

Abstract: Urease (Ur) and glutamate dehydrogenase (GLDH) have been co-immobilized onto superparamegnatic iron oxide (Fe3O4) nanoparticles-chitosan (CH) based nanobiocomposite film deposited onto indium-tin-oxide (ITO) coated glass plate via physical adsorption for urea detection. The magnitude of magnetization (60.9 emu/g) of Fe3O4 nanoparticles (∼22 nm) estimated using vibrating sample magnetometer (VSM) indicates superparamagnetic behaviour. It is shown that presence of Fe3O4 nanoparticles results in increased active surface area of CH-Fe3O4 nanobiocomposite for immobilization of enzymes (Ur and GLDH), enhanced electron transfer and increased shelf-life of nanobiocomposite electrode. Differential pulse voltammetry (DPV) studies show that Ur-GLDH/CH-Fe3O4/ITO bioelectrode is found to be sensitive in the 5–100 mg/dL urea concentration range and can detect as low as 0.5 mg/dL. A relatively low value of Michaelis–Menten constant (Km, 0.56 mM) indicates high affinity of enzymes (Ur and GLDH) for urea detection.

Luminescence properties of Tb3+-doped CaMoO4 nanoparticles: annealing effect, polar medium dispersible, polymer film and core–shell formation

Abstract: Tb3+-doped CaMoO4 (Tb3+ = 1, 3, 5, 7, 10, 15 and 20 atom%) core and core–shell nanoparticles have been prepared by urea hydrolysis in ethylene glycol (EG) as capping agent as well as reaction medium at low temperature ∼150 °C. As-prepared samples were annealed at 500 and 900 °C for 4 h to eliminate unwanted hydrocarbons and/or H2O present in the sample and to improve crystallinity. The synthesised nanophosphors show tetragonal phase structure. The crystallite size of as-prepared sample is found to be ∼18 nm. The luminescence intensity of the 5D4 → 7F5 transition at 547 nm of Tb3+ is much higher than that of the 5D4 → 7F6 transition at 492 nm. 900 °C annealed samples show the highest luminescence intensity. The intensity ratio R (I[5D4 → 7F6]/I[5D4 → 7F5]) lies between 0.3–0.6 for as-prepared, 500 and 900 °C annealed samples. The luminescence decay of 5D4 level under 355 nm excitation shows biexponential behaviour indicating availability of Tb3+ ions on surface and core regions of particle; whereas, contribution of Mo–O charge transfer to lifetime is obtained under 250 nm excitation. The CIE coordinates of as-prepared, 500 and 900 °C annealed 5 atom% Tb3+-doped CaMoO4 samples under 250 nm excitation are (0.28, 0.32), (0.22, 0.28) and (0.25, 0.52), respectively. The dispersed particles in polar medium and its polymer film show green light emission. The luminescence intensity is improved significantly after core–shell formation due to extent of decrease of non-radiative rates arising from surface dangling bonds and capping agent. Quantum yields of as-prepared samples of 1, 5 and 7 atom% Tb3+-doped CaMoO4 samples are found to be 10, 3 and 2, respectively.

Sol-gel derived nanostructured cerium oxide film for glucose sensor

Abstract: Sol-gel derived nanostructured cerium oxide (CeO2) film deposited on gold (Au) electrode has been utilized for physisorption of glucose oxidase (GOx). X-ray diffraction, atomic force microscopy, UV-visible spectroscopy, and electrochemical techniques have been used to characterize sol-gel derived CeO2∕Au electrode and GOx∕CeO2∕Au bioelectrode. The response characteristics of the glucose bioelectrode (GOx∕CeO2∕Au) indicate linearity, detection limit and shelf-life as 50–400mg∕dL, 12.0μM, and 12weeks, respectively. The value of apparent Michaelis–Menten constant (Km) of GOx∕CeO2∕Au bioelectrode has been found to be 13.55μM.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes

Abstract: Over the past few decades, researchers have established artificial enzymes as highly stable and low-cost alternatives to natural enzymes in a wide range of applications. A variety of materials including cyclodextrins, metal complexes, porphyrins, polymers, dendrimers and biomolecules have been extensively explored to mimic the structures and functions of naturally occurring enzymes. Recently, some nanomaterials have been found to exhibit unexpected enzyme-like activities, and great advances have been made in this area due to the tremendous progress in nano-research and the unique characteristics of nanomaterials. To highlight the progress in the field of nanomaterial-based artificial enzymes (nanozymes), this review discusses various nanomaterials that have been explored to mimic different kinds of enzymes. We cover their kinetics, mechanisms and applications in numerous fields, from biosensing and immunoassays, to stem cell growth and pollutant removal. We also summarize several approaches to tune the activities of nanozymes. Finally, we make comparisons between nanozymes and other catalytic materials (other artificial enzymes, natural enzymes, organic catalysts and nanomaterial-based catalysts) and address the current challenges and future directions (302 references).

Nanoparticles for photothermal therapies.

Abstract: The current status of the use of nanoparticles for photothermal treatments is reviewed in detail. The different families of heating nanoparticles are described paying special attention to the physical mechanisms at the root of the light-to-heat conversion processes. The heating efficiencies and spectral working ranges are listed and compared. The most important results obtained in both in vivo and in vitro nanoparticle assisted photothermal treatments are summarized. The advantages and disadvantages of the different heating nanoparticles are discussed.

Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology.

Abstract: Chemistries that Facilitate Nanotechnology Kim E. Sapsford,† W. Russ Algar, Lorenzo Berti, Kelly Boeneman Gemmill,‡ Brendan J. Casey,† Eunkeu Oh, Michael H. Stewart, and Igor L. Medintz*,‡ †Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States ‡Center for Bio/Molecular Science and Engineering Code 6900 and Division of Optical Sciences Code 5611, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States College of Science, George Mason University, 4400 University Drive, Fairfax, Virginia 22030, United States Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento, California 95817, United States Sotera Defense Solutions, Crofton, Maryland 21114, United States

Principles and mechanisms of photocatalytic dye degradation on TiO 2 based photocatalysts: a comparative overview

Abstract: The total annual production of synthetic dye is more than 7 × 105 tons. Annually, through only textile waste effluents, around one thousand tons of non-biodegradable textile dyes are discharged into natural streams and water bodies. Therefore, with growing environmental concerns and environmental awareness there is a need for the removal of dyes from local and industrial water effluents with a cost effective technology. In general, these dyes have been found to be resistant to biological as well as physical treatment technologies. In this regard, heterogeneous advanced oxidation processes (AOPs), involving photo-catalyzed degradation of dyes using semiconductor nanoparticles is considered as an efficient cure for dye pollution. In the last two decades TiO2 has received considerable interest because of its high potential as a photocatalyst to degrade a wide range of organic material including dyes. This review starts with (i) a brief overview on dye pollution, dye classification and dye decolourization/degradation strategies; (ii) focuses on the mechanisms involved in comparatively well understood TiO2 photocatalysts and (iii) discusses recent advancements to enhance TiO2 photocatalytic efficiency by (a) doping with metals, non-metals, transition metals, noble metals and lanthanide ions, (b) structural modifications of TiO2 and (c) immobilization of TiO2 by using various supports to make it a flexible and cost-effective commercial dye treatment technology.