Mashitah M. Yusoff

Bio: Mashitah M. Yusoff is an academic researcher from Universiti Malaysia Pahang. The author has contributed to research in topics: Liquid crystal & Electrospinning. The author has an hindex of 39, co-authored 219 publications receiving 5163 citations. Previous affiliations of Mashitah M. Yusoff include Universiti Malaysia Sabah.

Biosynthesis of metallic nanoparticles using plant derivatives and their new avenues in pharmacological applications – An updated report

Abstract: The field of nanotechnology mainly encompasses with biology, physics, chemistry and material sciences and it develops novel therapeutic nanosized materials for biomedical and pharmaceutical applications. The biological syntheses of nanoparticles are being carried out by different macro-microscopic organisms such as plant, bacteria, fungi, seaweeds and microalgae. The biosynthesized nanomaterials have been effectively controlling the various endemic diseases with less adverse effect. Plant contains abundant natural compounds such as alkaloids, flavonoids, saponins, steroids, tannins and other nutritional compounds. These natural products are derived from various parts of plant such as leaves, stems, roots shoots, flowers, barks, and seeds. Recently, many studies have proved that the plant extracts act as a potential precursor for the synthesis of nanomaterial in non-hazardous ways. Since the plant extract contains various secondary metabolites, it acts as reducing and stabilizing agents for the bioreduction reaction to synthesized novel metallic nanoparticles. The non-biological methods (chemical and physical) are used in the synthesis of nanoparticles, which has a serious hazardous and high toxicity for living organisms. In addition, the biological synthesis of metallic nanoparticles is inexpensive, single step and eco-friendly methods. The plants are used successfully in the synthesis of various greener nanoparticles such as cobalt, copper, silver, gold, palladium, platinum, zinc oxide and magnetite. Also, the plant mediated nanoparticles are potential remedy for various diseases such as malaria, cancer, HIV, hepatitis and other acute diseases.

A Comprehensive Review on l-Asparaginase and Its Applications

Abstract: L-asparaginase (LA) catalyzes the degradation of asparagine, an essential amino acid for leukemic cells, into ammonia and aspartate. Owing to its ability to inhibit protein biosynthesis in lymphoblasts, LA is used to treat acute lymphoblastic leukemia (ALL). Different isozymes of this enzyme have been isolated from a wide range of organisms, including plants and terrestrial and marine microorganisms. Pieces of information about the three-dimensional structure of L-asparaginase from Escherichia coli and Erwinia sp. have identified residues that are essential for catalytic activity. This review catalogues the major sources of L-asparaginase, the methods of its production through the solid state (SSF) and submerged (SmF) fermentation, purification, and characterization as well as its biological roles. In the same breath, this article explores both the past and present applications of this important enzyme and discusses its future prospects.

Superior supercapacitive performance in electrospun copper oxide nanowire electrodes

Abstract: Copper oxide (CuO) nanowires of diameter ∼30–50 nm were developed by an aqueous polymeric solution based electrospinning process and their structural, morphological, and electrochemical properties were studied with the aim to fabricate high performance supercapacitor devices. The wires consist of densely packed cuboidal particles of size ∼10 nm characterized by a low degree of crystal defects. Supercapacitor electrodes were fabricated on nickel foam substrates using 75 wt% CuO in 15 wt% conducting carbon and 10 wt% polyvinylidene fluoride. The supercapacitive properties of the electrodes were evaluated in a three-electrode configuration in aqueous electrolytes, viz. KOH and LiOH, employing cyclic voltammetry (CV), charge–discharge cycling (CDC) and electrochemical impedance spectroscopy (EIS). A record specific capacitance (CS) is observed for the present electrospun CuO nanowires: CS ∼ 620 F g−1 in KOH and 581 F g−1 in LiOH at a current density of 2 A g−1 with a Coulombic efficiency of ∼100%. Compared with the previous results on the electrochemical stability of CuO nanostructures, the material electrospun using an aqueous polymeric solution showed a much higher operational stability (98% at the end of 1000 cycles and 92% at the end of 2000 cycles) owing to its superior crystallinity. The electrochemical properties of the electrodes were determined using EIS to validate the CV and CDC results.

High performance dye-sensitized solar cells with record open circuit voltage using tin oxide nanoflowers developed by electrospinning

Abstract: Flower shaped nanostructures of an architypical transparent conducting oxide, SnO2, have been synthesized by an electrospinning technique for the first time by precisely controlling the precursor concentration in a polymeric solution. The flowers were made up of nanofibrils of diameter ∼70–100 nm, which in turn consisted of linear arrays of single crystalline nanoparticles of size 20–30 nm. Mott–Schottkey analysis shows that flowers have an order of magnitude higher electron density compared with the fibers despite their chemical similarity. Dye-sensitized solar cells fabricated using the flowers showed a record open circuit voltage of ∼700 mV and have one of the highest photoconversion efficiencies so far achieved with SnO2 and the iodide/triiodide electrolyte. The photoaction spectra and impedance spectroscopic measurements show that the flowers are characterized by a higher electron lifetime, owing to their enhanced crystallinity, compared to the conventional fibrous structure.

A review of electrolyte materials and compositions for electrochemical supercapacitors

Abstract: Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

Design and Mechanisms of Asymmetric Supercapacitors.

Abstract: Ongoing technological advances in diverse fields including portable electronics, transportation, and green energy are often hindered by the insufficient capability of energy-storage devices By taking advantage of two different electrode materials, asymmetric supercapacitors can extend their operating voltage window beyond the thermodynamic decomposition voltage of electrolytes while enabling a solution to the energy storage limitations of symmetric supercapacitors This review provides comprehensive knowledge to this field We first look at the essential energy-storage mechanisms and performance evaluation criteria for asymmetric supercapacitors to understand the wide-ranging research conducted in this area Then we move to the recent progress made for the design and fabrication of electrode materials and the overall structure of asymmetric supercapacitors in different categories We also highlight several key scientific challenges and present our perspectives on enhancing the electrochemical performance of future asymmetric supercapacitors