Fabrication of thermostable and reusable nanobiocatalyst for dye decolourization by immobilization of lignin peroxidase on graphene oxide functionalized MnFe2O4 superparamagnetic nanoparticles.

In view of the potential applications of immobilized enzymes, partially purified Lignin Peroxidase (LiP) from Pseudomonas fluorescens LiP-RL5 was immobilized on Graphene Oxide functionalized MnFe2O4 nanoparticles (10 nm, synthesized by sol-gel auto-combustion) to fabricate a new hyperactive and thermostable nanobiocatalyst and thereafter characterized by using standard techniques. Immobilized LiP was quite stable at 50 °C with the half-life of 14 h and showed higher tolerance towards various metal ions and solvents than free LiP. Immobilized LiP retained 50% of enzyme activity even after nine consecutive runs. When tested against various textile dyes, the immobilized LiP was found quite effective with higher dye decolourization efficiency (up to 88%) within 1 h of incubation at 30 °C. The results of this research effort confirmed that the immobilization of LiP and fabrication of nanobiocatalyst increase the efficacy, stability, and reusability of the enzyme which could be efficiently utilized under harsh industrial conditions.

Iron Oxide Nanoparticles as Potential Scaffold for Photocatalytic and Sensing Applications.

Herein, we report photocatalytic and fluorescence sensing applications of iron oxide (α-Fe2O3) nanoparticles synthesized by facile low-temperature simple solution process. The synthesized nanoparticles were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) attached with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), UV-visible spectroscopy and fluorescence spectroscopy. The detailed analysis revealed that the synthesized nanoparticles were well-crystalline, grown in very high density and possessing rhombohedral α-Fe2O3 crystal structure. The prepared nanoparticles were used as efficient scaffold for photocatalytic and sensing applications. The detailed photocatalysis results revealed that in presence of an appropriate amount of α-Fe2O3 nanoparticles as photocatalyst, a significant dye degradation of methyl orange (MO) was observed in 140 min. In addition, the fabricated florescence sensor based on α-Fe2O3 nanoparticles exhibited a low detection limit of ∼3.33 µM/L towards picric acid. The observed results clearly confirmed that the synthesized α-Fe2O3 nanoparticles are potential scaffold for photocatalysis and sensing applications.

Hexagonal cadmium oxide nanodisks: Efficient scaffold for cyanide ion sensing and photo-catalytic applications.

Herein, we report the large-scale low-temperature aqueous solution based synthesis of hexagonal-shaped cadmium oxide (CdO) nanodisks. The synthesized nanodisks were characterized in detail to investigate the morphological, structural, optical and compositional properties using various analytical tools. The detailed characterizations revealed that the synthesized CdO nanodisks are grown in high-density, possessing well-crystallinity with cubic crystal phase and exhibiting good optical properties. Further, the prepared CdO nanodisks were used as efficient scaffold for cyanide ion sensor and photocatalyst applications. A luminescent sensor for the determination of cyanide ion in aqueous solution was fabricated based on synthesized CdO nanodisks. The fabricated luminescent sensor exhibited an extremely low detection limit (~1.40µmolL(-1)) towards cyanide ion which is significantly lower than the maximum permitted value of cyanide ion by United States Environmental Protection Agency (EPA) for drinking water (7.69µmolL(-1)). The interference studies of the fabricated sensor also demonstrate excellent selectivity towards cyanide ions compared to other coexisting ions. As a photocatalyst, the synthesized CdO nanodisks exhibited high photodegradation (~99.7%) of toxic methyl orange dye just in 90min using 0.25g of CdO nanodisks.