Red emitting Y2O3:Eu3+ nanophosphors with >80% down conversion efficiency

Jadhav, A. P.,Pawar, A. U.,Pal, U.,Kang, Y. S. Royal Society of Chemistry 2014 Journal of Materials Chemistry C Vol.2 No.3

Obtaining nanophosphors of a controlled size and shape with a high quantum efficiency is the current challenge for display and imaging technologies. Although the surface state induced luminescence quenching in nanophosphors may be compensated to some extent by incorporating activators like rare-earth ions, or by exploiting their quantum size effect, obtaining nanophosphors with quantum efficiencies as high as their bulk counterparts remains elusive. In the present article, we report on the synthesis of uniform Eu-doped Y2O3 nanoparticles, with an average size of 20-53 nm and a down conversion efficiency as high as 85%, using a simple chemical precipitation technique. Along with size control, the effects of Eu3+ content on their emission behaviors have been discussed. We believe the low-cost synthesis process of these nanoparticles will greatly enhance their application potential in optical display and bio-imaging technologies.

Degradation and Detoxification of Disperse Dye Scarlet RR by Galactomyces geotrichum MTCC 1360

S. U. Jadhav,G. S. Ghodake,A. A. Telke,D. P. Tamboli,S. P. Govindwar 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.4

Purification and Characterization of Veratryl Alcohol Oxidase from Comamonas sp. UVS and Its Role in Decolorization of Textile Dyes

Umesh U. Jadhav,Vishal V. Dawkar,Dhawal P. Tamboli,Sanjay P. Govindwar 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.3

In the present work, we have purified veratryl alcohol oxidase (VAO) enzyme from Comamonas sp. UVS to evaluate its potential to decolorize textile dyes. VAO was purified (13.9 fold) by an ion exchange followed by the size exclusion chromatography. Molecular weight of the VAO was estimated to be about 66 kDa by SDS-PAGE. The optimum pH and temperature of oxidase were 30°C and 65°C, respectively. VAO showed maximum activity with n-propanol among the various substrates (n-propanol, veratryl alcohol, L-dopa, tryptophan, etc.). Under standard assay conditions, Km value of the enzyme was 2.5 mM towards veratrole. The enzyme activity was completely inhibited by 0.5 mM sodium azide. L-cysteine, dithiothreitol, and the metal chelator, EDTA had a slight inhibitory effect. The purified enzyme was able to decolorize textile dyes, Red HE7B (57.5%) and Direct Blue GLL (51.09%) within 15 h at 40 μg/mL concentration. GC-MS analysis of the metabolites suggested oxidative cleavage and desulphonation of these dyes In the present work, we have purified veratryl alcohol oxidase (VAO) enzyme from Comamonas sp. UVS to evaluate its potential to decolorize textile dyes. VAO was purified (13.9 fold) by an ion exchange followed by the size exclusion chromatography. Molecular weight of the VAO was estimated to be about 66 kDa by SDS-PAGE. The optimum pH and temperature of oxidase were 30°C and 65°C, respectively. VAO showed maximum activity with n-propanol among the various substrates (n-propanol, veratryl alcohol, L-dopa, tryptophan, etc.). Under standard assay conditions, Km value of the enzyme was 2.5 mM towards veratrole. The enzyme activity was completely inhibited by 0.5 mM sodium azide. L-cysteine, dithiothreitol, and the metal chelator, EDTA had a slight inhibitory effect. The purified enzyme was able to decolorize textile dyes, Red HE7B (57.5%) and Direct Blue GLL (51.09%) within 15 h at 40 μg/mL concentration. GC-MS analysis of the metabolites suggested oxidative cleavage and desulphonation of these dyes

Biodegradation of Disperse Dye Brown 3REL by Microbial Consortium of Galactomyces geotrichum MTCC 1360 and Bacillus sp. VUS

S. U. Jadhav,U. U. Jadhav,V. V. Dawkar,S. P. Govindwar 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.2

The consortium-GB (Galactomyces geotrichum MTCC 1360 and Bacillus sp. VUS) exhibited 100% decolorization ability with the dye Brown 3REL within 2 h at shaking condition with optima of pH 7 and at 50℃. However, G. geotrichum MTCC 1360 showed 39% decolorization within 24 h and Bacillus sp. VUS took 5 h for 100% decolorization, when incubated individually. Additional carbon and nitrogen sources like, starch, peptone, and urea were found to enhance decolorization. Induction in lignin peroxidase, tyrosinase, and riboflavin reductase was observed in consortium as that of individual organisms. GCMS identification showed different metabolites formed using consortium (2-(6,8-dichloro-quinazolin-4yloxy)-acetyl-urea and 2-(6,8-dichloro-quinazolin-4yloxy)-acetyl-formamide) and Bacillus sp. VUS (6,8-dichloro-4 methoxy-quinazoline) after 2 h of incubation with Brown 3REL. G. geotrichum MTCC 1360 showed minor modifications in structure of Brown 3REL. Phytotoxicity revealed non toxic nature of metabolites. This consortium-GB was also able to decolorize various industrial dyes.

Synthesis of Monodispersed Red Emitting LiAl₅O₈:Fe³⁺ Nanophosphors

Jadhav, Abhijit P.,Pawar, Amol,Pal, U.,Kim, Byung Kyu,Kang, Young Soo American Scientific Publishers 2012 Science Of Advanced Materials Vol.4 No.5

Peroxidase from Bacillus sp. VUS and Its Role in the Decolorization of Textile Dyes

Vishal V. Dawkar,Umesh U. Jadhav,Amar A. Telke,Sanjay P. Govindwar 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.3

Peroxidase was purified by an ion exchange chromatography followed by gel filtration chromatography from dye degrading Bacillus sp. strain VUS. The optimum pH and temperature of the enzyme activity was 3.0 and 65°C, respectively. This enzyme showed more activity with n-propanol than other substrates tested viz. xylidine, 3-(3,4-dihydroxy phenyl) Lalanine (L-DOPA), hydroxyquinone, ethanol, indole, and veratrole. Km value of the enzyme was 0.076 mM towards n-propanol under standard assay conditions. Peroxidase was more active in presence of the metal ions like Li²+ , Co²+ , K²+ , Zn²+, and Cu²+ where as it showed less activity in the presence of Ca²+ and Mn²+ . Inhibitors like ethylenediamine tetraacetic acid (EDTA), glutamine, and phenylalanine inhibited the enzyme partially, while sodium azide (NaN3) completely. The crude as well as the purified peroxidase was able to decolourize different industrial dyes. This enzyme decolourized various textile dyes and enhanced percent decolourization in the presence of redox mediators. Aniline was the most effective redox mediator than other mediators tested. Gas chromatography-Mass spectrometry (GC-MS) confirmed the formation of 7-Acetylamino-4-hydroxy-naphthalene-2-sulphonic acid as the final product of Reactive Orange 16 indicating asymmetric cleavage of the dye Peroxidase was purified by an ion exchange chromatography followed by gel filtration chromatography from dye degrading Bacillus sp. strain VUS. The optimum pH and temperature of the enzyme activity was 3.0 and 65°C, respectively. This enzyme showed more activity with n-propanol than other substrates tested viz. xylidine, 3-(3,4-dihydroxy phenyl) Lalanine (L-DOPA), hydroxyquinone, ethanol, indole, and veratrole. Km value of the enzyme was 0.076 mM towards n-propanol under standard assay conditions. Peroxidase was more active in presence of the metal ions like Li²+ , Co²+ , K²+ , Zn²+, and Cu²+ where as it showed less activity in the presence of Ca²+ and Mn²+ . Inhibitors like ethylenediamine tetraacetic acid (EDTA), glutamine, and phenylalanine inhibited the enzyme partially, while sodium azide (NaN3) completely. The crude as well as the purified peroxidase was able to decolourize different industrial dyes. This enzyme decolourized various textile dyes and enhanced percent decolourization in the presence of redox mediators. Aniline was the most effective redox mediator than other mediators tested. Gas chromatography-Mass spectrometry (GC-MS) confirmed the formation of 7-Acetylamino-4-hydroxy-naphthalene-2-sulphonic acid as the final product of Reactive Orange 16 indicating asymmetric cleavage of the dye

Biodegradation of Diazo Reactive Dye Navy blue HE2R (Reactive blue 172) by an Isolated Exiguobacterium sp. RD3

R. S. Dhanve,U. U. Shedbalkar,J. P. Jadhav 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1

The diazo reactive dye Navy blue HE2R (50 mg/L) was decolorized up to 91.2% within 48 h at static condition by the Exiguobacterium sp. isolated from the dyestuff contaminated soil, collected from the textile industrial area Solapur, India. It showed ability to decolorize seven different reactive textile dyes. Maximum decolorization was observed at 30℃ and pH 7. The presence and significant increase in the activity of enzymes lignin peroxidase, laccase, and azoreductase indicated prominent role of these enzymes in the decolorization of Navy blue HE2R. The degradation metabolites were analyzed by UV-Vis spectroscopy, TLC, HPLC, and FTIR spectroscopy. A possible pathway for biodegradation of this diazo reactive dye was proposed with the help of GC-MS analysis. The phytotoxicity studies confirmed the environmentally safe nature of degradation products.