Browsing by Author "JagadeeshBabu, P.E."

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Ag-TiO2 nanosheet embedded photocatalytic membrane for solar water treatment
(Elsevier Ltd, 2017) Nair, A.K.; JagadeeshBabu, P.E.
Solar photocatalytic degradation of contaminants in waste water using nanocatalysts is potentially sustainable water treatment. The major challenges in using nano size photocatalysts is catalyst recovery and its toxic effect. In the present work, the problem of catalyst recovery is mitigated by immobilising the photocatalyst on the surface of a membrane by pressurized ultrafiltration method. The membrane thus synthesised is capable of simultaneously degrading and filtering the pollutants. The photocatalyst employed in this work is silver doped TiO2 nanosheets, their thin structure and larger size favoured stable film formation on the membrane surface. The nanosheets were synthesised via hydrothermal route and their photocatalytic efficiency was future enhanced by doping with silver. The nanosheets were characterised using scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. Photocatalytic degradation studies were conducted using Congo red dye as the model pollutant. The effect of catalyst loading on permeation properties and dye removal were studied under ultra violet irradiation. M-200 membrane with Ag-TNS loading of 136.98 gm-2 was found optimum for superior flux and dye removal. M-200 membrane also showed good performance under solar radiation. © 2017 Elsevier Ltd.
Bed depth service time model for the biosorption of reactive red dye using the Portunus sanguinolentus shell
(2010) JagadeeshBabu, P.E.; Krishnan, R.; Singh, M.
Biosorption is an efficient and regenerative technique that often uses low-cost adsorbent materials, particularly for the treatment of wastewaters containing dyes and heavy metals. This study investigates the ability of crab shell (Portunus sanguinolentus) to remove reactive red dye in a packed bed up-flow column (internal diameter 2 cm; height 35 cm). Crab shell has high surface area (after proper size reduction) and high regenerative capacity. The experiments were performed with different bed heights (20 and 30 cm) and using different flow rates (12 and 17 ml/min) in order to obtain experimental breakthrough curves. The bed depth service time (BDST) model was used to analyze the experimental data and the model parameters were evaluated. The column regeneration studies were carried out for five different sorption-desorption cycles. The elutant used for the regeneration of the sorbent was 0.01 M EDTA (disodium) solution at pH 9.8 adjusted using NH4OH. This solution was found to have the best bed regeneration capacity and could be reused for several sorption-desorption cycles. The elution efficiency was greater than 99.1% in all seven cycles. Continuous use of the crab shell leads to a decrease in the adsorptive performance, as observed by the breakthrough curves becoming flatter and also because of a broader mass transfer zone. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Bio-conjugation of Bacillus Fastidiosus-Uricase with methoxy polyethylene glycol derivative and study of physiochemical properties
(2012) Nanda, P.; JagadeeshBabu, P.E.; Tekalkote, S.; Kunnummal, B.M.; Kaleekkal, N.
Uricase (EC 1.7.3.3, UC) is an enzyme belonging to the class of oxidoreductases and catalyses the oxidation of uric acid to allantoin, carbon dioxide and hydrogen peroxide. In this present work, Uricase from Bacillus fastidisous was conjugated with methoxypolyethyleneglycol p-nitrophenyl carbonate (mPEG-np) a polyethylene glycol derivative, in order to improve the pharmaceutical properties of therapeutic enzyme uricase. The PEGylated conjugates (uricase-mPEG-np) were synthesized using various ratios of uricase and mPEG-np to get maximum residual activity. The PEGylated uricase showed maximum residual uricolytic activity of 90.9% compared to the unmodified uricase, which was achieved at a ratio of 1:17 of uricase to mPEG-np. PEGylated uricase was further characterized using SDS-PAGE to determine its final molecular weight and approximate number of mPEG molecules attached. The result showed that the molecular weight was increased to 79.4 KDa and the number of mPEG molecules bound per subunit of uricase was approximately 9. Stability of the PEGylated uricase at various temperature and pH was studied and found to be 32°C and pH of 9.0. Further the mechanism of binding and possible sites of binding were studied using molecular modeling and docking software tool ArgusLab 4.0.1 and the two-dimensional image of docked uricase were generated.
Development of a Spectrophotometric Biphasic Assay for the Estimation of mPEG-maleimide in Thiol PEGylation Reaction Mixtures
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2016) Nanda, P.; JagadeeshBabu, P.E.; Gupta, P.; Prasad, A.G.
Methoxy(polyethylene glycol)-maleimide (mPEG-mal) is a PEG derivative used for thiol PEGylation of protein molecules and finds application in drug delivery studies. The maleimide group undergoes degradation in aqueous media, resulting in the difficult quantitative analysis of mPEG-mal. Routinely employed methods for separation and estimation of mPEG-mal include tedious chromatographic methods like ion exchange, high-performance liquid chromatography with refractive index detector and techniques like mass spectrometry and proton nuclear magnetic resonance. We present a direct and reproducible spectrophotometric method to quantify free and protein bound mPEG-mal in thiol PEGylation reaction mixtures. This method is based on the partitioning of a PEG bound chromophore between an aqueous ammonium isoferrothiocyanate phase to a chloroform phase in the presence of mPEG-mal. Several important parameters influencing the partitioning and stability of the chromophore, volume ratios of liquid phases, ethylenediaminetetraacetic acid concentration in the reaction mixture, mixing time, and chlorinated solvents used for partitioning have been studied. © 2016, Copyright © Taylor & Francis Group, LLC.
Drag reduction in co-current down flow packed column using xanthan gum
(2010) Iyyaswami, I.; JagadeeshBabu, P.E.; Chitra, M.; Murugesan, T.
Drag reduction is one of the most important techniques for reducing energy consumption in a packed bed contactor. The present work involves an experimental investigation on flow regime transition for air-water system with and without drag reducing agent (DRA), two-phase pressure drop, friction factor and drag reduction using xanthan gum as DRA. Drag reduction was quantified from the two-phase pressure drop data. Based on the present observations it was found that the percentage drag reduction increases with an increase in the concentration of DRA and it is only effective in the range of 300 ppm to 800 ppm. The experimental results indicate that a maximum of 80% drag reduction was achievable using xanthan gum (800 ppm) as DRA. Furthermore, the experimental data were validated with the available literature correlations. © 2010 Korean Institute of Chemical Engineers, Seoul, Korea.
Enhancement of a Novel Extracellular Uricase Production by Media Optimization and Partial Purification by Aqueous Three-Phase System
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Ram, S.K.; Raval, K.; JagadeeshBabu, P.E.
Uricase (urate: oxygen oxidoreductase, EC 1.7.3.3), an enzyme belonging to the class of oxidoreductases, catalyzes the enzymatic oxidation of uric acid to allantoin and finds a wide variety of application as therapeutic and clinical reagent. In this study, uricase production ability of the bacterial strains isolated from deep litter poultry soil is investigated. The strain with maximum extracellular uricase production capability was identified as Xanthomonas fuscans subsp. aurantifolii based on 16S rRNA sequencing. Effect of various carbon and nitrogen sources on uricase productivity was investigated. The uricase production for this strain was optimized using statistically based experimental designs and resulted in uricase activity of 306 U/L, which is 2 times higher than initial uricase activity. Two-step purification, such as ammonium sulfate precipitation and aqueous two-phase system, was carried out and a twofold increase in yield and specific activity was observed. © 2015 Taylor and Francis Group, LLC.
Equilibrium and kinetic study for the removal of malachite green using activated carbon prepared from Borassus flabellofer male flower
(2010) JagadeeshBabu, P.E.; Kumar, V.; Visvanathan, R.
Activated carbon was prepared from dried Borassus flabellofer male flower and batch adsorption experiments were conducted to study its potential to remove malachite green (MG) dye. The process was further optimized by studying the operating variables like initial pH of the stock solution, activation temperature, initial dye concentration, adsorbent loading and contact time. The optimized pH and activation temperatures were found to be 7.55 and 450.C respectively, where further analysis was made using these optimal variables. Linear, Freundlich and Langmuir isotherms were studied and it was found that the Langmuir isotherms have the highest correlation coefficients compared to the others. Further, the sorption kinetics were analysed using pseudo-first-order and pseudo-second-order kinetic models. The data showed that the second-order equation was the more appropriate, which indicate that the intra-particle diffusion is the rate limiting factor. © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Experimental and Computational Studies on Uricase and Its Bio- Conjugation With Bovine Serum Albumin For Hyperuricemia
(National Institute of Technology Karnataka, Surathkal, 2022) Kumar, N Anand; JagadeeshBabu, P.E.
Hyperuricemia is a significant risk factor for many health conditions like gout, obesity, diabetes, hyperlipidemia, hypertension, and renal disease. Hyperuricemia is generally caused by increased blood uric acid due to a high intake of purine-rich food, decreased renal uric acid removal, or combining the two. Hyperuricemia is described as high blood uric acid level, which further results in the deposition of urate crystals in the joints and kidneys. When the blood uric acid concentration in adult men is above 7.0 mg/dL and in adult women of 6.0 mg/dL, they are said to have hyperuricemia (Maiuolo et al. 2016). Hyperuricemia conditions, including refractory gout, are treated by uricases which effectively eliminate pre-existing uric acid crystals in the joints. Uricases have few drug-drug interactions. Though only uricases effectively treat refractory gout, the current uricase formulations are not appropriate for long-term use (Yang et al. 2012). Uricase is a naturally occurring enzyme (urate oxidase, E.C.1.7.3.3) that catalyzes the conversion of uric acid to allantoin and is a promising therapy for hyperuricemia. Rasburicase and pegloticase are the two major uricase formulations that have been approved for the treatment of hyperuricemia. However, unfortunately, prolonged intake of native form of uricase causes severe immunoreactions due to its foreignness (Garay et al. 2012). In the present research work, we made efforts to use bioinformatics tools to characterize uricase protein sequences from different sources computationally. These protein sequences were subjected to multiple sequence alignment, homology search, domain architecture, motif search, and physiochemical properties. Multiple sequence analysis and homology search results revealed that the amino acid sequences of all the selected sequences have a high degree of similarity. The phylogenetic analysis of all the selected sequences from diverse sources of organisms revealed distinct clusters and demonstrated sequence similarity based on the source of the organism. Each sequence contains six motifs, and each of the twenty-five motifs is unique to its group of uricase sources. The computational physicochemical features of all the selected uricase proteins gave a complete understanding of their properties, namely pI, EC, Ai, ii Ii, GRAVY, and are in the nature of basic properties of these enzymes with 33 kDa- 39 kDa molecular weight. The amino acid valine has the highest average frequency of 8.79 percent in all the selected sources, indicating that it plays a critical role in the formation of uricase. Literature survey shows that several Bacillus species can produce uricase with 25-30 U/ml of activity. The Bacillus fastidious uricase was commercialized by Sigma- Aldrich (product 94310, 9 U/mg) and used for various applications (Pustake et al. 2019a). To expand the usefulness of uricase, it is essential to screen more economical producers of unique properties of novel Bacillus uricase, considering the significance of the enzyme in treating hyperuricemia. The detection and identification of new strains capable of producing uricase have a high demand in the medical field. In this work, an attempt has been made to provide a comprehensive description of computational-based structural, functional, and phylogenetic analyses of uricase enzymes from various Bacillus species. Uricase protein sequences were analyzed for multiple sequence alignment, phylogenetic analysis, motif assessment, domain architecture review, basic physicochemical property understanding, and in-silico identification of uricase amino acid composition. Further, the structural and functional properties of uricase were analyzed. From the analysis, it has been observed that the selected Bacillus uricase proteins are active in an acidic to a neutral environment. CFSSP and PSIPRED were used to predict the secondary structure of uricase, which revealed that it is abundant in alpha helices and sheets. The tertiary structure model of the Bacillus simplex (WP_063232385.1) uricase protein was predicted and validated. Also, all Bacillus species of uricase enzyme and their corresponding genes showed a strong correlation from the phylogenetic comparison of the selected taxa. Due to the antigenicity issue, the clinical application of uricase as an anti- hyperuricemia agent is limited. To develop less immunogenic uricase, in-silico mutagenesis of B-cell and T-cell epitopes have been proposed. The linear B-cell epitopes of Arthrobacter globiformis (Ag)-uricase and Bacillus fastidious (Bf)-uricase were predicted using the Emini surface accessibility, Parker hydrophilicity, and Karplus & Schulz flexibility methods. T159W, D169C, N264W, and Y203D mutations in Ag-uricase resulted in a decreased antigenic probability, whereas S139V, iii K215W, G216F, and I172P mutations in Bf-uricase resulted in a decreased antigenic probability. Uric acid had a binding affinity of -48.71 kcal/mol for the catalytic pocket of Ag-uricase and Bf-uricase models, respectively. This energy is stabilized further in the mutant model by -6.36 kcal/mol for Ag-uricase and -1.45 kcal/mol for Bf-uricase. According to the 100ns MD simulation, both muteins are stable and retained their native-like structural characteristics. The outcome of the above analysis can be a guide for the experimental development of uricase to treat gout and related diseases. Modifications of proteins are the critical biological tools for the production of a wide variety of proteins. Uricase from Bacillus fastidious was successfully conjugated to bovine serum albumin to improve its therapeutic properties. Various molar ratios of bovine serum albumin and glutaraldehyde were conjugated with uricase, and the maximum enzymatic activity of 91.85 percent was obtained at a ratio of 1:6 (mg/ml) uricase: BSA with 0.5 % glutaraldehyde concentration. As determined by the TNBSA assay, the degree of modification indicates that a 1:6 molar ratio of uricase and BSA could result in 76.69 percent of the enzymatic activity. The stability of the conjugated and native uricases was compared at different temperatures (20°C to 60 °C). Likewise, pH stability was investigated at pH values of 7.2 and 9.0. Both native and modified uricase at optimum pH 9.0 shows better retention in enzyme activity after 48 hrs of incubation, which indicates a steady decrease in enzyme activity. The findings of this study indicate that conjugated uricase is effective under physiological conditions, suggesting that it may be a helpful drug for treating hyperuricemia. Considering the potency of the drug for hyperuricemia, this work aims to study the structure, function, and physiochemical properties of uricase by in-silico analysis, and to obtain uricase mutein, an enzyme with reduced immunogenicity, by in-silico mutagenesis. This study also aims to understand the various chemical modifications of the enzyme to enhance its efficacy in treating the disease.
Extraction, optimization and characterization of collagen from sole fish skin
(Elsevier B.V., 2018) Arumugam, G.K.S.; Sharma, D.; Mohan Balakrishnan, R.M.; JagadeeshBabu, P.E.
In this study, collagen was successfully extracted from marine waste i.e. Sole fish skin, which is available in the coastal area of Mangalore, India. The extraction process was optimized using One Variable at a Time (OVAT) and Response Surface Methodology (RSM) with Box-Behnken Design (BBD) was to achieve maximum yield and the extracted collagen was characterized. The optimal conditions to obtain highest collagen yield was determined to be, an acetic acid concentration of 0.54 M, NaCl concentration of 1.90 M, solvent/solid ratio of 8.97 ml/g and time of 32.32 h. The maximum collagen yield of 19.27 ± 0.05 mg/g of fish skin was achieved under the optimal conditions. The analysis of variance and contour plots exhibited a significant interaction of all the selected variables over collagen extraction process. The SDS-PAGE (Sodium dodecyl sulfate - polyacrylamide gel electrophoresis) analysis suggested that the extracted collagen contained three ?-chains i.e. (?1)2, ?2 (M.W. 118, 116 kDa) and one ? chain (M.W. 200 kDa) which was similar to commercially available calfskin Type I collagen. FT-IR (Fourier Transform Infrared Spectroscopy) analysis confirmed the existence of helical arrangements of collagen. SEM (Scanning electron microscopy) observation revealed that the extracted collagen was in the form of fibrils with irregular linkages. © 2018 Elsevier B.V.
In silico structural and functional analysis of bacillus uricases
(Bentham Science Publishers, 2021) Nelapati, A.K.; Meena, S.; Singh, A.K.; Bhakta, N.; JagadeeshBabu, P.E.
Background: Excluding humans, the peroxisomal uricase is responsible for the catabolism of uric acid into allantoin in many species like microorganisms, plants, and inverte-brates. Particularly in humans, the synthesis and excretion of uric acid are naturally balanced. When the uric acid concentration crosses 7 mg/dl, it results in conditions such as hyperuricemia and gout. Uricase is one of the potential sources for the reduction of uric acid in humans. Uricase is also widely used as a commercial diagnostic reagent in medical and clinical biochemistry to esti-mate the uric acid concentration in blood and other biological fluids. Computational approaches can be used for screening and investigation of uricase enzyme with desirable characteristics that can be employed in diverse industrial applications. Objectives: The present study deals with computational-based structural, functional, and phylogenetic analyses of uricase enzymes from various Bacillus species. Methods: Seventy uricase protein sequences from Bacillus species were selected for multiple sequence alignment, phylogenetic analysis, motif assessment, domain architecture examination, understanding of basic physicochemical properties and in silico identification of the composition of amino acids in uricase. Further, structural (secondary and tertiary structure prediction), and functional (CYS_REC, MOTIF scan, CD-search, STRING, SOSUI, and PeptideCutter) analyses of uric-ase were performed. Results: Bacillus simplex (WP_063232385.1) was chosen as the representative species of the Bacillus genera. The three-dimensional (3D) structure of B. simplex uricase was predicted and validated using QMEAN, RAMPAGE, ERRAT, Verify 3D and PROQ servers. The analysis revealed that the tertiary structure of the selected uricase has good quality and acceptability. Conclusion: Computational analysis of uricase from various Bacillus sources revealed that all the selected Bacillus uricases are active within acidic to a neutral environment, and thermally stable with a molecular weight ranging from 35.59-59.85kDa. The secondary structure analysis showed that all uricases are rich in alpha-helices and sheets. The CDD tool identified two conserved do-mains, one of which belongs to OHCU decarboxylase and another belongs to Uricase superfamily. The quality estimation of 3D modeled protein gave a high overall quality factor score of 94.64. Al-so, all Bacillus species of uricase enzyme and their corresponding genes showed a strong correlation from the phylogenetic comparison of the selected taxa. The present detailed computational investigation on the uricase protein could help in screening a suitable uricase producing microbe with desirable characteristics for industrial application. © 2021 Bentham Science Publishers.
Isolation, screening and production studies of uricase producing bacteria from poultry sources
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Nanda, P.; JagadeeshBabu, P.E.
Uricase (urate oxidase EC 1.7.3.3) is a therapeutic enzyme that is widely used to catalyze the enzymatic oxidation of uric acid in the treatment of hyperuricemia and gout diseases. In this study, three bacterial species capable of producing extracellular uricase were isolated from a poultry source and screened based on the size of the clear zone using a uric acid agar plate. The bacterial species capable of producing uricase with the highest uricolytic activity was identified as Bacillus cereus strain DL3 using a 16SrRNA gene sequencing approach. The time-course study of uricase production was performed and the medium was optimized. Carboxymethylcellulose and asparagine were found to be the best carbon and nitrogen sources. Maximum uricolytic activity was observed at pH 7.0 with an inducer concentration of 2.0 g/L. Inoculum size of 5% gave maximum uricolytic activity. The maximum uricolytic activity of 15.43 U/mL was achieved at optimized conditions, which is 1.61 times more than the initial activity. Further, enzymatic stability was determined at different pH and temperature. © 2014 Taylor and Francis Group, LLC.
Kinetics of esterification of acetic acid with methanol in the presence of ion exchange resin catalysts
(2011) JagadeeshBabu, P.E.; Sandesh, K.; Saidutta, M.B.
Esterification kinetics of acetic acid with methanol was studied with solid acid catalyst in an isothermal batch reactor at 333-353 K. Different types of ion exchange catalyst (Indion 130, Indion 190, and Amberlyst 15 wet) were used for the esterification of acetic acid. It was found that Indion 130 was an effective catalyst for acetic acid esterification. The effects of stirrer speed, reaction temperature, initial reactant concentration, and catalyst loading on reaction rate were investigated and optimized. Temperature dependence of the reaction rates and activation energies was determined by an Arrhenius plot. A complete kinetic equation for describing the reaction catalyzed by Indion 130 was developed. This equation can be used in the simulation and design of the catalytic distillation column for the synthesis of methyl acetate. © 2011 American Chemical Society.
Mechanistic insight into the endophytic fungus mediated synthesis of protein capped ZnO nanoparticles
(Elsevier Ltd, 2019) Kadam, V.V.; JagadeeshBabu, P.E.; Mohan Balakrishnan, R.
Present investigation is focused on the development of environment friendly protocol for ZnO nanoparticles synthesis using mycelial free filtrate of unexplored endophytic fungus Cochliobolus geniculatus. Zinc metal tolerant endophyte was isolated from leaves of Nothapodytes foetida and identified based on rDNA internal transcribed spacer region sequence. Surface plasmon resonance examined by UV–VIS spectroscopy analysis confirmed the synthesis of ZnO nanoparticles; exhibiting a band gap of 3.28 eV. The obtained nanoparticles were characterized by energy dispersive X-ray (EDX), high resolution transmission electron microscopy and XRD analysis. The synthesized ZnO nanoparticles were found to be polydispersed and well distributed deprived of agglomeration, crystalline, quasi spherical particles exhibiting a narrow range distribution. Fluorescence, FTIR and UV–VIS spectra depicted presence of extracellular proteins which was further confirmed by SDS-PAGE study that displayed occurrence of 52 kDa and 58 kDa protein bands involved in the synthesis of ZnO nanoparticles and further act as capping material. © 2019 Elsevier B.V.
One step synthesis of silver nanowires using fructose as a reducing agent and its antibacterial and antioxidant analysis
(Institute of Physics Publishing helen.craven@iop.org, 2019) Sharma, D.; Rakshana, D.A.; Mohan Balakrishnan, R.M.; JagadeeshBabu, P.E.
Silver nanowires were synthesised using hydrothermal method by reducing silver nitrate (AgNO3) using fructose in the presence of poly-vinylpyrrolidone (PVP). The parameters such as the effect of process temperature, AgNO3 molarity, PVP and fructose (C6H12O6) concentration influencing the synthesis of silver nanowires (Ag NWs) were investigated. The scanning electron microscope (SEM) images showed that ultra-long, uniform and thin silver nanowires were obtained under optimized conditions; 0.02 M AgNO3, 0.016 g ml-1 of fructose, 0.16 g ml-1 of PVP at 160 °C within 22 h. The dynamic light scattering (DLS) analysis revealed that the silver nanowires obtained have an average diameter of 77 nm possessing high level of crystallinity with face centered cubic (fcc) phase that is evident from the x-ray diffraction (XRD) patterns peaked at (111), (200), (220), (311) and (222) planes. FT-IR (Fourier transform infrared spectroscopy) results suggested that there is adsorption of PVP molecules on the silver atoms. Ag NWs exhibited better antibacterial activity against Escherichia coli and high antioxidant activity against 2,2-diphenyl-1- picrylhydrazyl (DPPH) free radical scavenger. This work gives a green approach to the hydrothermal synthesis of Ag NWs using fructose with a promising antibacterial and antioxidant properties. © 2019 IOP Publishing Ltd.
Performance enhancement of polysulfone ultrafiltration membrane using TiO2 nanofibers
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2016) Nair, A.K.; Shalin, P.M.; JagadeeshBabu, P.E.
Titanium dioxide nanofibers were synthesized via alkaline hydrothermal method using TiO2 nanopowder. The hydrothermal method was optimized by studying the operating variables to obtain nanosized TiO2 fibers. These nanofibers were used to make composite polysulfone ultrafiltration membranes along with polyethylene glycol as pore forming agent. The obtained samples were characterized using scanning electron microscope, X-ray diffraction, and attenuated total reflectance infrared spectroscopy. Contact angle measurements were used to estimate hydrophilicity of the membrane. Performance of the membrane was analyzed using pure water flux studies and antifouling studies with bovine serum albumin as the standard protein for rejection. The composite membranes exhibited better performance in both permeability and antifouling property. © 2015 Balaban Desalination Publications. All rights reserved.
Photocatalytic degradation of diclofenac using TiO2–SnO2 mixed oxide catalysts
(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Mugunthan, E.; Saidutta, M.B.; JagadeeshBabu, P.E.
The complex nature of diclofenac limits its biological degradation, posing a serious threat to aquatic organisms. Our present work aims to eliminate diclofenac from wastewater through photocatalytic degradation using TiO2–SnO2 mixed-oxide catalysts under various operating conditions such as catalyst loading, initial diclofenac concentration and initial pH. Different molar ratios of Ti–Sn (1:1, 5:1, 10:1, 20:1 and 30:1) were prepared by the hydrothermal method and were characterized. The results indicated that addition of Sn in small quantity enhances the catalytic activity of TiO2. Energy Band gap of the TiO2–SnO2 catalysts was found to increase with an increase in Tin content. TiO2–SnO2 catalyst with a molar ratio of 20:1 was found to be the most effective when compared to other catalysts. The results suggested that initial drug concentration of 20 mg/L, catalyst loading of 0.8 g/L and pH 5 were the optimum operating conditions for complete degradation of diclofenac. Also, the TiO2–SnO2 catalyst was effective in complete mineralization of diclofenac with a maximum total organic carbon removal of 90% achieved under ultraviolet irradiation. The repeatability and stability results showed that the TiO2–SnO2 catalyst exhibited an excellent repeatability and better stability over the repeated reaction cycles. The photocatalytic degradation of diclofenac resulted in several photoproducts, which were identified through LC-MS. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group.
Production and Optimization of Site-Specific monoPEGylated Uricase Conjugates Using mPEG-Maleimide Through RP–HPLC Methodology
(Springer New York LLC barbara.b.bertram@gsk.com, 2016) Nanda, P.; JagadeeshBabu, P.E.; Raju, J.R.
Purpose: Uricase (Uc), a therapeutic enzyme, is widely used in its PEGylated form to treat hyperuricemia and is largely manufactured by means of random/first generation PEGylation approach. Currently available randomly PEGylated uricase conjugates exhibit inadequacies like reduced uricolytic activity, risk of inducing immunogenic reactions, lack of selectivity, and molecular heterogeneity. In the present study, site-specific/second generation PEGylation strategy involving modification of specific and rare amino acids by means of terminally functionalized PEG polymers was applied. Methods: Uricase was conjugated with methoxypolyethyelenglycol-maleimide (mPEG-mal) by means of thiol PEGylation to synthesize monoPEGylated uricase conjugates. For enhancing the yield of monoPEGylated uricase conjugates, response surface methodology was employed to determine the yield of monoPEGylated conjugates using reverse phase high performance liquid chromatography. Using the optimized conditions, the developed method was validated for the production of monoPEGylated uricase conjugates which were further purified by size exclusion fast protein liquid chromatography (SE-FPLC). The molecular weights of the purified conjugates were determined by sodium dodecyl sulfide polyacrylamide gel electrophoresis (SDS-PAGE). Results: The optimum values of reaction conditions were determined as 1:12 concentration ratio of Uc to mPEG-mal, 2.76 kDa as mPEG-mal molecular weight and 3.55 mM EDTA concentration which resulted in a very high conjugate yield of 95.16 %. The conjugate synthesized using the optimized method retained a residual uricolytic activity of 84 % and a thiol group modification extent of 68.3 %. Conclusion: The PEGylation reaction was optimized using OVAT and statistical methods. Using the optimized conditions very high yield of conjugates were obtained and RP–HPLC method was used to quantify the PEGylated uricase. © 2016, Springer Science+Business Media New York.
Rapid removal of cobalt (II) from aqueous solution using cuttlefish bones; Equilibrium, kinetics, and thermodynamic study
(2013) Sandesh, K.; Suresh Kumar, R.; JagadeeshBabu, P.E.
The objective of this study is to assess the adsorption potential of cobalt (II) using cuttlefish bones. The bones were treated with 0.01 N HCl to enhance the heavy metal uptake. The adsorbent was characterized using scanning electron microscope and energy dispersive X-ray spectrometer. An adsorption study was conducted in a batch system to optimize process variables such as initial concentration of cobalt (II), pH, sorbent loading, particle size, process temperature, and contact time. The optimal pH was found to be 9. The kinetic data followed the pseudosecond-order kinetic model, and the equilibrium time was found to be 20 min. In the first minute of the adsorption process, 50% of the cobalt (II) was adsorbed by the cuttle bones. Adsorption isotherms were expressed by the Langmuir and Freundlich adsorption models. The Langmuir adsorption model fits the experimental data reasonably well compared with the Freundlich model. The maximum adsorption capacity of this new sorbent was found to be 76.6 mg g-1 at 40 °C. Thermodynamic parameters, including the Gibbs free energy (?Go), enthalpy (?Ho), and entropy (?So), indicated that the adsorption of cobalt (II) by cuttlefish bones was feasible and endothermic at a temperature range of 20-40 °C. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Reactive distillation using an ion-exchange catalyst: Experimental and simulation studies for the production of methyl acetate
(2013) Sandesh, K.; JagadeeshBabu, P.E.; Math, S.; Saidutta, M.B.
In this study, the performance of a packed-bed reactive distillation (RD) column for the production of methyl acetate (MeOAc) using an ion-exchange catalyst and simulation of the same using CHEMCAD were analyzed. An ion-exchange catalyst, Indion 190, was used in this study. The performance of the RD column was evaluated based on the MeOAc concentration in the top product. Both steady- and unsteady-state behavior of the column was simulated using CHEMCAD, and the results were experimentally validated. The process parameters, viz., reboiler temperature, enriching temperature, reactor temperature, catalyst loading, molar ratio of the reactant, and flow rate of reactants, were studied, and the optimal values were found to be 73 C, 56 C, 72 C, 100 g, 1:2, and 15 mL/min, respectively. Feed locations of acid and alcohol to the reactor that gave maximum MeOAc concentration in the top product were determined. A mathematical model based on the rigorous calculation using SCDS (used to calculate the nonideal K value) was used to simulate the RD in CHEMCAD. The simulated values were found to deviate from the experimental values within ±5-10%. © 2013 American Chemical Society.
Role of graphene quantum dots synthesized through pyrolysis in the release behavior of temperature responsive poly (N,N-diethyl acrylamide) hydrogel loaded with doxorubicin
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2018) Havanur, S.; JagadeeshBabu, P.E.
We have reported the synthesis and characterization of new drug carrier using Poly (N,N-diethyl acrylamide) (PDEA) and graphene quantum dots (GQDs). PDEA is a stimuli-responsive, macroporous polymer which has the ability to respond to change in surrounding temperature and addition of GQDs will help in improving the inherent characteristics of PDEA. In this research work, PDEA hydrogels along with GQDs have been synthesized by free radical polymerization. The effect of various concentrations of GQDs on the property of PDEA hydrogel was studied. The structural analysis of synthesized hydrogels was done using Fourier transform infrared spectroscopy (FT–IR). The internal surface morphology of porous hydrogels was observed using scanning electron microscope (SEM) micrographs. From the analysis, it has been observed that the equilibrium swelling ratio (ESR) and reswelling kinetics of the hydrogel significantly increased as the GQDs content was varied. The cancer drug (an anthracycline that is used for cancer chemotherapy) Doxorubicin (DOX) release behavior was studied and found that the performance of hydrogel is dependent on hydrogel composition, time, and surrounding temperature. The cytotoxicity of GQDs incorporated PDEA hydrogels gave a significant report which supports the potential application of hydrogel as an intelligent drug carrier. © 2018, © 2018 Taylor & Francis Group, LLC.