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1.
World Neurosurg ; 182: e847-e853, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38101538

ABSTRACT

OBJECTIVE: Surgeons commonly perform Decompressive craniectomy (DC) to manage patients with cerebral ischemic infarction. However, there are conflicting data on the long-term functional outcomes following DC. Therefore, this study aims to determine the functional outcome of patients with cerebral ischemic infarction after DC. METHODS: This prospective and retrospective cross-sectional study included 148 patients with cerebral ischemic infarction who underwent DC at Ghaem Hospital, Mashhad, Iran, from March 2011 to March 2021. The Modified Rankin Scale (mRS) assesses disability in these patients and determines the recovery and degree of long-term functional outcomes. Demographic and clinical data were extracted and recorded in a researcher-made questionnaire. RESULTS: In summary, the follow-up revealed a survival rate of 39.2% among patients with ischemic stroke. The comparison of the mean infarct volume in patients with various mRS scores showed that the mean infarct volume was significantly higher in patients with unfavorable functional outcomes, based on mRS scores at discharge (P = 0.05), 3 months mRS (P < 0.01), and mRS score at final follow-up (P = 0.01). Final mortality was higher in patients with higher mRS scores at discharge, after 3 months, and final follow-up (P < 0.01). Older age and infarction volume can predict mRS and mortality in patients with ischemic stroke (P < 0.01). CONCLUSIONS: The present study showed that mortality and mRS scores at various times are associated with infarction volume and older age in patients with ischemic stroke.


Subject(s)
Decompressive Craniectomy , Ischemic Stroke , Humans , Treatment Outcome , Cross-Sectional Studies , Infarction, Middle Cerebral Artery/surgery , Retrospective Studies , Prospective Studies , Ischemic Stroke/surgery
2.
RSC Adv ; 13(25): 17449-17464, 2023 Jun 05.
Article in English | MEDLINE | ID: mdl-37313518

ABSTRACT

In this study, a new palladium nanocatalyst was supported on l-threonine functionalized magnetic mesocellular silica foams (MMCF@Thr-Pd) and was characterized by FT-IR, XRD, BET, SEM, EDS, VSM, TGA, ICP-OES and elemental mapping techniques. The obtained MMCF@Thr-Pd performance can show excellent catalytic activity for Stille, Suzuki, and Heck coupling reactions, and the corresponding products were obtained with high yields. More importantly, the efficient and stable MMCF@Thr-Pd nanocatalyst was recovered by applying an external magnetic field and reused for at least five consecutive runs without a change in the catalytic activity.

3.
Nanoscale Adv ; 4(9): 2208-2223, 2022 May 03.
Article in English | MEDLINE | ID: mdl-36133448

ABSTRACT

In this work, magnetic mesocellular foam (M-MCF) silica nanoparticles were prepared via inserting magnetic nanoparticles into the pores of mesocellular foams, the inner surface of which was functionalized with a methionine-nickel complex (M-MCF@Met-Ni). The structure of the as-prepared nanocatalysts was studied by FT-IR spectroscopy, BET, TGA, VSM, SEM, HR-TEM, EDS, WDX, XRD, and ICP-OES techniques. Thereafter, this nanocatalyst was used as a new, effective, and magnetically reusable catalyst for C-S and C-Se bond formation under mild conditions. All corresponding products were prepared with good yields and appropriate turnover number (TON) and turnover frequency (TOF), which reveals the high activity of this magnetic nanocatalyst in both reactions. In addition, the recovery and hot filtration tests indicated that this catalyst could be simply separated from the reaction mixture using an outside magnet and reused five consecutive times without any significant loss of its catalyst activity or metal leaching.

4.
Org Biomol Chem ; 20(22): 4625-4634, 2022 06 08.
Article in English | MEDLINE | ID: mdl-35609285

ABSTRACT

Three novel and efficient protocols for the synthesis of phenyl aryl selenides through a three-component coupling reaction of triphenyltin chloride with aryl halides, phenolic esters or nitroarenes, and Se powder catalyzed by CuI or Cu(OAc)2 in the presence of a base in PEG200 at 90-100 °C have been developed. Also, NiFe2O4 as a magnetically reusable nanocatalyst was applied in these reactions under similar reaction conditions. The present methods are superior to other currently available methods due to the use of triphenyltin chloride/Se as a phenylselenating agent and phenolic esters and nitroarenes as a coupling partner for C-Se-C bond formation for the first time, a green solvent and inexpensive and reusable catalysts, and avoidance of any toxic and expensive arylselenating reagents.


Subject(s)
Organotin Compounds , Transition Elements , Catalysis , Esters , Molecular Structure
5.
BMC Biotechnol ; 21(1): 51, 2021 08 16.
Article in English | MEDLINE | ID: mdl-34399745

ABSTRACT

BACKGROUND: Human Growth Hormone (hGH) is a glycoprotein released from the pituitary gland. Due to the wide range of effects in humans, any disruption in hGH secretion could have serious consequences. This highlights the clinical importance of hGH production in the treatment of different diseases associated with a deficiency of this hormone. The production of recombinant mature hormone in suitable hosts and secretion of this therapeutic protein into the extracellular space can be considered as one of the best cost-effective approaches not only to obtain the active form of the protein but also endotoxin-free preparation. Since the natural growth hormone signal peptide is of eukaryotic origin and is not detectable by any of the Escherichia coli secretory systems, including Sec and Tat, and is therefore unable to secrete hGH in the prokaryotic systems, designing a new and efficient signal peptide is essential to direct hGh to the extracellular space. RESULTS: In this study, using a combination of the bioinformatics design and molecular genetics, the protein A signal peptide from Staphylococcus aureus was modified, redesigned and then fused to the mature hGH coding region. The recombinant hGH was then expressed in E. coli and successfully secreted to the medium through the Sec pathway. Secretion of the hGH into the medium was verified using SDS-PAGE and western blot analysis. Recombinant hGH was then expressed in E. coli and successfully secreted into cell culture medium via the Sec pathway. The secretion of hGH into the extracellular medium was confirmed by SDS-PAGE and Western blot analysis. Furthermore, the addition of glycine was shown to improve hGH secretion onto the culture medium. Equations for determining the optimal conditions were also determined. Functional hGH analysis using an ELISA-based method confirmed that the ratio of the active form of secreted hGH to the inactive form in the periplasm is higher than this ratio in the cytoplasm. CONCLUSIONS: Since the native signal protein peptide of S. aureus protein A was not able to deliver hGH to the extracellular space, it was modified using bioinformatics tools and fused to the n-terminal region of hGh to show that the redesigned signal peptide was functional.


Subject(s)
Escherichia coli/genetics , Gene Expression , Human Growth Hormone/genetics , Human Growth Hormone/isolation & purification , Staphylococcal Protein A/genetics , Culture Media/chemistry , Culture Media/metabolism , Escherichia coli/metabolism , Human Growth Hormone/metabolism , Humans , Protein Sorting Signals , Protein Transport , Recombinant Proteins/genetics , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Staphylococcal Protein A/metabolism
6.
RSC Adv ; 10(24): 14254-14261, 2020 Apr 06.
Article in English | MEDLINE | ID: mdl-35498453

ABSTRACT

The current study applied laccase/DDQ as a bioinspired cooperative catalytic system for the synthesis of quinazolinones (80-95% yield) and benzothiazoles (65-98% yield) using air or O2 as ideal oxidants in aqueous media at ambient temperature. The aerobic oxidative cyclization reactions occur in two steps: (i) chemical cyclization; (ii) chemoenzymatic oxidation. These methods are more environment-friendly, efficient, simple and practical than other reported methods due to the use of O2 as an oxidant, laccase as an eco-friendly biocatalyst, aqueous media as the solvent and free from any toxic transition metal and halide catalysts. Therefore, these methods can be applied in pharmaceutical and other sensitive synthetic procedures.

7.
J Hazard Mater ; 385: 121573, 2020 03 05.
Article in English | MEDLINE | ID: mdl-31761649

ABSTRACT

Woodlice and the earthworm alone or in combination were used to improve physical properties, nutrient release, and heavy metals stabilization during composting of sewage sludge. Chemical properties of raw sludge (IS) were compared to those of composted sludge (CS), sludge + earthworms (VS), sludge + woodlice (WS), and sludge + earthworms + woodlice (VWS) after 50 and 100 days of composting. Physical properties and heavy metals accumulation by the studied fauna was determined after 100 days of composting. Highest proportions of fine particles, porosity and water holding capacity were in the VWS treatment, electrical conductivity, ash content, inorganic N and the total concentrations of P, K, Ca and Mg increased, whereas the pH value, the organic C, C:N ratio and humic acids content decreased in following order: VWS > VC > WS > CS > IS. Total concentrations of Pb, Cd and Ni in composted sludge were lower whereas concentrations of Zn, Cu and Mn were higher than in raw sludge, and woodlice showed higher bioconcentration factor (BCFs) than earthworm for all heavy metals in all treatments. We concluded that woodlice and earthworms synergistically improved the physicochemical properties of the compost and enhanced its potential use as amendment in agricultural soils.


Subject(s)
Biodegradation, Environmental , Environmental Pollutants/metabolism , Isopoda/metabolism , Metals, Heavy/metabolism , Oligochaeta/metabolism , Sewage/chemistry , Animals
8.
Cell Biol Int ; 42(12): 1688-1694, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30238552

ABSTRACT

Neural differentiation involves drastic morphological alterations, essentially performed by a cell-homeostasis maintaining process known as autophagy. Here, we used the cocktail of choroid plexus epithelial cell-conditioned medium (CPEC-CM) and 15% knockout serum (KS) to induce human adipose-derived mesenchymal stem cells (hASCs) into tyrosine hydroxylase (TH)-positive neuron like cells. We showed that upon this induction, autophagy pathway was transcriptionally triggered. The expression levels of autophagy markers mTOR, BECN1, and MAP1LC3 were evidently changed throughout the dopaminergic (DAergic) differentiation of hASCs, highlighting the critical role of autophagy in this process at the level of transcription.


Subject(s)
Adipose Tissue/cytology , Autophagy/genetics , Dopaminergic Neurons/cytology , Mesenchymal Stem Cells/cytology , Transcriptional Activation/genetics , Adipocytes/cytology , Adipocytes/metabolism , Adult , Biomarkers/metabolism , Cell Differentiation/genetics , Cell Separation , Dopaminergic Neurons/metabolism , Female , Humans , Mesenchymal Stem Cells/metabolism , Middle Aged , Osteocytes/cytology , Osteocytes/metabolism , Young Adult
9.
AMB Express ; 8(1): 107, 2018 Jun 30.
Article in English | MEDLINE | ID: mdl-29961206

ABSTRACT

Sortases are enzymes mostly found in Gram-positive bacteria which cleave proteins site-specifically. This feature makes them a promising tool in molecular biology and biotechnology. In this study, using bacterial surface display of recombinant proteins and ability of sortase A in site-specifically cleavage of the amino acid sequences, a novel method for one-step purification of recombinant proteins was developed. Using computational program tools, a chimeric protein containing a metallothionein (mt) and chitin binding domain (ChBD) was attached to the C-terminal domain of the truncated outer membrane protein A (Lpp'-ompA) using sortase recognition site (amino acid residues: LPQTG) as a separator. The structure of the chimeric protein was simulated using molecular dynamics to determine if the LPQTG motif is accessible to the sortase active site. The designed chimeric protein was expressed and purified. The purified chimeric protein was also displayed on the surface of E. coli cells. Both purified chimeric protein and the E. coli cells displaying Lpp'-ompA-mt-ChBD carrier protein were then treated with sortase to evaluate the efficiency of sortase-mediated cleavage of purified chimeric protein as well as surface displayed-chimeric protein. It is shown that mt-ChBD protein was successfully cleaved and dissociated from Lpp'-ompA carrier and released into the medium after treatment with sortase in both recombinant protein and surface displayed-chimeric protein. The experimental results confirmed the molecular dynamics analysis results. The presented method could be regarded as a novel strategy for one step expression and purification of recombinant proteins.

10.
Iran J Biotechnol ; 16(3): e1284, 2018 Aug.
Article in English | MEDLINE | ID: mdl-31457020

ABSTRACT

BACKGROUND: Considering natural thermal stability, Geobacillus stearothermophilus amylase and Cel5E from Clostridium thermocellum are good candidates for industrial applications. To be compatible with the industrial applications, this enzyme should be stable in the high temperatures, so any improvement in their thermal stability is valuable. OBJECTIVES: Using in silico approach and identifying point mutations in the structure amylase of G. stearothermophilus and Cel5E from C. termocellum we tried to increase thermal stability of the enzymes along with their catalytic activity to reach a new industrial amylase with higher thermostability and an improved function. MATERIALS AND METHODS: In this study we predicted the 3D structure of the enzymes, then simulated the molecular docking study using MolDock, PLANTS, and Lamarkian genetic algorithm as scoring functions for the docking and in silico engineering of the protein aiming to increase the thermal stability and catalytic activity. RESULTS: A series of thermal stability increasing point mutations were exerted around the active site of the enzyme, then by docking procedure, the binding affinity was measured and finally a list of mutations which theoretically improved the increased thermal stability as well as catalytic activity were proposed. CONCLUSIONS: Based on the in silico results obtained the modified enzymes seems to be suitable candidates for considering in both laboratory and industrial scales.

11.
Sci Rep ; 7(1): 5760, 2017 07 18.
Article in English | MEDLINE | ID: mdl-28720783

ABSTRACT

In this paper, multiple linear regression (MLR) was used to build quantitative structure property relationship (QSPR) of n-octanol-water partition coefficient (logPo/w) of 195 substituted aromatic drugs. The molecular descriptors were calculated for each compound by the VLifeMDS. By applying genetic algorithm/multiple linear regressions (GA/MLR) the most relevant descriptors were selected to build a QSPR model. The robustness of the model was characterized by the statistical validation and applicability domain (AD). The prediction results from MLR are in good agreement with the experimental values. The R2 and Q2LOO for MLR are 0.9433, 0.9341. The AD of the model was analyzed based on the Williams plot. The effects of different selected descriptors are described.

12.
Pestic Biochem Physiol ; 140: 17-23, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28755689

ABSTRACT

BACKGROUND: Chitinases can inhibit the growth of many fungal diseases which are a great threat for global agricultural production. Biological control of pathogens like fungi, is believed to be one of the best ways to eliminate the adverse effects of plant pathogens. To this end, we expressed and displayed a chitinase from Bacillus pumilus (ChiS) on the surface of Bacillus subtilis spores, as a biocontrol agent. RESULT: ChiS enzyme from B. pumilus was expressed on the spores of B. subtilis using CotG as a carrier protein. Immunofluorescence microscopy confirmed the expression of ChiS on the surface of the spores. Enzyme activity assay showed that the surface displayed ChiS was active and was also able to inhibit the growth of Rhizoctonia solani and Trichoderma harzianum fungi. Western blot analysis also indicated that CotG-ChiS is partially processed after display. Molecular dynamics simulation showed that the stability of the heterologous protein was decreased after fusion. CONCLUSION: ChiS was successfully displayed on the surface of Bacillus spores by fusion to the CotG, one of the main spore coat proteins. In-vitro experiments showed that the displayed enzyme was effective in growth inhibition of R. solani and T. harzianum fungi.


Subject(s)
Antifungal Agents/pharmacology , Bacillus pumilus/enzymology , Bacillus subtilis/metabolism , Chitinases/pharmacology , Spores, Bacterial/metabolism , Antifungal Agents/chemistry , Biological Control Agents/pharmacology , Chitinases/metabolism , Gene Expression Regulation, Bacterial , Gene Expression Regulation, Enzymologic , Rhizoctonia/drug effects , Trichoderma/drug effects
13.
Protein Eng Des Sel ; 30(1): 39-45, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27887025

ABSTRACT

Necrotic enteritis is an economically important disease of poultry mainly caused by Clostridium perfringens The bacteria release multiple toxins of which NetB, alpha toxin and TpeL have been reported to play important roles in pathogenicity and/or severity of the disease. In this study, the sequence of clostridial toxins NetB, alpha toxin and TpeL were analyzed using bioinformatics tools to determine protein domains with high immunogenicity factor. Several chimeric trivalent proteins consisting of the immunogenic regions of the three toxins were designed and evaluated. The separate regions were fused together using rigid linkers. Based on a modeled tertiary structure, a proper combination was selected and expressed in a bacterial host (Escherichia coli) and successfully purified. The expression of the chimeric protein was further verified by western blotting. The ability of the immunized serum in recognizing each individual subunit of the chimeric protein was also examined. Circular dichroism was used to evaluate the predicted secondary structure of the chimeric protein. In vitro potency test demonstrated that the serum from a rabbit immunized with the chimeric protein is able to partially neutralize Alpha toxin, hence the construct can potentially be used as a vaccine against C. perfringens.


Subject(s)
Bacterial Toxins/genetics , Bacterial Toxins/immunology , Bacterial Vaccines/genetics , Chickens/microbiology , Clostridium perfringens/physiology , Enteritis/prevention & control , Protein Engineering/methods , Animals , Bacterial Toxins/chemistry , Bacterial Vaccines/chemistry , Bacterial Vaccines/immunology , Cloning, Molecular , Clostridium perfringens/immunology , Escherichia coli/genetics , Gene Expression , Immunization , Models, Molecular , Protein Domains , Protein Structure, Secondary , Rabbits
14.
J Lasers Med Sci ; 7(2): 120-5, 2016.
Article in English | MEDLINE | ID: mdl-27330708

ABSTRACT

INTRODUCTION: The effects of electromagnetic fields on biological organisms have been a controversial and also interesting debate over the past few decades, despite the wide range of investigations, many aspects of extremely low frequency electromagnetic fields (ELF/EMFs) effects including mechanism of their interaction with live organisms and also their possible biological applications still remain ambiguous. In the present study, we investigated whether the exposures of ELF/EMF with frequencies of 3 Hz and 60 Hz can affect the memory, anxiety like behaviors, electrophysiological properties and brain's proteome in rats. METHODS: Male rats were exposed to 3 Hz and 60 Hz ELF/EMFs in a protocol consisting of 2 cycles of 2 h/day exposure for 4 days separated with a 2-day interval. Short term memory and anxiety like behaviors were assessed immediately, 1 and 2 weeks after the exposures. Effects of short term exposure were also assessed using electrophysiological approach immediately after 2 hours exposure. RESULTS: Behavioral test revealed that immediately after the end of exposures, locomotor activity of both 3 Hz and 60 Hz exposed groups significantly decreased compared to sham group. This exposure protocol had no effect on anxiety like behavior during the 2 weeks after the treatment and also on short term memory. A significant reduction in firing rate of locus coeruleus (LC) was found after 2 hours of both 3 Hz and 60 Hz exposures. Proteome analysis also revealed global changes in whole brain proteome after treatment. CONCLUSION: Here, some evidence regarding the fact that such exposures can alter locomotor activity and neurons firing rate in male rats were presented.

15.
Adv Biomed Res ; 5: 41, 2016.
Article in English | MEDLINE | ID: mdl-27099854

ABSTRACT

BACKGROUND: Fibrocyte-specific protein, otospiralin, is a small protein, widely expressed in the central nervous system as neuronal cell bodies and glia. The increased expression of otospiralin in reactive astrocytes implicates its role in signaling pathways and reparative mechanisms subsequent to injury. Indeed, otospiralin is considered to be essential for the survival of fibrocytes of the mesenchymal nonsensory regions of the cochlea. It seems that other functions of this protein are not yet completely understood. MATERIALS AND METHODS: Amino acid sequences of otospiralin from 12 vertebrates were derived from National Center for Biotechnology Information database. Phylogenetic analysis and phylogeny estimation were performed using MEGA 5.0.5 program, and neighbor-joining tree was constructed by this software. RESULTS: In this computational study, the phylogenetic tree of otospiralin has been investigated. Therefore, dendrograms of otospiralin were depicted. Alignment performed in MUSCLE method by UPGMB algorithm. Also, entropy plot determined for a better illustration of amino acid variations in this protein. CONCLUSION: In the present study, we used otospiralin sequence of 12 different species and by constructing phylogenetic tree, we suggested out group for some related species.

16.
J Org Chem ; 80(17): 8694-704, 2015 Sep 04.
Article in English | MEDLINE | ID: mdl-26272238

ABSTRACT

In this article, we report three odorless methods for the thioarylation and thioalkylation of different nitroarenes using alkyl halides (Br, Cl), triphenyltin chloride, and arylboronic acids as the coupling partners. Triphenyltin chloride is capable of delivering all of its phenyl groups to the product. Depending on the reaction, sodium thiosulfate pentahydrate (Na2S2O3·5H2O), S8/KF, and S8/NaOH systems are found to be effective sources of sulfur in the presence of copper salts. The use of green solvents, inexpensive catalysts, and user-friendly starting materials has made these methods interesting from a green chemistry standpoint.

17.
Br J Clin Pharmacol ; 80(5): 1021-30, 2015 Nov.
Article in English | MEDLINE | ID: mdl-25917170

ABSTRACT

AIMS: The aim of the present study was to evaluate the disposition of metoprolol after oral administration of an immediate and controlled-release formulation before and after Roux-en-Y gastric bypass (RYGB) surgery in the same individuals and to validate a physiologically based pharmacokinetic (PBPK) model for predicting oral bioavailability following RYGB. METHODS: A single-dose pharmacokinetic study of metoprolol tartrate 200 mg immediate release and controlled release was performed in 14 volunteers before and 6-8 months after RYGB. The observed data were compared with predicted results from the PBPK modelling and simulation of metoprolol tartrate immediate and controlled-release formulation before and after RYGB. RESULTS: After administration of metoprolol immediate and controlled release, no statistically significant difference in the observed area under the curve (AUC(0-24 h)) was shown, although a tendency towards an increased oral exposure could be observed as the AUC(0-24 h) was 32.4% [95% confidence interval (CI) 1.36, 63.5] and 55.9% (95% CI 5.73, 106) higher following RYGB for the immediate and controlled-release formulation, respectively. This could be explained by surgery-related weight loss and a reduced presystemic biotransformation in the proximal gastrointestinal tract. The PBPK values predicted by modelling and simulation were similar to the observed data, confirming its validity. CONCLUSIONS: The disposition of metoprolol from an immediate-release and a controlled-release formulation was not significantly altered after RYGB; there was a tendency to an increase, which was also predicted by PBPK modelling and simulation.


Subject(s)
Delayed-Action Preparations/administration & dosage , Delayed-Action Preparations/pharmacokinetics , Gastric Bypass , Metoprolol/administration & dosage , Metoprolol/pharmacokinetics , Models, Biological , Administration, Oral , Adult , Biological Availability , Computer Simulation , Female , Humans , Male
18.
Iran J Biotechnol ; 13(4): 17-24, 2015 Dec.
Article in English | MEDLINE | ID: mdl-28959305

ABSTRACT

BACKGROUND: Chitin is an abundant natural polysaccharide found in fungi, algae, and exoskeleton of insects. Several bacterial species are capable of utilizing chitin as their carbon source. These bacteria produce chitinases for degradation of chitin into N-acetyl-D-glucosamine. So far, regulation of the chitinase encoding genes has been studied in different bacterial species. Among Bacillus species, B. pumilus strain SG2 encodes two chitinases, ChiS and ChiL. The promoter region of chiSL genes (P chiS ) is mainly regulated by the general carbon catabolite repression (CCR) system in B. subtilis due to the presence of a catabolite responsive element (cre). OBJECTIVES: Use of P chiS in constructing an inducible expression system in B. subtilis was investigated. MATERIALS AND METHODS: In the first step, complete and shortened versions of P chiS were inserted upstream of the lacZ on a pBS72/pUC18 shuttle plasmid. The ß-galactosidase activity of B. subtilis carrying one of the relevant plasmids was measured in the presence of different carbon sources. RESULTS: An expression system based on the chitinase promoter of B. pumilus SG2 was established. Modification of P chiS and the culture medium resulted in production of ß-galactosidase in B. subtilis up to 1,800 Miller unit (MU) activity. CONCLUSIONS: The chitinase promoter developed in this study, has potential to be used in an expression vector that could be induced by chitin. In addition, compared to the other inducers like IPTG and lactose, chitin is definitely cheaper and more available as an inducer.

19.
Anal Chim Acta ; 753: 32-41, 2012 Nov 13.
Article in English | MEDLINE | ID: mdl-23107134

ABSTRACT

A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH(2)-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH(2)-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH(2)-IL and negatively charged catalase a sensitive H(2)O(2) biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k(s)) and Michaelis-Menten constant (K(M)) of immobilized catalase were 3.32×10(-12) mol cm(-2), 5.28s(-1) and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 µA mM(-1)cm(-2) and low detection limit of 100 nM at concentration range up to 2.1 mM.


Subject(s)
Carbon/chemistry , Catalase/metabolism , Electrochemical Techniques , Ionic Liquids/chemistry , Metal Nanoparticles/chemistry , Titanium/chemistry , Amines/chemistry , Biocatalysis , Biosensing Techniques , Catalase/chemistry , Electrodes , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Hydrogen Peroxide/chemistry , Kinetics , Oxidation-Reduction
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