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1.
Soft Matter ; 11(2): 303-17, 2015 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-25411076

RESUMO

The combination of various experimental techniques with theoretical simulations has allowed elucidation of the mode of incorporation of fluorene based derivatives into phospholipid bilayers. Molecular dynamics (MD) simulations on a fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) bilayer, with benzene (B), biphenyl (BP), fluorene (F) and tri-(9,9-di-n-octylfluorenyl-2,7-diyl), TF, have provided insights into the topography of these molecules when they are present in the phospholipid bilayer, and suggest marked differences between the behavior of the small molecules and the oligomer. Further information on the interaction of neutral fluorenes within the phospholipid bilayer was obtained by an infrared (IR) spectroscopic study of films of DMPC and of the phospholipid with PFO deuterated specifically on its alkyl chains (DMPC-PFO-d34). This was complemented by measurements of the effect of F, TF and two neutral polymers: polyfluorene poly(9,9-di-n-octylfluorenyl-2,7-diyl), PFO, and poly(9,9-di-n-dodecylfluorenyl-2,7-diyl), PFD, on the phospholipid phase transition temperature using differential scanning calorimetry (DSC). Changes in liposome size upon addition of F and PFO were followed by dynamic light scattering. In addition, the spectroscopic properties of F, TF, PFO and PFD solubilised in DMPC liposomes (absorption, steady-state and time-resolved fluorescence) were compared with those of the same probes in typical organic solvents (chloroform, cyclohexane and ethanol). Combining the insight from MD simulations with the results at the molecular level from the various experimental techniques suggests that while the small molecules have a tendency to be located in the phospholipid head group region, the polymers are incorporated within the lipid bilayers, with the backbone predominantly orthogonal to the phospholipid alkyl chains and with interdigitation of them and the PFO alkyl chains.


Assuntos
Fluorenos/química , Bicamadas Lipídicas/química , Fosfolipídeos/química , Fluorenos/metabolismo , Bicamadas Lipídicas/metabolismo , Lipossomos/química , Lipossomos/metabolismo , Simulação de Dinâmica Molecular , Fosfolipídeos/metabolismo , Temperatura
2.
Appl Microbiol Biotechnol ; 98(2): 919-29, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23644771

RESUMO

Tributyl phosphate (TBP) has enormous applications in the field of extraction, fuel reprocessing, as defoamers and/or plasticizers. Excessive usage of this organophosphorus compound, poses an environmental threat. The present study deals with microbial degradation of TBP using Klebsiella pneumoniae S3 isolated from the soil. Diauxic growth curve pattern explains a preferential utilization of TBP. The strain S3 was able to biotransform TBP (1,000 mg L⁻¹) to dibutyl phosphate within 48 h and showed higher tolerance towards TBP up to 17.0 g L⁻¹. Toxicity of the parent as well as degraded product was assessed using comet assay. Generation of reactive oxygen species elaborates the oxidative stress imposed upon the bacterial strain by TBP. The antioxidant defense mechanism was studied using various biomarkers namely catalase, glutathione-S-transferase, and superoxide dismutase. The present study describes a faster and eco-friendly alternative for disposal of TBP.


Assuntos
Klebsiella pneumoniae/metabolismo , Organofosfatos/metabolismo , Biotransformação , Ensaio Cometa , Poluentes Ambientais/metabolismo , Poluentes Ambientais/toxicidade , Klebsiella pneumoniae/crescimento & desenvolvimento , Klebsiella pneumoniae/isolamento & purificação , Testes de Mutagenicidade , Organofosfatos/toxicidade , Estresse Oxidativo , Microbiologia do Solo
3.
Photodiagnosis Photodyn Ther ; 45: 103964, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38218570

RESUMO

BACKGROUND: The induction of phototoxicity during photodynamic therapy (PDT) is dependent on oxygen availability. For this reason, the development of sensors to measure oxygen and oxygen consumption is extremely important. APPROACH: In this project we have used Fluorescence Lifetime imaging (FLIM) and Phosphorescence Lifetime Imaging/ delayed Fluorescence Lifetime Imaging (PLIM/dFLIM) to investigate the ability of bromine indirubin derivatives as oxygen sensors. RESULTS: The oxygen sensitivity of bromine indirubins was detected through PLIM/dFLIM. Moreover, we have observed, by measuring nicotinamide adenine dinucleotide (NADH) FLIM, that bromine indirubin has a significant impact on cellular metabolism by shifting the SCC-4 Cells metabolism from oxidative phosphorylation (OXPHOS) to glycolysis. CONCLUSIONS: In conclusion, this study successfully achieves its goals and provides important insights into the use of indirubin as a potential oxygen consumption sensor with the capability to identify and differentiate between normoxic and hypoxic regions within the cells.


Assuntos
Oxigênio , Fotoquimioterapia , Humanos , Bromo , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Hipóxia , Indóis
4.
Eur Phys J E Soft Matter ; 31(4): 393-402, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20480963

RESUMO

Morphological transformation during evaporation-induced self-assembly of a mixed colloidal suspension in micrometric droplets has been investigated. It has been demonstrated that a buckling-driven shape transition of drying droplets of mixed colloidal suspension takes place during evaporation-induced self-assembly. Further, it is also shown that the distortion modulations get significantly amplified with enhancement in volume fraction of anisotropic soft colloidal component of the mixed colloids. It has been argued that the reduction in elastic modulus of formed shell, at the boundary of a drying droplet, and the anisotropic nature of one of the colloidal components facilitate the deformation process. Hierarchical structures of these assembled colloidal grains have been probed using electron microscopy and scattering techniques.


Assuntos
Coloides/química , Dessecação , Suspensões/química , Anisotropia , Módulo de Elasticidade , Escherichia coli/química , Escherichia coli/ultraestrutura , Luz , Microscopia Eletrônica de Varredura , Difração de Nêutrons , Espalhamento a Baixo Ângulo , Dióxido de Silício/química , Volatilização
5.
Ecotoxicol Environ Saf ; 71(3): 671-6, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18082265

RESUMO

Aseptically grown Vetiveria zizanoides were evaluated for their potential for phytoremediation of phenol from Murashige and Skoog's liquid medium. Phenol was found to be completely removed from incubation medium at the end of 4 days by V. zizanoides plantlets, when medium was supplemented with 50 and 100 mg L(-1) phenol, while with 200, 500, and 1000 mg L(-1) of phenol, 89%, 76% and 70%, respectively, were removed. Phenol removal was found to be associated with inherent production of peroxidase and hydrogen peroxide. Coupled with H(2)O(2) formation, the levels of antioxidant enzymes like superoxide dismutase and peroxidase showed an enhancement when plants were exposed to phenol, whereas catalase levels initially showed a decline due to the utilization of H(2)O(2) by peroxidase for phenol oxidation. However, when peroxidase levels declined, there was an enhancement in catalase levels to minimize the presence of H(2)O(2) in the medium. Having confirmed that the removal of phenol was by V. zizanoides plantlets, in the next phase, micropropagated plantlets and well-developed plants grown in hydroponics were used under in vivo conditions to study the effect of phenol (200 mg L(-1)) on plant growth and reuse. Although plant growth was reduced in presence of phenol, the results of the reuse study indicated the possibility of plants getting adapted to phenol without any decline in potential for phenol remediation.


Assuntos
Vetiveria/metabolismo , Fenol/metabolismo , Poluentes Químicos da Água/metabolismo , Antioxidantes/metabolismo , Biodegradação Ambiental , Catalase/metabolismo , Vetiveria/efeitos dos fármacos , Glutationa Peroxidase , Peróxido de Hidrogênio/metabolismo , Hidroponia , Oxirredução , Peroxidase/metabolismo , Fenol/análise , Fenol/toxicidade , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
6.
J Hazard Mater ; 158(2-3): 628-35, 2008 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-18375055

RESUMO

The biosorption characteristics of uranium(VI) onto Catenella repens (a red alga), were evaluated as a function of pH, biosorbent size, time, biomass dosage, initial uranium concentration and temperature. Within the pH range studied (1.5-7.5), 4.5 was the optimum pH for the uptake of uranium(VI) by C. repens. Reduction in particle size did not increase the biosorption capacity. The metal removal was rapid, with more than 90% of total biosorption taking place in 30 min, and equilibrium was attained in 45 min. The maximum metal loading capacity of the alga was 303 mg/g. Within the temperature range studied (15-55 degrees C), there was no significant change in biosorption, under optimal conditions. Adsorption process could be well defined by both the Langmuir and Freundlich isotherms with r(2) of 0.94 and 0.96, respectively. The kinetic data fitted the pseudo-second-order kinetic model with the r(2) value of 0.99. At a low pH of 2.5, where most of the biomasses show either no or less metal uptake, a good (>15%) metal loading capacity of 25% was achieved. Therefore biosorption characteristics were also evaluated at pH 2.5.


Assuntos
Rodófitas/metabolismo , Urânio/metabolismo , Biomassa , Concentração de Íons de Hidrogênio , Cinética , Tamanho da Partícula , Temperatura , Água
7.
Drug Alcohol Depend ; 182: 67-73, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29169035

RESUMO

BACKGROUND: The prevention of drug injecting is often cited as a justification for the deployment of law enforcement and for the continuation of drug criminalization policies. We sought to characterize the impact of law enforcement interactions on the risk that people who inject drugs (PWID) report assisting others with injection initiation in three North American countries. METHODS: Cross-sectional data from PWID participating in cohort studies in three cities (San Diego, USA; Tijuana, Mexico; Vancouver, Canada) were pooled (August 2014-December 2016). The dependent variable was defined as recently (i.e., past six months) providing injection initiation assistance; the primary independent variable was the frequency of recent law enforcement interactions, defined categorically (0 vs. 1 vs. 2-5 vs. ≥6). We employed multivariable logistic regression analyses to assess this relationship while controlling for potential confounders. RESULTS: Among 2122 participants, 87 (4.1%) reported recently providing injection initiation assistance, and 802 (37.8%) reported recent law enforcement interactions. Reporting either one or more than five recent interactions with law enforcement was not significantly associated with injection initiation assistance. Reporting 2-5 law enforcement interactions was associated with initiation assistance (Adjusted Odds Ratio=1.74, 95% Confidence Interval: 1.01-3.02). CONCLUSIONS: Reporting interactions with law enforcement was not associated with a reduced likelihood that PWID reported initiating others into injection drug use. Instead, we identified a positive association between reporting law enforcement interactions and injection initiation assistance among PWID in multiple settings. These findings raise concerns regarding the effectiveness of drug law enforcement to deter injection drug use initiation.


Assuntos
Aplicação da Lei/métodos , Abuso de Substâncias por Via Intravenosa/epidemiologia , Abuso de Substâncias por Via Intravenosa/prevenção & controle , Adulto , Colúmbia Britânica/epidemiologia , California/epidemiologia , Cognição , Estudos de Coortes , Estudos Transversais , Feminino , Humanos , Masculino , México/epidemiologia , Pessoa de Meia-Idade , América do Norte/epidemiologia , Estudos Prospectivos , Abuso de Substâncias por Via Intravenosa/diagnóstico
8.
Colloids Surf B Biointerfaces ; 154: 421-428, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28388528

RESUMO

Synthesis and characterization of nano-structured porous granules, with fairly defined morphology and porosity, is crucial because such granules are widely utilized for various technological applications. However, an easy, one-step, economic synthesis protocol for large scale production is extremely desirable. In the present work, we have reported the synthesis and characterization of the nano-structured micro-granules using aerosol drying of bi-colloidal suspension of nano-silica and milk. Removal of soft organic component from the granules results in formation of meso and macro pores with moderate specific surface area. Granule morphology and porosity depends strongly on the concentration ratio of the individual components in the drying aerosol as well as the interaction between them.


Assuntos
Leite/química , Nanoestruturas/química , Nanotecnologia/métodos , Dióxido de Silício/química , Aerossóis , Animais , Coloides , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Porosidade , Propriedades de Superfície , Suspensões
9.
Animal ; 11(5): 778-783, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27765079

RESUMO

The aim of this study was to evaluate the effect of dietary lysine on performance, protein deposition and respiratory chain gene expression in male broilers. A total of 252 Cobb 500 broilers were distributed, in a completely randomized design, into four treatments with seven replicates of nine birds per experimental unit. Experimental treatments consisted of diets based on corn and soybean meal, with four levels of digestible lysine: 1.016%, 1.099%, 1.182% and 1.265%. The increase in the level of digestible lysine in the diet provided higher weight gains, feed efficiency and body protein deposition. Birds fed the lowest level of dietary lysine (1.016%) showed a lower expression of genes such as NADH dehydrogenase subunit I (ND1), cytochrome b (CYTB) and cytochrome c oxidase subunits I (COX I), II (COX II) and III (COX III), displaying the worst performance and body protein deposition. This demonstrates the relationship existing between the expression of the evaluated genes and the performance responses. In conclusion, results indicate that broilers fed diets with higher levels of digestible lysine have increased messenger RNA expression of some genes coded in the mitochondrial electron transport chain (ND1, CYTB, COX I, COX II and COX III). It may be stated that diets with proper levels of digestible lysine, within the 'ideal protein' concept, promote the expression of genes, which increases the mitochondrial energy, thereby fostering body protein deposition and the performance of broilers in the starter phase.


Assuntos
Proteínas Aviárias/genética , Galinhas/crescimento & desenvolvimento , Lisina/metabolismo , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Proteínas Aviárias/metabolismo , Galinhas/metabolismo , Dieta/veterinária , Digestão , Masculino , Músculos Peitorais/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Distribuição Aleatória
10.
J Biotechnol ; 123(1): 43-9, 2006 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-16352361

RESUMO

Removal of phenol, a major pollutant in aqueous effluents was studied using plant hairy root cultures. Among four different species of hairy roots tested, Brassica juncea showed the highest potential for phenol removal. The effect of phenol concentration and reuse in a batch system was studied using B. juncea hairy root cultures. Unlike most of the studies reported earlier, phenol removal by the hairy roots was seen to take place without the need for addition of external hydrogen peroxide (H(2)O(2)). To understand the mechanism of phenol removal, levels of peroxidase and phenol oxidase were monitored in the hairy roots. Peroxidase activity in the roots was enhanced when exposed to phenol, while phenol oxidase remained constant. Since peroxidase has a pre-requisite for H(2)O(2), the levels of H(2)O(2) were monitored for its in situ synthesis. H(2)O(2) levels were seen to increase in the presence of phenol. Thus, a mechanism wherein hairy roots also produce H(2)O(2) besides peroxidase, as a protection strategy of plant against xenobiotic stress is plausible.


Assuntos
Peróxido de Hidrogênio/metabolismo , Mostardeira/metabolismo , Peroxidase/metabolismo , Fenol/farmacocinética , Raízes de Plantas/metabolismo , Purificação da Água/métodos , Biodegradação Ambiental , Fenol/isolamento & purificação
11.
Colloids Surf B Biointerfaces ; 127: 164-71, 2015 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-25677340

RESUMO

We have synthesized nano-structured silica-Escherichia coli composite micro-granules by spray drying of mixed suspension of silica and E. coli through evaporation-induced assembly. Synthesized micro-granules were subjected to calcination in order to form shape-matched macro-pores by removing the bacterial cells. The optimization of calcination temperature is crucial because calcination process leads to two contrasting effects, namely, (i) removal of E. coli from the granules and (ii) alteration of mesoscopic structure in the silica network. We have used small-angle neutron scattering and thermo-gravimetric analysis to determine the optimum temperature for calcination of these granules. It was found that calcination in the temperature range of 200°C to 400°C removes the cells without significant alteration of the nano-structured silica network. However, beyond 500°C, calcination results significant coalescence between the silica particles. Calcination at 600°C eventually collapses the meso-pore network of silica interstices.


Assuntos
Escherichia coli/fisiologia , Nanoestruturas/química , Nanotecnologia/métodos , Dióxido de Silício/química , Temperatura , Escherichia coli/ultraestrutura , Nanoestruturas/ultraestrutura , Difração de Nêutrons , Espalhamento a Baixo Ângulo , Termogravimetria , Difração de Raios X
12.
J Biochem Biophys Methods ; 42(3): 133-5, 2000 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-10737219

RESUMO

Crude cell-free extract of yeast cells was mixed with sufficient amount of Jack bean meal extract so as to precipitate all the invertase. The precipitate was then cross-linked using 2% glutaraldehyde retaining over 60% of the activity. The immobilized invertase could be reused for over ten batches without loss in activity.


Assuntos
Enzimas Imobilizadas , Glicosídeo Hidrolases/isolamento & purificação , Saccharomyces cerevisiae/enzimologia , Sistema Livre de Células , Concanavalina A , Reagentes de Ligações Cruzadas , Fabaceae/enzimologia , Farinha , Glutaral , Lectinas de Plantas , Plantas Medicinais , beta-Frutofuranosidase
13.
Enzyme Microb Technol ; 13(6): 508-11, 1991 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-1367333

RESUMO

A method has been described for obtaining coimmobilizates by the simultaneous binding of glucose oxidase to the cell and the enzyme-bound cell to cotton thread through adhesion using polyethylenimine (PEI). Glucose oxidase was found to adsorb onto PEI-coated yeast cells from a water suspension. The desorption observed at higher ionic strength could be obviated by cross-linking with 2% glutaraldehyde for 2 min. The enzyme-bound yeast cells could then be immobilized by adhesion on cotton thread. The coimmobilizate could be reused for over 10 batches without appreciable loss in activity.


Assuntos
Enzimas Imobilizadas , Glucose Oxidase/metabolismo , Polietilenoimina , Saccharomyces cerevisiae/metabolismo , Enzimas Imobilizadas/metabolismo , Cinética , Ligação Proteica
14.
Bioresour Technol ; 92(2): 151-5, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-14693447

RESUMO

Polysaccharides bound to bacteria or in isolated form have been shown to bind heavy metals. A limitation of this technology can be overcome by immobilization. In view of this Ocimum basilicum seeds which swell upon wetting could serve as natural immobilized source of agriculturally-based polysaccharides. The seeds consist of an inner hard core and a pectinous fibrillar outer layer. Pretreating the seeds with acid, alkali, periodate or boiling in water was found to alter the metal binding capacity. Of the various treatments given, seeds boiled in water were found to be superior in terms of mechanical stability and exhibited fairly optimal Cr(VI) uptake kinetics. The maximum adsorption capacity as calculated from the Langmuir isotherm was 205 mg Cr/g dry seeds. Biosorption of Cr(VI) was found to be pH dependent with maximum uptake at pH 1.5 wherein sorption was not affected by the presence of other metal ions such as Cd(2+), Cu(2+), Ca(2+) and Na(+). Seeds were used in a packed bed reactor for the continuous removal of Cr(VI). Thus O. basilicum seeds may have application as a potential bioresource in tropical countries such as India where they are widely available.


Assuntos
Cromo/farmacocinética , Ocimum basilicum/metabolismo , Polissacarídeos/metabolismo , Sementes/metabolismo , Poluentes Químicos da Água/farmacocinética , Adesivos , Adsorção , Biodegradação Ambiental , Concentração de Íons de Hidrogênio , Índia , Espectrofotometria
15.
Appl Biochem Biotechnol ; 32: 159-70, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1329654

RESUMO

Yeast invertase, a glycoprotein, was covalently coupled to Ocimum basilicum seeds either through its protein or carbohydrate moiety. Of the various methods investigated, binding of the enzyme through its carbohydrate moiety resulted in the retention of considerably higher amounts of enzyme activity. Immobilized invertase showed a shift in the pH optimum toward the alkaline side without appreciable change in temperature optimum. However, the immobilized preparation was more thermostable than the free enzyme. Invertase bound to the seeds could be used repeatedly for the hydrolysis of sucrose syrups in a batch process without appreciable loss in activity. The seeds could serve as an inexpensive, ready-to-use, natural pellicular polysaccharide support for immobilizing enzymes.


Assuntos
Carboidratos/química , Enzimas Imobilizadas , Glicosídeo Hidrolases/química , Sementes/química , Estabilidade Enzimática , Compostos de Epóxi/química , Óxido de Etileno/análise , Etilenodiaminas , Glutaral , Glicosídeo Hidrolases/análise , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Ácido Periódico , Temperatura , beta-Frutofuranosidase
16.
ACS Appl Mater Interfaces ; 5(21): 10541-50, 2013 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-24164312

RESUMO

The activated carbon was derived from tamarind fruit shell and utilized as electrodes in a solid state electrochemical double layer capacitor (SSEDLC). The fabricated SSEDLC with PVA (polyvinyl alcohol)/H2SO4 gel electrolyte delivered high specific capacitance and energy density of 412 F g(-1) and 9.166 W h kg(-1), respectively, at 1.56 A g(-1). Subsequently, Na2MoO4 (sodium molybdate) added PVA/H2SO4 gel electrolyte was also prepared and applied for SSEDLC, to improve the performance. Surprisingly, 57.2% of specific capacitance (648 F g(-1)) and of energy density (14.4 Wh kg(-1)) was increased while introducing Na2MoO4 as the redox mediator in PVA/H2SO4 gel electrolyte. This improved performance is owed to the redox reaction between Mo(VI)/Mo(V) and Mo(VI)/Mo(IV) redox couples in Na2MoO4/PVA/H2SO4 gel electrolyte. Similarly, the fabricated device shows the excellent capacitance retention of 93% for over 3000 cycles. The present work suggests that the Na2MoO4 added PVA/H2SO4 gel is a potential electrolyte to improve the performance instead of pristine PVA/H2SO4 gel electrolyte. Based on the overall performance, it is strongly believed that the combination of tamarind fruit shell derived activated carbon and Na2MoO4/PVA/H2SO4 gel electrolyte is more attractive in the near future for high performance SSEDLCs.


Assuntos
Frutas/química , Nanotubos de Carbono/química , Tamarindus/química , Capacitância Elétrica , Eletrólitos , Géis/química , Oxirredução , Polímeros/química , Porosidade , Propriedades de Superfície
17.
Bioresour Technol ; 129: 646-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23298772

RESUMO

In this study, synergetic effect of mild acid and alkali with electron beam irradiation (EBI) on the enzymatic hydrolysis of a selected grass biomass was assessed. Biomass samples prepared by soaking with 1% H2SO4, or 1% NaOH, were exposed to 75 and 150 kGy of EBI. Water presoaked biomass was used as control. Hydrolysis of pretreated samples was carried out using cellulase (15 FPU/g biomass) for 120 h. Structural changes were studied by FTIR and XRD analyses. Reducing sugar and glucose yields from enzymatic hydrolysis were significantly higher in acid and alkali presoaked EBI exposed samples. Theoretical glucose yield showed 40% increase from control in alkali presoaked EBI exposed (150 kGy) samples. Removal of hemicellulose, decreased crystallinity and structural changes were major factors for the combined treatment effect favoring the hydrolysis.


Assuntos
Celulase/química , Extratos Vegetais/química , Poaceae/química , Polissacarídeos/isolamento & purificação , Hidróxido de Sódio/química , Ácidos Sulfúricos/química , Álcalis/química , Álcalis/efeitos da radiação , Celulase/efeitos da radiação , Elétrons , Ativação Enzimática/efeitos da radiação , Hidrólise/efeitos da radiação , Lignina , Extratos Vegetais/efeitos da radiação , Poaceae/efeitos da radiação , Polissacarídeos/química , Polissacarídeos/efeitos da radiação , Doses de Radiação , Hidróxido de Sódio/efeitos da radiação
18.
Int J Biol Macromol ; 50(1): 300-2, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22062119

RESUMO

Lipase from Thermomyces lanuginosus was assembled into multiple layers on polyethylenimine treated cotton flannel cloth, utilising the enzymes property of forming bimolecular aggregates via layer-by-layer (LBL) immobilization technique. An increase in lipase activity with increasing enzyme layers confirmed lipase aggregation. A study to compare the activity of enzyme bound by classical LBL technique, containing alternate layers of polyethylenimine and lipase and the modified approach indicated above, showed that more enzyme was bound to cloth in the modified approach. A total of 13 U/cm(2) of enzyme were bound to cloth till the fifth layer whereas only 10.2 U/cm(2) were bound till the fifth bilayer in the classical approach. The successful assembly of lipase molecules has shown that this modified technique is a promising approach to immobilize enzymes that aggregate through hydrophobic interactions as nano-films on cloth.


Assuntos
Enzimas Imobilizadas/química , Lipase/química , Difusão , Gossypium , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Substâncias Macromoleculares , Modelos Químicos , Azeite de Oliva , Óleos de Plantas , Polietilenoimina/química , Polímeros/química , Propriedades de Superfície
20.
Langmuir ; 25(12): 6690-5, 2009 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-19323504

RESUMO

Morphological transition of droplets during evaporation driven self-assembly of colloidal dispersion of alumina particles has been investigated. It was found that a sphere to doughnut-like transition of the droplet morphology takes place even when the rate of drying remains moderate and is not extremely fast. Further, it has been seen that such transition is strongly dependent on the volume fraction of the colloids in the droplets. The transition proceeds via buckling of the initial spherical droplets, which occurs when the capillary forces driving the deformation overcomes the interparticle electrostatic forces. However, the transition is hindered and the buckling probability is reduced due to the inherent spatial constraint when the colloid volume fraction is increased. Mesoscopic structures of the assembled grains have been investigated by scanning electron microscopy, small-angle neutron scattering, and dynamic light scattering techniques. Interestingly, it has been observed that the functionality of photoluminescence spectrum of the dried nanoporous grains depends somewhat on the grain morphology.

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