Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.175
Filtrar
1.
Food Chem ; 299: 125037, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31279128

RESUMO

Immobilization of enzymes is an essential strategy with outstanding prospects in biocatalytic processes. Nontoxic, inexpensive immobilized enzyme approach is especially important for food enzymes. We here demonstrate that a carbohydrate-binding module family 56 domain (CBM56-Tag) mediates the immobilization of fusion enzymes with the curdlan (ß-1,3-glucan) particle support, thereby enabling the one-step immobilization-purification of target enzymes. CBM56-Tag exhibits an immunoglobulin-like ß-sandwich fold, which can be adsorbed by curdlan via hydrogen bond-mediated binding. The maximum adsorption capacity of a fusion chitosanase (CBM56-GsCsn46A) on curdlan is 50.72 mg/g. The immobilized enzyme could be directly used in the packed-bed reactor. This immobilization strategy utilizes a natural polysaccharide without any treatment, avoiding the negative environmental effects. Moreover, the one step immobilization-purification simplifies the purification step, which reduces the use of chemicals. Our study provides a nontoxic and inexpensive immobilization strategy for the biocatalytic reaction in food industry.


Assuntos
Enzimas Imobilizadas/química , Enzimas Imobilizadas/isolamento & purificação , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/isolamento & purificação , Receptores de Superfície Celular/metabolismo , Proteínas Recombinantes de Fusão/metabolismo , Biocatálise , Enzimas Imobilizadas/metabolismo , Glicosídeo Hidrolases/metabolismo , Ligações de Hidrogênio , beta-Glucanas/química
2.
Chem Asian J ; 14(17): 2953-2957, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31321878

RESUMO

This paper describes the synthesis of protein microtube motors having a urease interior surface and highlights their nonbubble-propelled behavior driven by enzymatic reaction (urea→NH3 and CO2 ). The precursor microtubes were prepared by layer-by-layer assembly using a track-etched microporous polycarbonate membrane. Immobilization of a urease on the internal wall was accomplished using avidin-biotin interaction. The tubules swam smoothly in an aqueous media containing a physiological concentration of urea. Each tubule was rotating laterally while moving forward. It is remarkable that the microtubes were digested completely by proteases, demonstrating perfect biodegradability.


Assuntos
Avidina/química , Biotina/química , Urease/metabolismo , Avidina/metabolismo , Biotina/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Cimento de Policarboxilato/química , Porosidade , Ureia/química , Ureia/metabolismo , Urease/química
3.
Sci Total Environ ; 690: 447-459, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31299577

RESUMO

Steroidal estrogens are widespread water contaminants with potential carcinogenic and endocrine-disrupting activities. The World Health Organization has listed estrogens as group 1 carcinogens. These contaminants are of substantial concern because of potential threats to human health, and aquatic organisms on long-term exposure. A range of methods, including oxidation, adsorption, electrochemical, and irradiation techniques have been employed for their remediation from aqueous systems. However, inadequate removal, toxic sludge generation, high operating costs, and the requisite for skilled operating and maintenance personnel commercially hampered the application of many methods. An interesting alternative treatment approach based on the use of oxidoreductases, particularly laccases, has recently gained amicability for the biotransformation of emerging pollutants. The use of immobilized enzymes is more cost-effective from an industrial perspective due to improved catalytic stability, reusability, reduction of product inhibition, and easier product separation. This review provides comprehensive knowledge on the use of laccases in the biodegradation of steroidal estrogens, including estrone, 17ß-estradiol, and 17α-ethinylestradiol with endocrine-disrupting potency from the environment. After an overview of estrogens and catalytic properties of laccase, the use of free, as well as immobilized laccases with a particular emphasis on estrogens removal by laccase-based fed-batch, packed bed bioreactors, and membrane reactors, is discussed. A comparison of existing treatment technologies with enzyme technology for the removal of estrogens from different environmental matrices is made. Lastly, along with concluding remarks, future research direction aimed at bridging knowledge gaps for estrogenic compounds removal are also proposed in this very important research area.


Assuntos
Biodegradação Ambiental , Estrogênios/metabolismo , Lacase/metabolismo , Biotransformação , Disruptores Endócrinos/metabolismo , Enzimas Imobilizadas/metabolismo , Poluentes Químicos da Água
4.
Bioresour Technol ; 289: 121772, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31307865

RESUMO

The present work aims to develop a magnetic biocatalyst for customized production of nucleoside analogues using mutant His-tagged purine 2'-deoxyribosyltransferase from Trypanosoma brucei (TbPDTV11S) immobilized onto Ni2+ chelate magnetic iron oxide porous microparticles (MTbPDTV11S). Biochemical characterization revealed MTbPDTV11S5 as optimal candidate for further studies (10,552 IU g-1; retained activity 54% at 50 °C and pH 6.5). Interestingly, MTbPDTV11S5 displayed the highest activity value described up to date for an immobilized NDT. Moreover, MTbPDTV11S5 was successfully employed in the one-pot, one-step production of different therapeutic nucleoside analogues, such as cladribine or 2'-deoxy-2-fluoroadenosine, among others. Finally, MTbPDTV11S5 proved to be stable when stored at 50 °C for 8 h and pH 6.0 and reusable up to 10 times without negligible loss of activity in the enzymatic production of the antitumor prodrug 2'-deoxy-2-fluoroadenosine.


Assuntos
Pentosiltransferases/metabolismo , Quelantes , Desoxiadenosinas , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Compostos Férricos , Magnetismo , Nucleosídeos , Purinas , Temperatura Ambiente
5.
Food Chem ; 297: 125005, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253325

RESUMO

Multiwalled carbon nanotubes molybdenum disulfide 3D nanocomposite (MWCNT-MoS2 NC) was successfully synthesized via eco-friendly hydrothermal method. The microstructural characterization of synthesized nanocomposite was carried out using different spectroscopic and microscopic techniques. Nanocomposite was activated using glutaraldehyde chemistry and used as a platform to immobilize Lens culinaris ß-galactosidase (Lsbgal) which resulted in 93% of immobilization efficiency. Attachment of Lsbgal onto nanocomposite was confirmed by AFM, FE-SEM, FTIR, and CLSM. The nanobiocatalyst showed broadening in operational pH and temperature working range. Remarkable increase in thermal stability was observed as compared to soluble enzyme. Nanobiocatalyst showed outstanding increase in storage stability, retained 92% of residual activity over a period of 8 months. This offers good reusability as it retained ∼50% residual activity up to 21 reuses and exhibited higher rate of lactose hydrolysis in whey. MWCNT-MoS2 NC conjugated to biomolecules can serve as a potential platform for fabrication of lactose biosensor.


Assuntos
Lactose/metabolismo , Lens (Planta)/enzimologia , Nanocompostos/química , Soro do Leite/metabolismo , beta-Galactosidase/metabolismo , Biocatálise , Dissulfetos/química , Estabilidade Enzimática , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Molibdênio/química , Nanotubos de Carbono/química , Temperatura Ambiente , beta-Galactosidase/química
6.
Food Chem ; 296: 1-8, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31202292

RESUMO

Immobilized lipases are excellent biocatalysts for the enzymatic synthesis of short- and medium-chain fatty esters used as food flavor compounds. Herein a new approach for a magnetic core-shell biocatalyst by immobilization of Candida antarctica B lipase is reported, coating single-core magnetic nanoparticles with an organic shell, preferably poly(benzofurane-co-arylacetic acid), followed by the covalent attachment of the enzyme and embedment of the primary biocatalyst in a silica layer. Although covalent and sol-gel immobilization were efficient on their own, their combination can ensure additional operational stability through multi-point linkages. Moreover, silanes holding glycidoxy groups, which can also form covalent linkages, have been successfully used as precursors for the silica coating layer. The structural, magnetic and morphological characteristics were assessed by TEM, SEM-EDX, X-ray photoelectron spectroscopy and vibrating sample magnetometry. The new biocatalysts demonstrated high catalytic efficiency in the solventless synthesis of isoamyl esters of natural carboxylic acids, also in multiple reaction cycles.


Assuntos
Ésteres/metabolismo , Proteínas Fúngicas/metabolismo , Lipase/metabolismo , Nanopartículas de Magnetita/química , Biocatálise , Ácidos Carboxílicos/química , Ácidos Carboxílicos/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Ésteres/análise , Proteínas Fúngicas/química , Cromatografia Gasosa-Espectrometria de Massas , Lipase/química , Dióxido de Silício/química
7.
Food Chem ; 296: 123-131, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31202296

RESUMO

Phospholipids (PL) rich in conjugated linolenic acid (CLA) have important health effects. Yields of phosphatidylcholine (PC) acidolysis with CLA use to be limited to <30%, due to competitive side-hydrolysis. Duolite A658-Lecitase is a very suitable biocatalyst for this reaction. In this study, PC hydrolysis has been practically eliminated using extremely dried lyophilized PC (279 ±â€¯4 mg water/Kg PC), obtaining close to 100% molar yield of modified PC (72.3% CLA) with Duolite-Lecitase in 24 h, the highest yield reported in the literature for this reaction. It has been better improved by changing the immobilization support, using three food grade hydrophobic supports (Styrene, and two Octadecyl methacrylates (OM and OMC)). In only 2 h, with a 1/12 PC/CLA molar ratio at 50 °C, similar almost quantitative yields of PC with 74.4% CLA content has been obtained using OM-Lecitase. The fatty acid composition of modified PCs is not affected by the enzyme immobilization protocol.


Assuntos
Ácidos Linoleicos Conjugados/metabolismo , Fosfolipases A1/metabolismo , Fosfolipídeos/química , Biocatálise , Cromatografia Gasosa , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Ácidos Graxos/análise , Hidrólise , Ácidos Linoleicos Conjugados/química , Fosfatidilcolinas/química , Fosfolipases A1/química , Fosfolipídeos/metabolismo
8.
J Microbiol Biotechnol ; 29(6): 913-922, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31154745

RESUMO

Magnetic Ni0.7Co0.3Fe2O4 nanoparticles that were prepared via the rapid combustion process were functionalized and modified to obtain magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites, on which penicillin G acylase (PGA) was covalently immobilized. Selections of immobilization concentration and time of fixation were explored. Catalytic performance of immobilized PGA was characterized. The free PGA had greatest activity at pH 8.0 and 45oC while immobilized PGA's a ctivities peaked a t pH 7.5 and 45°C. Immobilized PGA had better thermal stability than free PGA at the range of 30-50°C for different time intervals. The activity of free PGA would be 0 and that of immobilized PGA still retained some activities at 60°C after 2 h. Vmax and Km of immobilized PGA were 1.55 mol/min and 0.15 mol/l, respectively. Free PGA's Vmax and Km separately were 0.74 mol/min and 0.028 mol/l. Immobilized PGA displayed more than 50% activity after 10 successive cycles. We concluded that immobilized PGA with magnetic Ni0.7Co0.3Fe2O4@SiO2-CHO nanocomposites could become a novel example for the immobilization of other amidohydrolases.


Assuntos
Cobalto/química , Enzimas Imobilizadas/química , Nanopartículas de Magnetita/química , Nanocompostos/química , Níquel/química , Penicilina Amidase/química , Penicilina Amidase/metabolismo , Catálise , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Glutaral/química , Concentração de Íons de Hidrogênio , Dióxido de Silício/química , Temperatura Ambiente
9.
J Chromatogr A ; 1602: 481-488, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31230876

RESUMO

A covalent organic framework, Schiff base network-1 (SNW-1), was synthesized and incorporated into cellulase based poly(glycidyl methacrylate-co-ethylene dimethacrylate) (cellulase@poly(GMA-EDMA-SNW-1)) monolith to afford a novel chiral stationary phase for capillary electrochromatography (CEC). SNW-1 is attractive as a stationary phase for CEC because it not only features high surface areas but also provides conjugate structures and abundant amine groups to give π-π electrostatic stacking and hydrogen bonding property. Incorporation of SNW-1 into monolithic column could improve the column efficiency and increase the interactions between the tested racemates and the stationary phase thus significantly improved their CEC separation. The obtained monoliths were characterized by scanning electron microscopy, elemental analysis and nitrogen adsorption. Moreover, effects of SNW-1 concentration, immobilization pH of cellulase and CEC conditions were also investigated. Under the optimized conditions, the cellulase@poly(GMA-EDMA-SNW-1) monolith exhibited excellent enantioseparation performance for eight pairs of different classes of chiral drugs including ß-blockers, antihistamines and anticoagulants. Satisfactory repeatability was achieved with relative standard deviations for intra-day, inter-day and column-to-column runs less than 4.5%, and batch-to-batch runs less than 6.8%. The experiment results reveal that the combination of the versatile features of monoliths and unique properties of SNW-1 could be a promising strategy for chiral separation.


Assuntos
Eletrocromatografia Capilar/métodos , Estruturas Metalorgânicas/química , Polímeros/química , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Metilmetacrilatos/química , Nanopartículas/química , Nanopartículas/ultraestrutura , Reprodutibilidade dos Testes , Estereoisomerismo
10.
Anal Chim Acta ; 1067: 31-47, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31047147

RESUMO

Novel enzymatic microsystems have strong prospects in chemical and biological analysis due to their low consumption of reagents, fast analysis time, easy manipulation and satisfactory portability. Nanomaterials (NMs) provide a favorable platform for integrating enzymes into microsystems with enhanced selectivity and sensitivity. Various NM-enzyme immobilization strategies applied in the fabrication of capillary-based and chip-based enzymatic microsystems are summarized in this manuscript. We focus on highlighting the advantages of employing NM-based enzymatic microsystems for enantioseparation, inhibitor screening, bioreaction and biosensing. Innovative nanocomposites and NM-functionalized monoliths used to construct multienzymatic microsystems are also illustrated. The general development trend identified in this review indicates that the application of NMs has significantly improved enzymatic microsystem performance.


Assuntos
Disciplinas das Ciências Biológicas/métodos , Técnicas Biossensoriais , Química/métodos , Enzimas/química , Nanocompostos/química , Enzimas/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo
11.
Int J Nanomedicine ; 14: 3235-3244, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31118633

RESUMO

Purpose: Here, we present the successful preparation of a highly efficient gallic acid resin grafted with magnetic nanoparticles (MNPs) and containing a branched brush polymeric shell. Methods: Using a convenient co-precipitation method, we prepared Fe3O4 nanoparticles stabilized by citric acid. These nanoparticles underwent further silica modification and amino functionalization followed by gallic acid functionalization on their surface. Under alkaline conditions, we used a condensation reaction that combined formaldehyde and gallic, to graft the gallic acid-formaldehyde resin on the surface. We then evaluated the polymer-grafted MNPs to assay the Candida Antarctica B lipase(Cal-B) immobilization via physical adsorption. Conclusion: Furthermore, during optimization of parameters that defined conditions of immobilization, we found that the optimum immobilization was achieved in 15 mins. Also, optimal immobilization temperature and pH were 38ºC and 7.5, respectively. In addition, the reusability study of immobilized lipase polymer-grafted MNPs was done by isolating the MNPs from the reaction medium using magnetic separation, which showed that grafted MNPs reached 5 cycles with 91% activity retention.


Assuntos
Enzimas Imobilizadas/metabolismo , Compostos Férricos/química , Proteínas Fúngicas/metabolismo , Ácido Gálico/química , Lipase/metabolismo , Nanopartículas de Magnetita/química , Resinas Sintéticas/química , Adsorção , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Nanopartículas de Magnetita/ultraestrutura , Polímeros , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Termogravimetria , Fatores de Tempo , Difração de Raios X
12.
Nanoscale ; 11(18): 9163-9175, 2019 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-31038150

RESUMO

Diabetes is a chronic metabolic disorder disease characterized by high blood glucose levels and has become one of the most serious threats to human health. In recent decades, a number of insulin delivery systems, including bulk gels, nanogels, and polymeric micelles, have been developed for the treatment of diabetes. Herein, a kind of glucose and H2O2 dual-responsive polymeric nanogel was designed for enhanced glucose-responsive insulin delivery. The polymeric nanogels composed of poly(ethylene glycol) and poly(cyclic phenylboronic ester) (glucose and H2O2 dual-sensitive groups) were synthesized by a one-pot thiol-ene click chemistry approach. The nanogels displayed glucose-responsive release of insulin and the release rate could be promoted by the incorporation of glucose oxidase (GOx), which generated H2O2 at high glucose levels and H2O2 further oxidizes and hydrolyzes the phenylboronic ester group. The nanogels have characteristics of long blood circulation time, a fast response to glucose, and excellent biocompatibility. Moreover, subcutaneous delivery of insulin to diabetic mice with the insulin/GOx-loaded nanogels presented an effective hypoglycemic effect compared to that of injection of insulin or insulin-loaded nanogels. This kind of nanogel would be a promising candidate for the delivery of insulin in the future.


Assuntos
Glucose Oxidase/química , Glucose/metabolismo , Peróxido de Hidrogênio/metabolismo , Hipoglicemiantes/metabolismo , Insulina/metabolismo , Polietilenoglicóis/química , Polietilenoimina/química , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Química Click , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Portadores de Fármacos/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose/química , Glucose Oxidase/metabolismo , Teste de Tolerância a Glucose , Peróxido de Hidrogênio/química , Hipoglicemiantes/química , Hipoglicemiantes/uso terapêutico , Insulina/química , Insulina/uso terapêutico , Camundongos , Células NIH 3T3 , Polietilenoglicóis/toxicidade , Polietilenoimina/toxicidade
13.
Chem Commun (Camb) ; 55(50): 7155-7158, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31134258

RESUMO

Herein, the first example of crackled organosilica nanocapsules (CONs) is reported to directly immobilize enzymes without any further chemical modification. Enzymes are adsorbed on both the exterior and interior surfaces of CONs, integrating the merits of adsorption and encapsulation. When used for Candida rugosa lipase (CRL) immobilization, the CONs displayed higher enzyme loading, lower enzyme leaching, and elevated enzyme activity, compared to the conventional non-crackled nanocapsules/particles.


Assuntos
Candida/enzimologia , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Lipase/metabolismo , Nanocápsulas/química , Compostos de Silício/química , Lipase/química
14.
J Microbiol Biotechnol ; 29(4): 607-616, 2019 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-30954031

RESUMO

In this study, functionalized poplar powder (FPP) was used as a support material for the immobilization of enoate reductase (ER) and glucose-6-phosphate dehydrogenase (GDH) by covalent binding. Under optimal conditions, the immobilization efficiency of ER-FPP and GDH-FPP was 95.1% and 84.7%, and the activity recovery of ER and GDH was 47.5% and 37.8%, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis indicated that FPP was a suitable carrier for enzyme immobilization. ER-FPP and GDH-FPP exhibit excellent thermal stabilities and superior reusability. Especially, ER-FPP and GDH-FPP enable the continuous conversion of 4-(4-Methoxyphenyl)-3-buten-2-one with NAD+ recycling. While the immobilization strategies established here were simple and inexpensive, they exploited a new method for the immobilization and application of ER and its cofactor recycling system.


Assuntos
Coenzimas/metabolismo , Enzimas Imobilizadas/metabolismo , Imobilização/métodos , Oxirredutases/metabolismo , Populus/química , Estabilidade Enzimática , Etilenodiaminas , Glucosefosfato Desidrogenase/metabolismo , Glutaral , Lignina/química , Regeneração
15.
Food Chem ; 290: 47-55, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31000055

RESUMO

The immobilization of cellulase on amine-functionalized Fe3O4 magnetic nanoparticles (MNPs), via metal affinity immobilization, as a nano-biocatalyst was investigated. Copper was chosen as ligand and loaded onto MNPs in a buffering environment without adding any intermediates. Immobilization conditions were optimized by a 23 full factorial design method. Under optimized working conditions (Cu/MNPs = 1, E/MNPs = 0.11, pH = 6), the relative enzyme activity and the amount of enzyme immobilization were 91% and 164 (mg enzyme/g MNPs), respectively. The immobilized cellulase (tested by carboxymethyl cellulose hydrolysis at 1% concentration) was found to be more stable than the free enzyme. Also, the immobilized enzyme still retained 73% of its initial activity after five cycles of usage. Furthermore, the free and immobilized cellulases retained 70 and 84% of their initial activity after eight days storage at 4 °C, respectively. Immobilization of enzymes, using this method, could be a good and economic option for various industries.


Assuntos
Biocatálise , Celulase/química , Celulase/metabolismo , Cobre/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Nanopartículas de Magnetita/química , Carboximetilcelulose Sódica/metabolismo , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Hidrólise , Ligantes , Temperatura Ambiente
16.
Talanta ; 199: 116-123, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952234

RESUMO

In this study, we present the use of microreactors packed with immobilized trypsin particles for the rapid and efficient bottom-up analysis of proteins by on-line immobilized enzyme microreactor capillary electrophoresis mass spectrometry (IMER-CE-MS). The results obtained digesting ß-lactoglogulin (ß-LG) off-line with free trypsin in solution and with immobilized trypsin particles were taken as a reference for the optimization of the on-line protein digestion. Under the optimized conditions, on-line digestion, separation and characterization of the protein digests were possible in less than 30 min. The limit of detection for complete sequence coverage was around 10 µg mL-1 (~500 µM) of ß-LG, the repeatability was comparable to the off-line digestion methods and the microreactor could be reused until thirty times. The good performance of IMER-CE-MS was also demonstrated for several other proteins as α-casein (α-CSN), ß-casein (ß-CSN), and κ-casein (κ-CSN), as well as for a complex protein mixture (an Escherichia coli whole cell lysate).


Assuntos
Caseínas/metabolismo , Enzimas Imobilizadas/metabolismo , Lactoglobulinas/metabolismo , Tripsina/metabolismo , Caseínas/química , Eletroforese Capilar , Enzimas Imobilizadas/química , Humanos , Lactoglobulinas/química , Espectrometria de Massas , Tripsina/química
17.
Talanta ; 199: 541-546, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952296

RESUMO

A stable and reproducible layer of Prussian blue (PB) modified with copper was electrodeposited on carbon paper electrodes for the multiple detection of ester flavorants with a bienzymatic biosensor. Carbon fiber composite paper was investigated as high-surface, low-cost substrate for biosensor development. The pre-activation of the electrode surface by cyclic voltammetry was necessary to improve the electrochemical properties before the electrochemical deposition of Prussian blue-copper film (PB-Cu). The stability and the reproducibility of the obtained PB-Cu carbon paper electrode was demonstrated at pH 7.4, optimum for biosensor development. The developed biosensor is based on the immobilization of two enzymes (carboxyl esterase and alcohol oxidase) by cross-linking with glutaraldehyde onto PB-Cu carbon paper electrode. A mixture of key aroma ester compounds (methyl butyrate, ethyl butyrate, methyl cinnamate and ethyl cinnamate) was detected in several food samples with low interferences.


Assuntos
Técnicas Biossensoriais , Cobre/química , Ésteres/análise , Ferrocianetos/química , Aromatizantes/análise , Análise de Alimentos , Contaminação de Alimentos/análise , Papel , Oxirredutases do Álcool/metabolismo , Carbono/química , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/metabolismo , Propriedades de Superfície
18.
Food Chem ; 289: 95-102, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30955678

RESUMO

Aspergillus quadrilineatus RSNK-1 produced a multi-enzymatic system containing (U/gds) ß-mannanase (1021), endo-xylanase (1 9 1), α-galactosidase (3.42), ß-xylosidase (0.07) and ß-glucosidase (0.28) on low-cost copra meal (CM) in SSF. The enzyme preparation was covalently immobilized on aluminum oxide pellets (3 mm) under statistically optimized conditions leading to 73.17% immobilization yield. The immobilized enzyme (Man-AOP) displayed enhanced thermal and pH stability. Man-AOP was characterized by FTIR, SEM and PXRD revealing a covalent interaction. The bio-conjugate was successfully recycled for mannooligosaccharide (MOS) generation from locust bean gum (LBG) up to 10 cycles, yielding an average of 0.95 mg MOS/cycle. Man-AOP was also effective in clarification of apple, kiwi, orange and peach juices and enhanced their reducing sugar content. The bio-conjugate was useful in generation of MOS from mannan and enrichment of fruit juices.


Assuntos
Aspergillus/enzimologia , Sucos de Frutas e Vegetais/análise , Oligossacarídeos/metabolismo , Óxido de Alumínio/química , Estabilidade Enzimática , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Galactanos/metabolismo , Concentração de Íons de Hidrogênio , Mananas/metabolismo , Gomas Vegetais/metabolismo , Temperatura Ambiente , Xilosidases/química , Xilosidases/metabolismo , alfa-Galactosidase/química , alfa-Galactosidase/metabolismo , beta-Glucosidase/química , beta-Glucosidase/metabolismo , beta-Manosidase/química , beta-Manosidase/metabolismo
19.
Bioelectrochemistry ; 128: 66-73, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30928867

RESUMO

Different carbon-based nanostructures were used to investigate direct electron transfer (DET) of TetX2 monooxygenase (TetX2), and an enzyme-based biosensor for sensitive determination of tetracycline (TC) also fabricated. A polyethyleneimine (PEI) with positive charge groups was used for immobilization of TetX2 on modified glassy carbon electrodes. Cyclic voltammetry (CV) was employed to study the electrochemical characteristics of the immobilized enzyme and the performance of the proposed biosensor. Amongst multiple carbon-modified electrodes, nano-porous glassy carbon electrode (NPGCE) was selected because of its amplified signal response for flavin adenine dinucleotide (FAD) and superior electrocatalytic behavior toward oxygen reduction. The cyclic voltammogram of PEI/TetX2/NPGCE showed two couple of well-defined and quasi-reversible redox peaks of FAD, consistent with the realization of DET. The prepared electrode was then successfully introduced as a biosensing interface based on the oxygen reduction peak current, resulting in a linear range response from 0.5 to 5 µM with a good detection limit of 18 nM. The as-fabricated electrode demonstrates a fast response and excellent stability for the detection of TC. The results indicate that this simple, rapid, eco-friendly and economic strategy of PEI/TetX2/NPGCE preparation has potential for the fabrication of an enzyme-based biosensor for the practical detection of TC in food products.


Assuntos
Técnicas Biossensoriais , Carbono , Resíduos de Drogas/análise , Técnicas Eletroquímicas/instrumentação , Eletrodos , Enzimas Imobilizadas/metabolismo , Oxigenases de Função Mista/metabolismo , Tetraciclina/análise , Catálise , Flavina-Adenina Dinucleotídeo/análise , Oxirredução , Polietilenoimina/química , Reprodutibilidade dos Testes
20.
Bioelectrochemistry ; 128: 94-99, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30959399

RESUMO

We report on a hybrid bioelectrochemical system that integrates an energy converting part, viz. a glucose/oxygen enzymatic fuel cell, with a charge-storing component, in which the redox features of the immobilized redox protein cytochrome c (cyt c) were utilized. Bilirubin oxidase and pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) were employed as the biocatalysts for dioxygen reduction and glucose oxidation, respectively. A bi-protein PQQ-GDH/cyt c signal chain was created that facilitates electron transfer between the enzyme and the electrode surface. The assembled supercapacitor/biofuel cell hybrid biodevice displays a 15 times higher power density tested in the pulse mode compared to the performance achieved from the continuously operating regime (4.5 and 0.3 µW cm-2, respectively) with an 80% residual activity after 50 charge/discharge pulses. This can be considered as a notable step forward in the field of glucose/oxygen membrane-free, biocompatible hybrid power sources.


Assuntos
Fontes de Energia Bioelétrica , Citocromos c/metabolismo , Enzimas Imobilizadas/metabolismo , Glucose Desidrogenase/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Técnicas Eletroquímicas/instrumentação , Eletrodos , Transporte de Elétrons , Glucose/metabolismo , Oxirredução
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA