Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.868
Filtrar
1.
Chem Commun (Camb) ; 56(18): 2723-2726, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32021996

RESUMO

Encapsulation of two enzymes, alcohol dehydrogenase (ADH) and glucose oxidase (GOx), within peroxidase-like tourmaline microparticle (TM)-based colloidosomes was used to construct a functionalized microsystem capable of sustainable cascade cycling of nicotinamide cofactor (NAD+/NADH) via chemical signaling between spatially confined dual-enzyme and active membranes.


Assuntos
Álcool Desidrogenase/metabolismo , Glucose Oxidase/metabolismo , NAD/metabolismo , Álcool Desidrogenase/química , Glucose Oxidase/química , NAD/química , Tamanho da Partícula , Propriedades de Superfície
2.
Chem Commun (Camb) ; 56(13): 2004-2007, 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-31960849

RESUMO

The operation of wearable epidermal biofuel cells is prone to rapid irreversible deactivation effects under dynamic sweat pH changes from neutral to acidic. We demonstrate that the encapsulation of lactate-oxidase (LOx) within a hydrophobic protective carbon-paste anode imparts unusually high stability during dynamically changing pH fluctuations and allows the BFC to continue harvesting the lactate bioenergy even after long exposures to acidic conditions. The unique power-recovery ability of the carbon-paste BFC after its failure in harsh pH is attributed to the protective action of the non-polar paste environment.


Assuntos
Fontes de Energia Bioelétrica , Técnicas Biossensoriais/métodos , Glucose Oxidase/metabolismo , Carbono/química , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/química , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ácido Láctico/química , Suor/química , Dispositivos Eletrônicos Vestíveis
3.
J Chem Ecol ; 45(11-12): 972-981, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713110

RESUMO

Microplitis croceipes is a solitary parasitoid that specializes on noctuid larvae of Helicoverpa zea and Heliothis virescens. Both the parasitoid and its hosts are naturally distributed across a large part of North America. When parasitoids deposit their eggs into hosts, venom and polydnaviruses (PDVs) are also injected into the caterpillars, which can suppress host immune responses, thus allowing parasitoid larvae to develop. In addition, PDVs can regulate host oral cues, such as glucose oxidase (GOX). The purpose of this study was to determine if parasitized caterpillars differentially induce plant defenses compared to non-parasitized caterpillars using two different caterpillar host/plant systems. Heliothis virescens caterpillars parasitized by M. croceipes had significantly lower salivary GOX activity than non-parasitized caterpillars, resulting in lower levels of tomato defense responses, which benefited parasitoid performance by increasing the growth rate of parasitized caterpillars. In tobacco plants, parasitized Helicoverpa zea caterpillars had lower GOX activity but induced higher plant defense responses. The higher tobacco defense responses negatively affected parasitoid performance by reducing the growth rate of parasitized caterpillars, causing longer developmental periods, and reduced cocoon mass and survival of parasitoids. These studies demonstrate a species-specific effect in different plant-insect systems. Based on these results, plant perception of insect herbivores can be affected by parasitoids and lead to positive or negative consequences to higher trophic levels depending upon the particular host-plant system.


Assuntos
Lycopersicon esculentum/parasitologia , Mariposas/fisiologia , Tabaco/parasitologia , Vespas/fisiologia , Animais , Feminino , Glucose Desidrogenase/metabolismo , Glucose Oxidase/metabolismo , Interações Hospedeiro-Parasita , Larva/metabolismo , Lycopersicon esculentum/metabolismo , Oviposição/fisiologia , Parasitos , Doenças das Plantas/parasitologia , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Especificidade da Espécie , Tabaco/metabolismo
4.
Int J Nanomedicine ; 14: 7851-7860, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31632005

RESUMO

Background: Gestational diabetes mellitus is a commonly occurring metabolic disorder during pregnancy, affecting >4% of pregnant women. It is generally defined as the intolerance of glucose with the onset or initial diagnosis during pregnancy. This illness affects the placenta and poses a threat to the baby as it affects the supply of proper oxygen and nutrients. Purpose: Due to the high percentage of affected pregnant women, it should be mandatory to evaluate glucose levels during pregnancy and there is a need for a continuous monitoring system. Methods: Herein, the investigators modified the interdigitated (di)electrodes (IDE) sensing surface to detect the glucose on covalently immobilized glucose oxidase (GOx) with the graphene. The characterization of graphene and gold nanoparticle (GNP) was performed by high-resolution microscopy. Results: Sensitivity was found to be 0.06 mg/mL and to enhance the detection, GOx was complexed with GNP. GNP-GOx was improved the sensitive detection twofold from 0.06 to 0.03 mg/mL, and it also displayed higher levels of current changes at all the concentrations of glucose that were tested. High-performance of the above IDE sensing system was attested by the specificity, reproducibility and higher sensitivity detections. Further, the linear regression analysis indicated the limit of detection to be between 0.02 and 0.03 mg/mL. Conclusion: This study demonstrated the potential strategy with nanocomposite for diagnosing gestational diabetes mellitus.


Assuntos
Diabetes Gestacional/diagnóstico , Eletricidade , Glucose Oxidase/metabolismo , Glucose/análise , Ouro/química , Grafite/química , Nanocompostos/química , Eletrodos , Feminino , Humanos , Limite de Detecção , Modelos Lineares , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Nanocompostos/ultraestrutura , Gravidez , Sensibilidade e Especificidade , Propriedades de Superfície
5.
ACS Appl Mater Interfaces ; 11(40): 36782-36788, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31532179

RESUMO

Combining biocatalytic and chemocatalytic reactions in a one-pot reaction not only avoids the tedious isolation of intermediates during the reactions but also provides a desirable alternative to extend the range of catalytic reactions. Here, we report a facile strategy to immobilize an enzyme, glucose oxidase (GOx), on PCN-222(Fe) induced by electrostatic interaction in which PCN-222(Fe) serves as both a support and chemocatalyst. The immobilization was confirmed through ζ potential measurement, confocal laser scanning microscopy, Fourier transform infrared spectrometry, and UV-vis spectroscopy. This chemo-biocatalyst was applied to a cascade reaction to catalyze glucose oxidation and ABTS (ABTS = 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (or pyrogallol) oxidation. The catalytic kinetics studies show that these chemo-biocatalytic cascade reactions obey the Michaelis-Menten equation, which indicates that the cascade reactions follow the typical enzymatic dynamic regulation process. Interestingly, GOx/PCN-222(Fe) exhibits an exceptional acid-stable catalytic performance as evidenced by circular dichroism spectroscopy where no significant structure change was observed toward acidic solutions with different pH values. GOx/PCN-222(Fe) also displays desirable recyclability since no significant loss of conversion rates was found after six repeated reactions. This work presents a convenient strategy to construct metal-organic framework based chemo-biocatalysts, which may find potential applications in sensing and nanomachines.


Assuntos
Biocatálise , Glucose Oxidase/metabolismo , Estruturas Metalorgânicas/química , Eletricidade Estática , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Glucose/metabolismo , Glucose Oxidase/ultraestrutura , Estruturas Metalorgânicas/síntese química , Oxirredução
6.
Adv Mater ; 31(43): e1904495, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31497903

RESUMO

Natural killer (NK) cells can not only recognize and eliminate abnormal cells but also recruit and re-educate immune cells to protect the host. However, the functions of NK cells are often limited in the immunosuppressive tumor microenvironment (TME). Here, artificial NK cells (designated as aNK) with minor limitations of TME for specific tumor killing and renegade macrophage re-education are created. The red blood cell membrane (RBCM) cloaks perfluorohexane (PFC) and glucose oxidase (GOX) to construct the aNK. The aNK can directly kill tumor cells by exhausting glucose and generating hydrogen peroxide (H2 O2 ). The generated H2 O2 is also similar to cytokines and chemokines for recruiting immune cells and re-educating survived macrophages to attack tumor cells. In addition, the oxygen-carried PFC can strengthen the catalytic reaction of GOX and normalize the hypoxic TME. In vitro and in vivo experiments display that aNK with slight TME limitations exhibit efficient tumor inhibition and immune activation. The aNK will provide a new sight to treat tumor as the supplement of aggressive NK cells.


Assuntos
Biomimética , Células Matadoras Naturais/imunologia , Macrófagos/imunologia , Animais , Linhagem Celular Tumoral , Citocinas/metabolismo , Glucose/metabolismo , Glucose Oxidase/metabolismo , Peróxido de Hidrogênio/metabolismo , Células Matadoras Naturais/metabolismo , Camundongos , Microambiente Tumoral/imunologia
7.
ACS Appl Mater Interfaces ; 11(40): 37313-37321, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31517474

RESUMO

A simple process is developed for the one-step preparation of dual-compartment alginate microcapsules with controlled size and structure from microfluid-generated water-in-water-in-oil (W/W/O) emulsion droplet. Unlike other methods that rely on transient W/W/O emulsion droplet, we introduce an aqueous two-phase system (ATPS) to form a stable W/W/O emulsion droplet as a template for preparing dual-compartment alginate microcapsules. Two different bioactive molecules are able to be spatially confined encapsulated in the shell and core of alginate microcapsules due to the partitioning effect of ATPS and the high viscosity of alginate solution. Moreover, an enzyme cascade reaction with a spatial confined glucose oxidase and horseradish peroxidase in the shell and core of alginate microcapsules confirms its excellent biocompatibility and high activity. This method provides a green platform for enzyme-catalyzed tandem reactions and controlled sequential release of multiple drugs based on alginate microcapsules.


Assuntos
Alginatos/química , Cápsulas/química , Emulsões/química , Microfluídica , Óleos/química , Água/química , Biocatálise , Fluoresceína-5-Isotiocianato/análogos & derivados , Glucose Oxidase/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Microfluídica/instrumentação , Tamanho da Partícula , Soroalbumina Bovina
8.
ACS Appl Mater Interfaces ; 11(40): 37347-37356, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31502433

RESUMO

Noninvasive real-time biosensors to measure glucose levels in the body fluids have been widely investigated for continuous glucose monitoring of diabetic patients. However, they suffered from low sensitivity and reproducibility due to the instability of nanomaterials used for glucose biosensors. Here, we developed a hyaluronate-gold nanoparticle/glucose oxidase (HA-AuNP/GOx) complex and an ultralow-power application-specific integrated circuit chip for noninvasive and robust wireless patch-type glucose sensors. The HA-AuNP/GOx complex was prepared by the facile conjugation of thiolated HA to AuNPs and the following physical binding of GOx. The wireless glucose sensor exhibited slow water evaporation (0.11 µL/min), fast response (5 s), high sensitivity (12.37 µA·dL/mg·cm2) and selectivity, a low detection limit (0.5 mg/dL), and highly stable enzymatic activity (∼14 days). We successfully demonstrated the strong correlation between glucose concentrations measured by a commercially available blood glucometer and the wireless patch-type glucose sensor. Taken together, we could confirm the feasibility of the wireless patch-type robust glucose sensor for noninvasive and continuous diabetic diagnosis.


Assuntos
Técnicas Biossensoriais/métodos , Glucose Oxidase/metabolismo , Glucose/análise , Ouro/química , Ácido Hialurônico/química , Nanopartículas Metálicas/química , Tecnologia sem Fio , Animais , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus
9.
ACS Appl Mater Interfaces ; 11(36): 32769-32777, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31423772

RESUMO

The screening strategy based on α-glucosidase inhibition has been widely employed for the discovery of antidiabetic drugs, but it still faces some challenges in practical applications, such as poor stability of enzyme, high consumption of test compounds, low sensitivity of screening methods and so on. In this work, a bifunctional hybrid enzyme-catalytic metal organic framework reactor (GAA@GOx@Cu-MOF) with a flower-shaped globular structure was innovatively prepared via self-assembling of α-glucosidase (GAA), glucose oxidase (GOx), Cu2+, and 4,4'-bipyridine. It was found that GAA@GOx@Cu-MOF not only enjoyed merits of high stability, selectivity, and sensitivity but also possessed the character of assembly line work, with about 4.58 times enhanced enzyme activity compared with the free enzyme system. Based on the above characteristics, a highly sensitive screening of GAA inhibitors could be achieved with the detection limit of 7.05 nM for acarbose. Furthermore, the proposed method was successfully applied to the screening of oleanolic acid derivatives as potential antidiabetic drugs. Therefore, it was expected that this work could provide new insights and inspirations for the screening of clinical antidiabetic drugs and for further exploration of functional MOF composites.


Assuntos
Biocatálise , Inibidores de Glicosídeo Hidrolases/análise , Inibidores de Glicosídeo Hidrolases/farmacologia , Estruturas Metalorgânicas/química , Acarbose/farmacologia , Calibragem , Glucose Oxidase/metabolismo , Hipoglicemiantes/análise , Hipoglicemiantes/farmacologia , Concentração Inibidora 50 , Limite de Detecção , Ácido Oleanólico/análise , Ácido Oleanólico/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
10.
Chemistry ; 25(51): 11940-11944, 2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31317582

RESUMO

In addition to superior enzyme-mimicking abilities, nanozymes also have intrinsic physicochemical properties. Integrating the enzyme-like activities and tunable physicochemical properties into a single nanoparticle is a promising strategy for versatile nanozyme design and application. Herein, a composite nanozyme in which Au nanoparticles are encapsulated by Au nanoclusters (AuNP@AuNCs) is presented. By integrating the peroxidase-mimicking ability of fluorescent Au NCs with the glucose oxidase-like activity of Au NPs, the composite nanozyme realized cascade assay of glucose without the aid of external indicators. Compared to traditional multistep colorimetric methods, the analytical process was highly simplified by using the self-responsive nanozyme. This synthetic strategy provided valuable insights into exploring talented nanozymes for sensing diverse targets.


Assuntos
Glucose Oxidase/química , Glucose/metabolismo , Ouro/química , Nanopartículas Metálicas/química , Peroxidase/química , Colorimetria/métodos , Glucose/química , Glucose Oxidase/metabolismo
11.
Sensors (Basel) ; 19(13)2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31277338

RESUMO

The inhibition effect of the selected heavy metals (Ag+, Cd2+, Cu2+, and Hg2+) on glucose oxidase (GOx) enzyme from Aspergillus niger (EC 1.1.3.4.) was studied using a new amperometric biosensor with an electrochemical transducer based on a glassy carbon electrode (GCE) covered with a thin layer of multi-wall carbon nanotubes (MWCNTs) incorporated with ruthenium(IV) oxide as a redox mediator. Direct adsorption of multi-wall carbon nanotubes (MWCNTs) and subsequent covering with Nafion® layer was used for immobilization of GOx. The analytical figures of merit of the developed glucose (Glc) biosensor are sufficient for determination of Glc in body fluids in clinical analysis. From all tested heavy metals, mercury(II) has the highest inhibition effect. However, it is necessary to remember that cadmium and silver ions also significantly inhibit the catalytic activity of GOx. Therefore, the development of GOx biosensors for selective indirect determination of each heavy metal still represents a challenge in the field of bioelectroanalysis. It can be concluded that amperometric biosensors, differing in the utilized enzyme, could find their application in the toxicity studies of various poisons.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas/métodos , Inibidores Enzimáticos/toxicidade , Glucose Oxidase/antagonistas & inibidores , Metais Pesados/toxicidade , Aspergillus niger/enzimologia , Calibragem , Técnicas Eletroquímicas/instrumentação , Eletrodos , Inibidores Enzimáticos/farmacologia , Glucose/análise , Glucose Oxidase/metabolismo , Peróxido de Hidrogênio/análise , Limite de Detecção , Metais Pesados/farmacologia , Nanotubos de Carbono , Compostos de Rutênio/química
12.
Biomater Sci ; 7(9): 3683-3692, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31361291

RESUMO

Synergistic cancer starvation/ROS-mediated/chemo-therapy is developed through a cascade reaction with enzyme glucose oxidase (GOX) modified on the surface of an Fe-based metal organic framework (MOF(Fe)) and drug camptothecin (CPT) loaded into the cavities of MOF(Fe). Once internalized by tumor cells, GOX catalyzes endogenous glucose into hydrogen peroxide (H2O2) and gluconic acid (H+) enabling starvation therapy through choking off energy (glucose) supply. Meanwhile, the acidic micro-environment of tumor enhanced by the generated H+ degrades the MOF(Fe) simultaneously releasing CPT for chemotherapy and Fe3+, catalyzing H2O2 into one of the strongest reactive oxygen species (ROS) ˙OH enabling ROS-mediated therapy. Both in vitro and in vivo results show remarkable tri-modal synergistic anticancer effects. This work may shed some light on the development of novel multi-modal cancer therapies without any external intervention.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Camptotecina/farmacologia , Cloretos/farmacologia , Compostos Férricos/farmacologia , Glucose Oxidase/metabolismo , Estruturas Metalorgânicas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/metabolismo , Biocatálise , Camptotecina/química , Camptotecina/metabolismo , Proliferação de Células/efeitos dos fármacos , Cloretos/química , Cloretos/metabolismo , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Compostos Férricos/química , Compostos Férricos/metabolismo , Células HeLa , Humanos , Peróxido de Hidrogênio/metabolismo , Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Tamanho da Partícula , Relação Estrutura-Atividade , Células Tumorais Cultivadas
13.
Int J Biol Macromol ; 136: 1060-1068, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31202848

RESUMO

Gluconic acid (GA) and its alkali salts are extensively used in the food, feed, beverage, textile, pharmaceutical and construction industries. However, the cost-effective and eco-friendly production of GA remains a challenge. The biocatalytic process involving the conversion of glucose to GA is catalysed by glucose oxidase (GOD), in which the catalytic efficiency is highly dependent on the GOD stability. In this study, we used in silico design to enhance the stability of glucose oxidase from Aspergillus niger. A combination of the best mutations increased the apparent melting temperature by 8.5 °C and significantly enhanced thermostability and thermoactivation. The variant also showed an increased optimal temperature without compromising the catalytic activity at lower temperatures. Moreover, the combined variant showed higher tolerance at pH 6.0 and 7.0, at which the wild-type enzyme rapidly deactivated. For GA production, an approximate 2-fold higher GA production yield was obtained, in which an almost complete conversion of 324 g/L d-glucose to GA was achieved within 18 h. Collectively, this work provides novel and efficient approaches for improving GOD thermostability, and the obtained variant constructed by the computational strategy can be used as an efficient biocatalyst for GA production at industrially viable conditions.


Assuntos
Aspergillus niger/enzimologia , Gluconatos/metabolismo , Glucose Oxidase/metabolismo , Engenharia de Proteínas , Temperatura , Biocatálise , Estabilidade Enzimática/genética , Fermentação , Glucose Oxidase/química , Glucose Oxidase/genética , Concentração de Íons de Hidrogênio , Modelos Moleculares , Mutação , Conformação Proteica
14.
Food Chem ; 293: 529-536, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31151644

RESUMO

The effect of glucose oxidase (GOx) catalytic oxidation on the efficacy of gallic acid (GA) to modify the chemical structure and gelling behavior of myofibrillar protein (MP) was investigated. In contrast to non-oxidized MP samples where GA induced very little changes, GA (0, 6, 30, and 60 µmol/g MP) under GOx treatment promoted sulfhydryl and amine loss (up to 58% and 49%, respectively). The attenuation of intrinsic tryptophan fluorescence in the GA/GOx-treated MP corroborated the finding. The gelling capacity of MP, corresponding to disulfide and non-disulfide bond formation in protein aggregates, was markedly enhanced by 60 µmol GA under GOx, up to 86% in gel storage modulus G' and 53% in gel strength. The GOx-aided GA modification of MP could be a potential ingredient strategy in meat processing to promote textural attributes of cooked products.


Assuntos
Ácido Gálico/química , Géis/química , Glucose Oxidase/metabolismo , Proteínas Musculares/química , Aminas/química , Aminas/metabolismo , Animais , Ácido Gálico/metabolismo , Carne/análise , Microscopia Eletrônica de Varredura , Proteínas Musculares/metabolismo , Oxirredução , Reologia , Compostos de Sulfidrila/química , Compostos de Sulfidrila/metabolismo
15.
Sensors (Basel) ; 19(11)2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31159318

RESUMO

Glucose oxidase (EC 1.1.3.4) sensors that have been developed and widely used for glucose monitoring have generally relied on electrochemical principle. In this study, the potential use of colorimetric method for glucose detection utilizing glucose oxidase-magnetic cellulose nanocrystals (CNCs) is explored. Magnetic cellulose nanocrystals (magnetic CNCs) were fabricated using iron oxide nanoparticles (IONPs) and cellulose nanocrystals (CNCs) via electrostatic self-assembly technique. Glucose oxidase was successfully immobilized on magnetic CNCs using carbodiimide-coupling reaction. About 33% of GOx was successfully attached on magnetic CNCs, and the affinity of GOx-magnetic CNCs to glucose molecules was slightly higher than free enzymes. Furthermore, immobilization does not affect the specificity of GOx-magnetic CNCs towards glucose and can detect glucose from 0.25 mM to 2.5 mM. Apart from that, GOx-magnetic CNCs stored at 4 °C for 4 weeks retained 70% of its initial activity and can be recycled for at least ten consecutive cycles.


Assuntos
Celulose/química , Colorimetria/métodos , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Glicemia/análise , Automonitorização da Glicemia , Compostos Férricos/química , Nanopartículas/química
16.
Anal Sci ; 35(9): 1037-1043, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31155546

RESUMO

The characteristics of an electrochemical biosensor based on a Prussian-blue screen-printed electrode containing glucose oxidase incorporated into polyelectrolyte microcapsules (PMC) are considered. PMC with the embedded enzyme were formed using sodium polystyrene sulfonate and poly(allylamine hydrochloride). The characteristics were compared with those of the enzyme immobilized in chitosan gel. We assessed the dependences of biosensor signals on the composition of the buffer solution, on the glucose concentration; the operational and long-term stabilities. The enzyme immobilized in PMC proved to be more sensitive to buffer molarity at a maximum within 35 - 40 mM. The apparent Michaelis constants were 1.5 and 4.1 mM at the immobilization in, respectively, chitosan and PMC. The developed biosensors were used to assay commercial juices. The biosensors' data on the glucose contents were shown to have a high correlation with the standard spectrophotometric assay (0.92 - 0.95%), which implies a possible application of the fabricated biosensors in foodstuff analysis.


Assuntos
Técnicas Biossensoriais/métodos , Quitosana/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Polieletrólitos/química , Técnicas Biossensoriais/instrumentação , Tampões (Química) , Calibragem , Cápsulas , Eletroquímica , Eletrodos , Ferrocianetos/química , Géis , Glucose/análise , Poliaminas/química , Poliestirenos/química
17.
Int J Biol Macromol ; 136: 20-26, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31175901

RESUMO

Lignin peroxidase has high potential as ingredient in skin whitening cosmetics due to its high redox potential to oxidize recalcitrant melanin. Currently crude mixtures of lignin peroxidase from fungal fermentation are usually applied to cosmetics due to the intrinsic difficulties of expression and purification. However, the present study focused on heterologous expression and purification of lignin peroxidase isozyme H8 (LiPH8) from Phanerochaete chrysosporium and was further used for melanin decolorization. Results revealed that the optimum pH for melanin decolorization using LiPH8 was obtained at pH 4.0. The intermittent feeding of hydrogen peroxide (H2O2) was effectively elevating melanin decolorization efficiency up to 73%, since excessive H2O2 inactivated LiPH8. For cosmetic application, intermittent feeding of H2O2 is not feasible, thus glucose oxidase (GOx) from Aspergillus niger was employed for in-situ generation of H2O2. By optimizing the GOx and glucose concentrations, a melanin decolorization efficiency up to 63.3 ±â€¯2.4% was obtained within 1 h and continued to 84.0 ±â€¯1.8% in 8 h. Conclusively, lignin peroxidase-catalyzed decolorization of melanin with in-situ generated H2O2 revealed a promising approach for whitening cosmetics applications.


Assuntos
Biocatálise , Cosméticos/metabolismo , Peróxido de Hidrogênio/metabolismo , Melaninas/metabolismo , Peroxidases/metabolismo , Proteínas Recombinantes/metabolismo , Cor , Glucose Oxidase/química , Glucose Oxidase/metabolismo , Modelos Moleculares , Peroxidases/química , Conformação Proteica , Proteínas Recombinantes/química
18.
ACS Appl Mater Interfaces ; 11(21): 18995-19005, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31058483

RESUMO

Cutting off the glucose supply by glucose oxidase (GOx) has been regarded as an emerging strategy in cancer starvation therapy. However, the standalone GOx delivery suffered suboptimal potency for tumor elimination and potential risks of damaging vasculatures and normal organs during transportation. To enhance therapeutic efficacy and tumor specificity, a site-specific activated dual-catalytic nanoreactor was herein constructed by embedding GOx and ferrocene in hyaluronic acid (HA)-enveloped dendritic mesoporous silica nanoparticles to promote intratumoral oxidative stress in cancer starvation. In this nanoreactor, the encapsulated GOx served as the primary catalyst that accelerated oxidation of glucose and generation of H2O2, while the covalently linked ferrocene worked as the secondary catalyst for converting the upstream H2O2 to more toxic hydroxyl radicals (•OH) via a classic Fenton reaction. The outmost HA shell not only offered a shielding layer for preventing blood glucose from oxidation during nanoreactor transportation, thus minimizing the probable oxidative damage to normal tissues, but also imparted the nanoreactor with targeting ability for facilitating its internalization into CD44-overexpressing tumor cells. After the nanoreactor was endocytosed by target cells, the HA shell underwent hyaluronidase-triggered degradation in lysosomes and switched on the cascade catalytic reaction mediated by GOx and ferrocene. The resulting glucose exhaustion and •OH accumulation would effectively kill cancer cells and suppress tumor growth via combination of starvation and oxidative stress enhancement. Both in vitro and in vivo results indicated the significantly amplified therapeutic effects of this synergistic therapeutic strategy based on the dual-catalytic nanoreactor. Our study provides a new avenue for engineering therapeutic nanoreactors that take effect in a tumor-specific and orchestrated fashion for cancer starvation therapy.


Assuntos
Ácido Hialurônico/química , Nanopartículas/química , Neoplasias/patologia , Estresse Oxidativo , Animais , Antineoplásicos/farmacologia , Catálise , Morte Celular/efeitos dos fármacos , Feminino , Glucose Oxidase/metabolismo , Células HeLa , Humanos , Ácido Hialurônico/síntese química , Radical Hidroxila/metabolismo , Camundongos Nus , Nanopartículas/ultraestrutura , Estresse Oxidativo/efeitos dos fármacos
19.
Chem Asian J ; 14(14): 2491-2496, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31087617

RESUMO

Microshells are attractive in constructing bubble-propelled micromotors due to the lower energy consumption for bubbles forming on a concave surface. In this work, enzyme-powered microshell motors were fabricated on multimetallic (Au/Ag/Au) microshells along with the modification of catalase on its concave surface. The catalase triggered the decomposition of hydrogen peroxide to oxygen gas, hence propelling the autonomous motion of microshell motors. A size-dependent motion behaviour was observed for the microshell motors in the form of slow tremble and fast translation motion for a size smaller and larger than 5 µm, respectively, according to the size, generation efficiency and ejection mechanism of bubbles and the intensity of Brownian motion. In addition, the effect of fuel concentration on the motion speed of microshells was dependent on whether the bubble generation was affected by the limited mass transfer in the microshell space. These findings play an important role for the design of microshell motors.


Assuntos
Catalase/química , Glucose Oxidase/química , Técnicas Analíticas Microfluídicas , Catalase/metabolismo , Glucose Oxidase/metabolismo , Ouro/química , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Técnicas Analíticas Microfluídicas/instrumentação , Tamanho da Partícula , Prata/química , Propriedades de Superfície
20.
Biomater Sci ; 7(7): 2841-2849, 2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31069351

RESUMO

Considerable efforts have been made to develop reliable immobilization approaches to improve enzyme stability and reusability. However, relatively complicated preparation often leads to compromised enzyme activity. This study reports a facile method of retaining full enzymatic activity by immobilizing glucose oxidase (GOx) into core-shell nanoparticles with polydopamine (PDA) sandwiched between a gold nanoparticle (Au NP) core and a calcium phosphate (CaP) shell (Au@PDA@CaP). The strong adhesion of PDA on Au NPs and its metal chelating properties directed the preferential growth of the CaP shell on the Au NPs, leading to well-dispersed and uniform nanohybrids. Concurrent loading of GOx during the growth of CaP held the key to the successful immobilization of GOx. As a result, Au@PDA@CaP-immobilized GOx had similar activity but better resistance against heating, long-term storage and repeated uses compared to free GOx. This work provides a green strategy for constructing nanobiocatalysts with high enzyme activity and stability.


Assuntos
Fosfatos de Cálcio/química , Enzimas Imobilizadas/química , Glucose Oxidase/química , Ouro/química , Indóis/química , Nanopartículas/química , Nanotecnologia , Polímeros/química , Biocatálise , Técnicas de Química Sintética , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Glucose Oxidase/metabolismo , Concentração de Íons de Hidrogênio , Temperatura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA