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1.
J Oleo Sci ; 69(11): 1403-1409, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33055438

RESUMO

We studied the structures and properties of gel samples prepared by mixtures of N-[3-(dimethylamino)propyl]docosanamide (APA-22) acid salt (APA-22 L-lactic acid), 1-octadecanol (C18OH), and water. The gel samples prepared at the mole ratios [APA-22 L-lactic acid]:C18OH = 1:3, 1:4, and 1:5 yielded two phases; one being the α-gel (α-form hydrated crystal) phase, incorporating a significant quantity of water between lamellar bilayers, and the other being the excess water phase. The lamellar d-spacing remained practically unaltered at these mole ratios, thus maintaining the quantity of water incorporated between the lamellar bilayers relatively constant. Starting at 30°C, the gel samples transformed into a lamellar liquid crystal phase at high temperatures (85°C) and a ß-gel phase at low temperatures (5°C). Interestingly, following dilution by pure water, the viscosity of the gel samples decreased with increasing C18OH content. We expect that the viscosity change affects the performance of the gel samples as hair conditioners.


Assuntos
Amidas/química , Tensoativos/química , Cristalização , Géis , Preparações para Cabelo , Ácido Láctico/química , Bicamadas Lipídicas/química , Ácidos Esteáricos/química , Temperatura , Viscosidade , Água/química
2.
Nat Commun ; 11(1): 4899, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994420

RESUMO

Chemical synthesis of amino acids from renewable sources is an alternative route to the current processes based on fermentation. Here, we report visible-light-driven amination of biomass-derived α-hydroxyl acids and glucose into amino acids using NH3 at 50 °C. Ultrathin CdS nanosheets are identified as an efficient and stable catalyst, exhibiting an order of magnitude higher activity towards alanine production from lactic acid compared to commercial CdS as well as CdS nanoobjects bearing other morphologies. Its unique catalytic property is attributed mainly to the preferential formation of oxygen-centered radicals to promote α-hydroxyl acids conversion to α-keto acids, and partially to the poor H2 evolution which is an undesired side reaction. Encouragingly, a number of amino acids are prepared using the current protocol, and one-pot photocatalytic conversion of glucose to alanine is also achieved. This work offers an effective catalytic system for amino acid synthesis from biomass feedstocks under mild conditions.


Assuntos
Alanina/síntese química , Compostos de Cádmio/química , Sulfetos/química , Alanina/química , Biomassa , Catálise/efeitos da radiação , Hidrogênio/química , Ácido Láctico/química , Luz , Modelos Químicos , Oxigênio/química
3.
Life Sci ; 260: 118423, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32941896

RESUMO

AIMS: Increased expression of inhibitor of apoptosis (IAP) genes has been associated with progressive cancer and chemoresistance. Accordingly, blockade of IAPs by BV6 has resulted in ameliorative outcomes. Interleukin (IL)-6 is another important mediator involved in the growth and survival of tumor cells. Therefore, we hypothesized that simultaneous inhibition of IAPs and IL-6 could be a new promising anti-tumor treatment strategy. MATERIALS AND METHODS: In this study, we generated and characterized hyaluronate-PEG-Chitosan-Lactate (H-PCL) nanoparticles (NPs) to simultaneously deliver IL6-specific siRNA and BV6 to 4T1 (breast cancer) and CT26 (colon cancer) cells, and investigate the anti-tumor properties of this combination therapy both in vitro and in vivo. KEY FINDINGS: H-PCL NPs exhibited good physicochemical properties leading to efficient transfection of cancer cells and suppression of target molecules. Moreover, combination therapy synergistically increased apoptosis, as well as decreased cell migration, proliferation, colony formation, and angiogenesis in both 4T1 and CT26 cell lines and suppressed cancer progression in tumor-bearing mice that was associated with enhanced survival time. SIGNIFICANCE: These findings imply the effectiveness of cancer combination therapy by using H-PCL NPs loaded with anti-IL-6 siRNA and BV6.


Assuntos
Antineoplásicos/administração & dosagem , Interleucina-6/genética , Nanopartículas/administração & dosagem , Nanopartículas/química , Oligopeptídeos/administração & dosagem , RNA Interferente Pequeno/administração & dosagem , Animais , Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Embrião de Galinha/irrigação sanguínea , Embrião de Galinha/efeitos dos fármacos , Quitosana/química , Neoplasias do Colo/tratamento farmacológico , Neoplasias do Colo/patologia , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Feminino , Humanos , Interleucina-6/antagonistas & inibidores , Ácido Láctico/química , Espectroscopia de Ressonância Magnética , Camundongos Endogâmicos BALB C , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/patologia , Oligopeptídeos/farmacocinética , Oligopeptídeos/farmacologia , Polietilenoglicóis/química , RNA Interferente Pequeno/farmacocinética , RNA Interferente Pequeno/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Ensaios Antitumorais Modelo de Xenoenxerto
4.
Proc Natl Acad Sci U S A ; 117(36): 22378-22389, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839325

RESUMO

Hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging (MRSI) is a noninvasive metabolic-imaging modality that probes carbon flux in tissues and infers the state of metabolic reprograming in tumors. Prevailing models attribute elevated hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates in aggressive tumors to enhanced glycolytic flux and lactate dehydrogenase A (LDHA) activity (Warburg effect). By contrast, we find by cross-sectional analysis using genetic and pharmacological tools in mechanistic studies applied to well-defined genetically engineered cell lines and tumors that initial hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates as well as global conversion were highly dependent on and critically rate-limited by the transmembrane influx of [1-13C]pyruvate mediated predominately by monocarboxylate transporter-1 (MCT1). Specifically, in a cell-encapsulated alginate bead model, induced short hairpin (shRNA) knockdown or overexpression of MCT1 quantitatively inhibited or enhanced, respectively, unidirectional pyruvate influxes and [1-13C]pyruvate-to-[1-13C]lactate conversion rates, independent of glycolysis or LDHA activity. Similarly, in tumor models in vivo, hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion was highly dependent on and critically rate-limited by the induced transmembrane influx of [1-13C]pyruvate mediated by MCT1. Thus, hyperpolarized [1-13C]pyruvate MRSI measures primarily MCT1-mediated [1-13C]pyruvate transmembrane influx in vivo, not glycolytic flux or LDHA activity, driving a reinterpretation of this maturing new technology during clinical translation. Indeed, Kaplan-Meier survival analysis for patients with pancreatic, renal, lung, and cervical cancers showed that high-level expression of MCT1 correlated with poor overall survival, and only in selected tumors, coincident with LDHA expression. Thus, hyperpolarized [1-13C]pyruvate MRSI provides a noninvasive functional assessment primarily of MCT1 as a clinical biomarker in relevant patient populations.


Assuntos
Isótopos de Carbono/metabolismo , Membrana Celular/metabolismo , Ácido Láctico/metabolismo , Transportadores de Ácidos Monocarboxílicos/metabolismo , Ácido Pirúvico/metabolismo , Simportadores/metabolismo , Animais , Isótopos de Carbono/análise , Isótopos de Carbono/química , Linhagem Celular Tumoral , Membrana Celular/química , Feminino , Humanos , Ácido Láctico/análise , Ácido Láctico/química , Imagem por Ressonância Magnética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Nus , Ácido Pirúvico/análise , Ácido Pirúvico/química
5.
Chemosphere ; 261: 127684, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32721687

RESUMO

Surface modification of natural fibres by gamma irradiation is an economical and potent technique. The biodegradability of gamma irradiated Luffa cylindrica (LC) fibres having response of doses (0.5Gy, 1Gy and 2Gy) is studied. The degradation process is carried out in various environments like compost, sand, soil, salt water, brackish water and sweet water for a period of 90 days and microbial degradation using bacteria and fungi for a period of 90 days. The rate of biodegradation was calculated by measuring the loss of weight of composites at an interval of 30 days in each environmental condition. Preliminary results reported that the bacterial environment was the most prominent medium for degradation than fungi. B8 composites showed degradation of 27.5% and 3.59 in bacterial and fungal medium respectively. A minimum degradation was observed in compost medium (0.29%, 2.52%, 0.21%, 0.08%, 0.11%, 0.13%, 0.17%, 1.25% and 1.51% for B1-B9 respectively). For exploring the use of the composites in the field of biomedical sciences, the LC fibres are modified using calcium salts before reinforcement. The thermal properties like crystallization temperature (Tcc), glass transition temperature (Tg), melting peak temperature (Tm) and thermal stability of the bio-composites were analyzed using Differential scanning calorimetry (DSC) in temperature range from 30 °C to 250 °C and the thermogravimetric analysis (TGA) was done in the temperature range of 20 °C to 700 °C. With increase in irradiation dose, crystallization temperature and glass transition temperature increased. Increasing in the irradiation dose, thermal stability of the composites decreased.


Assuntos
Biodegradação Ambiental , Luffa/química , Varredura Diferencial de Calorimetria , Cristalização , Raios gama , Ácido Láctico/química , Poliésteres , Temperatura , Temperatura de Transição
6.
Adv Clin Exp Med ; 29(4): 431-440, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32364686

RESUMO

BACKGROUND: Autogenous or allogenic bone transplantation is the main treatment for bone defects and nonunions. However, the shortcomings of autogenous or allogenic bone transplantation limit its wide application in clinical use. OBJECTIVES: This study investigated the effect of poly(lactic-co-glycolic acid) (PLGA) microspheres loaded with pOsterix (pOsx)/polyethylenimine (PEI) nanoparticles in repairing bone defects and explored its mechanism. MATERIAL AND METHODS: Poly(lactic-co-glycolic acid) microspheres loaded with pOsx/PEI nanoparticles were constructed. The Osx transfection effect was detected by fluorescence quantitative PCR and western blotting methods. 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-diphenytetrazoliumromide (MTT) and flow cytometry methods were used to detect cell proliferation. The collagen I (Col-1), osteopontin (OPN) and osteocalcin (OC) expression levels were detected using real-time polymerase chain reaction (RT-PCR) and western blotting methods. Bone defect model was constructed. Bone repair was detected using X-ray, hematoxylin and eosin (H&E) staining, and Mason staining methods. RESULTS: PLGA@pOsx/PEI has transfection effect both in vitro and in vivo, does not affect cell proliferation and is safe for cells. PLGA@pOsx/PEI could promote the expression of Col-1, OPN and OC in vitro and in vivo. PLGA@pOsx/PEI could promote osteogenesis in vivo. CONCLUSIONS: PLGA@pOsx/PEI with high Osx expression could promote the expression of OC, OPN, and COL-I. PLGA@pOsx/PEI can be used as a material for repairing bone defects and can promote bone formation. These results provide a theoretical and practical basis for its further clinical application.


Assuntos
Regeneração Óssea/efeitos dos fármacos , Ácido Láctico/química , Nanopartículas , Polietilenoimina/química , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Western Blotting , Proliferação de Células/efeitos dos fármacos , Microesferas , Reação em Cadeia da Polimerase em Tempo Real
7.
Food Chem ; 326: 126977, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32447161

RESUMO

Changes in sensorial, chemical and microbiological qualities of kefirs fortified with black carrot (KBCJ), black mulberry (KBMJ), pomegranate (KPJ), and strawberry (KSJ) juices at different concentrations (10, 25 and 50%, w/w) were monitored throughout storage at 4 °C for 12 weeks. The most preferred kefirs by the sensorial panel were KSJ and KPJ, followed by KBMJ and KBCJ. KBMJ was associated with the highest anthocyanin stability, followed by KPJ, KSJ, and KBCJ. Lactic acid [r = (-0.688)-(-0.970)], glucose [r = (-0.563)-(-0.793)] and microorganisms [r = (-0.633)-(-0.961)] in kefirs had significant effect on anthocyanin stability and colour (p < 0.05). Copigmentation between lactic acid and anthocyanins were observed. Fortification with 25% juices led to an increase (1.8-4.8 times) in antioxidant activity (AA). Shelf-lives of samples, except for KPJ, ended after 12 weeks of storage, due to low sensorial scores. Additions of SJ, PJ and BMJ at 25% concentration are recommended for the production of more palatable kefir with high AA.


Assuntos
Antocianinas/química , Armazenamento de Alimentos/métodos , Sucos de Frutas e Vegetais/análise , Kefir/análise , Antocianinas/metabolismo , Antioxidantes/química , Temperatura Baixa , Cor , Concentração de Íons de Hidrogênio , Cinética , Ácido Láctico/química
8.
Zhonghua Zhong Liu Za Zhi ; 42(4): 319-324, 2020 Apr 23.
Artigo em Chinês | MEDLINE | ID: mdl-32375448

RESUMO

Objective: To analyze the effect of ultrasound contrast agent targeting gelatin on uptake of high lymphatic metastasis cell lines of mouse hepatocellular carcinoma with peritoneal effusion. Methods: The modified double emulsifying solvent evaporation method was used to construct the macromolecule contrast agent PLGA-Cooh. The carbodiimide was used to connect the monoclonal antibody of gelatin with the contrast agent PLGA-Cooh, and the targeted ultrasound contrast agent Gsn-PLGA was established. The particle size and Zeta potential of the targeted ultrasound contrast agent were measured by laser particle size analyzer. The surface binding of the contrast agent to the gelatin monoclonal antibody was evaluated by immunofluorescence. Hca-F cells with high lymphatic metastasis were cultured in mice with peritoneal effusion hepatocellular carcinoma. Target-seeking ability in vitro was evaluated by in vitro uptake test, and the imaging effect of the contrast agent in vitro was evaluated by in vitro developing test. Results: The contrast agent is white powder with good water solubility. The average particle size and surface potential were (569.68±6.96) nm and (-10.95±2.43) mV, respectively. The fluorescent antibody binding rate of non-targeted and targeted ultrasound contrast agent labeled with DiI were 0.84% and 95.89%, respectively. The results showed that the targeted ultrasound contrast agent Gsn-PLGA had a better of developing effect in vitro. Hca-F cells with high expression of gelsolin protein had stronger uptake ability of targeted ultrasound contrast agent and stronger green fluorescence in vitro than those with low expression of gelsolin protein (P<0.05). Moreover, targeted ultrasound contrast agent Gsn-PLGA had stronger targeting to the gelsolin protein. The echo of the targeted ultrasound contrast agent Gsn-PLGA was uniform and fine, without attenuating echo of the back. Simultaneously, the development effect was more obvious with the increase of contrast agent concentration (P<0.05). Conclusion: Ultrasound contrast agent Gsn-PLGA targeting gelatin can bind Hca-F cells with high expression of gelatin and display a good imaging effect in vitro.


Assuntos
Carcinoma Hepatocelular , Meios de Contraste/química , Diagnóstico por Imagem/métodos , Neoplasias Hepáticas , Ácido Poliglicólico/química , Ultrassonografia/métodos , Animais , Ascite , Linhagem Celular , Gelatina , Ácido Láctico/química , Metástase Linfática , Camundongos , Tamanho da Partícula , Copolímero de Ácido Poliláctico e Ácido Poliglicólico
9.
Pharm Res ; 37(3): 59, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32095934

RESUMO

PURPOSE: Evaluate fundamental parameters that dictate the effectiveness of drug loading. METHODS: A model water-soluble drug lacking ionizable groups, pirfenidone (PFD), was encapsulated through nanoprecipitation in poly(ethylene glycol)-poly(lactic acid) (PEG-PLA)-poly(lactic-co-glycolic acid) (PLGA) NPs. Firstly, the thermodynamic parameters predicting drug-polymer miscibility were determined to assess the system's suitability. Then, the encapsulation was evaluated experimentally by two different techniques, bulk and microfluidic (MF) nanoprecipitation. Additionally, the number of molecules that fit in a particle core were calculated and the loading determined experimentally for different core sizes. Lastly, the effect of co-encapsulation of α-lipoic acid (LA), a drug with complementary therapeutic effects and enhanced lipophilicity, was evaluated. RESULTS: The thermodynamic miscibility parameters predicted a good suitability of the selected system. MF manufacturing enhanced the encapsulation efficiency by 60-90% and achieved a 2-fold higher NP cellular uptake. Considering spatial constrictions for drug encapsulation and increasing the size of the PLGA core the number of PFD molecules per NP was raised from under 500 to up to 2000. More so, the co-encapsulation of LA increased the number of drug molecules per particle by 96%, with no interference with the release profile. CONCLUSIONS: Thermodynamic, spatial and methodological parameters should be considered to optimize drug encapsulation.


Assuntos
Antineoplásicos/administração & dosagem , Nanocápsulas/química , Polietilenoglicóis/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/análogos & derivados , Piridonas/administração & dosagem , Antineoplásicos/química , Liberação Controlada de Fármacos , Ácido Láctico/administração & dosagem , Ácido Láctico/química , Piridonas/química , Termodinâmica
10.
Mikrochim Acta ; 187(3): 180, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32076878

RESUMO

A rapid fluorometric method is described for the determination of lactate and cholesterol by using ZnO nanowires (ZnO NWs). The assay is based on the detection of the hydrogen peroxide generated during the enzymatic reactions of the oxidation of lactate or cholesterol. Taking advantage of the electrostatic interactions between the enzymes and the ZnO NWs, two bioconjugates were prepared by mixing the nanomaterial and the enzymes, viz. lactate oxidase (LOx) or cholesterol oxidase (ChOx). The enzymatically generated hydrogen peroxide quenches the fluorescence of the ZnO NWs, which have emission peaks at 384 nm and at 520 nm under 330 nm photoexcitation. H2O2 quenches the 520 nm band more strongly. Response is linear up to 1.9 µM lactate concentration, and up to 1.1 µM cholesterol concentration. Relative standard deviation was found to be 5%. The detection limits for lactate and cholesterol are 0.54 and 0.24 µM, respectively. Graphical abstractSchematic representation of fluorescence assay based on ZnO nanowires photoluminiscence for lactate and colesterol detection.


Assuntos
Colesterol/química , Fluorometria/métodos , Ácido Láctico/química , Óxido de Zinco/metabolismo
11.
Food Chem ; 316: 126351, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32050114

RESUMO

The debittering of natural table olives is a very slow process. The effect of acetic, lactic and citric acids on the hydrolysis rate of oleuropein was studied in vitro and at pilot plant scale. The acid hydrolysis of oleuropein was faster with lactic and citric acids than acetic acid, running the experiments at the same pH of 3.8-4.0 units. The temperature exerted a high effect of the hydrolysis of oleuropein in a range of 10-30 °C and the concentration of the organic acid did not show a significant trend. Moreover, the in vitro results were confirmed with three lots of olives that presented a higher content of oleuropein after 3-7 months of preservation when they were processed with acetic acid rather than lactic acid and the opposite for hydroxytyrosol. These results open the possibility of accelerating the debittering of natural olives by preserving them with lactic acid instead of acetic acid.


Assuntos
Ácido Acético/química , Iridoides/química , Ácido Láctico/química , Olea/química , Hidrólise
12.
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
13.
Analyst ; 145(5): 1894-1902, 2020 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-31984382

RESUMO

This work describes a fully-integrated portable microfluidic analysis system for real-time monitoring of dynamic changes in glucose and lactate occurring in the brain as a result of cardiac arrest and resuscitation. Brain metabolites are sampled using FDA-approved microdialysis probes and coupled to a high-temporal resolution 3D printed microfluidic chip housing glucose and lactate biosensors. The microfluidic biosensors are integrated with a wireless 2-channel potentiostat forming a compact analysis system that is ideal for use in a crowded operating theatre. Data are transmitted to a custom-written app running on a tablet for real-time visualisation of metabolic trends. In a proof-of-concept porcine model of cardiac arrest, the integrated analysis system proved reliable in a challenging environment resembling a clinical setting; noise levels were found to be comparable with those seen in the lab and were not affected by major clinical interventions such as defibrillation of the heart. Using this system, we were able, for the first time, to measure changes in brain glucose and lactate levels caused by cardiac arrest and resuscitation; the system was sensitive to clinical interventions such as infusion of adrenaline. Trends suggest that cardiopulmonary resuscitation alone does not meet the high energy demands of the brain as metabolite levels only return to their values preceding cardiac arrest upon return of spontaneous circulation.


Assuntos
Encéfalo/metabolismo , Reanimação Cardiopulmonar , Glucose/análise , Parada Cardíaca/metabolismo , Ácido Láctico/análise , Aerococcus/enzimologia , Animais , Aspergillus niger/enzimologia , Biomarcadores/análise , Biomarcadores/química , Técnicas Biossensoriais/métodos , Isquemia Encefálica/metabolismo , Feminino , Glucose/química , Glucose Oxidase/química , Parada Cardíaca/terapia , Ácido Láctico/química , Microdiálise , Técnicas Analíticas Microfluídicas/métodos , Oxigenases de Função Mista/química , Monitorização Neurofisiológica/métodos , Estudo de Prova de Conceito , Suínos
14.
Biosens Bioelectron ; 151: 111974, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31999581

RESUMO

The l-lactate oxidase (LOx) based lactate sensors are widely used for clinical diagnostics, sports medicine, and food quality control. However, dissolved oxygen interference and electroactive interferent effects are inherent issues of current lactate sensors. In this paper, a quasi-direct electron transfer (quasi-DET) type lactate sensor was developed using rationally engineered Aerococcus viridans LOx (AvLOx) modified with amine-reactive phenazine ethosulfate (PES). Since the modification of wild type AvLOx by PES did not result quasi-DET, engineered AvLOx with additional Lys residue was designed. The additional Lys residue was introduced by substituting residue locating on the surface of AvLOx, and within 20 Šof the isoalloxazine ring of FMN. Among several constructed mutants, Ala96Leu/Asn212Lys double mutant showed the highest dye-mediated dehydrogenase activity with negligible oxidase activity, showing quasi-DET properties after PES modification, when the enzyme was immobilized on screen printed carbon electrode. The constructed electrode did not show oxygen interference in cyclic voltammetric analysis and distinct catalytic current with 20 mM l-lactate. The sensor performance of a chronoamperometric l-lactate sensor employing PES modified Ala96Leu/Asn212Lys AvLOx, marked with linear range between 0 and 1 mM, with sensitivity of 13 µA/mM∙cm2, and a limit of detection of 25 µM for l-lactate. By applying -200 mV vs. Ag/AgCl, l-lactate could be monitored with negligible interference from 170 µM ascorbic acid, 1.3 mM acetaminophen, 1.4 mM uric acid or 20 mM glucose. These results indicated that a quasi-DET type lactate sensor was developed that did not suffer from the interference of oxygen and representative electroactive ingredient compounds.


Assuntos
Aerococcus/isolamento & purificação , Técnicas Biossensoriais , Ácido Láctico/isolamento & purificação , Oxigenases de Função Mista/química , Aerococcus/química , Catálise , Enzimas Imobilizadas/química , Glucose/química , Humanos , Ácido Láctico/química , Oxirredução
15.
Carbohydr Polym ; 230: 115593, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887873

RESUMO

The aim of this study was to investigate the in vitro digestion and fermentation prebiotic properties of three released-exopolysaccharide fractions (r-EPS1, r-EPS2 and r-EPS3) from Lactobacillus delbrueckii ssp. bulgaricus SRFM-1. There were no free oligosaccharides and/or monosaccharides for r-EPS1 before and after simulated buccal, gastric and small intestinal (GSI) digestion in vitro. In contrast, r-EPS2 (13.4 %) and r-EPS3 (10.6 %) generated a few monosaccharides after digestion. Additionally, r-EPS1 and r-EPS2 seemed to present a strong bifidogenic effect comparing to inulin, as they exhibited high values of selectivity index (13.17 and 12.84, respectively). Furthermore, the fermentation with r-EPS1 produced the highest contents of acetic acid and lactic acid (56.3 mM and 44.29 mM, respectively), which resulted in the highest amounts of total short chain fatty acid (145.51 mM) followed by r-EPS2 (135.57 mM) and inulin (99.28 mM). These results indicated that r-EPS from L. delbrueckii ssp. bulgaricus SRFM-1 could be a good potential candidate for new functional food prebiotic.


Assuntos
Digestão/efeitos dos fármacos , Lactobacillus delbrueckii/química , Polissacarídeos Bacterianos/química , Polissacarídeos/química , Meios de Cultura/química , Fermentação , Humanos , Ácido Láctico/química , Lactobacillus delbrueckii/metabolismo , Monossacarídeos/química , Polissacarídeos/metabolismo , Polissacarídeos Bacterianos/metabolismo
16.
BMC Bioinformatics ; 21(1): 13, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31924164

RESUMO

BACKGROUND: The rapid growth of available knowledge on metabolic processes across thousands of species continues to expand the possibilities of producing chemicals by combining pathways found in different species. Several computational search algorithms have been developed for automating the identification of possible heterologous pathways; however, these searches may return thousands of pathway results. Although the large number of results are in part due to the large number of possible compounds and reactions, a subset of core reaction modules is repeatedly observed in pathway results across multiple searches, suggesting that some subpaths between common compounds were more consistently explored than others.To reduce the resources spent on searching the same metabolic space, a new meta-algorithm for metabolic pathfinding, Hub Pathway search with Atom Tracking (HPAT), was developed to take advantage of a precomputed network of subpath modules. To investigate the efficacy of this method, we created a table describing a network of common hub metabolites and how they are biochemically connected and only offloaded searches to and from this hub network onto an interactive webserver capable of visualizing the resulting pathways. RESULTS: A test set of nineteen known pathways taken from literature and metabolic databases were used to evaluate if HPAT was capable of identifying known pathways. HPAT found the exact pathway for eleven of the nineteen test cases using a diverse set of precomputed subpaths, whereas a comparable pathfinding search algorithm that does not use precomputed subpaths found only seven of the nineteen test cases. The capability of HPAT to find novel pathways was demonstrated by its ability to identify novel 3-hydroxypropanoate (3-HP) synthesis pathways. As for pathway visualization, the new interactive pathway filters enable a reduction of the number of displayed pathways from hundreds down to less than ten pathways in several test cases, illustrating their utility in reducing the amount of presented information while retaining pathways of interest. CONCLUSIONS: This work presents the first step in incorporating a precomputed subpath network into metabolic pathfinding and demonstrates how this leads to a concise, interactive visualization of pathway results. The modular nature of metabolic pathways is exploited to facilitate efficient discovery of alternate pathways.


Assuntos
Algoritmos , Redes e Vias Metabólicas , Ácido Láctico/análogos & derivados , Ácido Láctico/química , Ácido Láctico/metabolismo , Ácido Pirúvico/metabolismo
17.
Mater Sci Eng C Mater Biol Appl ; 108: 110496, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923956

RESUMO

Simple addition of a minute quantity of non-toxic mustard oil in water/oil/water (W/O/W) double emulsion led to a porous morphology at the surface as well as in the interior of the biodegradable PLGA (Poly(l-lactide-co-glycolide)) microparticles. An attempt was made to understand the mechanism of pore formation by analyzing optical micrographs and SEM images in addition to solution viscosity of organic phase and interfacial tension values between organic and aqueous phases. The origin of surface porosity was thought to come from the inclusion of inner water droplet, stabilized by heteroaggregation of mustard oil and PLGA chains along with PVA (polyvinyl alcohol), to the solidifying polymer skin. The surface pores did not arise in absence of mustard oil. The encapsulation and release of antibacterial active (benzoic acid) from porous PLGA particles was studied in PBS buffer (pH 7) at 37 °C for 60 days. The release profiles were well-controlled in nature, and found to be influenced by surface porosity of the particles that can be manipulated by varying the amount of mustard oil. The release mechanism can well be explained with the help of power law model. Strikingly, in liquid medium, porous particles were found completely suppressing the growth of Escherichia coli and Staphylococcus aureus for a prolonged period of 60 days. The strong antimicrobial activity (100% inhibition of bacterial growth) in porous particles can be linked to the enhanced surface area due to the formation of micro/nano pores which accelerate the hydrolytic degradation of PLGA to release lactic acid/glycolic acid (antibacterial) in addition to encapsulated antibacterial (benzoic acid). In a food model system, the shelf life of the water melon juice was also found to be enhanced by suppressing the growth of the natural microbes in comparison to control.


Assuntos
Antibacterianos/farmacologia , Conservação de Alimentos , Microesferas , Ácido Poliglicólico/química , Antibacterianos/administração & dosagem , Ácido Benzoico/química , Varredura Diferencial de Calorimetria , Escherichia coli/efeitos dos fármacos , Contaminação de Alimentos/prevenção & controle , Glicolatos/química , Concentração de Íons de Hidrogênio , Hidrólise , Ácido Láctico/química , Testes de Sensibilidade Microbiana , Microscopia de Fluorescência , Mostardeira , Óleos Vegetais , Porosidade/efeitos dos fármacos , Solventes , Análise Espectral Raman , Staphylococcus aureus/efeitos dos fármacos , Temperatura , Viscosidade
18.
Prep Biochem Biotechnol ; 50(4): 365-378, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31794327

RESUMO

A low-cost Kodo millet bran residue was utilized as feedstock for the production of D (-) lactic acid (DLA) using Lactobacillus delbrueckii NBRC3202 under anaerobic condition. Data culled from a series of batch fermentation processes with different initial Kodo millet bran residue hydrolysate (KMBRH) and DLA concentrations were used for kinetic model development. Both simulated and experimental data were in good agreement for cell growth, KMBRH utilization, and DLA formation. The values of kinetic constants specific growth rate, (µm = 0.17 h-1); growth (αP = 0.96 g.g-1) and non-growth (ßP = 1.19 g.g-1.h-1) associated constant for DLA production and the maximum specific KMBRH utilization rate, (qG, max = 1.18 g.g-1.h-1) were in good agreement with the literature reports. Kinetic analysis elucidated that L. delbrueckii growth was predominantly influenced by KMBRH limitation and highly sensitive to DLA inhibition. Fed-batch fermentation studies demonstrated the existence of substrate and product inhibition paving the scope for process intensification.


Assuntos
Fermentação , Ácido Láctico/metabolismo , Paspalum/química , Sementes/química , Hidrólise , Cinética , Ácido Láctico/química , Lactobacillus delbrueckii/metabolismo
19.
Anal Chim Acta ; 1095: 219-225, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31864626

RESUMO

Herein we present a general and turn-on strategy for enzymatic bioassays on the basis of redox state dependent emission of gold nanoclusters (AuNCs). The photoluminescence of AuNCs was quenched obviously by the oxidative ferricyanide while unaffected by its corresponding reduced state, i.e., ferrocyanide. The distinctive quenching abilities for AuNCs by the redox couple (ferricyanide/ferrocyanide) enabled their utility as new fluorescent sensing platforms to detect redox-related phenomena. The proposed protocols were conducted by using the model oxidoreductases of glucose oxidase (GOx) and the enzyme cascade of lactate dehydrogenase (LDH)/diaphorase to catalytically convert ferricyanide to ferrocyanide, which switched on fluorescence of the detection systems. The detection limit for glucose and lactate was found to be as low as 0.12 and 0.09 µM, respectively. This work features the first use of the redox couple of ferricyanide/ferrocyanide in fluorescent bioanalysis, which enables versatile, signal on and highly sensitive/selective detections as compared to the state of the art fluorescently enzymatic sensing platforms. Importantly, considering the significance of ferricyanide/ferrocyanide involves in numerous other oxidoreductases mediated biocatalysis, this protocol has wide versatility that enables combination with oxidoreductases related reactions for biosensing.


Assuntos
Corantes Fluorescentes/química , Glucose/análise , Ácido Láctico/análise , Nanopartículas Metálicas/química , Espectrometria de Fluorescência/métodos , Animais , Bovinos , Ferricianetos/química , Fluorescência , Glucose/química , Glucose Oxidase/química , Ouro/química , Humanos , L-Lactato Desidrogenase/química , Ácido Láctico/química , Limite de Detecção , NADH Desidrogenase/química , Oxirredução , Soroalbumina Bovina/química
20.
Analyst ; 145(3): 887-896, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31820746

RESUMO

Owing to its high sensitivity, a solution-gated graphene transistor has rapidly emerged as a cutting edge technology in electrochemical sensing. In this work, composites of gold nanoparticles and reduced graphene oxide were synthesized on a glassy carbon electrode by using the electrodeposition method. A modified glassy carbon electrode was used as the gate electrode and assembled into the solution-gated graphene transistor device along with the graphene channel for a non-invasive glucose detection. The sensing mechanism was based on the change in current in the channel of the device caused by the addition of glucose, of which electro-oxidation on the surface of the gold nanoparticles and reduced graphene oxide led to a change in equivalent gate voltage, and consequently, affected the channel carrier concentration. The self-amplification effect of transistors was utilized in our sensors, which resulted in a detection limit that was 10 times lower than those of conventional electrochemical sensors. Compared to traditional enzymatic transistor sensors, the novel solution-gated graphene transistor nonenzymatic sensors based on gold nanoparticles and reduced graphene oxide demonstrated significant sensing advantages, such as a simple structure, wide linear range from 10 µM to 400 µM and 400 µM to 31 mM, and low detection limit down to 4 µM. The chemicals coexisting in human sweat e.g. sodium chloride, urea, and lactic acid imposed no distinct interference for the glucose detection. Therefore, we achieved a non-invasive detection of glucose in the artificial sweat samples with satisfactory sensing results. This work demonstrates an effective route for non-invasive glucose testing in practical clinical diagnosis by using nonenzymatic, solution-gated graphene transistor devices.


Assuntos
Técnicas Eletroquímicas/métodos , Glucose/análise , Grafite/química , Transistores Eletrônicos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Humanos , Ácido Láctico/química , Limite de Detecção , Nanopartículas Metálicas/química , Oxirredução , Suor/química , Suor/metabolismo , Ureia/química
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