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1.
Langmuir ; 40(18): 9676-9687, 2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38663019

RESUMO

Prehydrolysis liquid (PHL) from dissolving pulp and biorefinery industries is rich in saccharides and lignin, being considered as a potential source of value-added materials and platform molecules. This study proposed an environmentally friendly and simple method to prepare morphologically controllable hollow lignin nanoparticles (LNPs) and levulinic acid (LA) from PHL. In the first step, after hydrothermal treatment of PHL with p-toluenesulfonic acid (p-TsOH), lignin with a uniform molecular weight was obtained to prepare LNPs. The prepared LNPs have an obvious hollow structure, with an average size of 490-660 nm, and exhibit good stability during 30 days of storage. When the as-obtained LNPs were used as a sustained-release agent for amikacin sulfate, the encapsulation efficiency reached over 70% and the release efficiency within 40 h reached 69.2% in a pH 5.5 buffer. Subsequently, the remaining PHL that contains saccharides was directly used for LA production under the catalysis of p-TsOH. At 150 °C for 1.5 h, the LA yield reached 58.4% and remained at 56% after 5 cycles of p-TsOH. It is worth noting that only p-TsOH was used as a reactive reagent throughout the entire preparation process. Overall, this study provided a novel pathway for the integrated utilization of PHL and showed the immense potential of the preparation and application of LNPs.


Assuntos
Portadores de Fármacos , Ácidos Levulínicos , Lignina , Nanopartículas , Populus , Ácidos Levulínicos/química , Lignina/química , Nanopartículas/química , Populus/química , Portadores de Fármacos/química , Madeira/química , Hidrólise , Tamanho da Partícula
2.
Langmuir ; 40(1): 554-560, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38111205

RESUMO

Nanoscale composite lignin colloids were prepared on a large scale with a process of assembly-mediated internal cross-linking in a good solvent, thus possessing absolutely nanoscale dimensions, excellent robustness, and less aggregation. The therefore prime UV resistance and various natural visible colors contribute to the preservation and beautification of skin.

3.
Compr Rev Food Sci Food Saf ; 22(3): 2267-2291, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-37043598

RESUMO

Polyphenol oxidase (PPO) is a metalloenzyme with a type III copper core that is abundant in nature. As one of the most essential enzymes in the tea plant (Camellia sinensis), the further regulation of PPO is critical for enhancing defensive responses, cultivating high-quality germplasm resources of tea plants, and producing tea products that are both functional and sensory qualities. Due to their physiological and pharmacological values, the constituents from the oxidative polymerization of PPO in tea manufacturing may serve as functional foods to prevent and treat chronic non-communicable diseases. However, current knowledge of the utilization of PPO in the tea industry is only available from scattered sources, and a more comprehensive study is required to reveal the relationship between PPO and tea obviously. A more comprehensive review of the role of PPO in tea was reported for the first time, as its classification, catalytic mechanism, and utilization in modulating tea flavors, compositions, and nutrition, along with the relationships between PPO-mediated enzymatic reactions and the formation of functional constituents in tea, and the techniques for the modification and application of PPO based on modern enzymology and synthetic biology are summarized and suggested in this article.


Assuntos
Camellia sinensis , Catecol Oxidase/metabolismo , Oxirredução , Chá
4.
Molecules ; 27(18)2022 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-36144675

RESUMO

α-Galactosidase (EC 3.2.1.22) refers to a group of enzymes that hydrolyze oligosaccharides containing α-galactoside-banded glycosides, such as stachyose, raffinose, and verbascose. These enzymes also possess great potential for application in sugar production, and in the feed and pharmaceutical industries. In this study, a strain of Lactosphaera pasteurii (WHPC005) that produces α-galactosidase was identified from the soil of Western Hunan, China. It was determined that the optimal temperature and pH for this α-galactosidase were 45 °C and 5.5, respectively. The activity of α-galactosidase was inhibited by K+, Al3+, Fe3+, fructose, sucrose, lactose, galactose, SDS, EDTA, NaCl, and (NH4)2SO4, and enhanced by Ca2+, Fe2+, Mn2, Zn2+, glucose, and raffinose. The optimal inducer was raffinose, and the optimal induction concentration was 30 µmol/L. The α-galactosidase gene was cloned using random fragment cloning methods. Sequence analysis demonstrated that the open reading frame of the α-galactosidase gene was 1230 bp, which encodes a putative protein of 409 amino acids in length. Bioinformatics analysis showed that the isoelectric point and molecular weight of this α-galactosidase were 4.84 and 47.40 kD, respectively. Random coils, alpha helixes, and beta turns were observed in its secondary structure, and conserved regions were found in the tertiary structure of this α-galactosidase. Therefore, this α-galactosidase-producing bacterial strain has the potential for application in the feed industry.


Assuntos
Galactose , alfa-Galactosidase , Aminoácidos , Carnobacteriaceae , Ácido Edético , Frutose , Galactosídeos , Glucose , Glicosídeos , Concentração de Íons de Hidrogênio , Cinética , Lactose , Oligossacarídeos/química , Rafinose , Cloreto de Sódio , Solo , Especificidade por Substrato , Sacarose , alfa-Galactosidase/metabolismo
5.
Appl Microbiol Biotechnol ; 103(6): 2665-2674, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30734123

RESUMO

7-Ketolithocholic acid (7-KLCA) is an important intermediate for the synthesis of ursodeoxycholic acid (UDCA). UDCA is the main effective component of bear bile powder that is used in traditional Chinese medicine for the treatment of human cholesterol gallstones. 7α-Hydroxysteroid dehydrogenase (7α-HSDH) is the key enzyme used in the industrial production of 7-KLCA. Unfortunately, the natural 7α-HSDHs reported have difficulty meeting the requirements of industrial application, due to their poor activities and strong substrate inhibition. In this study, a directed evolution strategy combined with high-throughput screening was applied to improve the catalytic efficiency and tolerance of high substrate concentrations of NADP+-dependent 7α-HSDH from Clostridium absonum. Compared with the wild type, the best mutant (7α-3) showed 5.5-fold higher specific activity and exhibited 10-fold higher and 14-fold higher catalytic efficiency toward chenodeoxycholic acid (CDCA) and NADP+, respectively. Moreover, 7α-3 also displayed significantly enhanced tolerance in the presence of high concentrations of substrate compared to the wild type. Owing to its improved catalytic efficiency and enhanced substrate tolerance, 7α-3 could efficiently biosynthesize 7-KLCA with a substrate loading of 100 mM, resulting in 99% yield of 7-KLCA at 2 h, in contrast to only 85% yield of 7-KLCA achieved for the wild type at 16 h.


Assuntos
Clostridium/enzimologia , Evolução Molecular Direcionada , Hidroxiesteroide Desidrogenases/metabolismo , Ácido Litocólico/análogos & derivados , Clostridium/genética , Escherichia coli/genética , Ensaios de Triagem em Larga Escala , Hidroxiesteroide Desidrogenases/genética , Cinética , Ácido Litocólico/biossíntese , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Ácido Ursodesoxicólico/metabolismo
6.
Water Sci Technol ; 73(5): 1081-9, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26942530

RESUMO

Wastewater produced by hydraulic fracturing for oil and gas production is characterized by high salinity and high chemical oxygen demand (COD). We applied a combination of flocculation and wet air oxidation technology to optimize the reduction of COD in the treatment of hydraulic fracturing wastewater. The experiments used different values of flocculant, coagulant, and oxidizing agent added to the wastewater, as well as different reaction times and treatment temperatures. The use of flocculants for the pretreatment of fracturing wastewater was shown to improve treatment efficiency. The addition of 500 mg/L of polyaluminum chloride (PAC) and 20 mg/L of anionic polyacrylamide (APAM) during pretreatment resulted in a COD removal ratio of 8.2% and reduced the suspended solid concentration of fracturing wastewater to 150 mg/L. For a solution of pretreated fracturing wastewater with 12 mL of added H2O2, the COD was reduced to 104 mg/L when reacted at 300 °C for 75 min, and reduced to 127 mg/L when reacted at the same temperature for 45 min while using a 1 L autoclave. An optimal combination of these parameters produced treated wastewater that met the GB 8978-1996 'Integrated Wastewater Discharge Standard' level I emission standard.


Assuntos
Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Resinas Acrílicas/química , Hidróxido de Alumínio/química , Análise da Demanda Biológica de Oxigênio , Floculação , Peróxido de Hidrogênio/química , Oxidantes/química , Oxirredução
7.
Food Chem ; 453: 139571, 2024 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-38761741

RESUMO

The traditional strategies of chemical catalysis and biocatalysis for producing octenyl succinic anhydride modified starch can only randomly graft hydrophobic groups on the surface of starch, resulting in unsatisfactory emulsification performance. In this work, a lipase-inorganic hybrid catalytic system with multi-scale flower like structure is designed and applied to spatially selective catalytic preparation of ocenyl succinic anhydride modified starch. With the appropriate floral morphology and petal density, lipases distributed in the "flower center" can selectively catalyze the grafting of hydrophobic groups in a spatial manner, the hydrophobic groups are concentrated on one side of starch particles. The obtaining OSA starch exhibits excellent emulsifying property, and the pickering emulsion has good protective effect on the embedded curcumin. This work provides a direction for the development of high-performance starch-based emulsifiers for the food and pharmaceutical industries, which is of great significance for improving the preparation and emulsification theory research of modified starch.


Assuntos
Emulsões , Lipase , Amido , Amido/química , Amido/análogos & derivados , Emulsões/química , Lipase/química , Lipase/metabolismo , Emulsificantes/química , Catálise , Interações Hidrofóbicas e Hidrofílicas , Anidridos Succínicos/química , Tamanho da Partícula , Biocatálise
8.
J Agric Food Chem ; 72(30): 16900-16910, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39016109

RESUMO

S-Adenosylmethionine (SAM) is a crucial metabolic intermediate playing irreplaceable roles in organismal activities. However, the synthesis of SAM by methionine adenosyltransferase (MAT) is hindered by low conversion due to severe product inhibition. Herein structure-guided semirational engineering was conducted on MAT from Escherichia coli (EcMAT) to mitigate the product inhibitory effect. Compared with the wild-type EcMAT, the best variant E56Q/Q105R exhibited an 8.13-fold increase in half maximal inhibitory concentration and a 4.46-fold increase in conversion (150 mM ATP and l-methionine), leading to a SAM titer of 47.02 g/L. Another variant, E56N/Q105R, showed superior thermostability with an impressive 85.30-fold increase in half-life (50 °C) value. Furthermore, molecular dynamics (MD) simulation results demonstrate that the alleviation in product inhibitory effect could be attributed to facilitated product release. This study offers molecular insights into the mitigated product inhibition, and provides valuable guidance for engineering MAT toward enhanced catalytic performance.


Assuntos
Escherichia coli , Metionina Adenosiltransferase , S-Adenosilmetionina , Metionina Adenosiltransferase/genética , Metionina Adenosiltransferase/metabolismo , Metionina Adenosiltransferase/química , S-Adenosilmetionina/metabolismo , S-Adenosilmetionina/química , Escherichia coli/genética , Escherichia coli/metabolismo , Engenharia de Proteínas , Cinética , Simulação de Dinâmica Molecular , Estabilidade Enzimática , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/química
9.
Int J Biol Macromol ; 265(Pt 1): 130906, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38493611

RESUMO

The pre-hydrolysis liquor (PHL) produced during pulp dissolution and biomass refining is mainly composed of hemicellulose and lignin, and it is a potential source for production of value-added materials and platform chemicals; however, their utilization has been a serious challenge. In this study, we proposed a green and simple strategy to simultaneously prepare size-controlled functional lignin nanoparticles (LNPs) and levulinic acid (LA) from PHL as the raw material. The as-prepared LNPs exhibited remarkable stability thanks to the presence of saccharides with abundant oxygen-containing groups and surface charges, which prevented aggregation and maintained long-term storage stability. Trace amounts of the LNPs (≤ 0.2 wt%) could stabilize various Pickering emulsions, even with oil-to-water ratios as high as 5:5 (v/v). Subsequently, the remaining PHL was directly used to produce LA without adding a catalyst; under optimal conditions (160 °C and 1 h), the yield of LA was 56.3 % based on the dry saccharide content in the raw PHL. More importantly, p-toluenesulfonic acid (p-TsOH), the only reactive reagent used during the entire preparation process, including the two preparation steps of the LNPs and LA, was reusable, and the recovery rate was >70 % after five cycles. Overall, this green and simple strategy effectively and comprehensively utilized the PHL and showed potential for producing biobased nanomaterials and platform chemicals.


Assuntos
Ácidos Levulínicos , Nanopartículas , Populus , Lignina/química , Hidrólise , Madeira/química , Carboidratos/análise
10.
Int J Biol Macromol ; 265(Pt 2): 130796, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38479665

RESUMO

Supercapacitors, pivotal in mitigating the energy crisis stemming from dwindling fossil fuel reservoirs, necessitate meticulous consideration of electrode material preparation. While lignin-derived carbon materials sourced sustainably exhibit commendable potential as electrode materials, their intrinsic low capacitance limits widespread utilization. Herein, nitrogen atom doping of lignin (CNL) was accomplished employing a chemical modification technique employing cyanuric chloride as a dopant. The resultant nitrogen content measured at 2.85 %. Subsequent to CNL carbonation, the generated C3N4 was selectively confined to the internal surface of the CNLMS-800 through a domain-limited activation method, thereby rendering it suitable for deployment as a supercapacitor electrode material. CNLMS-800 manifests a substantial specific surface area of 1778.0 m2 g-1 and a concomitantly diminutive pore size of 2.6 nm. Noteworthy, the specific capacitance of CNLMS-800 attains 473.0 F g-1 at a current density of 0.5 A g-1 in a 6 M KOH electrolyte. The resultant energy density reaches 39.0 Wh kg-1 at a power density of 338.0 W kg-1. Crucially, even after 20,000 charge/discharge cycles at a current density of 10 A g-1, the capacitance retention attains an impressive 87.5 % in the KOH electrolyte. This innovative utilization of sustainable resources for electrode fabrication epitomizes a seminal advancement in the field of energy technology.


Assuntos
Líquidos Corporais , Lignina , Eletrodos , Nitrogênio , Eletrólitos
11.
Int J Biol Macromol ; 256(Pt 1): 127878, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37949269

RESUMO

Nowadays, great effort has been devoted to designing biomass-derived nanoscale carbon fibers with controllable fibrous morphology, high conductivity, big specific surface area and multifunctional characteristics. Herein, a green and renewable strategy is performed to prepare the biomass-based nanoscale carbon fibers for fire warning sensor, supercapacitor and moist-electric generator. This preparation strategy thoroughly gets over the dependence of petroleum-based polymeride, and effectually improves the energy storage capacity, sensing sensitivity, humidity power generation efficiency of the obtaining biomass-based carbon nanofibers. Without the introduction of any active components or pseudocapacitive materials, the specific capacitance and energy density for biomass-based nanoscale carbon fibers achieve 143.58 F/g and 19.9 Wh/kg, severally. The biomass-based fire sensor displays excellent fire resistance, stability, and flame sensitivity with a response time of 2 s. Furthermore, the biomass-based moist-electric generator shows high power generation efficiency. The output voltage and current of five series connected and parallel-connected biomass-based moist-electric generators reaches 4.30 V and 43 µA, respectively. Notably, as the number of biomass-based moist-electric generators in series or parallel increases, the overall output voltage and current of the device system have a linear relationship. This work proposes a self-powered fire prediction system based on nanoscale carbon fibers that integrates sensing, power generation, and energy storage functions.


Assuntos
Carbono , Nanofibras , Fibra de Carbono , Biomassa , Capacitância Elétrica
12.
Int J Biol Macromol ; 266(Pt 2): 130619, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38460629

RESUMO

Lignin, a natural polyphenol polymer, is a biocompatible, cost-effective and accessible material. To fully utilize the benefits of lignin, it is crucial to transform its complex macromolecules into nanoscale particles in a single solvent. In this research, an assembly-mediated internal cross-linking method in single solvent was proposed to manufacture cross-linked lignin colloidal particles with nanoscale particle size controlled to be around 50 nm. Then, cross-linked lignin composite particles with a unique "patchy" structure for dental cleansing were obtained by rapidly grafting the cross-linked lignin colloidal particles onto the surface of silica microspheres through the bridging effect of silane coupling agent. The resulting composite particles have rivets with adjustable hardness, significantly lower than traditional abrasives like silica in both hardness and modulus. Through the group cleansing behavior of soft interlocking, a breakthrough has been achieved in the high solid content agglomeration friction mode of traditional abrasives, which effectively reduces tooth wear and exhibits an excellent plaque removal effect.


Assuntos
Lignina , Lignina/química , Tamanho da Partícula , Dióxido de Silício/química , Reagentes de Ligações Cruzadas/química , Dureza , Microesferas , Humanos , Coloides/química , Nanopartículas/química
13.
J Anim Sci ; 1022024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38682465

RESUMO

Vitamin E (VE) is a potent nutritional antioxidant that is critical in alleviating poultry oxidative stress. However, the hydrophobic nature and limited stability of VE restrict its effective utilization. Nanotechnology offers a promising approach to enhance the bioavailability of lipophilic vitamins. The objective of this experiment was to investigate the effects of different sources and addition levels of VE on the growth performance, antioxidant capacity, VE absorption site, and pharmacokinetics of Arbor Acres (AA) broilers. Three hundred and eighty-four 1-d-old AA chicks were randomly allocated into four groups supplemented with 30 and 75 IU/kg VE as regular or nano. The results showed that dietary VE sources had no significant impact on broiler growth performance. However, chickens fed 30 IU/kg VE had a higher average daily gain at 22 to 42 d and 1 to 42 d, and lower feed conversion ratio at 22 to 42 d than 75 IU/kg VE (P < 0.05). Under normal feeding conditions, broilers fed nano VE (NVE) displayed significantly higher superoxide dismutase (SOD) activity and glutathione peroxidase (GSH-Px) enzyme activities and lower malonic dialdehyde (MDA) concentration (P < 0.05). Similarly, NVE had a higher antioxidant effect in the dexamethasone-constructed oxidative stress model. It was found that nanosizing technology had no significant effect on the absorption of VE in the intestinal tract by examining the concentration of VE in the intestinal tract (P > 0.05). However, compared to broilers perfused with regular VE (RVE), the NVE group displayed notably higher absorption rates at 11.5 and 14.5 h (P < 0.05). Additionally, broilers perfused with NVE showed a significant increase in the area under the concentration versus time curve from zero to infinity (AUC0-∞), mean residence time (MRT0-∞), elimination half-life (t1/2z), and peak concentration (Cmax) of VE in plasma (P < 0.05). In summary, nanotechnology provides more effective absorption and persistence of VE in the blood circulation for broilers, which is conducive to the function of VE and further improves the antioxidant performance of broilers.


With the rapid development of intensive farming, factors such as high temperature, harmful gases, high-fat and high-protein diets, and changes in feeding methods have become causes of oxidative stress in animals. Studies have shown that oxidative stress decreases livestock feed intake and slows growth in animals, thereby affecting the quality of livestock products. Antioxidants and micronutrients are commonly added to animal feed to reduce the effects of oxidative stress. Since the progress in nanotechnology, nanovitamins have gained extensive recognition due to their novel qualities, including a high level of adsorption capacity and low toxicity. Therefore, the present study compared the effects of dietary supplementation with different sources of vitamin E (regular, RVE vs. nano, NVE) and varying inclusion levels on the growth performance, antioxidant capacity, VE absorption sites, and pharmacokinetics in AA broilers. The results indicated that supplementing broiler diets with NVE provides superior antioxidant benefits compared to RVE. This improvement is attributed to the enhanced absorption efficiency and extended half-life of NVE, both contributing to increased antioxidant performance of broilers.


Assuntos
Ração Animal , Antioxidantes , Galinhas , Dieta , Suplementos Nutricionais , Vitamina E , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Ração Animal/análise , Dieta/veterinária , Vitamina E/administração & dosagem , Vitamina E/farmacocinética , Vitamina E/farmacologia , Suplementos Nutricionais/análise , Estresse Oxidativo/efeitos dos fármacos , Nanopartículas/química , Nanopartículas/administração & dosagem , Fenômenos Fisiológicos da Nutrição Animal , Masculino , Distribuição Aleatória
14.
Int J Biol Macromol ; 242(Pt 2): 124751, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37164137

RESUMO

To achieve sustainable whole process of carbon-fiber production and high-value utilization of lignin, one-step ethanol fractionation followed by coaxial electrospinning was applied to produce lignin-based monocomponent carbon-fiber. To elucidate the mechanism, hydrothermal extracted poplar lignin (HPL) were obtained to be divide into two parts through ethanol fractionation, in which the ethanol-soluble lignin (ESL) was eletrcospun into fiber precursors. Then, to verify the universality of this method, four more lignin were extracted to produce fiber precursors, after which five kinds of carbon fibers were prepared by carbonization of the corresponding precursors. Structural analysis showed that ESL of HPL is a small and highly branched three-dimensional stereomolecules. Combined with the SEM results of fiber precursors, the mechanism which hydrogen bonding promotes fiber formation was elucidated. Among all five samples, carbon-fiber prepared from HPL possesses the minimum fiber diameter of 557 nm, the smallest interplanar spacing of 0.3909 nm, ID/IG value of 0.6345 and the largest specific surface area of 408.15 m2/g. This work proposes a universal method to prepare lignin-based monocomponent carbon-fiber, in which carbon-fibers prepared from HPL exhibits the best comprehensive performance and can be applied to capture radioactive iodine.


Assuntos
Lignina , Neoplasias da Glândula Tireoide , Humanos , Lignina/química , Carbono/química , Etanol , Radioisótopos do Iodo , Fibra de Carbono
15.
ACS Appl Mater Interfaces ; 15(1): 1969-1983, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36573338

RESUMO

For the application of lignin-based materials, it is necessary to develop simple and efficient chemical modification strategies for lignin. In this work, the iodization modification strategy is selected to improve the specific surface area and graphitization degree of lignin-based carbon fibers. The introduction of an iodine atom can effectively increase the π electron cloud density of the lignin aromatic hydrocarbon structure. High π electron cloud density can effectively enhance the π-π interaction force between lignin molecules (the supramolecular bonds). The biomass precursors with this intermolecular microstructure exhibit good thermal stability and can maintain the original fibrous morphology during high-temperature treatment, which is beneficial for increasing the specific surface area of biomass-based carbon materials. Furthermore, this intermolecular microstructure also contributes to the graphitization of biomass precursor materials and reduces the spacing of graphite micro-lamellae. The obtained lignin-based carbon fibers with iodization modification exhibit a specific capacitance of 333 F/g at a current density of 1 A/g in the three-electrode tests in 6 M KOH solution. As the assembled supercapacitor, the specific capacitance of lignin-based carbon fibers reaches 87 F/g in 1 M Na2SO4 solution. Compared to other modification processes for raw materials, this strategy is simple and efficient and has reference value for the synthesis of other high-performance biomass-based materials.

16.
Int J Biol Macromol ; 225: 219-226, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36343839

RESUMO

A novel binary solvent system consisting of alcohols (e.g., methanol, ethanol, isopropanol) and dichloromethane was developed as an efficient dissolution system for dissolving various types of lignin. It was found that in this dissolution system, adjusting the volume ratio of alcohol and dichloromethane will significantly affect the solubility of lignin. At the same time, this study proposed that the reason why the solvent can dissolve lignin was the hydrophobic skeleton and hydrophilic groups can be solvated by dichloromethane and alcohols respectively, which significantly promoted the dissolution of lignin. Furthermore, the solvent did not significantly alter the structure of the lignin. The proposed novel solvent is simple, efficient, versatile and flexible, can adapt to the high diversity of lignin, and has broad application prospects.


Assuntos
Lignina , Cloreto de Metileno , Solventes/química , Lignina/química , Solubilidade , Etanol
17.
Int J Biol Macromol ; 251: 126325, 2023 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-37579896

RESUMO

One more effective measure to solve the energy crisis caused by the shortage of fossil energy is to convert natural renewable resources into high-value chemical products for electrochemical energy storage. Lignin has broad application prospects in this field. In this paper, three kinds of lignin with different molecular weights were obtained by the ethanol/water grading of Kraft lignin (KL). Then, different surface morphology lignin microspheres were prepared by spray drying. Finally, petal-like microspheres were successfully prepared by mixing and grinding the above four kinds of surface morphology lignin microspheres with potassium ferrate and cyanogen chloride and carbonizing at 800 °C and were later used as electrode materials for supercapacitors. Compared with the other microspheres, LMS-F3@Fe3C has the highest specific surface area (1041.42 m2 g-1), the smallest pore size (2.36 nm) and the largest degree of graphitization (ID/IG = 1.06). At a current density of 1 A g-1, the maximum specific capacitance is 786.7 F g-1. At a power density of 1000 W kg-1, the high energy density of 83.3 Wh kg-1 is displayed. This work provides a novel approach to the modulation of surface morphology and structure of lignin microspheres.

18.
Artigo em Inglês | MEDLINE | ID: mdl-37642924

RESUMO

As an important dietary supplement, S-adenosylmethionine (SAM) is currently synthesized by methionine adenosyltransferase (MAT) using ATP and methionine as substrates. However, the activity of MAT is severely inhibited by product inhibition, which limits the industrial production of SAM. Here, MAT from Bacteroides fragilis (BfMAT), exhibiting relatively low product inhibition and moderate specific activity, was identified by gene mining. Based on molecular docking, residues within 5 Å of ATP in BfMAT were subjected to mutagenesis for enhanced catalytic activity. Triple variants M3-1 (E42M/E55L/K290I), M3-2 (E42R/E55L/K290I), and M3-3 (E42C/E55L/K290I) with specific activities of 1.83, 1.81, and 1.94 U/mg were obtained, which were 110.5-125.6% higher than that of the wild type (WT). Furthermore, compared with WT, the Km values of M3-1 and M3-3 were decreased by 31.4% and 60.6%, leading to significant improvement in catalytic efficiency (kcat/Km) by 322.5% and 681.1%. All triple variants showed shifted optimal pH from 8.0 to 7.5. Moreover, interaction analysis suggests that the enhanced catalytic efficiency may be attributed to the decreased electrostatic interactions between ATP and the mutation sites (E42, E55, and K290). Based on MD simulation, coulomb energy and binding free energy analysis further reveal the importance of electrostatic interactions for catalytic activity of BfMAT, which could be an efficient strategy for improving catalytic performance of MATs.

19.
Int J Biol Macromol ; 232: 123383, 2023 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-36693601

RESUMO

Octenyl succinic anhydride modified starch is a common green and safe emulsifier. Although the conventional pretreatment method of free enzyme hydrolysis increases the hydroxyl content on the starch surface, thus improving the grafting degree of octenyl succinic anhydride and the amphiphilicity of the modified starch, the amylose and amylopectin structures are indiscriminately hydrolyzed, reducing the emulsion stability of modified starch. In this work, α-amylase organic-inorganic hybrid nanoflower biocatalyst is designed and synthesized for pretreatment of synthetic octenyl succinic anhydride modified starch. The α-amylase organic-inorganic hybrid nanoflower biocatalyst with a unique micro-nano spatial structure can selectively hydrolyze the amylopectin and protect the amylose of starch. The amylose ratio of starch pretreated by nanoflower biocatalyst is about twice that of starch pretreated by free enzyme, reaching 22.62 %. Meanwhile, the granular structure of starch is not damaged. The obtained octenyl succinic anhydride modified starch exhibits a high degree of substitution, up to 0.0213. The emulsion prepared with this modified starch maintains excellent emulsifying properties and stability. This study provides a novel strategy for the preparation of octenyl succinic anhydride modified starch with excellent emulsifying properties, which promote the application of octenyl succinic anhydride modified starch in food, pharmaceutical and cosmetic industries.


Assuntos
Amilopectina , Amilose , Amilose/química , Emulsões/química , Enzimas Imobilizadas , Hidrólise , Anidridos Succínicos/química , Amido/química , alfa-Amilases
20.
Int J Biol Macromol ; 238: 123938, 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-36898468

RESUMO

The inherent complexity and large particle size of native-state lignin are the major factors limiting its performance in high value-added materials. To realize the high-value application of lignin, nanotechnology is a promising method. Therefore, we offer a nanomanufacturing approach to produce lignin nanoparticles with uniform size, regular shape and high yield using electrospray. They are efficient in stabilizing oil-in-water (O/W) Pickering emulsions that remain for one month. Lignin has the abilities to demonstrate broad-spectrum UV resistance and green antioxidant properties in advanced materials, taking advantage of its inherent chemical characteristics. In addition, lignin has high safety for topical products according to an in vitro cytotoxicity test. In addition, the nanoparticle concentrations used in the emulsion were as low as 0.1 mg/ml, which maintained UV-resistant ability and overcame traditional lignin-based materials with unfavorable dark colors. Overall, lignin nanoparticles not only act as stabilizers at the water-oil interface but also realize the high functionality of lignin.


Assuntos
Antioxidantes , Nanopartículas , Emulsões/química , Antioxidantes/farmacologia , Lignina/química , Nanopartículas/química , Tamanho da Partícula , Água/química
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