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1.
Int J Mol Sci ; 22(4)2021 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-33669209

RESUMO

Nisin Z, an amphipathic peptide, with a significant antibacterial activity against Gram-positive bacteria and low toxicity in humans, has been studied for food preservation applications. Thus far, very little research has been done to explore its potential in biomedicine. Here, we report the modification of sodium alginate (SA) and gelatin (GN) blended microfibers, produced via the wet-spinning technique, with Nisin Z, with the purpose of eradicating Staphylococcus aureus-induced infections. Wet-spun SAGN microfibers were successfully produced at a 70/30% v/v of SA (2 wt%)/GN (1 wt%) polymer ratio by extrusion within a calcium chloride (CaCl2) coagulation bath. Modifications to the biodegradable fibers' chemical stability and structure were then introduced via crosslinking with CaCl2 and glutaraldehyde (SAGNCL). Regardless of the chemical modification employed, all microfibers were labelled as homogeneous both in size (≈246.79 µm) and shape (cylindrical and defect-free). SA-free microfibers, with an increased surface area for peptide immobilization, originated from the action of phosphate buffer saline solution on SAGN fibers, were also produced (GNCL). Their durability in physiological conditions (simulated body fluid) was, however, compromised very early in the experiment (day 1 and 3, with and without Nisin Z, respectively). Only the crosslinked SAGNCL fibers remained intact for the 28 day-testing period. Their thermal resilience in comparison with the unmodified and SA-free fibers was also demonstrated. Nisin Z was functionalized onto the unmodified and chemically altered fibers at an average concentration of 178 µg/mL. Nisin Z did not impact on the fiber's morphology nor on their chemical/thermal stability. However, the peptide improved the SA fibers (control) structural integrity, guaranteeing its stability for longer, in physiological conditions. Its main effect was detected on the time-kill kinetics of the bacteria S. aureus. SAGNCL and GNCL loaded with Nisin Z were capable of progressively eliminating the bacteria, reaching an inhibition superior to 99% after 24 h of culture. The peptide-modified SA and SAGN were not as effective, losing their antimicrobial action after 6 h of incubation. Bacteria elimination was consistent with the release kinetics of Nisin Z from the fibers. In general, data revealed the increased potential and durable effect of Nisin Z (significantly superior to its free, unloaded form) against S. aureus-induced infections, while loaded onto prospective biomedical wet-spun scaffolds.


Assuntos
Alginatos/química , Antibacterianos/química , Antibacterianos/farmacologia , Reagentes para Ligações Cruzadas/química , Gelatina/química , Nisina/análogos & derivados , Staphylococcus aureus/efeitos dos fármacos , Materiais Biocompatíveis/química , Plásticos Biodegradáveis/química , Biopolímeros/química , Cloreto de Cálcio/química , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Glutaral/química , Cinética , Testes de Sensibilidade Microbiana , Nisina/química , Nisina/farmacologia , Porosidade , Solubilidade , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Água/química
2.
Int J Biol Macromol ; 172: 270-280, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33418049

RESUMO

Enzyme immobilization can increase enzyme reusability to reduce cost of industrial production. Ginkgo biloba leaf extract is commonly used for medical purposes, but it contains ginkgolic acid, which has negative effects on human health. Here, we report a novel approach to solve the problem by degrading the ginkgolic acid with immobilized-laccase, where core/shell composite nanoparticles prepared by coaxial electrospraying might be first applied to enzyme immobilization. The core/shell Fe3O4/nylon 6,6 composite nanoparticles (FNCNs) were prepared using one-step coaxial electrospraying and can be simply recovered by magnetic force. The glutaraldehyde-treated FNCNs (FNGCNs) were used to immobilize laccase. As a result, thermal stability of the free laccase was significantly improved in the range of 60-90 °C after immobilization. The laccase-immobilized FNGCNs (L-FNGCNs) were applied to degrade the ginkgolic acids, and the rate constants (k) and times (τ50) were ~0.02 min-1 and lower than 39 min, respectively, showing good catalytic performance. Furthermore, the L-FNGCNs exhibited a relative activity higher than 0.5 after being stored for 21 days or reused for 5 cycles, showing good storage stability and reusability. Therefore, the FNGCNs carrier was a promising enzyme immobilization system and its further development and applications were of interest.


Assuntos
Óxido Ferroso-Férrico/química , Proteínas Fúngicas/química , Ginkgo biloba/química , Lacase/química , Nanopartículas de Magnetita/química , Salicilatos/química , Reagentes para Ligações Cruzadas/química , Técnicas Eletroquímicas , Enzimas Imobilizadas/química , Enzimas Imobilizadas/isolamento & purificação , Reutilização de Equipamento , Proteínas Fúngicas/isolamento & purificação , Glutaral/química , Hidrólise , Cinética , Lacase/isolamento & purificação , Nanopartículas de Magnetita/ultraestrutura , Nylons/química , Extratos Vegetais/química , Folhas de Planta/química , Polyporaceae/química , Polyporaceae/enzimologia
3.
Molecules ; 26(2)2021 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-33467076

RESUMO

Cross-linked enzyme aggregates (CLEAs) of the Y509E mutant of glycoside hydrolase family 52 ß-xylosidase from Geobacillus stearothermophilus with dual activity of ß-xylosidase and xylanase (XynB2Y509E) were prepared. Ammonium sulfate was used as the precipitant agent, and glutaraldehyde as cross-linking agent. The optimum conditions were found to be 90% ammonium sulfate, 12.5 mM glutaraldehyde, 3 h of cross-linking reaction at 25 °C, and pH 8.5. Under these (most effective) conditions, XynB2Y509E-CLEAs retained 92.3% of their original ß-xylosidase activity. Biochemical characterization of both crude and immobilized enzymes demonstrated that the maximum pH and temperature after immobilization remained unchanged (pH 6.5 and 65 °C). Moreover, an improvement in pH stability and thermostability was also found after immobilization. Analysis of kinetic parameters shows that the K m value of XynB2Y509E-CLEAs obtained was slightly higher than that of free XynB2Y509E (1.2 versus 0.9 mM). Interestingly, the xylanase activity developed by the mutation was also conserved after the immobilization process.


Assuntos
Substituição de Aminoácidos , Proteínas de Bactérias/química , Reagentes para Ligações Cruzadas/química , Geobacillus stearothermophilus/enzimologia , Glutaral/química , Glicosídeo Hidrolases/química , Agregados Proteicos , Proteínas de Bactérias/genética , Geobacillus stearothermophilus/genética , Glicosídeo Hidrolases/genética , Mutação de Sentido Incorreto
4.
Int J Biol Macromol ; 169: 541-550, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33358952

RESUMO

Genipin is a nontoxic natural cross-linker that was successfully used to prepare cross-linked enzyme aggregates (CLEAs) of Trametes versicolor laccase. The recovered activity of CLEAs was influenced by the co-solvent type, genipin concentration, cross-linking time, preparation pH, and bovine serum albumin (BSA; amino group feeder) concentration. The characteristics of CLEAs prepared using genipin under optimal conditions (genipin-BSA-CLEAs) were compared with those of typical CLEAs prepared using glutaraldehyde or dextran polyaldehyde. Genipin-BSA-CLEAs were nano-sized (average diameter, approximately 700 nm), had a ball-like shape, showed a narrow size distribution, and exhibited the highest substrate affinity among the prepared CLEAs. The thermal stability of genipin-BSA-CLEAs was 6.8-fold higher than that of free laccase, and their pH stability was also much higher than that of free laccase in the tested range. Additionally, genipin-BSA-CLEAs retained 85% of their initial activity after 10 cycles of reuse. Particularly, genipin-BSA-CLEAs showed higher thermal and pH stability than CLEAs that were cross-linked using glutaraldehyde. Therefore, genipin represents an alternative to toxic compounds such as glutaraldehyde during cross-linking to prepare CLEAs.


Assuntos
Reagentes para Ligações Cruzadas/química , Iridoides/química , Lacase/química , Estabilidade Enzimática , Enzimas Imobilizadas/química , Glutaral/química , Concentração de Íons de Hidrogênio , Cinética , Polyporaceae/enzimologia , Soroalbumina Bovina/química , Temperatura , Trametes/enzimologia
5.
AAPS PharmSciTech ; 21(5): 173, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32548717

RESUMO

Innovative strategies for periodontal regeneration have been the focus of research clusters across the globe for decades. In order to overcome the drawbacks of currently available options, investigators have suggested a novel concept of functionally graded membrane (FGM) templates with different structural and morphological gradients. Chitosan (CH) has been used in the past for similar purpose. However, the composite formulation of composite and tetracycline when cross-linked with glutaraldehyde have received little attention. Therefore, the purpose of the study was to investigate the drug loading and release characteristics of novel freeze gelated chitosan templates at different percentages of glutaraldehyde. These were cross-linked with 0.1 and 1% glutaraldehyde and loaded with doxycycline hyclate. The electron micrographs depicted porous morphology of neat templates. After cross-linking, these templates showed compressed ultrastructures. Computerized tomography analysis showed that the templates had 88 to 92% porosity with average pore diameter decreased from 78 to 44.9 µm with increasing concentration. Fourier transform infrared spectroscopy showed alterations in the glycosidic segment of chitosan fingerprint region which after drug loading showed a dominant doxycycline spectral composite profile. Interestingly, swelling profile was not affected by cross-linking either at 0.1 and 1% glutaraldehyde and template showed a swelling ratio of 80%, which gained equilibrium after 15 min. The drug release pattern also showed a 40 µg/mL of release after 24 h. These doxycycline-loaded templates show their tendency to be used in a functionally graded membrane facing the defect site.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Reagentes para Ligações Cruzadas/química , Congelamento , Regeneração Tecidual Guiada Periodontal/métodos , Materiais Biocompatíveis/farmacocinética , Quitosana/farmacocinética , Reagentes para Ligações Cruzadas/farmacocinética , Liberação Controlada de Fármacos , Géis , Glutaral/química , Glutaral/farmacocinética , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
6.
Artigo em Inglês | MEDLINE | ID: mdl-32361468

RESUMO

The present study aimed to evaluate the effect of the immobilization method of trypsin on biochar on the hydrolysis of casein from different sources, when compared to the process using trypsin in native form, to obtain bioactive peptides. The modification of the surface of biochar with glutaraldehyde was effective, as shown by the results of FTIR assay and the texture profile of the materials. Both activated and functionalized biochar showed high immobilization efficiency (greater than 87%) and high binding capacity (greater than 91 mg/g). During hydrolysis, the biocatalyst obtained by enzyme immobilization on the functionalized biochar presented a higher hydrolysis capacity for the different caseins when compared to the enzyme immobilized by adsorption, with values of 3.05 and 2.73 U/mg for goat casein, 2.36 and 1.85 U/mg for bovine casein, and 2.60 and 2.37 U/mg for buffalo, casein, respectively, with 60 min of reaction. The results of inhibitory activity in this study ranged from 93.5% and 25.5% for trypsin in its free form and immobilized on functionalized activated carbon, respectively, under the same reaction conditions. The immobilization methods were efficient, presenting high immobilization capacity. The proteolytic activity of trypsin immobilized via covalent binding was higher when compared the immobilization by adsorption. Thus, the functionalized biochar has proven to be potential support for enzyme immobilization, and the biocatalyst can be reused for more than 4 cycles. Despite lower ACE inhibition values of hydrolyzed obtained with the immobilized enzymes compared to free enzymes, biocatalysts present advantage due to the possibility of reuse.


Assuntos
Caseínas/química , Carvão Vegetal/química , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Tripsina/química , Tripsina/metabolismo , Adsorção , Animais , Biocatálise , Bovinos , Estabilidade Enzimática , Glutaral/química , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Ácidos Fosfóricos/química , Proteólise , Propriedades de Superfície , Temperatura
7.
Food Chem ; 318: 126404, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32135426

RESUMO

The physicochemical properties of collagen casings were successfully improved by glutaraldehyde (GA) cross-linking, where the properties could be further regulated by drying temperature. Transverse direction (TD) showed a lower heat shrinkage rate than that in machine direction (MD). GA cross-linking significantly improved the mechanical properties of films under wet and boiled state. The mechanical properties of films in MD were more susceptible to wet and boiling water. The chemical composition was unchanged after GA cross-linking, but higher drying temperatures led to higher triple helix contents. The GA cross-linking mainly promoted the low temperature thermostability of collagen casings. All film samples had a rough fibrous morphology and a majority of collagen fibers was oriented under the lower drying temperature (55 â„ƒ). These results reported in this study can be used to better guide the preparation of collagen casings.


Assuntos
Colágeno/química , Reagentes para Ligações Cruzadas/química , Glutaral/química , Animais , Dessecação , Módulo de Elasticidade , Ligação de Hidrogênio , Conformação Proteica em alfa-Hélice , Estabilidade Proteica , Temperatura
8.
Carbohydr Polym ; 236: 116094, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32172896

RESUMO

Different size and morphology monodispersed chitosan (CS) microspheres loaded with the anticancer drug of 5-fluorouracil (5-Fu) were prepared by the microfluidic method assisted by a crosslinking unit with crosslinkers of tripolyphosphate (TPP) and glutaraldehyde (GTA). The sizes, morphologies, drug loading, encapsulation efficiency, drug release and cytotoxicity of 5-Fu loaded CS microspheres were characterized and determined. Results indicated that the CS microspheres were uniform in size distributions. They possessed excellent encapsulation efficiency and drug loading. The TPP-crosslinked CS microspheres had rough surfaces and exhibited faster drug release, whereas the CS microspheres crosslinked with GTA had smooth surfaces and showed slower drug release. Furthermore, 5-Fu-loaded CS microspheres exhibited sustained drug release which well fitted the first-order kinetics model and were pH-responsive in that the drug cumulative release was greater at acidic environments than at neutral conditions. Finally, 5-Fu loaded CS microspheres provided sufficient cytotoxicity and were satisfactory in the cancer cell inhibition.


Assuntos
Antimetabólitos Antineoplásicos/farmacologia , Quitosana/química , Portadores de Fármacos/química , Fluoruracila/farmacologia , Microesferas , Antimetabólitos Antineoplásicos/química , Sobrevivência Celular/efeitos dos fármacos , Reagentes para Ligações Cruzadas/química , Liberação Controlada de Fármacos , Fluoruracila/química , Glutaral/química , Células Hep G2 , Humanos , Concentração de Íons de Hidrogênio , Cinética , Dispositivos Lab-On-A-Chip , Microfluídica/instrumentação , Microfluídica/métodos , Polifosfatos/química
9.
Int J Pharm ; 578: 119118, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32032642

RESUMO

The present study evaluates the preparation of systemic administrated NSAID gelatin nanoparticles with the aid of quality by design and artificial neural networks (ANNs). Specifically, two different preparation techniques (i.e. nanoprecipitation and two-step desolvation) were implemented for the formulation of diclofenac sodium (DLC) gelatin nanoparticles (GNs). Preliminary screening experiments showed that in the case of nanoprecipitation the best compromise (in terms of achieving both small particle size and high encapsulation efficiency) was the use of poloxamer 407 (as stabilizer) and acetone (as non-solvent), while in the case of two-step desolvation significant effect had the use of acetone, gelatin type and bloom number (type B with bloom 150 was selected for further evaluation). Implementation of a central composite experimental design (CCD), showed that in the case of nanoprecipitation the optimum formulation can be achieved at high poloxamer, high gelatin and moderate to high glutaraldehyde (GTA used for crosslinking) concentrations, while in the case of two-step desolvation high gelatin and GTA concentrations are needed. Artificial neural networks (ANN) implementation showed significantly improved prediction ability compared to MLR, while verification experiments showed good agreement between the ANN predicted and the experimentally obtained results. SEM analysis of the optimum suggested formulations showed nanoparticles with smooth surface, while powder X-ray diffraction (XRD) analysis showed the formation of amorphously dispersed systems, and Fourier transform infrared spectroscopy (FTIR) revealed the presence of molecular interactions irrespectively of the preparation method followed. A slightly faster release profile was observed in the case of nanoprecipitation based GNs, while all formulations followed biphasic release profile.


Assuntos
Anti-Inflamatórios não Esteroides/química , Gelatina/química , Nanopartículas/química , Acetona/química , Administração Cutânea , Química Farmacêutica/métodos , Composição de Medicamentos/métodos , Glutaral/química , Redes Neurais de Computação , Tamanho da Partícula , Poloxâmero/química , Pós/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Difração de Raios X/métodos
10.
J Agric Food Chem ; 68(9): 2773-2782, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32013417

RESUMO

The influence of covalent protein modifications resulting from the Maillard reaction (glycation) of casein and lactose on the noncovalent association behavior of the protein was studied. Nonenzymatic cross-linking with methylglyoxal (MGO) and glutaraldehyde (GTA) as well as enzymatic cross-linking with microbial transglutaminase (mTG) was investigated in comparison. Molar mass, particle size, and conformational characteristics of nonmicellar casein associates as well as the extent of intraparticle protein cross-linking were examined utilizing size-exclusion chromatography (SEC) combined with UV detection and static and dynamic light scattering. Cross-linking resulted in the stabilization of a certain fraction of casein associates, with particle sizes of approximately 30 nm in radius of gyration (Rg), and promoted an incorporation of further casein molecules into those particles, yielding molar masses (Mw) of 1.0-1.2 × 106 g/mol. When caseins were additionally conjugated with lactose during the early Maillard reaction, a further growth of the associates up to approximately 50 nm in Rg with a Mw of 2.1 × 106 g/mol was observed. Furthermore, glycation reactions induced a transition from slightly elongated, random-coil structures toward more anisotropic conformations. Associates consisting of caseins cross-linked with GTA appeared to preserve the original particle conformation.


Assuntos
Caseínas/química , Cromatografia em Gel , Reagentes para Ligações Cruzadas/química , Difusão Dinâmica da Luz , Glutaral/química , Lactose/química , Reação de Maillard , Tamanho da Partícula , Aldeído Pirúvico/química
11.
J Am Chem Soc ; 142(7): 3311-3315, 2020 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-32011869

RESUMO

DNA nanostructures (DNs) have garnered a large amount of interest as a potential therapeutic modality. However, DNs are prone to nuclease-mediated degradation and are unstable in low Mg2+ conditions; this greatly limits their utility in physiological settings. Previously, PEGylated oligolysines were found to protect DNs against low-salt denaturation and to increase nuclease resistance by up to ∼400-fold. Here we demonstrate that glutaraldehyde cross-linking of PEGylated oligolysine-coated DNs extends survival by up to another ∼250-fold to >48 h during incubation with 2600 times the physiological concentration of DNase I. DNA origami with cross-linked oligolysine coats are non-toxic and are internalized into cells more readily than non-cross-linked origami. Our strategy provides an off-the-shelf and generalizable method for protecting DNs in vivo.


Assuntos
Reagentes para Ligações Cruzadas/metabolismo , DNA/metabolismo , Desoxirribonuclease I/metabolismo , Glutaral/metabolismo , Polilisina/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Reagentes para Ligações Cruzadas/química , Reagentes para Ligações Cruzadas/toxicidade , DNA/química , DNA/toxicidade , Glutaral/química , Glutaral/toxicidade , Células HEK293 , Humanos , Hidrólise , Nanoestruturas/química , Nanoestruturas/toxicidade , Conformação de Ácido Nucleico , Polietilenoglicóis/química , Polietilenoglicóis/metabolismo , Polietilenoglicóis/toxicidade , Polilisina/química , Polilisina/toxicidade
12.
ACS Appl Mater Interfaces ; 12(5): 6768-6775, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31944654

RESUMO

Millifluidic devices decorated with enzymes have been used for enzymatic reactions in continuous processes, but low enzymatic activity and enzyme leaching remain as challenges. Herein, we develop a strategy to embed cross-linked enzyme aggregates (CLEAs) on the surfaces of millifluidic devices to achieve higher enzymatic activity and better stability. Catalase was chosen as a model enzyme to degrade H2O2 in wastewater samples. First, CLEA of catalase (153 ± 10 nm) was formed by simultaneous precipitation and cross-linking with 25.0 wt % acetonitrile containing 0.025 wt % glutaraldehyde in a millifluidic device. To immobilize CLEA, we first swell a piece of plastic tubing by using 5.0 wt % acetonitrile and then immerse it in an aqueous solution with 5.0 wt % (3-aminopropyl)triethoxysilane (APTES) and 5.0 wt % dextran polyaldehyde (DPA) subsequently. After CLEA is absorbed inside the expanded polymer network of the tubing, the tubing is tightened by using a vacuum to secure the immobilized CLEA. The millifluidic device decorated with CLEA of catalase has total activity of 660 U for degradation of H2O2, and it shows good stability under a flow rate of 200 µL/min. The tubing can be used to degrade 0.1 wt % H2O2 solution continuously for 3 h or remove 2 wt % residual H2O2 in wastewater for 2 h. The technique is general enough and can be applied to other types of enzymes for continuous enzymatic reactions.


Assuntos
Catalase/metabolismo , Peróxido de Hidrogênio/metabolismo , Microfluídica/métodos , Estabilidade Enzimática , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glutaral/química , Microfluídica/instrumentação , Tamanho da Partícula , Polímeros/química , Temperatura , Águas Residuárias/química
13.
Int J Biol Macromol ; 142: 222-231, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31726168

RESUMO

This study was aimed the covalently immobilization of Aspergillus niger amyloglucosidase (ANAG) onto activated carbon (AC) obtained from sesame seed shell. AC was firstly functionalized with ethylenediamine, and after then activated with glutaraldehyde. 99.80% immobilization yield and 99.83% activity yield were obtained as the result of optimization of immobilization conditions (pH and molarity of immobilization buffer, AC amount, and reaction time). The optimum pH (5.5) and the optimum temperature range (55-60 °C) for ANAG were not affected by immobilization. After immobilization, Vmax value decreased from 1464.1 µmol D-glucose/L.min to 1342.3 µmol D-glucose/L.min, while Km value decreased from 116.3 g maltodextrin/L to 109.9 g maltodextrin/L. The immobilized enzyme retained 99.30% and 98.30% of its initial activity, respectively after twenty repeated uses and after twenty days of storage in 5 mL sodium phosphate buffer (0.1 M, pH 5.5) at +4 °C in a refrigerator. Finally, glucose syrup was produced from maltodextrin solution having 1% (w/v) concentration by using the immobilized ANAG. Maltodextrin was completely converted to glucose after four hours. Consequently, it can be said that the immobilized ANAG obtained in this study can be used in the industrial production of glucose syrup.


Assuntos
Aspergillus niger/enzimologia , Carvão Vegetal/química , Enzimas Imobilizadas/metabolismo , Etilenodiaminas/química , Glucana 1,4-alfa-Glucosidase/metabolismo , Glutaral/química , Sesamum/química , Estabilidade Enzimática , Proteínas Fúngicas/metabolismo , Glucose , Concentração de Íons de Hidrogênio , Imobilização , Polissacarídeos , Temperatura
14.
Int J Biol Macromol ; 144: 389-402, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31843603

RESUMO

In this study, the bioactivity of glutaraldehyde (GA)-crosslinked chitosan (CS)/poly(vinyl alcohol) (PVA)/ascorbic acid (ASC)-multiwalled carbon nanotube (MWCNTs) nanocomposites (NCs) was investigated. These NCs were fabricated via incorporation of 3, 5, and 7 wt% of ASC-MWCNTs into CS/PVA blend using ultrasonication. The polymeric matrix was crosslinked using a low amount of GA to fabricate completely water-insoluble NCs with high tolerance against the dynamic and static stress of body fluid environment. The synthesized NCs were characterized via various techniques. The field emission scanning electron microscopy studies showed the homogenous distribution of nanofiller throughout the matrix. The results of the thermogravimetric analysis demonstrated that the fabricated NCs have greater thermal stability than GA-crosslinked CS/PVA. The bioactivity was studied using in vitro test via immersion of samples in simulated body fluid (SBF) for 30 days. The results showed that the GA-crosslinked CS/PVA/ASC-MWCNTs NC 3 wt% has good hydroxyapatite-forming ability in SBF solution.


Assuntos
Ácido Ascórbico/química , Quitosana/química , Durapatita/química , Glutaral/química , Nanocompostos/química , Nanotubos de Carbono/química , Microscopia Eletrônica de Varredura , Nanocompostos/ultraestrutura , Nanotubos de Carbono/ultraestrutura , Álcool de Polivinil/química , Engenharia Tecidual
15.
Int J Biol Macromol ; 144: 770-780, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31730953

RESUMO

In the present study, Multiwalled carbon nanotubes (MWCNT) decorated with two different nanoparticles namely tungsten disulfide (WS2) and tin oxide (SnO2), nanocomposites (NCs) were synthesized via hydrothermal method. Spectroscopic studies showed that both synthesized NCs possess nearly same functional groups but MWCNT-SnO2 NCs are rich in O-functional group. Microscopic studies revealed that both NCs have different morphological microstructure. Lens culinaris ß-galactosidase (Lcß-gal) was immobilized using glutaraldehyde cross-linker resulted in immobilization efficiency of 91.5% and 88% with MWCNT-WS2 and MWCNT-SnO2 NCs, respectively. Remarkable increase in rate of hydrolysis of whey lactose has been observed with both NCs i.e. Lcß-gal immobilized MWCNT-WS2 hydrolyzes the 97% whey lactose in 1.5 h while MWCNT-SnO2 showed maximum 92% of whey hydrolysis in 2 h at optimum conditions. Both nanobiocatalyst could serve as a promising candidates for dairy industries and would offer a potential platform for enzyme based biosensor fabrication.


Assuntos
Enzimas Imobilizadas/química , Galactosidases/química , Lactose/análise , Lens (Planta)/química , Nanopartículas Metálicas/química , Nanocompostos/química , Nanotubos de Carbono/química , Animais , Técnicas Biossensoriais , Catálise , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Reagentes para Ligações Cruzadas/química , Dissulfetos/química , Glutaral/química , Hidrólise , Cinética , Camundongos , Propriedades de Superfície , Compostos de Estanho/química , Compostos de Tungstênio/química , Soro do Leite/química
16.
Enzyme Microb Technol ; 132: 109397, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31731972

RESUMO

Pectin lyase (from Rohapect 10 L) was immobilized on glutaraldehyde supports at low ionic strength at pH 5, 6.5 or 8 and later incubated at pH 8 for 48 h. The activity recovery of the biocatalysts versus pectin was quite low, under 10% for all of the immobilized biocatalyst at 20 °C. However, a high stabilization was found when the enzyme was immobilized at pH 5, (e.g., the immobilized enzyme kept 83% of the activity when the free enzyme was fully inactivated (pH 4.8 and 55 °C in 5 h)). This biocatalyst increased the activity versus pectin in an almost exponential way when temperature increased until reach the maximum temperature used in the study (90 °C), conditions where the free enzyme was almost inactive. The immobilized biocatalyst was also active even at pH 9, where the free enzyme was fully inactive. This biocatalyst could be reused for pectin hydrolysis 5 times for 72 h reaction cycles at 40 °C maintaining more than 90% of the initial activity.


Assuntos
Enzimas Imobilizadas/metabolismo , Glutaral/química , Polissacarídeo-Liase/metabolismo , Estabilidade Enzimática , Enzimas , Concentração de Íons de Hidrogênio , Hidrólise , Temperatura
17.
Colloids Surf B Biointerfaces ; 185: 110633, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31740324

RESUMO

The microcystin-LR (MC-LR) produced due to harmful cyanobacterial blooms have brought great harm to human and aquatic organisms, attracting a wide public health attention. To deal with MC-LR contamination, we synthesized a novel bio-functionalized composite for the high-efficient and sustainable biodegradation of microcystin-LR by covalent immobilizing Sphingopyxis sp. YF1 onto chitosan-grafted Fe3O4 magnetic particles (Fe3O4@CTS). The Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM) were utilized to characterize the structural properties of Fe3O4@CTS/Sphingopyxis sp. YF1. The immobilization conditions were optimized. And the MC-LR-degrading capabilities of Fe3O4@CTS/Sphingopyxis sp. YF1 were assessed under various conditions. The results showed that the optimal immobilization conditions containing 1.0 % (v/v) glutaraldehyde, immobilization for 4 h at 30 ℃. The Fe3O4@CTS/Sphingopyxis sp. YF1 showed an attractive degradation performance which possesed a wide torlerance to pH (6.0-9.0) and temperature (25-35 ℃). More interesting is that the Fe3O4@CTS/Sphingopyxis sp. YF1 exhibited significantly increased MC-LR-degrading capabilities after recycling and reusing which degradation rate reached 1.50 µg/mL/h in the sixth cycle, and it was easily recycled by using a magnet (Ms 21.5 emug-1). Two intermediates (tetrapeptide and Adda) and three degradation related genes (mlrA, mlrB and mlrC) were obtained in this study and the pathway for the degradation was proposed. These results revealed that Fe3O4@CTS/Sphingopyxis sp. YF1 can be potentially used for treatment of MC-LR contaminated environment.


Assuntos
Quitosana/química , Compostos Férricos/química , Microcistinas/metabolismo , Sphingomonadaceae/metabolismo , Biodegradação Ambiental , Células Imobilizadas/citologia , Glutaral/química , Concentração de Íons de Hidrogênio , Toxinas Marinhas , Sphingomonadaceae/citologia , Sphingomonadaceae/ultraestrutura , Temperatura
18.
Carbohydr Polym ; 229: 115559, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826459

RESUMO

We report a facile but robust approach to fabricate fruit peel-mimetic microcapsules (FPMCs) of which shell was structured by layering cellulose nanofibers (CNFs) with an antioxidant and a waxy compound on monodisperse gelatin microparticles using the layer-by-layer deposition. The thickness and moduli of the shell increased commonly depending on the number of CNF layers, indicating that the incorporation of CNFs made the shell layer rigid. We determined that the coating of the outermost FPMC layer with dodecane nanoemulsions softened the shell surface, thus preventing the generation of microcracks, which is essential for minimizing dehydration in the drying process. Furthermore, we also confirmed that the co-deposition of a phenolic compound, gallic acid, which is encapsulated in the polymeric micelles, with the shell layers allowed the FPMCs to exert antioxidant effects against the influx of oxygen from the atmosphere. These results highlight that our FPMC system could pave the way for the development of a micropackaging technology that enables encapsulation and stabilization of bioactive ingredients.


Assuntos
Cápsulas/química , Celulose/química , Hidrogéis/química , Nanofibras/química , Antioxidantes/química , Força Compressiva , Frutas/química , Gelatina/química , Glutaral/química , Tamanho da Partícula
19.
Carbohydr Polym ; 229: 115531, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31826523

RESUMO

Microencapsulated phase change material (MPCM) composites of capric acid were synthesized utilizing protein (Gelatin, GE)-polysaccharide (Gum Arabic, GA) interactions as shell material. Mechanical and thermal stabilities of these MPCM composites were achieved using glutaraldehyde cross-linker and silica coating respectively. Thermal properties (enthalpy and, melting/crystallization and cyclic tests) were estimated using differential scanning calorimeter (DSC) while, thermal stability was obtained from thermogravimetric analyzer (TGA). Morphology and particle size were analyzed using scanning electron microscope (SEM). FTIR and EDX (energy-dispersive X-ray) data interpreted nature of chemical bonds while crystalloid structures were obtained from XRD (X-Ray Diffraction). Based on morphology and thermal stability, the composite made with the core: shell ratio of 2:3 was chosen for analyzing the role of process parameters i.e. cross-linker amount and duration of cross-link reaction, and surfactant amount influencing encapsulation ratio. The composite tested and found stable for 50 heating/cooling cycles.


Assuntos
Gelatina/química , Polissacarídeos/química , Varredura Diferencial de Calorimetria , Glutaral/química , Goma Arábica/metabolismo , Tamanho da Partícula , Transição de Fase , Dióxido de Silício/química , Propriedades de Superfície , Temperatura , Termodinâmica
20.
Int J Biol Macromol ; 142: 732-741, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31760013

RESUMO

In this study, tunable Schiff's base-cross-linked chitosan-glutaraldehyde (CS-GLA) was modified and applied to remove reactive red 120 (RR120) dye from an aqueous solution. Different ratios of TiO2 nanoparticles, such as 25% TiO2 nanoparticles (CS-GLA/TNC-25) and 50% TiO2 nanoparticles (CS-GLA/TNC-50), were loaded into the CS-GLA's molecular structure. The adsorptive properties of CS-GLA, CS-GLA/TNC-25, and CS-GLA/TNC-50 for the RR120 dye in the aqueous solution were evaluated. CS-GLA/TNC-25 exhibited the best adsorptive property possibly because of the perfect balancing between the surface area and available amine (NH2) groups in the composite formulation. The impact of adsorption key parameters, such as adsorbent dosage (0.01-1.2 g), RR120 dye concentration (30-400 mg/L), solution pH (3-12), and contact time (0-400 min) were explored by batch adsorption mode. The adsorption was well described by the Freundlich model and pseudo-second order kinetic model. The adsorption capacity of CS-GLA/TNC-25 for RR120 dye was 103.1 mg/g at 303K. The adsorption mechanism of RR120 on the CS-GLA/TNC-25 surface can be assigned to various interactions, such as electrostatic attraction, n-π stacking, and H-bonding. Results indicate the potential application of CS-GLA/TNC-25 as environment-friendly biosorbent for removing acid and/or textile dyes, such as RR120, from aqueous environments.


Assuntos
Quitosana/química , Reagentes para Ligações Cruzadas/química , Glutaral/química , Nanocompostos/química , Bases de Schiff/química , Titânio/química , Triazinas/química , Adsorção , Aminas/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Propriedades de Superfície , Temperatura , Fatores de Tempo , Água , Poluentes Químicos da Água/química
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