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1.
Int J Biol Macromol ; 271(Pt 1): 132644, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38821808

RESUMO

Presently, the construction industry demands components that are exceptionally strong and long-lasting. The initial important construction material is concrete, which contains between 1 % and 2 % of air voids. The structural damage caused by water that enters through the air spaces are improved with filler material. Chemical filler materials are environmentally harmful; therefore, eco-friendly materials are selected for this study. The environmentally benign character of agro-waste byproduct usage is a driving factor in the field of research. Numerous uses can be found for waste materials, especially after they have been repurposed. We used a byproduct of an essential oil extraction company, an extract made from the leaves of lemon grass (Cymbopogan citrus), in our research. Alkalization, slow pyrolysis, acid hydrolysis, and bleaching are only some of the chemical treatments that could be used to easily extract microcrystalline cellulose from the discarded waste material. In our study the chemicals used are mild harmful to the environment and a surface reactant (linear alkyl benzene sulfonic acid) is utilised to bleach and purify the microcrystalline cellulose. Thermal analysis, scanning electron microscopy, transmission electron microscopy and Fourier transform spectroscopy were all used to learn more about the cellulose that had been extracted. The extracted cellulose powder comprises a high crystallinity index (68.14 %) and low crystallite size (5.13 nm) found using X-ray diffraction analysis. The smooth and porous surface is observable in scanning electron microscope analysis. The Differential scanning calorimeter curve shows the highest degradation temperature at 218.16 °C. The micro sized particles mostly range between 100 and 120 µm and are found using ImageJ. The surface roughness and permissible skewness of cellulose particles were examined using atomic force microscopy. The density of extracted cellulose is 1.092 g/cm3. The microcrystalline cellulose yield % was notably maximum (40.45 %). This cellulose was introduced in a M30 grade cement concrete as fillers up to 5 % by the weight of cement. The fresh and mechanical properties of the concrete was found to get improved with the addition of cellulose up to 3 %. As a result, the characteristics of cellulose boost its utility within the construction sector.


Assuntos
Celulose , Resíduos Industriais , Celulose/química , Celulose/isolamento & purificação , Cymbopogon/química , Materiais de Construção , Óleos Voláteis/química , Óleos Voláteis/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Carbohydr Polym ; 278: 118929, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34973747

RESUMO

The superhydrophilic/underwater superoleophobic nanocellulose-based membranes show great potential in oil/water emulsion separation. However, nanocellulose composed of polysaccharides inevitably suffered from bacterial erosion during use or storage, resulting in structural damage or reduced separation efficiency. In this work, silver nanoparticles (AgNPs) as effective bactericidal materials are uniformly deposited on tunicate cellulose nanocrystals (TCNCs) by in situ hydrothermal reduction of silver nitrate. TCNCs not only act as reducing agents for silver ions, but also work as dispersant and stabilizers of AgNPs. Nanocomposite membranes are fabricated by vacuum-assisted filtrating of AgNPs@TCNC suspension, which exhibit nanoporous structure, superhydrophilicity, and underwater superoleophobicity. These membranes could efficiently separate oil/water microemulsion with water flux (>324 L m-2 h-1 bar-1) and oil rejection (>99%). Importantly, these membranes show excellent antibacterial efficacy against E. coli and S. aureus, benefiting to their long-term use and storage.


Assuntos
Antibacterianos/farmacologia , Celulose/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Nanopartículas/química , Prata/farmacologia , Antibacterianos/química , Antibacterianos/isolamento & purificação , Celulose/química , Celulose/isolamento & purificação , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/isolamento & purificação , Emulsões , Escherichia coli/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Testes de Sensibilidade Microbiana , Óleos/química , Prata/química , Prata/isolamento & purificação , Staphylococcus aureus/efeitos dos fármacos , Água/química
3.
Int J Biol Macromol ; 175: 304-312, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33516854

RESUMO

Steam explosion can be used to pretreat lignocellulosic materials to decrease energy and chemical consumption during pulping to obtain environmentally friendly lignin and to improve lignin yield without changing its structure. The objective of this study was to evaluate the extraction of lignin from oil palm mesocarp fibers and sugarcane bagasse using steam explosion pretreatment followed by acetosolv. The biomasses were pretreated at 168 °C for a reaction time of 10 min. Steam explosion combined with acetosolv at lower severities was also carried out. Steam explosion followed by acetosolv increased the lignin yield by approximately 15% and 17% in oil palm mesocarp fibers and sugarcane bagasse, respectively. In addition, steam explosion decreased the reaction time of acetosolv four-fold while maintaining the lignin yield from sugarcane bagasse. Similar results were not obtained for oil palm mesocarp. High-purity and high-quality lignins were obtained using steam explosion pretreatment with structural characteristics similar to raw ones. Sugarcane bagasse lignin seems to be a better option for application in material science due its higher lignin yield and higher thermal stability. Our findings demonstrate that steam explosion is efficient for improving lignin yield and/or decreasing pulping severity.


Assuntos
Celulose/isolamento & purificação , Lignina/isolamento & purificação , Óleo de Palmeira/isolamento & purificação , Ácido Acético/química , Biomassa , Biotecnologia/métodos , Celulose/química , Etanol , Hidrólise , Lignina/química , Extratos Vegetais/isolamento & purificação , Saccharum/química , Vapor
4.
Int J Biol Macromol ; 170: 178-188, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33359257

RESUMO

Chitosan-based hydrogels have received significant interest in tissue engineering and regenerative medicine applications owing to their superior biocompatibility. However, their applications are restricted owing to their weak mechanical strength. Cellulose nanocrystals (CNCs) are often explored as reinforcing agents to improve the native properties of polymers owing to their superior physicochemical properties. We fabricated a multi-functional hydrogel scaffold of chitosan/CNCs by incorporating different amounts of CNCs into a chitosan (CH) hydrogel. Significant enhancement in the mechanical strength was noted in the CH/CNCs as compared to that in pure CH hydrogel scaffolds. The cytocompatibility of the fabricated scaffolds was monitored in the presence of bone-marrow-derived mesenchymal stem cells (BMSCs). Improved cell viability and mineralization were observed with CH/CNC hydrogel scaffolds than those with pure CH hydrogel scaffolds. Enhanced osteogenic-related gene expression was observed in the CH/CNC hydrogel scaffold environment than that in the control, indicating their osteogenic potential, in addition to enhanced antibacterial activity. Developed composite scaffolds exhibited improved sustained drug release compared to that by pure polymer scaffolds, and this was more sustained in the scaffolds with higher CNC content. Therefore, the fabricated scaffolds may have been used in tissue engineering for osteogenesis, as antibacterial agents, and in sustained drug delivery.


Assuntos
Antibacterianos/química , Materiais Biocompatíveis/química , Celulose/química , Quitosana/química , Sistemas de Liberação de Medicamentos , Nanopartículas/química , Alicerces Teciduais/química , Animais , Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Materiais Biocompatíveis/isolamento & purificação , Materiais Biocompatíveis/farmacologia , Células Cultivadas , Celulose/administração & dosagem , Celulose/isolamento & purificação , Celulose/farmacologia , Quitosana/administração & dosagem , Quitosana/isolamento & purificação , Quitosana/farmacologia , Preparações de Ação Retardada , Relação Dose-Resposta a Droga , Liberação Controlada de Fármacos , Hemólise/efeitos dos fármacos , Humanos , Hidrogéis/química , Teste de Materiais , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Oryza/química , Osteogênese/efeitos dos fármacos , RNA/genética , RNA/isolamento & purificação
5.
Cardiovasc Eng Technol ; 11(6): 646-654, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33205361

RESUMO

PURPOSE: The paper present findings from an in vitro experimental study of a stentless human aortic bioprosthesis (HAB) made of bacterial cellulose (BC). Three variants of the basic model were designed and tested to identify the valve prosthesis with the best performance parameters. The modified models were made of BC, and the basic model of pericardium. METHODS: Each model (named V1, V2 and V3) was implanted into a 90 mm porcine aorta. Effective Orifice Area (EOA), rapid valve opening time (RVOT) and rapid valve closing time (RVCT) were determined. The flow resistance of each bioprosthesis model during the simulated heart systole, i.e. for the mean differential pressure (ΔP) at the time of full valve opening was measured. All experimental specimens were exposed to a mean blood pressure (MBP) of 90.5 ± 2.3 mmHg. RESULTS: The V3 model demonstrated the best performance. The index defining the maximum opening of the bioprosthesis during systole for models V1, V2 and V3 was 2.67 ± 0.59, 2.04 ± 0.23 and 2.85 ± 0.59 cm2, respectively. The mean flow rate through the V3 valve was 5.7 ± 1, 6.9 ± 0.7 and 8.9 ± 1.4 l/min for stroke volume (SV) of 65, 90 and 110 mL, respectively. The phase of immediate opening and closure for models V1, V2 and V3 was 8, 7 and 5% of the cycle duration, respectively. The mean flow resistance of the models was: 4.07 ± 2.1, 4.28 ± 2.51 and 5.6 ± 2.32 mmHg. CONCLUSIONS: The V3 model of the aortic valve prosthesis is the most effective. In vivo tests using BC as a structural material for this model are recommended. The response time of the V3 model to changed work conditions is comparable to that of a healthy human heart. The model functions as an aortic valve prosthesis in in vitro conditions.


Assuntos
Aorta/cirurgia , Bioprótese , Celulose/isolamento & purificação , Gluconacetobacter xylinus/metabolismo , Implante de Prótese de Valva Cardíaca/instrumentação , Próteses Valvulares Cardíacas , Animais , Aorta/fisiopatologia , Hemodinâmica , Teste de Materiais , Desenho de Prótese , Sus scrofa
6.
Carbohydr Polym ; 246: 116632, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32747267

RESUMO

Bacterial cellulose (BC) has been widely used as a model system to investigate the interaction of polyphenols with the polysaccharides of cell walls. In this study, the water absorption ability and the adsorption ability of epicatechin of the never-dried and freeze-dried BC produced by a high-yield Komagataeibacter hansenii strain ATCC 53582 was compared with two normal-yield strains. The structural characteristics of BC were investigated via microscopy observation and mechanical/rheological tests. The 1-butyl-3-methylimidazolium acetate/dimethyl sulfoxide ([BMIM]Ac/DMSO) co-solvent was used to dissolve BC to calculate the degree of polymerization (DP). Results showed that compared with the other two strain, the BC synthesised by ATCC 53582 had a higher cellulose concentration (1.2 wt%) but lower epicatechin adsorption (29 µg/mg under 4 mM, pH 7). Its fibril network collapsed and led to a reduced recovery ratio (86 %) in the compression-relaxation test, which may be due to large DP (2856).


Assuntos
Acetobacteraceae/química , Catequina/metabolismo , Celulose/metabolismo , Água/química , Acetobacteraceae/fisiologia , Adsorção , Catequina/química , Celulose/química , Celulose/isolamento & purificação , Dimetil Sulfóxido/química , Liofilização , Concentração de Íons de Hidrogênio , Imidazóis/química , Polimerização , Reologia , Solventes/química , Estresse Mecânico
7.
Int J Biol Macromol ; 144: 198-207, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31843613

RESUMO

Optimization of the culture parameters used for biocellulose (BC) production by a previously isolated bacterial strain (Komagataeibacter hansenii AS.5) was carried out. The effect of nine culture parameters on BC production was evaluated by implementing the Plackett-Burman design, and the results revealed that, the most significant variables affecting BC production were MgSO4, ethanol, pH and yeast extract. A three-level and four-factor Box-Behnken design was applied to determine the optimum level of each significant variable. According to the results of the Plackett-Burman (PBD) and Box-Behnken designs (BBD), the following medium composition and parameters were calculated to be optimum (g/l): glucose 25, yeast extract 13, MgSO4 0.15, KH2PO4 2, ethanol 7.18 ml/l, pH 5.5, inoclume size 7%, cultivation temperature 20 °C and incubation time 9 days. Characterization of purified BC was performed to determine the network morphology by scanning electron microscopy, crystallinity by X-ray diffraction, chemical structure and functional groups by Fourier-transform infrared spectroscopy, thermal stability by thermogravimetric analysis and mechanical properties such as Young's modulus, tensile strength and elongation at beak % of BC.


Assuntos
Acetobacteraceae/metabolismo , Celulose/biossíntese , Celulose/isolamento & purificação , Celulose/ultraestrutura , Meios de Cultura , Glucose/metabolismo , Fenômenos Mecânicos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Resistência à Tração , Termogravimetria , Difração de Raios X
8.
Int J Biol Macromol ; 155: 1060-1068, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31712155

RESUMO

Passion fruit bagasse extract (PFBE) is a rich source of polyphenols, including piceatannol. This work produced alginate (1, 2, 3 wt%) aerogel and investigated the impregnation of gallic acid (GA) and PFBE in alginate aerogel microparticles. The microparticles of ca. 100 µm in diameter were obtained by emulsion-gelation method, submitted to solvent exchange, wet impregnation (WI) and supercritical drying. Alginate aerogels derived from 1 wt% solution led to a higher GA loading and, therefore, this formulation was used to impregnate PFBE. The loading of PFBE, total phenolic, and piceatannol contents based on grams of raw aerogel were 0.62 g, 10.77 mg, and 741.85 µg, respectively, which means a loading efficiency of total phenolics and piceatannol of 47.1% and 34.7%. DSC analysis and X-ray diffraction showed that particles behave as amorphous materials and ORAC assay revealed that impregnated aerogel microparticles presented antioxidant capacity. Alginate aerogel microparticles presented as an appropriated material for drug loading, whereas WI and supercritical drying demonstrated to be useful techniques to load PBBE in aerogels.


Assuntos
Alginatos/química , Celulose/química , Portadores de Fármacos/química , Géis/química , Passiflora/química , Extratos Vegetais/química , Celulose/isolamento & purificação , Dessecação , Microesferas , Porosidade , Solubilidade , Difração de Raios X
9.
Int J Biol Macromol ; 136: 241-252, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31195048

RESUMO

In this work, sunflower oil cake (SOC) was identified as bio-sourced material for cellulose nanocrystals (CNC) production using chemical treatments followed by sulfuric acid hydrolysis. The hydrolysis was performed at 64% acid concentration, a temperature of 50 °C and at two different hydrolysis times, 15 min (CNC15) and 30 min (CNC30). It was found that CNC exhibited a diameter of 9 ±â€¯3 nm and 5 ±â€¯2 nm, a length of 354 ±â€¯101 nm and 329 ±â€¯98 nm, a crystallinity of 75% and 87%, a surface charge density of ~1.57 and ~1.88 sulfate groups per 100 anhydroglucose units and a zeta potential value of -25.6 and -30.7 mV, for CNC15 and CNC30, respectively. The thermal degradation under nitrogen atmosphere started at 225 °C (CNC15), which is relatively higher than the temperature for sulfuric acid hydrolyzed CNC from other sources. Due to a high importance of CNC application in aqueous systems, the rheological behaviour of CNC suspensions at various concentrations was evaluated by the steady shear viscosity measurements and the oscillatory dynamic tests. The results showed that the CNC suspensions exhibited a gel-like behaviour at very low CNC concentrations (0.1-1%) wherein a strong CNC entangled network is formed. Polymer nanoreinforcing capability of the newly produced CNC was also investigated in this study. CNC filled PVA nanocomposite films were produced at various CNC contents (1, 3, 5 and 8 wt%) and their mechanical and transparency properties were investigated, resulting in transparent nanocomposite materials with strong mechanical properties. The study suggested other possibilities to utilize agricultural wastes from SOC for CNC production with potential application as reinforcement in polymer nanocomposites.


Assuntos
Celulose/química , Celulose/isolamento & purificação , Fenômenos Químicos , Nanopartículas/química , Óleo de Girassol/química , Nanocompostos/química , Fenômenos Ópticos , Álcool de Polivinil/química , Propriedades de Superfície , Temperatura
10.
Bioresour Technol ; 284: 98-104, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30927653

RESUMO

Rice straw was pretreated with ethylene glycol (EG) and AlCl3 for enzymatic hydrolysis. EG-AlCl3 pretreatment had an extremely good selectivity for component fractionation, resulting in 88% delignification and 90% hemicellulose removal, with 100% cellulose recovered or 76% (w/w) cellulose content in solid residue at 150 °C with 0.055 mol/L AlCl3. The pretreated residue (5%, w/v) presented a higher enzymatic hydrolysis rate (glucose yield increased 2 times to 94%) for 24 h at cellulase loading of 10 FPU/g. The hydrolysis behavior was correlated with the composition and structure of substrates characterized by SEM, FT-IR, BET, XRD and TGA. The enzyme adsorption ability of pretreated straw was 12-folds that for the original sample. EG-AlCl3 solution was further cycled for 3 times with 100% cellulose recovery but only 29% lignin removal due to the loss of AlCl3. EG-AlCl3 pretreatment is an efficient method with little loss of cellulose for lignocelluloses.


Assuntos
Cloreto de Alumínio/química , Celulase/metabolismo , Celulose/isolamento & purificação , Etilenoglicol/química , Oryza/química , Celulose/química , Celulose/metabolismo , Hidrólise , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Polissacarídeos/metabolismo
11.
Int J Biol Macromol ; 129: 750-777, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30593803

RESUMO

Cellulose is a renewable natural fiber, which has gained enormous and significant research interest and evolved as the prime and promising candidate for replacing synthetic fibers. The various sources of cellulose, which is one of the world's most ubiquitous and renewable biopolymer resources, include trees, plants, tunicate and bacteria. The renewable biomaterial in the form of nanocellulose and its composites have been included in this review having the broad range of medical applications, viz.; tissue engineering, cardiovascular surgery, dental, pharmaceuticals, veterinary, adhesion barriers and skin therapy. These grafts are being fabricated from biodegradable materials. Bacterial cellulose is also an emerging renewable biomaterial with immense potential in biomedical field. The fabrication methods, characteristic properties and various overwhelming applications of cellulosic composites are explicitly elucidated in this review. The crux of this review is to exhibit the latest state of art, development in the field of cellulosic nanocomposite science and technology research and their applications towards biomedical field. Among the fourteen principle of green chemistry the two key principles i.e. using environmentally preferable solvents and bio-renewable feed-stocks covers in dissolution of cellulose in ionic liquids (ILs). In addition, this review covers about the comprehensive extraction and dissolution of cellulose and nanocellulose using ILs.


Assuntos
Pesquisa Biomédica , Celulose/química , Celulose/isolamento & purificação , Química Verde/métodos , Líquidos Iônicos/química , Nanotecnologia/métodos , Humanos , Nanocompostos/química
12.
Chem Asian J ; 12(24): 3150-3155, 2017 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-28990285

RESUMO

There is significant interest in the development of a sustainable and integrated process for the extraction of essential oils and separation of biopolymers by using novel and efficient solvent systems. Herein, cassia essential oil enriched in coumarin is extracted from Cinnamomum cassia bark by using a protic ionic liquid (IL), ethylammonium nitrate (EAN), through dissolution and the creation of a biphasic system with the help of diethyl ether. The process has been perfected, in terms of higher biomass dissolution ability and essential oil yield through the addition of aprotic ILs (based on the 1-butyl-3-methylimidazolium (C4 mim) cation and chloride or acetate anions) to EAN. After extraction of oil, cellulose-rich material and free lignin were regenerated from biomass-IL solutions by using a 1:1 mixture of acetone-water. The purity of the extracted essential oil and biopolymers were ascertained by means of FTIR spectroscopy, NMR spectroscopy, and GC-MS techniques. Because lignin contains UV-blocking chromophores, the oil-free residual lignocellulosic material has been directly utilized to construct UV-light-resistant composite materials in conjunction with the biopolymer chitosan. Composite material thus obtained was processed to form biodegradable films, which were characterized for mechanical and optical properties. The films showed excellent UV-light resistance and mechanical properties, thereby making it a material suitable for packaging and light-sensitive applications.


Assuntos
Plásticos Biodegradáveis/química , Cinnamomum aromaticum/química , Química Verde , Líquidos Iônicos/química , Óleos de Plantas/isolamento & purificação , Plásticos Biodegradáveis/isolamento & purificação , Celulose/química , Celulose/isolamento & purificação , Quitosana/química , Quitosana/isolamento & purificação , Imidazóis/química , Luz , Lignina/química , Lignina/isolamento & purificação , Óleos de Plantas/química , Compostos de Amônio Quaternário/química
13.
Int J Biol Macromol ; 103: 931-940, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28549863

RESUMO

In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28µm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.


Assuntos
Celulose/química , Celulose/isolamento & purificação , Hibiscus/química , Propriedades de Superfície , Temperatura
14.
Int J Biol Macromol ; 95: 1228-1234, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27836655

RESUMO

In the present study, microcrystalline cellulose (MCC) was isolated from oil palm fronds (OPF) using chemo-mechanical process. Wherein, alkaline hydrogen peroxide (AHP) was utilized to extract OPF fibre at different AHP concentrations. The OPF pulp fibre was then bleached with acidified sodium chlorite solution followed by the acid hydrolysis using hydrochloric acid. Several analytical methods were conducted to determine the influence of AHP concentration on thermal properties, morphological properties, microscopic and crystalline behaviour of isolated MCC. Results showed that the MCC extracted from OPF fibres had fibre diameters of 7.55-9.11nm. X-ray diffraction (XRD) analyses revealed that the obtained microcrystalline fibre had both celluloses I and cellulose II polymorphs structure, depending on the AHP concentrations. The Fourier transmission infrared (FTIR) analyses showed that the AHP pre-hydrolysis was successfully removed hemicelluloses and lignin from the OPF fibre. The crystallinity of the MCC was increased with the AHP concentrations. The degradation temperature of MCC was about 300°C. The finding of the present study showed that pre-treatment process potentially influenced the quality of the isolation of MCC from oil palm fronds.


Assuntos
Arecaceae/química , Celulose/isolamento & purificação , Peróxido de Hidrogênio/química , Folhas de Planta/química , Caules de Planta/química , Celulose/química , Cloretos/química , Ácido Clorídrico/química , Concentração de Íons de Hidrogênio , Hidrólise
15.
Ultrason Sonochem ; 34: 631-639, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27773290

RESUMO

Highly stable and dispersible nanocrystalline cellulose (NCC) was successfully isolated from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC), with yields of 93% via a sono-assisted TEMPO-oxidation and a subsequent sonication process. The sono-assisted treatment has a remarkable effect, resulting in an increase of more than 100% in the carboxylate content and a significant increase of approximately 39% in yield compared with the non-assisted process. TEM images reveal the OPEFB-NCC to have rod-like crystalline morphology with an average length and width of 122 and 6nm, respectively. FTIR and solid-state 13C-NMR analyses suggest that oxidation of cellulose chain hydroxyl groups occurs at C6. XRD analysis shows that OPEFB-NCC consists primarily of a crystalline cellulose I structure. Both XRD and 13C-NMR indicate that the OPEFB-NCC has a lower crystallinity than the OPEFB-MCC starting material. Thermogravimetric analysis illustrates that OPEFB-NCC is less thermally stable than OPEFB-MCC but has a char content of 46% compared with 7% for the latter, which signifies that the carboxylate functionality acts as a flame retardant.


Assuntos
Arecaceae/química , Biomassa , Celulose/isolamento & purificação , Óxidos N-Cíclicos/química , Lignina/química , Nanopartículas/química , Sonicação , Celulose/química , Oxirredução
16.
Carbohydr Polym ; 156: 409-416, 2017 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-27842840

RESUMO

Cellulose nanocrystals were isolated from oil palm trunk by total chlorine free method. The samples were either water pre-hydrolyzed or non-water pre-hydrolyzed, subjected to soda pulping, acidified and ozone bleached. Cellulose and cellulose nanocrystal (CNC) physical, chemical, thermal properties, and crystallinity index were investigated by composition analysis, scanning electron microscopy, transmission electron microscopy, fourier transform infrared, thermogravimetric analysis and X-ray diffraction. Water pre-hydrolysis reduced lignin (<0.5%) and increased holocellulose (99.6%) of ozone-bleached cellulose. Water pre-hydrolyzed cellulose exhibited surface fibrillation and peeling off after acid hydrolysis process compared to non-fibrillated of non-water pre-hydrolyzed cellulose. Water pre-hydrolysis improved final CNC crystallinity (up to 75%) compared to CNC without water pre-hydrolysis crystallinity (69%). Cellulose degradation was found to occur during ozone bleaching stage but CNC showed an increase in crystallinity after acid hydrolysis. Thus, oil palm trunk CNC can be potentially applied in pharmaceutical, food, medical and nanocomposites.


Assuntos
Arecaceae/química , Celulose/química , Celulose/isolamento & purificação , Nanopartículas/química , Caules de Planta/química , Hidrólise , Água/química
17.
Sci Rep ; 6: 38330, 2016 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-27922065

RESUMO

The treatment of leishmaniasis still relies on drugs with potentially serious adverse effects. Herein, we tested a topical formulation of bacterial cellulose (BC) membranes containing Diethyldithiocarbamate (DETC), a superoxide dismutase 1 inhibitor. Leishmania-infected macrophages exposed to BC-DETC resulted in parasite killing, without pronounced toxic effects to host cells. This outcome was associated with lower SOD1 activity and higher production of superoxide and cytokine mediators. Topical application of BC-DETC significantly decreased lesion size, parasite load and the inflammatory response at the infection site, as well as the production of both IFN-γ and TNF. Combination of topical BC-DETC plus intraperitoneal Sbv also significantly reduced disease development and parasite load. The leishmanicidal effect of BC-DETC was extended to human macrophages infected with L. braziliensis, highlighting the feasibility of BC-DETC as a topical formulation for chemotherapy of cutaneous leishmaniasis caused by L. braziliensis.


Assuntos
Antiprotozoários/farmacologia , Celulose/química , Ditiocarb/farmacologia , Leishmania braziliensis/efeitos dos fármacos , Leishmaniose Cutânea/tratamento farmacológico , Meglumina/farmacologia , Compostos Organometálicos/farmacologia , Administração Cutânea , Animais , Antiprotozoários/química , Celulose/isolamento & purificação , Citocinas/biossíntese , Ditiocarb/química , Quimioterapia Combinada , Feminino , Gluconacetobacter/química , Humanos , Injeções Intraperitoneais , Leishmania braziliensis/crescimento & desenvolvimento , Leishmaniose Cutânea/metabolismo , Leishmaniose Cutânea/parasitologia , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Antimoniato de Meglumina , Camundongos , Camundongos Endogâmicos BALB C , Cultura Primária de Células , Superóxido Dismutase-1/metabolismo , Superóxidos/metabolismo
18.
Carbohydr Polym ; 134: 534-40, 2015 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-26428155

RESUMO

In this study cellulose nanocrystals were isolated through acid hydrolysis process from parenchyma and vascular bundle of oil palm trunk (Elaeis guineensis). The morphological properties of obtained cellulose nanocrystals were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The microscopy images showed smoother and cleaner surface of parenchyma cellulose nanocrystals when compared to vascular bundle cellulose nanocrystals. The TEM image shows a higher length and diameter for parenchyma cellulose nanocrystals compared to vascular bundle cellulose nanocrystals. The Fourier transform infrared (FTIR) spectra showed changes in functional groups after acid hydrolysis due to removal of lignin, hemicelluloses and other impurities in both type of cellulose nanocrystals. Crystallinity index of cellulose nanocrystals was observed higher for vascular bundle as compared to parenchyma. Thermogravimetric analysis (TGA) was performed to study the thermal stability of cellulose nanocrystals and it was observed higher for parenchyma cellulose nanocrystals compared to vascular bundle.


Assuntos
Arecaceae/química , Celulose/química , Celulose/isolamento & purificação , Nanopartículas , Arecaceae/citologia
19.
J Agric Food Chem ; 62(36): 8973-81, 2014 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-25140731

RESUMO

A process based on a steam explosion pretreatment and alkali solution post-treatment was applied to fractionate olive stones (whole and fragmented, without seeds) and olive cake into their main constitutive polymers of cellulose (C), hemicelluloses (H), and lignin (L) under optimal conditions for each fraction according to earlier works. The chemical characterization (chromatographic method and UV and IR spectroscopy) and the functional properties (water- and oil-holding capacities, bile acid binding, and glucose retardation index) of each fraction were analyzed. The in vitro studies showed a substantial bile acid binding activity in the fraction containing lignin from olive stones (L) and the alkaline extractable fraction from olive cake (Lp). Lignin bound significantly more bile acid than any other fraction and an amount similar to that bound by cholestyramine (a cholesterol-lowering, bile acid-binding drug), especially when cholic acid (CA) was tested. These results highlight the health-promoting potential of lignin from olive stones and olive cake extracted from olive byproducts.


Assuntos
Ácidos e Sais Biliares/metabolismo , Celulose/metabolismo , Glucose/metabolismo , Lignina/metabolismo , Olea/química , Polissacarídeos/metabolismo , Celulose/isolamento & purificação , Fracionamento Químico/métodos , Fibras na Dieta , Frutas/química , Lignina/isolamento & purificação , Polissacarídeos/isolamento & purificação , Sementes/química , Óleo de Soja/metabolismo , Vapor , Água/metabolismo
20.
Carbohydr Polym ; 110: 423-9, 2014 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-24906775

RESUMO

Fiber reinforced polymer composites are replacing many metallic structures due to its high specific strength and modulus. However commonly used man-made E-glass fibers are hazardous for health and carcinogenic by nature. Comprehensive characterization of Cissus quadrangularis root fiber such as anatomical study, chemical analysis, physical analysis, FTIR, XRD, SEM analysis and thermo gravimetric analysis are done. The results are very encouraging for its application in fiber industries, composite manufacturing, etc. Due to its light weight and the presence of high cellulose content (77.17%) with very little wax (0.14%) provide high specific strength and good bonding properties. The flaky honeycomb outer surface and low microfibril angle revealed through electron microscopy contributes for its high modulus. The thermo gravimetric analysis indicates better thermal stability of the fiber up to 230°C, which is well within the polymerization process temperature.


Assuntos
Celulose/química , Celulose/ultraestrutura , Cissus/química , Celulose/isolamento & purificação , Módulo de Elasticidade , Teste de Materiais , Raízes de Plantas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Resistência à Tração , Termogravimetria , Difração de Raios X
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