scholarly journals Agglomeration of cellulose nanocrystals: the effect of secondary sulfates and their use in product separation

Cellulose ◽  
2020 ◽  
Vol 27 (17) ◽  
pp. 9839-9851
Author(s):  
Christoph Metzger ◽  
David Auber ◽  
Stephan Dähnhardt-Pfeiffer ◽  
Heiko Briesen
Keyword(s):  
Ionic Strength ◽  
Cellulose Nanocrystals ◽  
High Yield ◽  
Downstream Process ◽  
Critical Concentrations ◽  
Product Separation

AbstractThis study was aimed at the development of a better understanding of the agglomeration behavior of sulfated cellulose nanocrystals (CNCs) in the presence of sulfates with monovalent (NH4+, K+, Na+) and divalent (Ca2+) cations, and to demonstrate their potential in simple and efficient product separation. Protonated CNCs were counterion-exchanged and their ionic strength was increased by adding sulfates of the respective cation to trigger agglomeration. The critical concentrations of agglomeration (CAC) and peptization (CPC) were determined. We found that the agglomeration behavior of CNCs could be attributed to matching affinities between the cations and the sulfate half-ester groups on the CNC surfaces. Based on these findings, a facile and efficient downstream process was designed to separate CNCs from neutralized reactant solutions using CAC and CPC. This method provides colloidally stable CNCs at high yield provided by centrifugation. When salt concentrations in the product are maintained below the CAC, as prepared CNCs from neutralized reactant solutions might be used in hydrogels and emulsions.

scholarly journals Improved downstream process for the production of plasmid DNA for gene therapy.

2005 ◽  
Vol 52 (3) ◽  
pp. 703-711 ◽  
Author(s):  
Jochen Urthaler ◽  
Wolfgang Buchinger ◽  
Roman Necina
Keyword(s):  
Gene Therapy ◽  
Plasmid Dna ◽  
Viral Vectors ◽  
Continuous System ◽  
Size Exclusion ◽  
High Yield ◽  
Downstream Process ◽  
Naked Dna ◽  
Supercoiled Form ◽  
Exclusion Chromatography

Gene therapy and genetic vaccines promise to revolutionize the treatment of inherited and acquired diseases. Since viral vectors are generally associated with numerous disadvantages when applied to humans, the administration of naked DNA, or DNA packed into lipo- or polyplexes emerge as viable alternatives. To satisfy the increasing demand for pharmaceutical grade plasmids we developed a novel economic downstream process which overcomes the bottlenecks of common lab-scale techniques and meets all regulatory requirements. After cell lysis by an in-house developed gentle, automated continuous system the sequence of hydrophobic interaction, anion exchange and size exclusion chromatography guarantees the separation of impurities as well as undesired plasmid isoforms. After the consecutive chromatography steps, adjustment of concentration and final filtration are carried out. The final process was proven to be generally applicable and can be used from early clinical phases to market-supply. It is scaleable and free of animal-derived substances, detergents (except lysis) and organic solvents. The process delivers high-purity plasmid DNA of homogeneities up to 98% supercoiled form at a high yield in any desired final buffer.

Stable and sensitive stimuli-responsive anisotropic hydrogels for sensing ionic strength and pressure

2018 ◽  
Vol 5 (6) ◽  
pp. 1076-1081 ◽  
Author(s):  
Takayuki Hiratani ◽  
Osamu Kose ◽  
Wadood Y. Hamad ◽  
Mark J. MacLachlan
Keyword(s):  
Ionic Strength ◽  
Cellulose Nanocrystals ◽  
Stimuli Responsive ◽  
Responsive Hydrogels

Stimuli-responsive hydrogels that respond to pressure and ionic strength were prepared with large mono-domain, nematic organization of cellulose nanocrystals (CNCs).

Room temperature preparation of cellulose nanocrystals with high yield via a new ZnCl2 solvent system

2021 ◽  
pp. 118946
Author(s):  
Junchai Zhao ◽  
Mengwei Deng ◽  
Shuaiyao Li ◽  
Zheng Guan ◽  
Yixuan Xia ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Room Temperature ◽  
Solvent System ◽  
High Yield ◽  
Temperature Preparation

Simple Process To Produce High-Yield Cellulose Nanocrystals Using Recyclable Citric/Hydrochloric Acids

2019 ◽  
Vol 7 (5) ◽  
pp. 4912-4923 ◽  
Author(s):  
Houyong Yu ◽  
Somia Yassin Hussain Abdalkarim ◽  
Heng Zhang ◽  
Chuang Wang ◽  
Kam Chiu Tam
Keyword(s):  
Cellulose Nanocrystals ◽  
High Yield ◽  
Simple Process

Production with a High Yield of Bacterial Cellulose Nanocrystals by Enzymatic Hydrolysis

2019 ◽  
Vol 19 (03) ◽  
pp. 1950015
Author(s):  
Ricardo Brandes ◽  
Leticia de Souza ◽  
Claudimir Carminatti ◽  
Derce Recouvreux
Keyword(s):  
Enzymatic Hydrolysis ◽  
Bacterial Cellulose ◽  
Cellulose Nanocrystals ◽  
Primary Objective ◽  
High Yield ◽  
Low Density ◽  
Enzymatic Method ◽  
Citrate Buffer ◽  
Cellulose Hydrogel ◽  
Time Required

Bacterial cellulose nanocrystals are highly crystalline structures with nanoscopic scale dimensions that have received increased attention in the nanocomposites area. Its properties, such as large surface area, low density, mechanical strength and ease of modification, are attractive to the preparation many kinds of nanomaterials applied multifunctional in various fields. Besides, the cellulose nanocrystals are from abundant and renewable sources that are biodegradable. An altemative method is to obtain bacterial cellulose nanocrystal by enzymatic hydrolysis because it is, less expensive, it does not use chemicals and it requires much less energy. In this sense, the primary objective of this study was to produce bacterial cellulose using glycerol as a carbon source and isolate nanocrystals from bacterial cellulose using the enzymatic hydrolysis. This study also investigated the yield of nanocrystals depending on the weight of the bacterial cellulose hydrogel, keeping constant some enzymes. The study shows us that the enzymatic method has the best performance when using cellulose hydrogel 2[Formula: see text]g to 40[Formula: see text][Formula: see text]L cellulase enzyme (endoglucanase) and 1[Formula: see text]mL of citrate buffer. Also, it was observed that the yield of nanocrystals decrease with increasing time required for the hydrolysis.

High-Yield Synthesis of Functionalized Cellulose Nanocrystals for Nano-Biocomposites

2019 ◽  
Vol 2 (4) ◽  
pp. 2036-2043 ◽  
Author(s):  
Qilin Lu ◽  
Linna Lu ◽  
Yonggui Li ◽  
Yuxin Yan ◽  
Zhaofeng Fang ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
High Yield

scholarly journals Hyaluronidase in ram semen. Quantitative determination, and isolation of multiple forms

1988 ◽  
Vol 252 (3) ◽  
pp. 865-874 ◽  
Author(s):  
R A Harrison
Keyword(s):  
Ionic Strength ◽  
Quantitative Determination ◽  
Specific Activity ◽  
Gel Filtration ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
High Yield ◽  
Poly Vinyl Alcohol ◽  
The Media ◽  
Low Ionic Strength

A study was made of hyaluronidase in ram semen. The end-group assay conditions used to determine activity quantitatively were chosen to ensure reliability as well as sensitivity [Gacesa, Savitsky, Dodgson & Olavesen (1981) Anal. Biochem. 118, 76-84]; they led to 1 W.H.O. Standard International Hyaluronidase Unit displaying 0.1263 EC munit (1 EC unit of activity releases 1 mumol equivalent of N-acetylglucosamine end groups/min at 37 degrees C). All the activity in the semen was shown to be sperm-derived, and intact spermatozoa were estimated to contain 1.23 EC units per 10(9) cells. In a low-ionic-strength medium, only some 20% of the hyaluronidase was extractable, although up to 80% of the activity could be extracted as the ionic strength was increased; further addition of detergent extracted the remainder. During purification of the enzyme, it was found that inclusion of poly(vinyl alcohol) in the media stabilized the activity; detergent inclusion also improved the yield, especially during early stages. As a consequence both of reliable quantitative determination and of stabilization, a number of forms of hyaluronidase could be isolated in high yield, by using anion-exchange chromatography, cation-exchange chromatography, affinity chromatography and gel filtration. The existence of all these forms was confirmed by electrophoresis and immunoblotting with the use of a monoclonal anti-(ram hyaluronidase) antibody, and their presence in very freshly prepared sperm extracts was demonstrated. The specific activity of the isolated major hyaluronidase form was 15.0 EC units/mg; this was equivalent to 119,000 W.H.O. units/mg, higher than any other previously reported values.

scholarly journals Mobility of Cellulose Nanocrystals in Porous Media: Effects of Ionic Strength, Iron Oxides, and Soil Colloids

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 348 ◽  
Author(s):  
Shuang Xu ◽  
Chongyang Shen ◽  
Xueyong Zhang ◽  
Xijuan Chen ◽  
Mark Radosevich ◽  
...  
Keyword(s):  
Porous Media ◽  
Ionic Strength ◽  
Iron Oxides ◽  
Cellulose Nanocrystals ◽  
Solution Chemistry ◽  
Water Remediation ◽  
Natural Soils ◽  
Ionic Strength Effect ◽  
Red Earth ◽  
Soil Colloids

Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were conducted to investigate the coupled effects of ionic strength, iron oxides (hematite), and soil colloids on the transport of CNCs through quartz sand and natural soils (red earth and brown earth). Results showed that CNCs had high mobility in oxide-free sand and that iron oxide coating reduced the mobility of CNCs. An analysis of Derjaguin-Landau-Verwey-Overbeek interactions indicated that CNCs exhibited a deep primary minimum, nonexistent maximum repulsion and secondary minimum on hematite-coated sand, favorable for the attachment of CNCs. The maximum effluent percentage of CNCs was 96% in natural soils at 5 mM, but this value decreased to 4% at 50 mM. Soil colloids facilitated the transport of CNCs in brown earth with larger effect at higher ionic strength. The ionic strength effect was larger in natural soils than sand and in red earth than brown earth. The study showed that CNCs can travel 0.2 m to 72 m in porous media, depending on soil properties, solution chemistry, and soil colloids.

Strategy towards one-step preparation of carboxylic cellulose nanocrystals and nanofibrils with high yield, carboxylation and highly stable dispersibility using innocuous citric acid

2019 ◽  
Vol 21 (8) ◽  
pp. 1956-1964 ◽  
Author(s):  
Hui Ji ◽  
Zhouyang Xiang ◽  
Haisong Qi ◽  
Tingting Han ◽  
Andrey Pranovich ◽  
...  
Keyword(s):  
Citric Acid ◽  
Cellulose Nanocrystals ◽  
High Yield ◽  
Highly Efficient ◽  
One Step

Highly efficient preparation and carboxylation of nanocelluloses were achieved simultaneously using innocuous and recyclable citric acid with the assistance of ultrasonication.

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