Abstract:Magnetic nanocrystalline cellulose (MNCC), a novel bio-based nanocomposite, was prepared via a simple co-precipitation-cross-linking technique and structurally characterized. Papain (PA) was successfully immobilized onto the MNCC. The resulting nano-biocatalyst PA@MNCC showed high PA loading (333 mg/g) and enzyme activity recovery (more than 80%). The stabilities of PA@MNCC was greatly superior to that of its free counterpart. Also, PA@MNCC manifested markedly enhanced solvent tolerance. The secondary structur… Show more
“…This report also demonstrated that immobilization materials could function with water molecules to lower a
w to stabilize the forward reaction.Fig. 7Protease-catalyzed reactions in DESs(adapted from ( a ) Zhao et al 2011b) ( b ) Cao et al 2015;
…”
Section: The Application Of Dess In Biocatalysismentioning
Deep eutectic solvents (DESs) are eutectic mixtures of salts and hydrogen bond donors with melting points low enough to be used as solvents. DESs have proved to be a good alternative to traditional organic solvents and ionic liquids (ILs) in many biocatalytic processes. Apart from the benign characteristics similar to those of ILs (e.g., low volatility, low inflammability and low melting point), DESs have their unique merits of easy preparation and low cost owing to their renewable and available raw materials. To better apply such solvents in green and sustainable chemistry, this review firstly describes some basic properties, mainly the toxicity and biodegradability of DESs. Secondly, it presents several valuable applications of DES as solvent/co-solvent in biocatalytic reactions, such as lipase-catalyzed transesterification and ester hydrolysis reactions. The roles, serving as extractive reagent for an enzymatic product and pretreatment solvent of enzymatic biomass hydrolysis, are also discussed. Further understanding how DESs affect biocatalytic reaction will facilitate the design of novel solvents and contribute to the discovery of new reactions in these solvents.
“…This report also demonstrated that immobilization materials could function with water molecules to lower a
w to stabilize the forward reaction.Fig. 7Protease-catalyzed reactions in DESs(adapted from ( a ) Zhao et al 2011b) ( b ) Cao et al 2015;
…”
Section: The Application Of Dess In Biocatalysismentioning
Deep eutectic solvents (DESs) are eutectic mixtures of salts and hydrogen bond donors with melting points low enough to be used as solvents. DESs have proved to be a good alternative to traditional organic solvents and ionic liquids (ILs) in many biocatalytic processes. Apart from the benign characteristics similar to those of ILs (e.g., low volatility, low inflammability and low melting point), DESs have their unique merits of easy preparation and low cost owing to their renewable and available raw materials. To better apply such solvents in green and sustainable chemistry, this review firstly describes some basic properties, mainly the toxicity and biodegradability of DESs. Secondly, it presents several valuable applications of DES as solvent/co-solvent in biocatalytic reactions, such as lipase-catalyzed transesterification and ester hydrolysis reactions. The roles, serving as extractive reagent for an enzymatic product and pretreatment solvent of enzymatic biomass hydrolysis, are also discussed. Further understanding how DESs affect biocatalytic reaction will facilitate the design of novel solvents and contribute to the discovery of new reactions in these solvents.
“…Nevertheless, their use as supports is restricted in industry due to their stable dispersion which hinders facile separation for recycling. For this reason, they have been coated with magnetic nanoparticles which leads to the formation of inorganic–organic hybrid nanocomposites . Magnetically recoverable catalysts often exhibit excellent selectivity, giving high yields, and have several additional advantages.…”
Nano‐Fe3O4@Cellulose‐NH2‐CuI as a novel magnetically separable composite was prepared and fully characterized using various techniques including Fourier transform infrared, X‐ray photoelectron and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction, field‐emission scanning and transmission electron microscopies, thermogravimetric analysis and vibrating sample magnetometry. To obtain an appropriate structure and also to describe to some extent the different kinds of metal–ligand interactions present in the nano‐Fe3O4@Cellulose‐NH2‐CuI composite, covalent and electrostatic interactions, density functional theory model chemistry and quantum theory of atoms in molecules method were employed, respectively. This cellulose‐based heterogeneous catalyst can effectively promote the one‐pot three‐component reaction of a variety of terminal alkynes bearing substituted phenyls or propargylic alcohol together with substituted benzyl halides and sodium azide, so‐called click reaction, in water to afford the corresponding 1,4‐disubstituted 1,2,3‐triazoles with improved yields and regioselectivity. The magnetic catalyst was conventionally recovered using an external magnet and reused in at least four successive runs under the optimal reaction conditions, without appreciable loss of its activity.
“…Such Co-Fe impregnated CNCs were incorporated into polyvinyl alcohol fibers through electrospinning which showed high magneto-responsive behavior along with hyperthermia properties for potential biomedical applications 20 . Interestingly, in another study 21 papain enzyme was immobilized onto the magnetic CNCs through coprecipitation-crosslinking techniques, which showed enhanced enzyme-substrate activity for dipeptide biosynthesis. The Fe 3 O 4 based magnetic CNCs showed enhanced enzyme immobilization capacity, with improved thermal, storage stability and recyclability 21,22 .…”
This paper reports a single-step co-precipitation method for the fabrication of magnetic cellulose nanocrystals (MGCNCs) with high iron oxide nanoparticle content (∼51 wt % loading) adsorbed onto cellulose nanocrystals (CNCs). X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopic studies confirmed that the hydroxyl groups on the surface of CNCs (derived from the bamboo pulp) acted as anchor points for the adsorption of Fe3O4 nanoparticles. The fabricated MGCNCs have a high magnetic moment, which is utilized to orient the magnetoresponsive nanofillers in parallel or perpendicular orientations inside the polylactic acid (PLA) matrix. Magnetic-field-assisted directional alignment of MGCNCs led to the incorporation of anisotropic mechanical, thermal, and electrical properties in the fabricated PLA-MGCNC nanocomposites. Thermomechanical studies showed significant improvement in the elastic modulus and glass-transition temperature for the magnetically oriented samples. Differential scanning calorimetry (DSC) and XRD studies confirmed that the alignment of MGCNCs led to the improvement in the percentage crystallinity and, with the absence of the cold-crystallization phenomenon, finds a potential application in polymer processing in the presence of magnetic field. The tensile strength and percentage elongation for the parallel-oriented samples improved by ∼70 and 240%, respectively, and for perpendicular-oriented samples, by ∼58 and 172%, respectively, in comparison to the unoriented samples. Furthermore, its anisotropically induced electrical and magnetic properties are desirable for fabricating self-biased electronics products. We also demonstrate that the fabricated anisotropic PLA-MGCNC nanocomposites could be laminated into films with the incorporation of directionally tunable mechanical properties. Therefore, the current study provides a novel noninvasive approach of orienting nontoxic bioderived CNCs in the presence of low magnetic fields, with potential applications in the manufacturing of three-dimensional composites with microstructural features comparable to biological materials for high-performance engineering applications.
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