Isotherms for adsorption of cellobiohydrolase I and II fromtrichoderma reesei on microcrystalline cellulose

Adsorption to microcrystalline cellulose (Avicel) of pure cellobiohydrolase I and II (CBH I and CBH II) fromTrichoderma reesei has been studied. Adsorption isotherms of the enzymes were measured at 4‡C using CBH I and CBH II alone and in reconstituted equimolar mixtures. Several models (Langmuir, Freundlich, Temkin, Jovanovic) were tested to describe the experimental adsorption isotherms. The isotherms did not follow the basic (one site) Langmuir equation that has often been used to describe adsorption isotherms of cellulases; correlation coefficients (R²) were only 0.926 and 0.947, for CBH I and II, respectively. The experimental isotherms were best described by a model of Langmuir type with two adsorption sites and by a combined Langmuir-Freundlich model (analogous to the Hill equation); using these models the correlation coefficients were in most cases higher than 0.995. Apparent binding parameters derived from the two sites Langmuir model indicated stronger binding of CBH II compared to CBH I; the distribution coefficients were 20.7 and 3.7 L/g for the two enzymes, respectively. The binding capacity, on the other hand, was higher for CBH I, 1.0 Μmol (67 mg) per gram Avicel, compared to 0.57 Μmol/g (30 mg/g) for CBH II. The isotherms when analyzed with the combined Langmuir-Freundlich model indicated presence of unequal binding sites on cellulose and/or negative cooperativity in the binding of the enzyme molecules.     

Sustainable and Robust Graphene Cellulose Paper Decorated with Lithiophilic Au Nanoparticles to Enable Dendrite-free and High-Power Lithium Metal Anode

Lithium metal anodes (LMAs) with high energy density have recently captured increasing attention for development of next-generation batteries. However, practical viability of LMAs is hindered by the uncontrolled Li dendrite growth and infinite dimension change. Even though constructing 3D conductive skeleton has been regarded as a reliable strategy to prepare stable and low volume stress LMAs, engineering the renewable and lithiophilic conductive scaffold is still a challenge. Herein, a robust conductive scaffold derived from renewable cellulose paper, which is coated with reduced graphene oxide and decorated with lithiophilic Au nanoparticles, is engineered for LMAs. The graphene cellulose fibres with high surface area can reduce the local current density, while the well-dispersed Au nanoparticles can serve as lithiophilic nanoseeds to lower the nucleation overpotential of Li plating. The coupled relationship can guarantee uniform Li nucleation and unique spherical Li growth into 3D carbon matrix. Moreover, the natural cellulose paper possesses outstanding mechanical strength to tolerate the volume stress. In virtue of the modulated deposition behaviour and near-zero volume change, the hybrid LMAs can achieve reversible Li plating/stripping even at an ultrahigh current density of 10 mA cm⁻² as evidenced by high Coulombic efficiency (97.2 % after 60 cycles) and ultralong lifespan (1000 cycles) together with ultralow overpotential (25 mV). Therefore, this strategy sheds light on a scalable approach to multiscale design versatile Li host, promising highly stable Li metal batteries to be feasible and practical.     

羧甲基纤维素系列高分子表面活性剂超声合成的研究

研究了在超声波作用下羧甲基纤维素的降解反应及ＣＭＣ与具有不同亲水亲油比值的活性大单体「烷基醇（酚）聚氧乙烯醚丙烯酸酯及第三单体」的超声共聚反应。经萃取提纯的共聚产物用ＩＲ，＾１３Ｃ ＮＭＲ和ＵＶ等方法进行表证，证实通过超声反应制得了二元和三元共聚物。     

苯乙烯和丙烯酸-β-羟乙酯不同温度的竞聚率测定

苯乙烯和丙烯酸 β 羟乙酯不同温度的竞聚率测定吴平平吴玉芳陆琛杨全兴韩哲文（华东理工大学材料科学研究所上海２００２３７）陈顺喜朱清仁（中科院中国科技大学结构分析开放实验室合肥２３００２６）关键词苯乙烯，丙烯酸 β 羟乙酯，共聚合，竞聚率丙烯酸 β?..     

淀粉接枝丙烯酸乙酯及其增容性

研究了在挤出机中采用高温和剪切力的作用直接引发淀粉与丙烯酸乙酯的接枝共聚合反应．讨论了反应条件对接枝反应的影响，研究了接枝物在淀粉与聚乙烯共混物中的增容作用．实验结果表明，高温和剪切力可以引发淀粉与丙烯酸乙酯的接枝共聚合反应．接枝物作为增容剂，可以明显地改善淀粉与聚乙烯共混物的力学性能和流变性能．     

Water-soluble ABC triblock copolymers based on vinyl ethers: Synthesis by living cationic polymerization and solution characterization

Water-soluble ABC triblock copolymers of methyl vinyl ether (MVE), ethyl vinyl ether (EVE), and methyl tri(ethylene glycol) vinyl ether (MTEGVE) of various block sequences and carrying 20 monomer units in each block were synthesized by living cationic polymerization. In addition to the triblocks, one AB diblock, one BA diblock, and one statistical copolymer of MVE and MTEGVE carrying 20 units of each type of monomer were synthesized as controls. Moreover, three homopolymers each carrying 20 units of MVE and end groups of varying hydrophobicity were synthesized using three different initiators. The molecular weights and molecular weight distributions of all the polymers were determined by gel permeation chromatography (GPC) in tetrahydrofuran (THF). The number average degrees of polymerization (DP_ns) and composition of all the polymers were calculated by proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The molecular weights and degrees of polymerization corresponded to the values expected from the monomer/initiator ratios. The calculated polydispersities were reasonably narrow at 1.3. Aqueous GPC studies at room temperature on the triblock copolymers showed that the polymers exist as isolated chains (unimers) in solution but they tend to assemble and form micelles in the presence of a sufficiently high salt concentration apparently due to the insolubility of the EVE units under the latter conditions. Triblocks with a different block sequence exhibited a different susceptibility to salt-induced micellization, as indicated by the retention volume of the micelles and the relative micelle/unimer peak areas. Similarly, the cloud points of the triblock copolymers covered a relatively wide temperature range from 56 to 72°C. These differences in micellization and cloud points suggest a profound effect of the location of the hydrophilic MTEGVE block on copolymer association. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1181–1195, 1997     

Living anionic homo- and block copolymerization of 2-(tert-butylamino)ethyl methacrylate

Anionic polymerization of 2-(tert-butylamino)ethyl methacrylate (tBAEMA), which bears an unprotected secondary amine moiety, has been investigated in THF at −78°C. The presence of lithium chloride has been shown to be desirable to afford narrow molecular weight distribution as well as a good agreement between theoretical and observed molecular weight. The living character of the polymerization has also been demonstrated, and the synthesis of block copolymers carried out successfully. They have been analyzed by SEC by adding a mixture of secondary and tertiary amines to the eluent (THF) so as to avoid any polymer adsorption during elution. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2035–2040, 1997     

2-氨基-4-噻唑乙酸乙酯构筑的两个镉配合物的晶体结构及荧光性质

以2-氨基-4-噻唑乙酸乙酯(EATA)和氯化镉水合物为原料,在无水乙醇和乙醇-水混合物两种溶剂中分别合成了配合物[CdCl2(EATA)]n(1)和[CdCl2(EATA)2](2),并利用X-射线单晶衍射、元素分析、红外光谱和荧光光谱对它们进行了表征。配合物1和2都属于单斜晶系,分别为P21/c和Cc空间群,它们的中心金属离子Cd2+均为扭曲的六配位八面体构型。在配合物1中,相邻的2个八面体单元通过2个μ2-Cl-阴离子双桥连形成一维链结构,该一维链进一步通过N-H…Cl分子间氢键形成了三维网络结构,而配合物2则通过大量的N-H…Cl和C-H…Cl分子间氢键等弱作用组装成二维超分子结构。固态荧光光谱分析表明,配合物1和2荧光性质相似,均可归属于由配体到金属间的电荷转移(LMCT)。     

Study of Antibacterial and Anticancer Properties of bioAgNPs Synthesized Using Streptomyces sp. PBD-311B and the Application of bioAgNP-CNC/Alg as an Antibacterial Hydrogel Film against P. aeruginosa USM-AR2 and MRSA

Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site.     

Electrosprayed Shrimp and Mushroom Nanochitins on Cellulose Tissue for Skin Contact Application

Cosmetics has recently focused on biobased skin-compatible materials. Materials from natural sources can be used to produce more sustainable skin contact products with enhanced bioactivity. Surface functionalization using natural-based nano/microparticles is thus a subject of study, aimed at better understanding the skin compatibility of many biopolymers also deriving from biowaste. This research investigated electrospray as a method for surface modification of cellulose tissues with chitin nanofibrils (CNs) using two different sources—namely, vegetable (i.e., from fungi), and animal (from crustaceans)—and different solvent systems to obtain a biobased and skin-compatible product. The surface of cellulose tissues was uniformly decorated with electrosprayed CNs. Biological analysis revealed that all treated samples were suitable for skin applications since human dermal keratinocytes (i.e., HaCaT cells) successfully adhered to the processed tissues and were viable after being in contact with released substances in culture media. These results indicate that the use of solvents did not affect the final cytocompatibility due to their effective evaporation during the electrospray process. Such treatments did not also affect the characteristics of cellulose; in addition, they showed promising anti-inflammatory and indirect antimicrobial activity toward dermal keratinocytes in vitro. Specifically, cellulosic substrates decorated with nanochitins from shrimp showed strong immunomodulatory activity by first upregulating then downregulating the pro-inflammatory cytokines, whereas nanochitins from mushrooms displayed an overall anti-inflammatory activity via a slight decrement of the pro-inflammatory cytokines and increment of the anti-inflammatory marker. Electrospray could represent a green method for surface modification of sustainable and biofunctional skincare products.