Synthesis and Study of Copper-Containing Polymers Based on Sulfated Arabinogalactan

Synthesis of water-soluble copper-containing sulfates of arabinogalactan was carried out for the first time by the ion exchange method. Their composition and structure were studied by the methods of elemental and chemical analysis, X-ray spectral microanalysis, atomic force microscopy (AFM), infrared spectroscopy (FTIR), and electron paramagnetic resonance (EPR). According to the AFM data, the surface of copper-containing polymer films does not have inclusions and consists of homogeneous crystallites of a spherical and slightly elongated shape and transverse dimensions of about 100 nm. The composition of copper- containing polymers was studied by the chemical method and X-ray spectral microanalysis. The absence of nitrogen in the obtained polymer indicates the complete replacement of ammonium cations in the ammonium salt of AG sulfate with the copper cations. The IR spectrum of copper-containing AG sulfate is similar to that of the sodium salt of sulfated arabinogalactan. Superposition of two signals was observed in the EPR spectrum of copper-containing AG sulfate. One of them belongs to isolated Cu²⁺ ions; another, to associated Cu²⁺ ions in the salt-like compounds. The integral intensity of isolated Cu²⁺ ion signals (anisotropic signal) and associated ions (isotropic signal) depends on the copper content in the polymer. Water-soluble coppercontaining polymers of AG sulfates have prospects for their use in medicine.     

An ionic liquid as reaction media for radiation-induced grafting of thermosensitive poly (N-isopropylacrylamide) onto microcrystalline cellulose

This paper reports a homogeneous modification of microcrystalline cellulose (MCC) in ionic liquids via radiation-induced grafting. Thermosensitive poly (N-isopropylacrylamide) (PNIPAAm) was successfully grafted onto MCC in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid using γ-ray irradiation technique at room temperature. The grafting yield (GY) increased with dose up to 40 kGy, while decreased slightly with dose rate from 22 to 102 Gy/min. The results of TGA indicated that cellulose grafted PNIPAAm (cellulose-g-PNIPAAm) had higher thermal stability than that of ungrafted regenerated cellulose (reg-cellulose). The crystalline structure of original MCC was largely destroyed during the dissolution process according to the XRD profiles, and grafting PNIPAAm onto cellulose further decreased the intensity of crystallinity. SEM showed that reg-cellulose and cellulose-g-PNIPAAm films displayed dense and homogeneous morphology. Moreover, the resulting cellulose-g-PNIPAAm exhibited obvious thermal sensitivity with a lower critical solution temperature around 35 °C, which was observed from the swelling behavior in water at different temperatures.     

Hydrolysis of cellulose in SO₃H-functionalized ionic liquids

Influence of acidity and structure of ionic liquids on microcrystalline cellulose (MCC) hydrolysis was investigated. MnCl₂-containing ionic liquids (ILs) were efficient catalysts and achieved MCC conversion rates of 91.2% and selectivities for 5-hydroxymethyl furfural (HMF), furfural and levulinic acid (LA) of 45.7%, 26.2% and 10.5%, respectively. X-ray diffractometry indicated that catalytic hydrolysis of MCC in ionic liquids resulted in the changes to MCC crystallinity and transformation of cellulose I into cellulose II. SO₃H-functionalized ionic liquids showed higher activities than non-functionalized ILs. The simplicity of the chemical transformation of cellulose provides a new approach for the use this polymer as raw material for renewable energy and chemical industries.     

A novel copper-containing protein from brain

A novel copper-containing protein has been isolated in electrophoretically homogeneous state from bovine brain extracts. Some physico-chemical properties of the protein are determined (molecular weight, copper content, isoelectric point, amino acid composition, optical and EPR spectra), and they are compared with those of neurocuprein, an extremely acidic copper protein isolated earlier from brain. A number of differences between neurocuprein and the novel protein are clearly shown, although certain similarities are also detected.     

Manufacture of cellulose nanocrystals by cation exchange resin-catalyzed hydrolysis of cellulose

Cellulose nanocrystals (CNC) were prepared from microcrystalline cellulose (MCC) by hydrolysis with cation exchange resin (NKC-9) or 64% sulfuric acid. The cation exchange resin hydrolysis parameters were optimized by using the Box–Behnken design and response surface methodology. An optimum yield (50.04%) was achieved at a ratio of resin to MCC (w/w) of 10, a temperature of 48 °C and a reaction time of 189 min. Electron microscopy (EM) showed that the diameter of CNCs was about 10–40 nm, and the length was 100–400 nm. Regular short rod-like CNCs were obtained by sulfuric acid hydrolysis, while long and thin crystals of cellulose were obtained with the cation exchange resin. X-ray diffraction (XRD) showed that, compared with MCC, the crystallinity of H₂SO₄-CNC and resin-CNC increased from 72.25% to 77.29% and 84.26%, respectively. The research shows that cation exchange resin-catalyzed hydrolysis of cellulose could be an excellent method for manufacturing of CNC in an environmental-friendly way.     

Properties of polylactic acid composites reinforced with oil palm biomass microcrystalline cellulose

In this work, polylactic acid (PLA) composites filled with microcrystalline cellulose (MCC) from oil palm biomass were successfully prepared through solution casting. Fourier transform infrared (FT-IR) spectroscopy indicates that there are no significant changes in the peak positions, suggesting that incorporation of MCC in PLA did not result in any significant change in chemical structure of PLA. Thermogravimetric analysis was conducted on the samples. The T₅₀ decomposition temperature improved with addition of MCC, showing increase in thermal stability of the composites. The synthesized composites were characterized in terms of tensile properties. The Young's modulus increased by about 30%, while the tensile strength and elongation at break for composites decreased with addition of MCC. Scanning electron microscopy (SEM) of the composites fractured surface shows that the MCC remained as aggregates of crystalline cellulose. Atomic force microscopy (AFM) topographic image of the composite surfaces show clustering of MCC with uneven distribution.     

微晶和芦苇浆纳米纤维素的粒度分布分析

在一定工艺条件下,硫酸分别水解微晶纤维素和芦苇浆制备纳米纤维素,采用激光粒度分析法分别分析了微晶和芦苇浆纳米纤维素的粒度分布,结果表明以微晶纤维素为原料,在控制制备工艺条件下可以制备出三维尺度相差不大的纳米纤维素,Z均粒径为163.8 nm。芦苇浆纳米纤维素为非球形颗粒,且不同方向的尺寸相差较大,Z均粒径为942.0 nm。     

水葫芦中叶绿素铜钠提取及其抗细胞氧化损伤作用研究

目的:从水葫芦中提取叶绿素铜钠初产物,完善叶绿素铜钠盐的提取工艺,研究叶绿素铜钠的抗细胞氧化损伤作用。方法:采用丙酮乙醇混合液提取水葫芦中的叶绿素铜钠,通过红外光谱分析、分光检测、X射线衍射等方法对产物产率、样品成分、纯度进行检测,之后利用连二亚硫酸/PC12制作细胞模型,研究了叶绿素铜钠的抗细胞氧化损伤作用。结果:采用本文工艺提取得的叶绿素铜钠产率较佳,提取物中未见Pb、Cd等水葫芦生长流域常见的重金属污染;MTT法显示叶绿素铜钠未见细胞毒作用,且对细胞氧化损伤具有明显抑制作用。结论:研究结果如可应用于叶绿素铜钠的工业提取,可降低目前含叶绿素铜钠类药物与保健品的生产成本,为入侵植物水葫芦的综合利用提供有价值的参考。     

Nanocellulose 3, 5‐Dimethylphenylcarbamate Derivative Coated Chiral Stationary Phase: Preparation and Enantioseparation Performance

Nanocrystalline cellulose (NCC) with high surface area and high ordered crystalline structure was prepared from microcrystalline cellulose (MCC) under the hydrolysis of sodium hypochlorite. NCC was further reacted with 3,5‐dimethylphenyl isocyanate to obtain the nanocellulose derivative, and then coated successfully on the surface of silica gel to a prepared NCC‐coated chiral stationary phase (CSP) as a new kind of chiral separation material. Similarly, MCC derivative‐coated CSP was also prepared as contrast. The chiral separation performance of NCC‐based CSP was evaluated and compared with MCC‐based CSP by high‐performance liquid chromatography. Moreover, the effects of the alcohol modifiers, mobile phase additives, and flow rates on chiral separations were investigated in detail. The results showed that 10 chiral compounds were separated on NCC‐based CSP with better peak shape and higher column efficiency than MCC‐based CSP, which confirmed that NCC‐based CSP was a promising packing material for the resolution of chiral compounds.Chirality 28:376–381, 2016. © 2016 Wiley Periodicals, Inc.     

Improved effects of okara atomized by a water jet system on α-amylase inhibition and butyrate production by Roseburia intestinalis

ABSTRACT

Improving the physicochemical properties of okara for various applications in foods is of great importance. Here, okara and microcrystalline cellulose (MCC) were atomized using a water jet (WJ) system. The WJ-treated okara and MCC dispersed homogeneously in water, and their median sizes in particle size distribution were 6.6 μm and 9.5 μm, respectively. The dispersions of WJ-treated okara and MCC showed high apparent viscosity and shear thinning behavior. Moreover, the inhibition of α-amylase activities by WJ-treated okara was more effective than that by untreated MCC and cellulose. Furthermore, the production of short-chain fatty acids by 32 dominant species of human gut microbes was determined. An increase in butyrate production by Roseburia intestinalis was observed in the presence of WJ-treated okara, but not in untreated okara or WJ-treated MCC. These results demonstrate that WJ system can be used on okara to increase inhibited α-amylase activities and butyrate production by gut microbiota.     

Formation of the porous structure of carbon materials during carbonization of microcrystalline cellulose modified by phosphoric acid and potassium hydroxide

Formation of the porous structure of carbon material obtained by carbonization of microcrystalline cellulose (MCC) in the presence of modifying additives KOH and H₃PO₄ has been investigated. The optimal conditions for the synthesis of porous carbon materials (PCMs) from chemically activated MCC have been revealed. The highest specific surface area (about 1500 m²/g) is observed for water-washed carbon products obtained by carbonization at 800°C of MCC containing 50 wt % KOH and by carbonization at 400°C of MCC with the addition of 50 wt % H₃PO₄.     

Radiation effects on microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride ionic liquid

The radiation processing of cellulose in ionic liquids (ILs) demands a comprehensive knowledge of radiation effects on cellulose in ILs. Herein, gamma radiation-induced degradation kinetics of microcrystalline cellulose (MCC) in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was studied by viscometry. The intrinsic viscosity of MCC in [Bmim]Cl decreased slightly with increasing dose; while chemical structure and crystalline state of cellulose has no obvious change up to 300kGy. The radiation degradation rate constant (k) of MCC in [Bmim]Cl was 2.60×10(-7)/kGy, lower than that of solid cellulose, but higher than that in N-methylmorpholine-N-oxide (NMMO) solvent. Furthermore, k value decreased to 1.12×10(-7)/kGy in dimethyl sulfoxide (DMSO)/[Bmim]Cl system due to the free radicals scavenging of DMSO. The radicals generated during irradiation play main role in the radiation degradation of MCC in [Bmim]Cl. This work provides a new way to control the average molecular weight of cellulose by radiation-induced degradation of cellulose in ILs.     

Comparative Characterization of Methods for Removal of Cu(II) from the Active Sites of Fungal Laccases

Copper-containing sites of laccases isolated from the Basidiomycetes Coriolus hirsutus and Coriolus zonatus were characterized by optical methods and EPR spectroscopy. Methods for preparation of fungal laccase derivatives free from type 2 copper ions were compared. The data of EPR spectroscopy and spectrophotometric titration of copper sites showed that only a modified method based on the use of bathocuproine as a chelator for type 2 copper yielded laccase derivatives completely free from type 2 copper. The original enzymes can be reconstituted from the derivatives by dialysis under anaerobic conditions, resulting in complete recovery of native conformation of the protein molecule and the structure of the copper-containing site.     

Effect of Stearic Acid on Enalapril Stability and Dissolution from Multiparticulate Solid Dosage Forms

Enalapril maleate (EM) is a widely used anti-hypertensive drug which is unstable when mixed with excipients. Enalaprilate and diketopiperazine (DPK) are the main degradation products of enalapril. The in situ preparation of enalapril sodium salt (NaE) has been used to improve drug stability in dosage forms; however, gas release and product rejection ensue when the chemical reaction for obtaining the sodium salt is not completely finished before packaging. This study evaluated the effect of stearic acid (SA) on enalapril stability in microcrystalline cellulose (MCC) pellets containing EM or NaE. MCC pellets containing SA were prepared by the extrusion–spheronization technique and characterized. Enalapril stability and dissolution were then evaluated. DPK and enalaprilate formation were reduced by the addition of SA in pellets containing EM. The overall enalapril degradation in these formulations was lower when compared with pellets containing EM or even NaE prepared without SA. The immediate-release characteristic was maintained by the addition of 5% crospovidone to all the formulations tested. The incorporation of SA into NaE pellets resulted in unexpected enalapril degradation, caused by the interaction of these compounds, as suggested by a thermal analysis of the SA–NaE binary mixture. The findings presented here showed that formulations containing SA could substitute the formation of NaE, since they provide better enalapril stability in solid dosage forms. In addition, it is suggested that the stabilization effects would be observed for other N-carboxyalkyl dipeptide analogs with angiotensin converting enzyme inhibition activity, since these new entities share the same degradation pathway of enalapril.     

Digestive ability of the freshwater crayfish Paranephrops zealandicus (White) (Parastacidae) and the role of microbial enzymes

SUMMARY. 1 Ingestion rate, assimilation efficiency and digestive enzyme activity were investigated in the New Zealand freshwater crayfish, Paranephrops zealandicus (White). Rates of ingestion of fresh and decaying Elodea canadensis Michx. were highly variable at 15°C and assimilation efficiency averaged 21%.
2.Hepatopancreas extracts showed enzyme activity towards each of nine substrates tested; microcrystalline cellulose (MCC), carboxymethyl cellulose (CMC), cellobiose, amylose, pectin, mannan, laminarin, chitin and'Azocoll' (a dye-collagen complex).
3. Three genera of Enterobacteriacae were isolated from digestive juices and hepatopancreas samples and microbial activity was implicated in the breakdown of MCC, laminarin and protein. Host-specific activity was not detected in the assays with MCC suggesting a solely microbial source for this enzyme.
4. Although cellulose cannot be broken down without some degree of prior conditioning, the polytrophic feeding strategy of P. zealandicus is indicated by the presence of host-specific enzymes that hydrolyse storage and structural sugars of algae, fungi and higher plants as well as animal protein.     

The Effect of Microcrystalline Cellulose Crystallinity on the Hydrophilic Property of Tablets and the Hydrolysis of Acetylsalicylic Acid as Active Pharmaceutical Ingredient Inside Tablets

The crystal structures of active pharmaceutical ingredients and excipients should be strictly controlled because they influence pharmaceutical properties of products which cause the change in the quality or the bioavailability of the products. In this study, we investigated the effects of microcrystalline cellulose (MCC) crystallinity on the hydrophilic properties of tablets and the hydrolysis of active pharmaceutical ingredient, acetylsalicylic acid (ASA), inside tablets by using tablets containing 20% MCC as an excipient. Different levels of grinding were applied to MCC prior to tablet formulation, to intentionally cause structural variation in the MCC. The water penetration and moisture absorbability of the tablets increased with decreasing the crystallinity of MCC through higher level of grinding. More importantly, the hydrolysis of ASA inside tablets was also accelerated. These results indicate that the crystallinity of MCC has crucial effects on the pharmaceutical properties of tablets even when the tablets contain a relatively small amount of MCC. Therefore, controlling the crystal structure of excipients is important for controlling product qualities.     

Survival of bacteria on metallic copper surfaces in a hospital trial

Basic chemistry of copper is responsible for its Janus-faced feature: on one hand, copper is an essential trace element required to interact efficiently with molecular oxygen. On the other hand, interaction with reactive oxygen species in undesired Fenton-like reactions leads to the production of hydroxyl radicals, which rapidly damage cellular macromolecules. Moreover, copper cations strongly bind to thiol compounds disturbing redox-homeostasis and may also remove cations of other transition metals from their native binding sites in enzymes. Nature has learned during evolution to deal with the dangerous yet important copper cations. Bacterial cells use different efflux systems to detoxify the metal from the cytoplasm or periplasm. Despite this ability, bacteria are rapidly killed on dry metallic copper surfaces. The mode of killing likely involves copper cations being released from the metallic copper and reactive oxygen species. With all this knowledge about the interaction of copper and its cations with cellular macromolecules in mind, experiments were moved to the next level, and the antimicrobial properties of copper-containing alloys in an “everyday” hospital setting were investigated. The alloys tested decreased the number of colony-forming units on metallic copper-containing surfaces by one third compared to control aluminum or plastic surfaces. Moreover, after disinfection, repopulation of the surfaces was delayed on copper alloys. This study bridges a gap between basic research concerning cellular copper homeostasis and application of this knowledge. It demonstrates that the use of copper-containing alloys may limit the spread of multiple drug-resistant bacteria in hospitals.     

Similarities of physico-chimical and antigenic properties of neurocupreins and extremely acidic copper proteins from chromaffin granules

Extremely acidic copper-containing proteins, neurocupreins, were isolated from brains of various mammals (bovine, rabbit, pig and sheep). Neurocupreins from all these sources were found to have similar physico-chemical and antigenic properties. Using the immunological approach, it was shown that neurocuprein is located only in brain cytosol and synaptosomal fractions. Extremely acidic copper-containing proteins were also isolated from soluble and membranous fractions of chromaffin granules from bovine adrenal medulla. The soluble form of the protein from the granules has practically the same physico-chemical and antigenic properties as neurocupreins. The copper protein isolated from membranes of granules has slightly higher molecular weight and somewhat different amino acid composition, although their EPR spectra are identical. However, both copper proteins from chromaffin granules are immunoprecipitated with antibodies to neurocuprein. It is suggested that the membranous form differs from the soluble one in possessing a peptide which prolongs the protein chain without changes in its antigenic properties.     

Solid-state 13C NMR study of na-cellulose complexes

The interaction of microcrystalline cellulose from cotton and aqueous sodium hydroxide was investigated by 13C NMR solid-state spectroscopy as a function of temperature and sodium hydroxide concentration. When the concentration of NaOH was increased, the initial cellulose spectrum was replaced successively by that of Na-cellulose I followed by that of Na-cellulose II. In Na-cellulose I, each carbon atom occurred as a singlet, thus implying that one glucosyl moiety was the independent magnetic residue in the structure of this allomorph. In addition, the occurrence of the C6 near 62 ppm is an indication of a gt conformation for the hydroxymethyl group of Na-cellulose I. In Na-cellulose II, the analysis of the resonances of C1 and C6 points toward a structure based on a cellotriosyl moiety as the independent magnetic residue, in agreement with the established X-ray analysis that has shown that for this allomorph, the fiber repeat was also that of a cellotriosyl residue. For Na-cellulose II, the occurrence of the C6 in the 60 ppm region indicates an overall gg conformation for the hydroxymethyl groups. A comparison of the spectra recorded at 268 K and at room temperature confirms the stronger interaction of NaOH with cellulose when the temperature is lowered. In the Q region, corresponding to NaOH concentrations of around 9% and temperatures below 277 K, most of the sample was dissolved and no specific solid-state 13C NMR spectrum could be recorded, except for that of a small fraction of undissolved cellulose I. The same experiment run on a wood pulp sample leads to a new spectrum, with spectral characteristics different from those of Na-cellulose I and Na-cellulose II. This new spectrum is assigned to the Q phase, which appears to result from topological constraints that are present in whole wood pulp fibers but not in microcrystalline cellulose. A spectrum recorded for samples in the Na-cellulose III conditions resembled that of Na-cellulose II but of lower resolution. Similarly, a spectrum of a sample of Na-cellulose IV was identical to that of hydrated cellulose II. These observations have allowed us to propose a simplified phase diagram of the cellulose/NaOH system in terms of temperature and NaOH concentration. This diagram, which is simpler than the one deduced from X-ray analysis, consists of only four different regions partially overlapping.     

Similarities of physico-chemical and antigenic properties of neurocupreins and extremely acidic copper proteins from chromaffin granules

Extremely acidic copper-containing proteins, neurocupreins, were isolated from brains of various mammals (bovine, rabbit, pig and sheep). Neurocupreins from all these sources were found to have similar physico-chemical and antigenic properties. Using the immunological approach, it was shown that neurocuprein is located only in brain cytosol and synaptosomal fractions. Extremely acidic copper-containing proteins were also isolated from soluble and membranous fractions of chromaffin granules from bovine adrenal medulla. The soluble form of the protein from the granules has practically the same physico-chemical and antigenic properties as neurocupreins. The copper protein isolated from membranes of granules has slightly higher molecular weight and somewhat different amino acid composition, although their EPR spectra are identical. However, both copper proteins from chromaffin granules are immunoprecipitated with antibodies to neurocuprein. It is suggested the the membranous form differs from the soluble one in possessing a peptide which prolongs the protein chain without changes in its antigenic properties.