KMnO4引发魔芋粉-丙烯腈的接枝共聚反应

以KMnO4为引发剂进行魔芋粉与丙烯腈的接枝共聚反应。研究了魔芋粉预氧化时间、引发剂浓度、单体浓度、酸度、反应时间、反应温度和反应物加料方式等聚合条件对接枝效率的影响，并对接枝机理作了探讨。     

脱乙酰基对天然魔芋葡甘聚糖分子形貌的影响

通过原子力显微镜直接观察魔芋葡甘聚糖（KGM）分子的三维结构形貌，KGM水溶液铺展在经Ca^2 处理的云母片上，干燥固定后，可获得稳定，重复的图像，实验结果表明，稀溶液中KGM分子具有伸展的螺旋链状结构，单股的长度达200－400nm，厚度为1．0nm，宽度为35．0－35．2nm，脱乙酰后分子链卷曲成直径约40－50nm,厚3．5－5．0nm的弹性圆台状。     

Cellulose Synthesized by Acetobacter Xylinum in the Presence of Acetyl Glucomannan

Acetobacter xylinum was cultured in Hestrin-Schramm medium (control medium) and Hestrin-Schramm medium containing acetyl glucomannan (mannan medium). Loose bundles of the cellulose microfibrils are formed in the mannan medium in contrast to the normal ribbons being produced in the control medium. Rapid-freeze and substitution method followed by metal-shadowing revealed the droplet-like structures around the microfibril synthesized in the mannan medium. The cellulose synthesized in the mannan medium was stained heavily by the periodic acid-thiocarbohydrazide-silver proteinate (PATAg) method, while the cellulose synthesized in the control medium was not stained. X-ray diffractometry and FT-IR spectroscopy indicated that the addition of mannan induced a change in the crystal structure from the algal-bacterial type to the cotton-ramie type. Thus the presence of acetyl glucomannan in the medium prevents the assembly of cellulose microfibrils and changes the crystal structure of cellulose.     

Glucomannan from Narcissus poeticus Studied by PMR and 13C NMR Spectroscopy

Native acetylated glucomannan of molecular weight (MW) 32000 with a glucose:mannose ratio 1:30 was isolated from bulbs of Narcissus poeticus. Glucomannan was depolymerized to a fragment of MW 15000 with an unchanged primary structure and was studied using PMR and ¹³C NMR spectroscopy. It was found that the linear chain of the biopolymer consists of 1-4-bound D-gluco- and D-mannopyranose units and the O-Ac groups are localized on C-2, C-3, and C-6 hydroxyls in certain anhydromannose units.     

Studies on the Molecular Chain Conformation Stability of Aminated Konjac Glucomannan

Konjac glucomannan （KGM） was aminated by 2-chloroethyl-amine （CEA） as reagent so as to study the influence of concentration of CEA （based on the amount of KGM）, concentration of NaOH, reaction time and temperature on the extent of amination. And the molecular simulation technology was adopted to analyze the conformation stability of aminate （AKGM）. The results indicate that when the amount of CEA is higher, the extent of amination is higher. The optimum concentration of NaOH, reaction time and temperature are 10% NaOH, 70 ℃ and 45 rain, respectively. IR shows KGM is successfully aminated. The conformation of AKGM is in a random clew-like shape.     

Effect of Plasma Treatment on the Structures and Properties of Konjac Glucomannan Film

To understand the effect of plasma treatment on the Konjac glucomannan film, the nitrogen plasma was injected into the film by ion beam injection machine in this study. The structures and properties of Konjac glucomannan film after plasma treatment were analyzed by Infrared spectroscopy, Raman spectrum, X-ray, ect. The result showed that nitrogen groups appeared in the KGM molecular chain and part of this chain fractured, and the number of hydrogen bonds increased after the treatment of plasma. The form of KGM molecule remained amorphous non-crystalline state, but the crystalline region was increased and became more ordered. The mechanical property of tensile strength and breaking elongation was improved, while the WVP was decreased. The nitrogen groups were grafted on the KGM molecular chain after plasma treatment, which led to the improvement of the properties of KGM film.     

Preparation and physicochemical properties of konjac glucomannan ibuprofen ester as a polysaccharide-drug conjugate

Abstract

A novel drug-polysaccharide conjugate with konjac glucomannan (KGM) as a drug carrier was fabricated through the esterification of ibuprofen (IBU), an anti-inflammatory drug, with KGM. The influences of the reaction conditions, such as the amount of ibuprofen acryl chloride, reaction time, reaction temperature, and the amount of catalyst, on the degree of substitution were investigated. KGM ibuprofen ester (KGM-IBU) was characterized by Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), solid-state ¹³C NMR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). The hydrophobic structure of IBU in KGM-IBU was proven by the fluorescence emission spectra of pyrene. In addition, by using commercially available ibuprofen sustained-release capsules (IBU-SRC) as a control, the in vitro controlled release performance of KGM-IBU was evaluated. The cumulative release of IBU-SRC within 36?h was 94%, while that of KGM-IBU within 36?h was 77%. The results showed that KGM-IBU had better sustained-release performance without a burst release effect. The obtained products could be used as a potential biocompatible sustained-release drug delivery system.     

Preparation and Performance of Thickened Liquids for Patients with Konjac Glucomannan-Mediated Dysphagia

The present study sought to characterize the rheological and thickening properties of Konjac glucomannan (KGM) and prepare thickening components for special medical purposes using KGM and maltodextrin as the primary raw materials and guar gum (GG), xanthan gum (XG), locust bean gum (LBG), and carrageenan (KC) as the supplemented materials. The formulation and preparation processes were optimized through single factor experiments taking sensory evaluation as an indicator. The results confirm that KGM had excellent thickening performance, reaching about 90 times its own mass. The optimal formulation process of the thickening components based on KGM was as follows: the mass concentration of the compound thickener (KGM/GG/XG/LBG/KC = 13:2:2:2:1) was 5.0–7.0 mg/mL; the maltodextrin concentration was 10.0 mg/mL; the brewing temperature of the thickening component was 60 °C with no restriction on consumption time. The rheology test results revealed that the thickening components had shear thinning characteristics, which could provide three different thickening effects of nectar-thick level (350 mPa·s), honey-thick level (1250 mPa·s), and pudding-thick level (1810 mPa·s) suitable for people with different degrees of chewing disorders. Overall, this study provides a theoretical basis and technical reference for KGM as a dietary nutrition support for patients with dysphagia.     

双醛葡甘聚糖溶液的荧光光谱特性研究

研究了双醛葡甘聚糖水溶液在不同紫外光激发下的荧光光谱特性。结果表明,在220～320 nm紫外光激发下,双醛葡甘聚糖分子环结构中C—O—C醚键单元的氧未共价成键电子吸收激发光子产生n→σ＊跃迁,醛基单元中C=O氧未共价成键电子吸收激发光子产生n→π＊跃迁,最大发射波长分别在425 nm和465 nm左右;溶剂通过氢键等相互作用对双醛葡甘聚糖溶液荧光光谱产生显著影响。研究结果对探索葡甘聚糖水凝胶给药载体与小分子药物的相互作用机理及其释药行为具有指导意义。     

Study on the Dynamics of Blending of Glucomannan with Carrageenan and Guaran Gum

In order to prove up the interaction between konjac glucomannan (KGM) and other amyloses, by using KGM, guaran gum and carrageenan as materials, their blending in different external conditions was modeled by means of molecular dynamics (MD) method. The result showed that 323 K was a significant turning point for the formation of hydrogen bond, and KGM and guaran gum were just juxtaposed together via intermolecular hydrogen bond; but with the addition of carrageenan, KGM, guaran gum and carrageenan were spirally twisted together, and when their blending proportion is 3:2:9 the combination was the most compact. Moreover, the research result has provided the sequent studies afterwards on amyloses with some references.