Ting Ye

Nanogels fabricated by lysozyme and sodium carboxymethyl cellulose for 5-fluorouracil controlled release.

Lysozyme (Ly) and sodium carboxymethyl cellulose (CMC) were used to fabricate nanogels by a convenient method without using any chemical treatment except simple heating to achieve the denaturation temperature of Ly. The prepared nanogels were characterized by dynamic laser scattering (DLS), rheological analysis, transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The nanogels are of spherical shape with average hydrodynamic diameter of 241 nm and the swelling ratio of nanogels is about 5. Then 5-fluorouracil was used as a model drug to investigate the entrapment efficiency and release ability in nanogels. It turned out to be that the release in simulated gastric fluid (SGF) was more slowly compared with that in simulated intestinal fluid (SIF), which could protect the 5-Fu in stomach and ensure it released in intestines.

Plasma treated polyethylene terephthalate/polypropylene films assembled with chitosan and various preservatives for antimicrobial food packaging.

In this study, polyethylene terephthalate/polypropylene (PET/PP) films were treated via atmospheric pressure plasma, assembled with chitosan and various preservatives and applied for antimicrobial food packaging. Surface properties of these obtained films were studied by contact angle measurement, atomic force microscopy (ATM), X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared spectroscopy (FT-IR) and dynamic laser scattering (DLS). The above results showed that the surface hydrophilicity and roughness of the films increased after the plasma treatment. Besides, chitosan and the preservatives were successfully assembled onto the surface of the films. In addition, the antimicrobial activities of the films against three kinds of microorganisms (Staphylococcus aureus, Bacillus subtilis and Escherichia coli) were investigated and the results indicated that the inhibition ratios against B. subtilis and E. coli reached almost 100% while the inhibition ratios against S. aureus were lower than 85%. Moreover, the accumulative release profiles of the antimicrobial substances migrating from the assembled films into the release solutions revealed that their release speed increased with the increment of temperature and acidity, but decreased with enhancing the ionic strength regulated by sodium chloride or with lowering the ionic mobility regulated by sucrose.

Silver ions/ovalbumin films layer-by-layer self-assembled polyacrylonitrile nanofibrous mats and their antibacterial activity.

The CN groups of polyacrylonitrile (PAN) can strongly adsorb silver ions. The possibility of using this attraction as a layer-by-layer (LBL) self-assembly driving force was investigated. Firstly, the surface of the PAN nanofibrous mats was modified by silver ions to make sure it was positively charged. Then oppositely charged ovalbumin (OVA) and silver ions in aqueous media were alternatively deposited onto the surface of the obtained composite mats by layer-by-layer self-assembly technique. The morphology of the LBL films coating mats was observed by field emission scanning electron microscope (FE-SEM). The deposition of silver ions and OVA was confirmed by X-ray photoelectron spectroscopy (XPS) and wide-angle X-ray diffraction (XRD). The thermal degradation properties were investigated by thermo-gravimetric analysis (TGA). Besides these, the cytotoxicity and antibacterial activity of the prepared mats were studied via flow cytometry (FCM) and inhibition zone test, respectively. The results showed that the composite mats after LBL self-assembly processing exhibited improved thermal stability, slightly decreased cytotoxicity, and excellent antibacterial activity against Escherichia coil and Staphylococcus aureus.

A simple and feasible approach to purify konjac glucomannan from konjac flour – Temperature effect

A simple one-step purification process was provided to extract KGM from KF by phase separation. The results showed that appropriate temperature control was a key factor and the products were inodorous, colourless and of high purity at the optimal temperature 68 °C. In this purification, soluble sugar and starch of extracted KGM were nearly clearly reduced and up to 95%, 80% (T68) of protein and ash were removed, respectively as compared with KF. Odour and transparency were improved 4 ranks and 30%, respectively. Besides, the ηapp reached 42.30 Pa s and increased by 93.55% as compared, which could stay at a steady level for a week. Furthermore, morphology of extracted KGM displayed regular lamellar and wrinkling distribution for removed impurities. The temperature-controlled method not only enriches the knowledge of KGM purification but also has the potential to broaden the application of KGM.

Preparation and characterization of a novel pH-response dietary fiber: Chitosan-coated konjac glucomannan

The purpose of this study was to prepare a kind of novel pH-response dietary fiber from chitosan-coated konjac glucomannan (KGM) powders (KGM/Chitosan or K/C powders) by a physical grind method. The K/C powders were selectively soluble in aqueous solutions of different pH. Meanwhile, the coated chitosan could largely decrease the viscosity of KGM in neutral condition, which is the main limitation for KGM application in food industry. Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), swelling ability and rheological measurements were utilized to characterize the performance of K/C powders. K/C powders exhibited much higher viscosity and swelling ability in acidic condition than in neutral condition. Therefore, this study will extend the application of KGM in food industry and in other pH-specific applications as well.

Facile preparation of clay reinforced konjac glucomannan aerogels

Low density and foam-like aerogels based on abundant renewable konjac glucomannan and montmorillonite clay were prepared by a facile freeze-drying process. The amount of montmorillonite and alkali added into the aerogel and the freezing temperature greatly influenced the properties of the aerogel.

Dissolution and rheological behavior of deacetylated konjac glucomannan in urea aqueous solution.

Deacetylation adversely affected the solubility of konjac glucomannan (KGM). Herein the dissolution behavior of deacetylated KGM (da-KGM) was studied in 10 wt% urea solution at various temperatures. KGM with different degrees of deacetylation (DD) could be well dissolved at -4°C. Low temperature was conducive to the dissolution of da-KGM. The result from steady shear showed that the zero-shear viscosity decreased with the increase of DD, with the rheological model being conformed to the Cross equation. Dynamic viscoelastic properties indicated the da-KGM gel formed more easily with increasing concentration, or decreasing temperature and DD. Temperature sweep revealed that gel process could be divided into two stages. The first stage was that both storage modulus (G) and loss modulus (G″) fell until the temperature reached 90°C. The second stage was that G and G″ increased abruptly, presenting the transition from sol to gel.

Phase behavior of ovalbumin and carboxymethylcellulose composite system

The phase behavior, rheological properties and microstructure of ovalbumin and carboxymethylcellulose (OVA-CMC) conjugates were studied and the influence parameters were investigated. The results showed that the phase behavior of OVA-CMC conjugates was related to pH and concentration of CMC and NaCl. When pH was over 5.0, discrete phase separation occurred in the mixture system, which indicated that OVA and CMC were thermodynamic incompatible. The mixture system turned into uniform stable emulsion system when pH reduced below 5.0. The addition of NaCl can improve the stability of composite system against pH sensitivity. CLSM and particle size distribution and ultraviolet spectrum analysis results confirm that emptying interactions play a leading role in the separation system.

Phase separation in mixtures of ovalbumin and konjac glucomannan: Physicochemical and microscopic investigations

The phase behavior and microstructure of ovalbumin (OVA)/konjac glucomannan (KGM) mixtures were studied at pH 7.0. Phase diagrams were established by centrifugation and visual observation. Micro-phase separation of the OVA/KGM mixtures was quantified by measuring the turbidity. The microstructures of the phase separated mixtures were studied by measuring rheological property and confocal laser scanning microscopy (CLSM). The phase behavior of OVA/KGM mixtures appeared to be one single phase or two separated phases depending on the content of OVA and KGM. OVA had a pronounced effect on turbidity of OVA/KGM mixtures. The particle size of mixtures increased with increasing OVA and KGM concentration, which was the largest (119.1 μm) at 0.25 wt.% KGM and 5 wt.% OVA. The G and G″ cross-over at a mixture of 0.20 wt.% KGM and 4 wt.% OVA demonstrated the buildup of microstructure during phase separation. The association of OVA aggregates could be observed under CLSM.

Antioxidant activities of chick embryo egg hydrolysates

Chick embryo egg hydrolysates (CEEH) were obtained by enzymatic hydrolysis of chick embryo egg in vitro-simulated gastrointestinal digestion. The antioxidant activities of CEEH were investigated by employing three in vitro assays, including the 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonate)/1,1-diphenyl-2-picrylhydrazyl (ABTS/DPPH)/hydroxyl radical-scavenging assays. The radical-scavenging effect of CEEH (1.0u2003mg/mL) was in a dose-dependent manner, with the highest trolox equivalent antioxidant capacity for ABTS, DPPH, and that of hydroxyl radicals found to be 569, 2097, and 259.6u2003μmol/L, respectively; whereas the trolox equivalent antioxidant capacity of unhatched egg for ABTS, DPPH, and that of hydroxyl radicals were found to be 199, 993, and 226.5u2003μmol/L, respectively. CEEH showed stronger scavenging activity than the hydrolysates of unhatched egg against free radicals such as ABTS, DPPH, and hydroxyl radicals. The antioxidant amino acid analysis indicated that the 14-day CEEH possess more antioxidant amino acids than that of the unhatched egg. In addition, essential amino acids analysis showed that the 14-day CEEH have the highest nutritional value. Combined with the results of the amino acid profiles, CEEH were believed to have higher nutritive value in addition to antioxidant activities than the unhatched egg.