Calcium-binding ability of soy protein hydrolysates

This present study investigated the ability of various soy protein hydrolysates(SPHs)in binding calcium.It was demonstrated that the amount of Ca-bound depended greatly on the SPHs obtained using different proteases,which included:neutrase, flavourzyme,protease M and pepsin.The maximum level of Ca-bound(66.9 mg/g)occurred when protease M was used to hydrolyze soy protein.Peptide fragments exhibiting high Ca-binding capacity had molecular weights of either 14.4 or 8-9 kDa.The level of Ca-bound increased linearly with the increment of carboxyl content in SPHs,and further deamidation on SPHs from protease M improved Ca-binding of the hydrolysate.     

STUDIES ON ULTRASONIC ABSORPTION AND VISCO-RELAXATION OF POLY (ETHYLENE GLYCOL) AQUEOUS SOLUTIONS

Ultrasonic absorption and velocity measurements were made on aqueous solutions of poly (ethylene glycol)(PEG)of different molecular weights and concentrations, using a pulse sender-receiver ultrasonic generator, Measurements were obtained at a frequency of 2MHz. , and a temperature of 293 K. The results show a linear increase of the Values of velocity, density and viscosity with increase of molecu lar weight and concentration of PEG. On the contrary, the attenuation values decreased with increase of molecular weight and concentration of PEG. A mathematical equation correlating relaxation amplitude and molecular weight of the polymer is suggested. This was applied to calculate the molecular weights of unknown samples of PEG from their measured relaxation amplitude. The results obtained were in good agreement with those obtained from osmometry.     

Production and characterization of poly(3-hydroxybutyrateco-3-hydroxyhexanoate)-poly(ethylene glycol) hybird copolymer with adjustable molecular weight

A novel natural-synthetic hybrid block copolymer was synthesized by Aeromonas hydrophila 4AK4 in poly(ethylene glycol)(PEG,M_n=200) modified fermentation.This hybrid biomaterial consists of the natural hydrophobic polymer poly(3-hydroxybutyrat-co-3-hydroxyhexanoate)(PHBHHx) end-capped with hydrophilic PEG,which has the increased flexibility as well as the improved thermal stability.Addition of diethylene glycol(DEG) and ethylene glycol could not result in the accumulation of hybrid block copolymer.DEG and ethylene glycol,together with PEG-200,could cause a reduction of molar mass of PHBHHx,resulting in a series of low molecular weight polymer and the reduction of the polymer yield as well as the cellular productivity.In vitro degradation of PHBHHx and PHBHHx-PEG with different molecular weight showed that the decrease of molecular weight accelerated the degradation of copolymers,but PEG modification has little effect on its degradation rate.The results in this study provided a convenient and direct method to produce a series of PHBHHx and PHBHHx-PEG materials with adjustable molecular weight and broad molecular weight distribution which will be very useful for the biomedical applications.     

PREPARATION AND CELL COMPATIBILITY OF FUNCTIONALIZED BIODEGRADABLE POLY(DL-LACTIDE-co-RS-β-MALIC ACID

In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL- lactide-co-RS-β-benzyl malolactonate)(PDLLMA),which was from the ring-opening polymerization of DL-lactide(DLLA) and RS-β-benzyl malolactonate(MA)using stannous octoate as catalyst.The copolymers were characterized by ~1H-NMR, FTIR,GPC and DSC.The tensile strength and water uptake of the copolymers were measured.In copolymerization,the proportion of MA in the derived copolymers was lower than that in the feeding dose,a consequence of its lower reactivity. The molecular weight of the copolymers decreased with increasing MA content.The protective benzyl groups were completely removed in hydrogenolysis.The glass transition temperature(T_g)of the protected copolymers decreased with increasing MA content.The mechanical strength test showed that the tensile strength of PDLLMA decreased while elongation increased with MA content increasing,and the tensile strength increased and elongation decreased with increasing malic acid content in PDLLMAc for the formation of hydrogen bonding.The water uptake showed that more hydrophilic malic acid adsorbed more water in PDLLMAc.In order to test the reactivity of functional pendant groups,bioactive RGD peptide was immobilized on the functionalized polymer film surface and smooth muscle cells(SMCs)were cultured on it. The results showed that the functionalized copolymer was biocompatible and could be potentially applied in vascular tissue engineering.     

Partial Hydrolysis of the Fucosylated Chondroitin Sulfate from Sea Cucumber Isostichopus badionotus and Its Mechanism

The method for preparing low molecular weight fucosylated chondroitin sulfate from sea cucumber Isostichopus badionotus using partial acid hydrolysis was reported, and its hydrolysis mechanism was also investigated. The sea cucumber chondroitin sulfate FCS was hydrolyzed under different conditions (80 ℃ 3 h and 6 h), then isolated and purified on a Bio-P-4 geltration to prepare low molecular weight fractions (LMWF-FCS). The chemical compositions of LMWF-FCS showed the branched fucose (Fuc) was cleaved during acid hydrolysis process, whereas the mole ratio of acetyl-galactosamine (GalNAc) and glucuronic acid (GlcA) in the backbone remained the same, which indicated the backbone was a typical chondroitin sulfate structure. The disaccharide composition analysis of LMWF-FCS suggested that the sulfation patterns of GalNAc in the backbone chain changed and the substitution value was reduced. Furthermore, the 1 D NMR analysis illustrated the branched-Fuc was cleaved during acid hydrolysis, but their substitution patterns were not influenced, which was distinct from the previous reports that the substitutions of branched-Fuc in FCS were easy to change. Simultaneously, the sulfation pattern of GalNAc in backbone chain changed obviously in the acid hydrolysis process. The anticoagulant activity in vitro illuminated the anticoagulant activity of the degradation products over time in the acid hydrolysis are gradually declined, but still kept good. Therefore, the LMWF-FCS prepared could be developed as a new anticoagulant and antithrombotic drug like low molecular weight heparin.     

Preparation and characterization of waterborne polyurethanes modified with bis(3-(1-methoxy-2-hydroxypropoxy) propyl) terminated polysiloxanes

Polyurethanes(PU) were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU(PSU) was obtained through reaction of the PU prepolymers with bis(3-(1-methoxy-2-hydroxypropoxy)propyl) terminated polysiloxanes(PMTS) of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.     

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.     

Initiating system Me_3SiCl/AlCl_3 for cationic polymerization of 1,3-pentadiene in toluene

Cationic polymerization of 1,3-pentadiene (PD) initiated by trimethylsilyl chloride/aluminium chloride (TMSCl/AlCl3) was carried out in toluene at 30℃.The polymer yield was increased by the addition of TMSC1.However,introduction of TMSC1 gave rise to a drop of the polymer molecular weight.Kinetic results demonstrated that the polymerization initiated by TMSCl/AlCl3 was 2.8 times faster than that induced by AlCl3 alone.Various ethers and ketones were used to mediate the initiating system TMSCl/AlCl3.The polymer yield and molecular weight of the polymer were decreased in the presence of ether.Ketones and ethers had different effects on the polymerization,and the polymer yield and molecular weight were lower than those initiated by AlCl3 alone or TMSCl/AlCl3 Structural evidence revealed that the polymerization was indeed initiated by AlCl3 and HCl rcsulting from hydrolysis of TMSC1 by adventitious water.     

An ultra-fast and highly efficient multiple proteases digestion strategy using graphene-oxide-based immobilized protease reagents

Highly efficient and rapid proteolytic digestion of proteins into peptides is a crucial step in shotgun-based proteome-analysis strategy.Tandem digestion by two or more proteases is demonstrated to be helpful for increasing digestion efficiency and decreasing missed cleavages,which results in more peptides that are compatible with mass-spectrometry analysis.Compared to conventional solution digestion,immobilized protease digestion has the obvious advantages of short digestion time,no self-proteolysis,and reusability.We proposed a multiple-immobilized proteases-digestion strategy that combines the advantages of the two digestion strategies mentioned above.Graphene-oxide(GO)-based immobilized trypsin and endoproteinase Glu-C were prepared by covalently attaching them onto the GO surface.The prepared GO-trypsin and GO-Glu-C were successfully applied in standard protein digestion and multiple immobilized proteases digestion of total proteins of Thermoanaerobacter tengcongensis.Compared to 12-hour solution digestion using trypsin or Glu-C,14%and 7%improvement were obtained,respectively,in the sequence coverage of BSA by one-minute digestion using GO-trypsin and GO-Glu-C.Multiple immobilized-proteases digestion of the total proteins of Thermoanaerobacter tengcongensis showed 24.3%and 48.7%enhancement in the numbers of identified proteins than was obtained using GO-trypsin or GO-Glu-C alone.The ultra-fast and highly efficient digestion can be contributed to the high loading capacity of protease on GO,which leads to fewer missed cleavages and more complete digestion.As a result,improved protein identification and sequence coverage can be expected.     

Photo-polymerization of liquid crystalline monomer in oriented liquid crystal phase

<正>A new approach to synthesize liquid crystalline polymer with narrow polydispersity index(PDI) was developed.Photopolymerization of 4-cyanophenyl-4'-(6-acryloyloxyhexyloxy)benzoate(RM23) in nematic liquid crystals with macroscopic orientation was studied.The effects of the monomer concentration on the molecular weight and PDI of the resulting polymers were studied through gel permeation chromatography(GPC) and polarized optical microscopy.The low PDI of 1.19 and 1.22 was obtained in the reverse and normal modes,respectively.The PDI and molecular weight increased with monomer concentration.     

A Novel β-1, 4-N, 6-O-Diacetylmuramidase from Streptomyces griseus and its Chemical Modification

A novel lysozyme namedβ-1, 4-N, 6-O-diacetylmuramidase R2 was purified and characterized from Streptomyces griseus. The molecular weight of the enzyme was determined by MALDI-TOF-MS as 23.5 kDa. The N-terminal amino acid sequence was DTSGVQGIDVS-HWQG.Chemical modification ofβ-1, 4-N, 6-O-diacetylmuramidase R2 indicated that sulfhydry1 group and carbamidine of arginine residues are not essential for the activity of the enzyme, but lysine residues and imidazole of histidine residues are essential for the activity. The number of essential tryptophan and carboxyl groups was found that only one tryptophan residue and three carboxyl groups in the active site.     

Synthesis and characterization of a novel polymer electrolyte based on acrylonitrile/N-[4-(aminosulfonyl)phenyl]acrylamide copolymers

<正>Acrylonitrile/N-[4-(aminosulfonyl)phenyl]acrylamide(AN/ASPAA) copolymers were synthesized and used as a host of lithium ion conducting electrolytes.The composition,molecular weight and molecular weight distribution of AN/ASPAA copolymers were determined,and the influence of copolymer composition on the glass temperature of AN/ASPAA copolymers and the ion conductivity of electrolytes were investigated.The molecular weights of AN/ASPAA copolymers were lower than those of AN and ASPAA homopolymers due to the cross-termination reaction.The glass temperatures of AN/ASPAA copolymers increased as the molar fraction of ASPAA units in copolymers increased.The lithium ion conductivities of the polymer electrolytes increased initially as the molar fraction of ASPAA units in copolymers increased,and a maximum conductivity was achieved when the molar fraction of ASPAA in the copolymer was 16.8%.     

Effect of Molecular Weight on the Properties of Poly（butylene succinate）

Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.     

Effects of matrix molecular weight on structure and reinforcement of high density polyethylene/mica composites

Three types of high-density polyethylene(HDPE)with different molecular weights(high,medium and low)were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM,2d-WAXS,DSC,DMA and tensile testing.Various structural factors including orientation,filler dispersion,interfacial interaction between HDPE and mica,etc.,which can impact the macroscopic mechanics,were compared in detail among the three HDPE/mica composites.The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence.Obvious transcrystalline structure was found in the composite with low molecular weight HDPE,whereas it was hard to be detected in the composites with increased HDPE molecular weight.The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interfacial adhesion between matrix and mica filler,which arises from the transcrystallization mechanism.     

Synthesis and Antibacterial Activity of Selenium-functionalized Poly(ε-caprolactone)

A selenium-functionalizedε-caprolactone was synthesized by introducing a phenyl selenide group at the 7-position.A polymer was obtained through the ring-opening polymerization of this monomer in a base/thiourea binary organocatalytic system.A living polymerization process was achieved under mild conditions.The resulting polymers had a controlled molecular weight with a narrow molecular weight distributions and high end-group fidelity.Random copolymers could be obtained by copolymerizing this monomer withε-caprolactone.The thermal degradation temperature of the obtained copolymers decreased with the increasing molar ratio of selenide functionalized monomer in copolymers,while the glass transition temperature increased.In addition,the phenyl selenide side group could be further modified to a polyselenonium salt,which resulted in a polymer with good antibacterial properties.The survival rate of E.coli and S.aureus was only 9%with a polymer concentration of 62.5μg/mL.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.     

EFFECTS OF DEOXYCORTICOSTERONE ACETATE ON MUSCLE ELECTROLYTES,RESTING POTENTIAL AND MITOCHONDRIA IN RATS

Deoxycorticosterone acetate, injected daily for 5, 10, 20 or 30 days, reduced the serum potassium levels of rats by about 25%, a decrease that was independent of the treatment period employed. Serum sodium concentrations were unchanged with treatment duration. The potassium concentrations in extensor digitorum longus (EDL) and soleus (SOL) muscles were significantly decreased, and those of sodium increased, after treatment. Accompanying these changes of electrolyte concentration, the resting membrane potentials of treated EDL and SOL were hyperpolarized in vivo, and showed depolarization with the decreases of external potassium concentrations in vitro. The mitochondria in the muscles of treated rats were damaged. The degree of damage was more serious in EDL than in SOL and was dependent on the duration of deoxycorticosterone acetate treatment.     

Pervaporation for separating benzene/cyclohexane mixture by P(AA-MA) copolymer membranes

P(AA-MA)copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis.These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation.The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail.For the random copolymers,the permeate flux decreased rapidly with the increasing of molecular weight.The separation factor was also influenced by the molecular weight,which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight.Contrarily,the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/(m~2h)to 50 wt%benzene/cyclohexane mixture.     

聚合物固载化聚乙二醇季胺盐型相转移催化剂的结构与催化活性

The gelatinous and macroporous phase transfer catalysts with multiple active centers were synthesized by means of quarterisation of PEG tertiary amine and chloromethylated St DVB copolymer. They were examined as phase transfer catalysts in the reaction of n C 8H 17 Br with solid NaI. The experimental results showed that the reaction rate was first order with respect to the concentration of n C 8H 17 Br. The effects of catalyst structure on the catalytic activity were also investigated. The observed reaction rate constant ( k obsd ) increased as the degree of cross linking of polymer decreased. Macroporous catalysts showed a higher activity (2～2 5 times) than that of microporous catalysts with the same degree of cross linking of polymer, particle size and amount of supported PEG. Molecular weight of PEG also showed much influence on k obsd . As molecular weight of PEG rose properly, the catalysts showed a higher activity. The results were discussed from the aspect of triphase catalysis reaction mechanism.     

NOVEL HYPERBRANCHED POLY（PHENYLENE OXIDE）S WITH PHENOLIC TERMINAL GROUPS： EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.