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Biomedical subjects

Yumin Du

Publications and source records attributed to Yumin Du.

14 recordsLinked to original sources
PubMed2006

Chitosan/starch fibers and their properties for drug controlled release.

Fibers of chitosan and starch, with salicylic acid (SA) as model drug incorporated in different concentrations, were obtained by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous tripolyphosphate (TPP) and ethanol. Chemical, morphological and mechanical properties characterization was carried out, as well as the studies of the factors that influence the drug releasing from chitosan/starch fibers. These factors included the component ratio of chitosan and starch, the loaded amount of SA, the pH and the ionic strength of the release solution and others. The diameter of the fibers is around 15+/-3 microm. The best values of the tensile strength at 12.21 cN/tex and breaking elongation at 25.13% of blend fibers were obtained when the starch content was 30 wt%; the water-retention value (WRV) of blend fibers increased as the composition of starch was raised. The results of controlled release tests showed that the amount of SA released increased with an increase in the proportion of starch present in the fiber. Moreover, the release rate of drug decreased as the amount of drug loaded in the fiber increased, but the cumulative release amount is increasing. The chitosan/starch fibers were also sensitive to pH and ionic strength. The release rate was being accelerated by a lower pH and a higher ionic strength, respectively. All the results indicated that the chitosan/starch fiber was potentially useful in drug delivery systems.

Chitosan↗
PubMed2006

Preparation and third-order optical nonlinearity of self-assembled chitosan/CdSe-ZnS core-shell quantum dots multilayer films.

The self-assembled chitosan CdSe quantum dots (QDs) and chitosan CdSe-ZnS core-shell QDs films have been prepared by using layer-by-layer electrostatic technique. The well-ordered nanostructure and the layer-by-layer deposition of the QDs are revealed by AFM and exciton absorption spectra, respectively. The optical nonlinearity of the composite films were studied by using Z-scan technique with femtosecond pulses at the wavelength of 790 nm, the value of third-order susceptibility of core-shell QDs are measured to be about 1.1 x 10(-8) esu, which is about 200% larger than that of CdSe QDs of 5.3 x 10(-9) esu. This has potential applications in all-optical switches in optical information processing.

Journal Article↗
PubMed2005

The structure-anticoagulant activity relationships of sulfated lacquer polysaccharide: effect of carboxyl group and position of sulfation.

Regiospecific oxidation of the primary hydroxyl groups in lacquer polysaccharide (LPL, Mw 6.85 x 10(4)) and its NaIO4 oxidation derivatives (LPLde) to C-6 carboxy groups was achieved with NaOCl in the presence of Tempo and NaBr. Sulfate groups were incorporated into the oxidated polysaccharides using Py.SO3 complex as a reagent. Reactivity of polysaccharide hydroxyl group was C-6 > C-2 > C-4. Sulfate groups were mainly linked to the second hydroxy at C-2 in the products. The results of APTT assay showed after incorporation of carboxyl groups into lacquer polysaccharides, the intrinsic coagulation pathway was promoted, and all sulfated polysaccharides had very weak anticoagulant activity within the scope of studied DS (0.39-1.11). These indicated that carboxyl groups and sulfate groups had the synergistic action. At the same time, the anticoagulant activity increased very slowly with the DS in the second hydroxy. This indicated that 6-O-SO3- in the side chains took an important role in the anticoagulant activity.

Anticoagulants↗
PubMed2004

Chitosan kills bacteria through cell membrane damage.

The bactericidal activity of chitosan (CS) acetate solution against Escherichia coli and Staphylococcus aureus was evaluated by the enumeration of viable organisms at different incubation times. Morphologies of bacteria treated with CS were observed by transmission electron microscopy (TEM). The integrity of the cell membranes of both species and the permeabilities of the outer membrane (OM) and inner membrane (IM) of E. coli were investigated by determining the release from cells of materials that absorb at 260 nm, changes in the fluorescence of cells treated with the fluorescent probe 1-N-phenylnaphthylamine (NPN) and release of cytoplasmic beta-galactosidase activity. In addition, the interaction of CS with synthetic phospholipid membranes was studied using gel permeation chromatography (GPC), UV-VIS spectrophotometery, Fourier-transform infrared spectroscopy (FT-IR) and thermal analysis. Results showed that CS increased the permeability of the OM and IM and ultimately disrupted bacterial cell membranes, with the release of cellular contents. This damage was likely caused by the electrostatic interaction between NH(3)(+) groups of CS acetate and phosphoryl groups of phospholipid components of cell membranes.

Bacterial Outer Membrane Proteins↗
PubMed2004

Synthesis and pH sensitivity of carboxymethyl chitosan-based polyampholyte hydrogels for protein carrier matrices.

Novel polyampholyte hydrogels based on carboxymethyl chitosans (CMC) of various degree of deacetylation (DD) and substitution (DS) were prepared by crosslinking with glutaraldehyde. The hydrogel showed typical amphoteric character responding to pH of the external medium. At the isoelectric point (IEP), the hydrogel shrunk most, when the pH deviated from IEP, the swelling degree (Ds) increased. With increasing DD or DS value, the hydrogel changed from polyampholyte into polycations or polyanions, respectively. Osmotic forces and intermolecular interactions among CMC chains regulate the swelling behavior of CMC gel. The carboxymethyl chitin hydrogels were loaded with bovine blood proteins (BSA), and their release studies were performed in both the simulated gastric and intestinal pH conditions. The release was much quicker in pH 7.4 buffer than pH 1.2 solution; the release followed Fickian diffusion in the first 4h and then steadily increased with the dissolution of the hydrogels.

Absorption↗
PubMed2004

[Study on composite contamination of PM2.5 in aerosol of metallurgical plant].

OBJECTIVE: To detect whether there still have PM2.5 compound contamination on the condition of dedust equipment through the study. METHODS: Both qualitative and quantitative analysis on the multiple contaminants and the particle radius of the sample were done by using chemical and electron microscope, electron spectrum, GC-MS, etc. RESULT: The ingredient of the compound contamination: H2O 22%, organics 34.75%, inorganics 43.75%. Main inorganics were Cu, C, Pb, Al, and most of their radius < or = 1.1 microm. There were over 140 kinds of organics, mainly the hydroxybenzene and PAHs. Besides heavy metals such as Pb, As, inorganics also included arsenic acid and phosphoric acid. CONCLUSION: On the existing condition of existing dedust equipment, the compound contamination in aerosol of metallurgical plant were multiple kinds of heavy metals, acidic oxide and tens of kinds of organic contaminations (hydroxybenzene and PAHs), and their radius < or = 1.1 microm.

Dust↗
PubMed2003

Influence of functional groups on the in vitro anticoagulant activity of chitosan sulfate.

A new method for the chemical modification of chitosan sulfate was used to prepare N-propanoyl-, N-hexanoyl- and N,O-quaternary substituted chitosan sulfate. Structural analysis by elemental analysis, FTIR, 13C NMR, and 1H NMR spectroscopy, and gel-permeation chromatography showed that these methods could conveniently be used for the introduction of functional groups. The influences of the acyl or quaternary groups on the anticoagulant activity of the polysaccharides were studied with respect to activated partial thromboplastin time (APTT) thrombin time (TT), and prothrombin time (PT). The propanoyl and hexanoyl groups increased the APTT activity, and the propanoyl groups also increased the TT anticoagulant activity slightly, while the N,O-quaternary chitosan sulfate showed only a slight TT coagulant activity.

Acylation↗
PubMed2003

Relationships between the molecular structure and moisture-absorption and moisture-retention abilities of carboxymethyl chitosan. II. Effect of degree of deacetylation and carboxymethylation.

Carboxymethyl chitosans (CM-chitosan) of various degrees of deacetylation (DD 28-95%) and substitution (DS 0.15-1.21) were successfully prepared from N-acetylchitosans in NaOH of varying concentrations. Infrared spectroscopy (IR), elemental analysis, potentiometric titration, 13C NMR, X-ray diffraction and gel-permeation chromatographic (GPC) techniques were used to characterize their molecular structures. The moisture-absorption (R(a)) and -retention (R(h)) abilities of CM-chitosan are closely related to the DD and DS values. Under conditions of high relative humidity, the maximum R(a) and R(h) were obtained at DD values of about 50%, and when the DD value deviated from 50%, R(a) and R(h) decreased. Under dry conditions, when the DD value was 50%, the R(h) was the lowest. With the DS value increasing, R(a) and R(h) increased. However, further increase of the DS value above 1.0 reduced the increasing tendency of R(a) and R(h), and even some decreases in R(a) and R(h) were observed. Intermolecular hydrogen bonds play a very important role in moisture-absorption and retention ability of CM-chitosan.

Absorption↗
PubMed2003

Effect of molecular structure of chitosan on protein delivery properties of chitosan nanoparticles.

Chitosan nanoparticles (CS NP) with various formations were produced based on ionic gelation process of tripolyphosphate (TPP) and chitosan. They were examined with diameter 20-200 nm and spherical shape using TEM. FTIR confirmed tripolyphosphoric groups of TPP linked with ammonium groups of chitosan in the nanoparticles. Factors affecting delivery properties of bovine serum albumin (BSA) as model protein have been tested, they included molecular weight (Mw) and deacetylation degree (DD) of chitosan, the concentration of chitosan and initial BSA, and the presence of polyethylene glycol (PEG) in encapsulation medium. Increasing Mws of chitosan from 10 to 210 kDa, BSA encapsulation efficiency was enhanced about two times, BSA total release in PBS (phosphate buffer saline) pH 7.4 in 8 days was reduced from 73.9 to 17.6%. Increasing DD from 75.5 to 92% promoted slightly the encapsulation efficiency and decelerated the release rate. The encapsulation efficiency was highly decreased by increase of initial BSA and chitosan concentration; higher loading capacity of BSA speeded the BSA release from the nanoparticles. Adding PEG hindered the BSA encapsulation and accelerated the release rate.

Acetylation↗
PubMed2003

Preparation and modification of N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride nanoparticle as a protein carrier.

N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is water-soluble derivative of chitosan (CS), synthesized by the reaction between glycidyl-trimethyl-ammonium chloride and CS. HTCC nanoparticles have been formed based on ionic gelation process of HTCC and sodium tripolyphosphate (TPP). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the HTCC nanoparticles. HTCC nanoparticles were 110-180 nm in size, and their encapsulation efficiency was up to 90%. In vitro release studies showed a burst effect and a slow and continuous release followed. Encapsulation efficiency was obviously increased with increase of initial BSA concentration. Increasing TPP concentration from 0.5 to 0.7 mg/ml promoted encapsulation efficiency from 46.7% to 90%, and delayed release. As for modified HTCC nanoparticles, adding polyethylene glycol (PEG) or sodium alginate obviously decreased the burst effect of BSA from 42% to 18%. Encapsulation efficiency was significantly reduced from 47.6% to 2% with increase of PEG from 1.0 to 20.0 mg/ml. Encapsulation efficiency was increased from 14.5% to 25.4% with increase of alginate from 0.3 to 1.0 mg/ml.

Adsorption↗
PubMed2003

Biodegradation of exploded cotton stalk by Bacillus sp.

The exploded bast, branch and stem of cotton stalk were degraded by alkalophilic Bacillus NT-19, with weight losses of 24%, 20% and 14%, respectively, after 14 d. Compared with a white-rot fungus (Phanerochaete chrysosporium), Bacillus NT- 19 preferentially degraded the non-cellulose components of cotton stem. The relative degree of crystallinity of bast fibers decreased by 8% and the middle lamella was partially removed from the fiber bundle by the Bacillus.

Agriculture↗
PubMed2002

Enzymic preparation of water-soluble chitosan and their antitumor activity.

Water-soluble low-molecular-weight (LMW) chitosan was prepared from enzymatic hydrolysis with efficient hemicellulase. The hydrolysates were separated by ultrafiltration membranes. A separated fraction with Mw more than 5x10(3) and with a degree of deacetylation of 58% was water-soluble in the free amine form. The intraperitoneal injection of LMW chitosan and its N-acetyl product inhibited the growth of sacroma 180 (S180) tumor cells in the mice, and the maximum inhibitory rate reached 64.2%. The oral administration was also effective on decreasing weight of tumor, and the maximum inhibitory rate reached 33.7%. The Water-soluble chitosan with higher Mw than hexamer might have better antitumor activity.

Acetylation↗
PubMed2002

Chemical modification, characterization and structure-anticoagulant activity relationships of Chinese lacquer polysaccharides.

A natural lacquer polysaccharide with complex branches was separated into two fractions, LPH (MW 16.9x10(4)) and LPL (MW 6.85x10(4)). Results of 13C NMR and FT-IR indicated they had the same structure. The treatment of LPL with sodium periodate led to a partial cut-off of side chains with 4-O-methyl-D-glucuronic acid in the terminal. These polysaccharides were sulfated in the presence of Py*SO3/DMSO. Depending on the reaction conditions, the products showed a different degree of sulfation (DS) ranging from 0.57 to 1.57 and different molecular weights ranging from 1.71x10(4) to 3.49x10(4). FT-IR analysis showed the equatorial primary OH at O-6 and the axial secondary OH at O-4 were sulfated. Activated partial thromboplastin time (APTT), prothrombin time and thrombin time (TT) assays showed the sulfated polysaccharides could prolong APTT and TT, but not TP. These activities strongly depended on the DS, the molecular weights (MW) and the branching structure of polysaccharides. DS of above 0.8 was essential for anticoagulant activity. The anticoagulant activity increased with the DS and the molecular weights. The molecular weights played a more important role. The branching structure of polysaccharides increased the activities. In our studies, the sulfated polysaccharides with the DS of 1.15 and the highest MW of 3.49x10(4) had the best blood anticoagulant activities.

Anticoagulants↗