Lihong Fan

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.

Preparation and Properties of Alginate/Water‐Soluble Chitin Blend Fibers

Water‐soluble chitin (half‐deacetylated chitin) was prepared from chitosan by N‐acetylation with acetic anhydride. Alginate/water‐soluble chitin blend fibers were prepared by spinning their mixture solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. The structure and properties of the blend fibers were studied with the aids of infrared spectra (IR), X‐ray diffraction (XRD) and scanning electron microscopy (SEM). structure analysis indicated good miscibility existed between alginate and water‐soluble chitin, due to the strong interaction from the intermolecular hydrogen bonds and electrostatic interactions. Best values for the dry tensile strength and breaking elongation were obtained when the water‐soluble chitin content was 30 wt%. The wet tensile strength and breaking elongation decreased with the increase of water‐soluble chitin content. The introduction of water‐soluble chitin in the blend fiber can improve the water‐retention properties of the blend fiber compared to pure alginate fiber. The fibers treated with aqueous solution of silver nitrate have good antibacterial activity to Staphylococcus aureus.

Preparation and Characterization of Alginate/Poly(Vinyl Alcohol) Blend Fibers

Alginate and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. The structure and properties of the blend fibers were studied with the aid of infrared spectra (IR), scanning electron micrography (SEM), x‐ray diffraction (XRD), and thermogravimetric analysis (TGA). Mechanical properties and water‐retention properties were measured. The best values of the tensile strength of blend fibers, 13.57 cN/tex in the dry state and 3.02 cN/tex in the wet state, respectively, were obtained when the poly(vinyl alcohol) content was 10wt%. The breaking elongation and water‐retention values (WRV) of blend fibers increase as the amount of poly(vinyl alcohol) is raised. Structure analysis indicated that there was strong interaction and a certain level of miscibility between the alginate and poly(vinyl alcohol) molecules.