The Preparation And Application As Wound Dressings Of Electrospun Polysaccharide Nanofibers

Natural polysaccharides have good biocompatibility,biodegradability and bioactivity.Electrospun nanofiber mats have the features of high porosity,high specific surface area,high aspect ratio and nanofibrious structure.By integrating the properties of natural polysaccharides and the features of electrospun nanofiber mats,electrospun polysaccharide nanofiber mats exhibit abilities of maintaining moisture,permeating gas and preventing bacteria,and thus are promising as wound dressings.At present the variety of electrospun nanofiber mats used as dressing mats is very few,which greatly limitsthe available properties and the types of wounds they may treat.This work intends to enrich the variety of electrospun polysaccharide nanofiber mats,and thus expand the available properties,satisfying the demands of treatment of more types of wounds.The details of our work are as follows:In the first part,the properties of electrospun pectinate nanofiber mats related to wound dressing applications were characterized,and were compared with widely studied electrospun alginate nanofiber mats and chitosan nanofiber mats.The pectinate nanofiber mat had Young's Modulus of 63.9 MPa in hydrated state,could transport 0.27 g water vapour per cm2 in 24 hours,could absorb simulated exudate solution with weight equal to 76.5 times of its own weight,could absorb water droplet completely in 1 s and exclude it from fiber mats in 30 minutes,and showed antibacterial activity as high as 73.1%.In comparison,the alginate nanofiber mats had Young's Modulus of 13.2 MPa,could transport 0.24 g vapour water per cm2 in 24 hours,could absorb simulated exudate solution with weight equal to 35.5 times of its own weight,could absorb droplet completely in 12 minutes but the fluid may flow to surrounding area upon interference,and showed antibacterial activity of 11.8%.The chitosan nanofiber mat had Young's Modulus of 93.3 MPa,could transport 0.23 g vapour water per cm2 in 24 hours,absorb simulated exudate solution with weight equal to 15.7 times of its own weight,could absorb water droplet completely in 60 s but the excess fluid diffused dramatically and failed to exclude from mats,and showed antibacterial activity of 17.1%.The electrospun pectinate nanofiber mat had comparable mechanical strength and vapour permeability with the alginate and chitosan nanofiber mats,but could absorb more liquid with a faster speed and suppress the proliferation of bacteria more efficiently,and thus is promising for wound dressing applications.In the second part,we developed a new method to prepare crosslinked electrospun polysaccharide nanofiber mats.Polysaccharides were firstly oxided with periodate and then electrospun into nanofibers and then crosslinked with adipodihydrazide.Using pectin as a representative polysaccharide,we explored the preparation parameters,verified the feasibility of the method,and characterized the properties of the obtained nanofiber mats.Periodate oxidized pectinsuccessfully,generating aldehyde groups and leading to the decrease of the molecular weight.The amount of the generated aldehyde groups was linear with the amount of the input periodate.When mixture solvent of ethanol and water with volume ratio of 80:20 or 70:30 was used as the solvent,the nanofibers could be crosslinked successfully by adipodihydrazide without significantly losing weight or morphology.Around half of the aldehyde groups reacted with adipodihydrazide.With the increase of the degree of oxidation,the Young's Modulus of polysaccharide nanofiber mats firstly increased and then decreased,their degradation slowed down,and the adhesion,spreading and proliferation of cells on nanofiber mats was improved gradually.The crosslinked dialdehyde pectinate nanofiber mats could absorb a certain amount of fluid and showed no obvious cytotoxicity.The electrospun nanofibers of konjac glucomannan and corn starch were prepared with the same method,showing different mechanical,degradation and absorbency properties.Tosummarize,in this work,we developed a new method to prepare electrospun polysaccharide nanofibers,fabricated several new types of electrospun polysaccharide nanofibers with different properties,and examined their properties related to wound dressing applications.This work lays a foundation for the applications of electrospun polysaccharide nanofiberas wound dressings.