Mechanical Ball Milling Assisted Preparation Of Chitosan Composite Electrospinning Membrane And The Blood Compatibility Of The Membranes

Electrospinning preparation of nano fiber is one of the most popular fields in recent scientific researches.Its simple structure,low price,easy operating characteristics of which won the favour of many researchers;nano fiber have large specific surface area,uniform sizes.Chitosan(CS),carboxymethyl chitosan(CMC),polyvinyl alcohol(PVA)and polylactic acid(PLA)are good biocompatible materials.The content of this paper is to prepare chitosan and carboxymethyl chitosan nanofibers by electrospinning.Because of the high weight of molecular chitosan and carboxymethyl chitosan,the easy wrapping of molecular chain makes it difficult to achieve separate spinning.Chitosan and carboxymethyl chitosan are typically dissolved in an acidic solution.The presence of the amino group of chitosan and carboxymethyl chitosan would make them protonated.In the presence of high pressure spinning process,repulsive force of particles within the polymer backbone increases and uniform fibers could not be obtained.Nanofibers can be produced from Poly(vinyl alcohol)and poly(lactic acid)by electrospinning process.The diameter of the fiber is about 200 to 600 nm.and also we found that the mechanical ball milling of the ball mill can make the particle diameter meet the nanometer level.Therefore,in this paper,we prepare nano fiber membrane under these four systems:chitosan nanoparticles and polyvinyl alcohol;chitosan particles and poly lactic acid;carboxymethyl chitosan particles with poly lactic acid;carboxymethyl chitosan and poly(ethylene alcohol in the bacterial cellulose sodium sulfate fiber membrane.The corresponding characterization and analysis of surface micro structure,hydrophilicity and blood compatibility of nano fiber membrane(biomimetic membrane)had been done by us.(1)In the spinning system of chitosan and 50 mL of 8 percent of polylactic acid,the amount of being added chitosan can influence the properties of solvent,then leading different apperences of nanofilm in the same condition of spinning.In general,the wrapping angle and clotting time of 400 mg chitosan sample is bigger than the 200 mg one.By contrast,400 mg of chitosan sample in condition of 13 kV,receiving distance is 10 cm,after ball milling 4 h can achieve well-distributed fibrous membrane without any peaberry on the surface.The clotting time of APTT is 33.4 s,PT is 12.3 s and TT is 20 s and the absorption result of blood platelet is completely scattered,thus the nanofilm has excellent blood compatibility.(2)In the spinning system of 200 mg chitosan being milled in 4 h and 16 g of 8 percent of polyvinyl alcohol,we found high voltage can promote the extending of jet current,and long distance can promote the volatilization of menstruum by changing the spinning voltage and receiving distance.When the voltage is 35 kV and receiving distance is 16 cm,we can achieve well-distributed fibrous film.The clotting time of APTT is 31.4 s,PT is 11.8 s and TT is 20 s,thus the nanofilm has excellent blood compatibility.(3)In spinning system of 400 mg of carboxymethyl chitosan which has been ball milled for 4 h and 50 mL of 8 percent polylaidic acid solvent,regulating spinning voltage and receiving distance can produce fibrous membrane in different kinds of appearances.adsorption experiment of blood platelet in fibrous membranes shows great dispersion and all the fibrous membranes have excellent blood compatibility.Clotting times of fibrous membrane are as fellows,APTT is 33.3 s,PT is 11.3 s and TT is 20.3 s,when spinning voltage is 18 kV and receiving distance is 10 cm.(4)We using electrostatic spin on bacterial-cell-sulfuric acid ester film to produce complex film by mixing 200 mg of carboxymethyl chitosan which has been ball milled for 2 h and 22 g of 8 percent of polyvinyl alcohol as a solvent.Regulating spinning voltage and receiving distance can produce fibrous membrane in different kinds of appearances.All the fibrous membranes have excellent blood anti-compatibility.Clotting times of fibrous membrane are as fellows,APTT is 67.4 s and PT is 48.4 s when spinning voltage is 40 kV and receiving distance is 16 cm.Clotting time improved significantly compared to normal blood and blood platelet seldom adhered to the surface of film.