Fabrication And Application Of Chitosan And Its Derivative Microspheres Via Electrospraying

Electrospraying is a novel technique to fabricate polymeric microspheres by using highvoltage to make polymer charged to overcome its surface tension so that jet flow out fromTaylor cone in the end of nozzle. Electrospraying is not only a simple technology, shape andsize controlled and monodispersed, but also can avoid harzard organic solvents, improvingdrug stability to have a better control of drug release rate. During the electrosprayingprocess,there are several parameters which have an mutual relationship with each other thatrender its optimization highly complex. As a consequence, it is necessary to study how theseparameters influence the characteristics of electrosprayed microspheres for its furtherapplication in drug carriers.In this study, we synthesised chitosan microsphere via electrospray. According to thesingle factor analysis, we systematically investigated how solution properties (relativemolecular mass, polymer soltuion concentration, acetic acid concentration) and processparameters (voltage, distance, flow rate) effected electrosprayed microspheres’ morphologycharacteristics, size and size distribution. The orthogonal test tabulation was designed basedon the results of the single factor analysis. The results demonstrated that monodispersemicrospheres was obtained when the chitosan concentration was1.5%dissolved in90%acetic acid. The voltage,distance and flow rate were22kV,10cm and50r/min. With theincrease of chitosan concentration, the size and size distribution of microspheres increased aswell, but when acetic acid concentration raised, the change of particle size was not obvious,the distribution greatly varied. Besides that, the size and size distribution decreasd along withthe increasing of voltage, distance and flow rate. The hydrophobicity of electrosprayedmicrosphere was much better than that in the traditional manner of ionic gelation.We prepared the chitosan microspheres loaded with bovine serum albumin as a modeldrug via electrospraying, and investigated the compatibility of the drug and carrier materials,carefully studied how the particle size and drug concentration affected encapsulationefficiency and drug release kinetics. The study found out that drug and carrier material had agreat compatibility. When the content of BSA was4%, the drug loading capacity was as high as91.84%. The drug release curves demonstrated that an initial burst release followed by asustained release over the period of150h. In the previous2hours, the drug initial burst releaseonly reaches30%. This showed that the drug loaded microspheres had a good sustained drugrelease effect.In this paper, we designed the orthogonal experiments for choosing the best of DMFmoisture water and reaction time in order to synthesis chemoselectively N-phthaloylatedchitosan. Besides that, we prepared the N-phthaloylated chitosan microspheres byelectrospraying and simply studied its surface properties. The study found that chemoselectiveN-phthaloylation chitosan could be synthesised successfully by using DMF containing5%water as a solvent and reaction time was8h. It had a great thermal stability compared to purechitosan. The electrosprayed N-phthaloylation chitosan micropheres had a narrow sizedistribution and had a favoable hydrophiic property compared to the electrosprayed chitosanmicrospheres.