Preparation And Characterization Of Chitosan Microspheres/Nanoparticles

Antibacterial drugs are often used in daily life. In the traditional delivery systems, a serious drain on drugs resulted in low bioavailability. Chitosan is one kind of polysaccharides with good biocompatibility, non-toxic to human body, with antibacterial and anti-inflammatory effects. The existence of amino and hydroxyl groups in the molecular chains as well as the linear molecule structure can give rise to its strong adhesion on biological mucosa. The purpose of this work is to study the preparation and characterization of chitosan microspheres/nanoparticles, to get drug carriers applied for mucosal drug delivery, thereby realizing the sustained release of antibacterial drugs.Chitosan microspheres were prepared via emulsion cross-linking method. Influencing factors on particle morphology and size were studied, including the manner of glutaraldehyde addition, oil types, oil-water ratio, stirring speed, and organic solvents. A suitable condition for preparation of the chitosan microspheres was thus optimited. At the same time, porous chitosan microspheres were prepared through multiple emulsion cross-linking. Ciprofloxacin and cetylpyridinium chloride were chosen as the representative of water-soluble antibacterial drugs, and triclosan as the representative of water-insoluble antibacterial drugs. The loading and release properties of the chitosan microspheres were investigated.On the basis of chitosan microspheres preparation, nanoparticles were prepared successfully by utilizing olive oil as the continuous phase and introducing magnesium stearate as cosurfactants in the process. A series of studies were performed in terms of particle morphology, size, pH sensitivity, storage stability, drug loading and release property and biocompatibility. The system has good biocompatibility. Antibacterial cetylpyridinium chloride and sodium fluoride were loaded. Sustained and stable release of the drugs was realized. Nanoparticles were expected to adhere on teeth andmucous membrane, thus achieving lasting antibacterial effect in the oral cavity. However, this method has poorer reproducibility, and involves the use of organic solvents.Finally, the more moderate ionic cross-linking method was used to prepare chitosan nanoparticles. A series of studies were performed in terms of fabrication optimization, physical and chemical properties, storage stability, biocompatibility and drug loading and release properties of the nanoparticles. Chitosan and tripolyphosphate mass ratio, pH value, salt concentration etc. all affected the state of nanoparticles. Nanoparticles could be prepared only within appropriate chitosan and tripolyphosphate concentration. Moreover, uniform size and good dispersion of nanoparticles could be prepared steadily within certain scope. Nanoparticles have good stability within 251 days, and showed good biocompatibility. Ciprofloxacin could be loaded and released sustained sustainedly.