Modification Of Chitosan And Praparation And Characterization Of Nanoparticle Drug Carriers

In order to overcome the disadvantage of water-insolubility of chitosan, polarfunctional groups (such as carboxymethyl, phosphonic and hydroethyl groups) wereintroduced onto chitosan chains and hence three water-soluble derivatives(carboxymethyl chitosan, phosphonic chitosan and hydroethyl chitosan) were preparedand characterized.Positive and negative polyelectrolytes could form polyelectrolyte complex bystatic-electric interaction. By the formation mechanism of polyelectrolyte complex,carboxymethyl chitosan/phosphonic chitosan and heparin/phosphonic chitosannanoparticles were prepared with positive phosphonic chitosan and negativecarboxymethyl chitosan and heparin. The nanoparticles were used to deliver the drug oflomefloxacin hydrochloride. Chemical structures and morphology of the nanoparticleswere characterized by means of IR and TEM. The size, polydispersity and zeta potentialof the nanoparticles, as well as pH and ion strength stability were evaluated. In addition,the effects of the concentration of polymers and drug loading on the physicochemcialproperties of the nanoparticles and the drug entrapment efficiency were investigated. Asthe results shown, the nanoparticles obtained are of the size of 200～300 nm andadjustable zeta potential and the modification chitosan derivatives are promising drugcarriers.Besides, we also fabricated Ca²⁺/carboxymethyl chitosan bead-nanoparticlescomplex systems by embedding the nanoparticles into the beads. Through the SEMobservation, the complex systems had porous structure and the nanoparticles wereembedded into the beads by different modes. Compared with plain Ca²⁺/carboxymethylchitosan beads, the obtained complex systems had higher drug entrapment ability anddisplayed controlled-release behavior of drug.