Preparation And Properties Of Drug Delayed Release Microspheres And Gels From Sodium Alginate

Alginate is a natural polymer polysaccharide compounds isolated from algae.Recently,sodium alginate has been attracted significant attention for their great biocompatibility and environmental characteristics,and widely used in chemical and biomedical fields.In this paper,sodium alginate and hydroxypropyl methyl cellulose was through chemical modification and blend for the preparation of new composite materials.Afterwards,properties of new composite materials were analyzed and the research results are as follows(1)Based on esterification reaction,the structure of IPN between sodium alginate and HPMC polymer was constructed.Microspheres,possessing porous network structure,were formed in calcium chloride solution and the average size of microspheres was 2mm.The infrared spectrum showed a significant absorption peak at 1732cm-1,which demonstrated that the esterification reaction of sodium alginate and hydroxypropyl methylcellulose was successfully achieved.The cumulative release of diclofenac sodium was less than 1%in the acidic solution,while that was close to 100%in phosphate buffer in the sustained drug release experiments.The drug release kinetics data obtained from empirical equation showed that the samples of SH-1(SA:HPMC=2:1)and SH-3(SA:HPMC=1:2)were belonged to the Fickian diffusion,which was mainly depended on the concentration of drug carrier material.And the drug release mechanism of SH-2 was the superposition of second type of mass transfer,which was determined by drug diffusion and dissolution of carrier materials.The results of copper ions adsorption experiments showed all the ratios of microspheres could adsorb heavy metal ions.Especially SH-3,the adsorption of copper ion rate reached 88.43%.(2)Sodium alginate/hydroxypropyl methylcellulose/oxide graphene aerogels were prepared with sodium alginate and hydroxypropyl methyl cellulose as the continuous phase and the graphene oxide as enhancement phase.The results of SEM showed the aerogels possessed the uniform porous structure and inherited the hierarchical structure of graphene molecule.It was noted that there was no characteristic diffraction peaks of graphene found in XRD spectra of composite materials,which proved that graphene were uniformly dispersed in the alginate system by hydrogen bonds.The adsorption capacity of heavy metal Cu2+was taken as index.The copper ion adsorption quantity increased sharply first and then reached equilibrium.By fitting the empirical equation,the adsorption behavior of Cu2+was more belonged to the Freundlich adsorption process and pseudo-second-order kinetic model.