Study On The Covalent Immobilization Of Captopril Onto Polymer Microspheres And The Protein Adsorption

Affinity polymer microsphere (APM) is synthesized by the principleof biological compatibility, whose surface is covalently immobilized withbiological activity material that has the special affinity, biologicalcompatibility and binding ability toward bioactive compounds, such asdrugs, antibodies and enzymes. The target material can be selectivelyisolated by binding with the biological activity material. APM has thegeneral characteristics of polymer microsphere, such as cheapness,high-efficiency, good stability, large specific surface areas and versatilefunction. In addition, the APM has many particular features, such as highsensitivity, biological inert, recycle and small pollution. APM will haveextensive application in the field of biochemistry and pharmaceutical. Thisresearch is based on APM. The effects on the reaction of polymermicrosphere being grafted with drug molecules have been studiedemphatically. The adsorption performance of APM on the model protein isstudied.The poly(styrene-co-glycidyl methacrylate)(PSG) latex microspheres are prepared by soap-free emulsion polymerization, and then they arefurther modified with1,6-hexane-diamine as a space arm to get theamino-modified PSGN microsphere. Captopril is coupled onto the surfaceof PSGN microspheres via acylation reaction, which is activated withN-(3-dimethylaminopropyl)-N’-ethylcar-bodiimide hydrochloride (EDC)and N-hydroxysuccinimide (NHS), so that the APM immobilized captoprilis finally obtained. The effects of the ratio, concentration of catalysts, pH,temperature and time on the coupling reaction between the PSGNmicrospheres and captopril are examined. Finally, the appropriate reactionconditions are obtained. In order to make the effect of immobilization muchbetter, the response surface methodlogy is used for optimizing conditions.Then, as the adsorbent, adsorption characteristic of APM on the modelprotein (BSA) is studied. The trend of adsorption capacity with the time isshown. The effects of pH, initial concentrations of BSA and ionic strengthon adsorption capacity of protein are examined. In the pH value of6.0, theelectrostatic attraction plays a significant role in the adsorption quantity.The appropriate initial concentration of BSA has a very big effect on theequilibrium adsorption. When the condition of ion concentration is low, theadsorption quantity of BSA is larger.