Protein-imprinted　polyacrylamide　(PAM)-grafted　calcium　alginate　(CaA)　microspheres　were　synthesized　via　free-radical　grafting　polymerization　with　potassium　persulfate　and　sodium　bisulfite　as　initiators.　FTIR,　13C-NMR　and　SEM　were　used　for　characterization.　Swelling　behaviors　were　studied　and　it　was　found　that　modified　calcium　alginate　(CaA)　microspheres　possessed　larger　swelling　degree　than　calcium　alginate,　because　grafted　hydrophilic　PAM　side　chains　contributed　to　more　water　absorption.　Moreover,　the　durability　of　the　swollen　samples　was　improved　for　the　modified　microspheres.　Compared　with　calcium　alginate　microspheres,　modified　calcium　alginate　samples　exhibited　higher　absorption　capacity　(approximately,　13.1　and　10.3 mg/g)　for　MIPs　in　single　and　binary　protein　solution.　The　rebinding　selectivity　of　CaA-g-PAM　microspheres　(approximately,　2.7)　was　higher　than　that　of　calcium　alginate　(CaA)　microspheres　(approximately,　1.5)　in　binary　protein　solution.　It　was　suggested　that　the　introduction　of　PAM　side　chains　was　beneficial　for　the　specific　recognition　of　protein.　©　2017,　Springer-Verlag　GmbH　Germany.