Amphiphilic dextran bearing biotin

cholesterol and hydrazide side groups was synthesized by esterifying of dextran polyaldehyde with cholesterol 3-hemisuccinyl chloride

followed by reacting aldehyde groups with adipic dihydrazie．and then conjugating carbodiimide—activated biotin to amino groups．The resultant dextran derivates were used to co-dialyze with poly(lactic acid)(PLA)DMSO solutions against water to form PLA submicron particles with dextran derivates anchored on the surface．The morphologies of the submicron particles were observed by TEM and AFM

and the diameter and diameter distribution were measured using photon correlation spectrum.The results showed that the submicion particles were spherical in shape

and the diameters could be controlled by adjusting the ratio of the Chol-Dex-Biotin to the(PLA)．The surface structure of the submicron particles was measured by XPS and the results demonstrated the existing of the dextran derivates．By conjugating these submicron particles with transferrin through acryl hydrazone reaction and IgG via biotin—avidin mediated physical linking

respectively

PLA submicron particles bearing transferrin and IgG protein simultaneously on the surface were obtained．The conjugation of transferrin and IgG was proved by fluorescence microscope and color development reaction of antiIgG—HRP．