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Gene transfer vector is one of the key technologies of gene therapy.Gene carriers generally can be divided into two major categories of virus and non-virus,the former is subjected to security challenges.The latter much favored in medical science and also is currently the main object of pharmaceutical research because of its safety,vector design diversity and low cost.In non-virus carrier,polycation gene carrier due to the high rate of transfection and become a main research subject.Polyamidoamine(PAMAM)is one of the important member in the family of cationic polymer carrier,PAMAM dentrimers are attracted highly attention recently due to their special properties in the drug and gene delivery systems,especially the high generation PAMAM as the gene vector shows strength transfection ability compared with the other non-viral carrier materials.The main drawback for the materials is presenting serious cell toxicity.In order to overcome this problem,one new gene delivery system has been designed by our research group.This is that PAMAMs are covalently conjugated onto α-cyclodextrin(α-CD)via amide bonds to obtain the starburst-like cationic polymers(CD-PG2).The chemical structure and composition of CD-PG2 was characterized by H-NMR.The physicochemical and biological properties of CD-PG2/pDNApolyplex were evaluated by agarose gel retardation,stability test against DNaseⅠ,MTT assay,DLS measurement,CLSM observation,LDH leakage test,and in vitro cell transfection.The test results tell us that the CD-PG2 could efficiently condense pDNA into nano-scale particles with a narrow size distribution,and protest from DNaseⅠ degradation.CD-PG2 shows excellent gene transfection efficiency without serum interference as well as relatively low cytotoxicity,compared with free PET-25K and commercial product Lipofectamine 2000(one good gene vector).The cell uptake route analysis shows cellular uptake CD-PG2/pDNApolyplex is mainly through Clathrin-mediated endocytosis,CME and Caveolae-mediated endocytosis,CvME route and further investigations demonstrate that α-CD could regulate CvME pathway to improve polyplex transfection behavior.