Improvement of Cellular Uptake and Transfection Ability of pDNA Using α-Cyclodextrin-Polyamidoamine Conjugates as Gene Delivery System

Polyamidoamine (PAMAM) dendrimers are a class of unique nanomaterials which attracted attention because of their extraordinary properties, such as highly branched structure and types of terminal primary groups. In addition, development in PAMAM chemical modification has broadened its biological application especially for drug and gene delivery. In this study, PAMAMs are covalently conjugated onto alpha-Cyclodextrin (alpha-CD) via amide bonds obtaining the starburst cationic polymers (CD-PG2). The chemical structure and composition of CD-PG2 was characterized by H-1 NMR. Physicochemical and biological properties of CD-PG2/pDNA polyplex were evaluated by agarose gel retardation, stability test against DNaseon, MTT assay, DLS measurement, CLSM observation, LDH leakage test, cellular uptake, route analysis and in-vitro cell transfection. Results showed that CD-PG2 can efficiently condense pDNA into nanoscale particles with a narrow size distribution, and protect pDNA form DNase I degradation. Compared with free PEI-25K and commercial product Lipofectamine2000, CD-PG2 shows excellent gene transfection efficiency without serum interference as well as relatively low cytotoxicity. Cellular uptake of CD-PG2/pDNA polyplex is mainly through CME and CvME route and further investigations demonstrate that alpha-CD can regulate CvME pathway to improve polyplex transfection behavior. In conclusion, CD-PG2 can be considered as a versatile tool for gene delivery, especially for gene transfer in-vivo.