Synthesis, Characterization, and Biological Evaluation of Poly(glycoamidoamine)s as DNA Delivery Vectors
Abstract (Summary)Synthetic polycations readily bind to the negatively charged phosphate groups in nucleic acids and can serve as carriers to deliver genetic materials into cells. Simplicity of use, ease of large-scale production, and lack of an immune response in vivo are the main merits of polymeric delivery. However, the lack of knowledge of the structure-biological property relationships of polymeric vectors has hampered further efforts to invent highly efficient non-viral gene delivery agents through a systematic, rational approach. In an effort to understand such structure-bioactivity relationships, a library of 20 poly(glycoamidoamine)s have been constructed by polycondensation of esterified D-glucaric acid (D), dimethyl-meso-galactarate (G), D-mannaro-1,4:6,3-dilactone (M), and dimethyl-L-tartarate (T) with diethylenetriamine (1), triethylenetetramine (2), tetraethylenepentamine (3), pentaethylenehexamine (4), and spermine (S). These polymers are of similar degrees of polymerization (11 - 14), but with varied amine stoichiometry (1 to 4), amine spacer (ethylene or butylene), hydroxyl stereochemistry (D, G, and M), and hydroxyl number (2 or 4) within the repeat units, serving as a platform for investigation of how structural variations affect their gene delivery efficiencies. Furthermore, two noncarbohydrate-containing analogous polymers have also been synthesized to elucidate the biological functions of the carbohydrate moieties. The biological properties of these polymers as delivery vectors have been evaluated and correlated to their detailed chemical structures. Examination of amine stoichiometry showed that the polymers with four amines in the repeat unit exhibited the best transfection efficiency without eliciting cytotoxicity. Examination of amine spacer showed that polymers with an ethylene spacer conveyed higher cell viability than those with a butylene spacer. Examination of carbohydrate hydroxyl stereochemistry showed that polymers with meso-galactrate (G) as the carbohydrate moiety possessed higher transfection efficiency than polymers containing D-glucarate (D) and D-mannarate (M). Examination of the effect of hydroxyl number showed that L-tartarate (T, 2 hydroxyls per carbohydrate) polymers formed smaller complexes and had higher DNase protection capability than D, G, and M polymers (4 hydroxyls per carbohydrate). Elucidation of these structure-biological property relationships clarified what structures were most promising to generate the desired properties in further exploration and rational design of glycopolyamines for gene therapy.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/2006