Intracellular Delivery and Triggered Release of DNA Using Biodegradable Poly(2-hydroxypropylene imine)s Containing Cystamine Units

Poly(2-hydroxypropylene imine)s containing segments of cystamine (PHPI-CA) are synthesized by polycondensation of 1,3-dibromo-2-propanol with a mixture of 1,3-diamino-2-propanol and cystamine. High molecular weight fractions of these polymers are collected by ultrafiltration and characterized by chemical analysis, H-1 and C-13-NMR spectroscopy, size-exclusion chromatography with triple detection, and potentiometric titration, and are tested for DNA delivery in vitro. It is shown that PHPI-CA are highly branched polymers containing disulfide linkages. Transfection efficiency of PHPI-CA for DNA gives similar results to that of PHPI with GFP(+) cell percent reaching 80-90%. Cytotoxicity levels for PHPI-CA are lower than that of PHPI. Novel polymers containing different amounts of disulfide linkages are able to disintegrate and release DNA following the treatment with reducing agent 1,4-dithiothreitol. Downstream application of PHPI-CA transfected cells for RNA purification shows that RNA yield is not affected even after the double transfection suggesting that these polymers could be great candidates for in vitro and in vivo transfection.