Biomacromolecules, Vol.15, No.1, 12-19, 2014
Effect of Pendant Group on pDNA Delivery by Cationic-beta-Cyclodextrin:Alkyl-PVA-PEG Pendant Polymer Complexes
We have previously shown that cationic-beta-cyclodextrin:R-poly(vinyl alcohol)-poly(ethylene glycol) (CD +:R-PVA-PEG) pendant polymer host:guest complexes are safe and efficient vehicles for nucleic acid delivery, where R = benzylidene-linked adamantyl or cholesteryl esters. Herein, we report the synthesis and biological performance of a family of PVA-PEG pendant polymers whose pendant groups have a wide range of different affinities for the beta-CD cavity. Cytotoxicity studies revealed that all of the cationic-beta-CD:pendant polymer host:guest complexes have 100-1000-fold lower toxicity than branched polyethylenimine (bPEI), with pDNA transfection efficiencies that are comparable to bPEI and Lipofectamine 2000. Complexes formed with pDNA at N/P ratios greater than 5 produced particles with diameters in the 100-170 nm range and zeta-potentials of 15-35 mV. Gel shift and heparin challenge experiments showed that the complexes are most stable at N/P >= 10, with adamantyl- and noradamantyl-modified complexes displaying the best resistance toward heparin-induced decomplexation. Disassembly rates of fluoresceinated-pDNA:CD+:R-PVA-PEG-rhodamine complexes within He La cells showed a modest dependence on host:guest binding constant, with adamantyl-, noradamantyl-, and dodecyl-based complexes showing the highest loss in FRET efficiency 9 h after cellular exposure. These findings suggest that the host:guest binding constant has a significant impact on the colloidal stability in the presence of serum and cellular uptake efficiency, whereas endosomal disassembly and transfection performance of cationic-beta-CD:R-poly(vinyl alcohol)-poly(ethylene glycol) pendant polymer complexes appears to be controlled by the hydrolysis rates of the acetal grafts onto the PVA main chain.