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Endothelial cells are an important cell type to both cardiovascular disease and cancer, as they play critical roles in vascular function and angiogenesis. However, effective and safe gene delivery to primary endothelial cells in the presence of serum proteins is known to be particularly challenging. A library of biodegradable poly(beta-amino esters) was synthesized for use as potential vectors. Promising vectors were optimized for high efficacy and low cytotoxicity to human umbilical vein endothelial cells (HUVECs) in serum. Vector parameters including polymer type, polymer weight, and DNA loading were varied, and biophysical properties including particle size, zeta potential, and particle stability over time were studied. While many of the poly(beta-amino ester) vectors have similar biophysical properties in the presence of buffer, their biophysical properties changed differentially in the presence of serum proteins, and the properties of these serum-interacting particles correlated to transfection efficacy. Leading poly(beta-amino ester) vectors were found to transfect HUVECs in the presence of serum significantly higher (47 +/- 9% positive, n = 10) than the best commercially available transfection reagents including jetPEI (p < 0.001) and Lipofectamine 2000 (p < 0.01). These results demonstrate the potential of a new class of biomaterials, poly(beta-amino esters), for effective human endothelial cell gene therapy.

Controlled chemical precipitation of yttrium hydroxynitrate has been used to synthesize nanocrystalline yttrium oxide powders with high thermal stability. The type of base employed as the precipitating agent has a significant effect on the properties of the yttrium oxide product. Precipitation with tetraalkylammonium hydroxides was shown to produce a much finer-grained product than a conventional ammonium hydroxide synthesis route. This is attributed to the higher pH that can be achieved with tetraalkylammonium hydroxides, as well as the ability of tetraalkylammonium cations to inhibit precipitate particle growth by lowering the rate of diffusion of soluble precursors to the particle surface.