Nanoparticles formed through complexation of plasmid DNA and copolymers are promising gene-delivery vectors, offering a wide range of advantages over alternative delivery strategies. Notably, recent research has shown that the shape of these particles can be tuned, which makes it possible to gain understanding of their shape-dependent transfection properties. Whereas earlier methods achieved shape tuning through the use of block copolymers and variation of solvent polarity, here we demonstrate through a combined experimental and computational approach that the same degree of shape control can be achieved through the use of graft copolymers that are easier to synthesize and provide a wider range of parameters for shape control. Moreover, the approach presented here does not require the use of organic solvents. The simulation work provides insight into the mechanism governing the shape variation as well as an effective model to guide further design of nonviral gene-delivery vectors. Our experimental findings offer important opportunities for the facile and large-scale synthesis of biocompatible gene-delivery vectors with well-controlled shape and tunable transfection properties. The in vitro study shows that both micelle shape and transfection efficiency are strongly correlated with the key structural parameters of the graft copolymer carriers.Keywords: DNA packaging; micelles; self-assembly; shape control; transfection

Tetrapods are among the most promising building blocks for nanoscale self-assembly, offering various desirable features. Whereas these particles can be fabricated with remarkable precision, comparatively less is known about their aggregation behavior. Employing a novel, powerful simulation method, we demonstrate that charged nanoparticles offer considerable control over the assembly of tip-functionalized tetrapods. Extending these findings to tetrapods confined to a gas/liquid interface, we show that regular structures can be achieved even without functionalization.

We investigate the role of hydrodynamic interactions in the formation of clusters of attractive colloids by means of computer simulations. In simulations employing the multiparticle collision dynamics scheme to represent hydrodynamics, larger and, to a lesser extent, more elongated transient clusters are formed than in simulations merely employing Langevin dynamics. As these clusters constitute the precursors to a colloidal gel, their shape affects the structure of the gel as well as the threshold concentration and colloidal attraction strength at which gelation occurs. Our findings support recent observations regarding the effect of hydrodynamics on colloidal gel formation.