Alexei V. Tkachenko

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We examine the network of forces to be expected in a static assembly of hard, frictionless spherical beads of random sizes, such as a colloidal glass. Such an assembly is minimally connected: the ratio of constraint equations to contact forces approaches unity for a large assembly. However, the bead positions in a finite subregion of the assembly are(More)
We study theoretically a novel drug delivery system that utilizes the overexpression of certain proteins in cancerous cells for cell-specific chemotherapy. The system consists of dendrimers conjugated with "keys" (ex: folic acid) which "key-lock" bind to particular cell-membrane proteins (ex: folate receptor). The increased concentration of "locks" on the(More)
We investigate the reversible association of micrometer-sized colloids coated with complementary single-stranded DNA "sticky ends" as a function of the temperature and the sticky end coverage. We find that even a qualitative description of the dissociation transition curves requires the inclusion of an entropic cost. We develop a simple general model for(More)
Colloids coated with complementary single-stranded DNA "sticky ends" associate and dissociate upon heating. Recently, microscopy experiments have been carried out where this association-dissociation transition has been investigated for different types of DNA and different DNA coverages [R. Dreyfus, M. E. Leunissen, R. Sha, A. V. Tkachenko, N. C. Seeman, D.(More)
We study theoretically a binary system in which an attraction of unlike particles is combined with a type-independent soft-core repulsion. The possible experimental implementation of the system is a mixture of DNA-covered colloids, in which both the repulsion and the attraction may be induced by DNA solution. The system is shown to exhibit surprisingly(More)
Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via(More)
We study theoretically a generic scheme of programmable self-assembly of nanoparticles into clusters of desired geometry. The problem is motivated by the feasibility of highly selective DNA-mediated interactions between colloidal particles. By analyzing both a simple generic model and a more realistic description of a DNA-colloidal system, we demonstrate(More)
The science of self-assembly has undergone a radical shift from asking questions about why individual components self-organize into ordered structures, to manipulating the resultant order. However, the quest for far-reaching nanomanufacturing requires addressing an even more challenging question: how to form nanoparticle (NP) structures with designed(More)