Programmable Sequential Assembly in a DNA Functionalized Emulsion System

Assembling a complex structure requires not only the appropriate association of specific units, but putting the pieces together sequentially in the right order. We present the sequential self-assembly of a system of micron-sized emulsion droplets functionalized by pre-programmed DNA molecules. Each droplet is initially inert with the DNA protected by a partially complementary strand with a toehold. A Yurke process [1] utilizes the toehold to free the protected strand which can then act in a similar way to bind to the toehold on the next droplet in the sequence and deprotect a strand which continues the reaction to subsequent droplets. Since the DNA attached to a lipid on an emulsion is mobile this design enables the cyclic strand displacement on the nanoscale to produce sequence-specific interactions on the microscale. We demonstrate such programmed assembly in a system of three types of droplets with different cyclically complementary protected strands. \\[4pt] [1] B. Yurke et al., Nature, 406, 605-608(2000)