Researchers at Brookhaven National Laboratory have adapted DNA strands as switching mechanisms for organizing nanoparticles into specific structures. This ability to switch between different nanostructure configurations may allow for the creation of biosensors and nanodevices that can perform specific tasks within the body.
The scientists achieved the goal of responsiveness by creating structures where the distance between nanoparticles could be carefully controlled with nanometer accuracy.
In their previous studies, the scientists used single strands of DNA attached to individual nanoparticles as linker molecules. When the free ends of these DNA strands had complementary genetic code, they would bind to attach the particles. Constraining the interactions by anchoring some of the particles on a surface allowed the scientists to reliably form a variety of structures from two-particle clusters (called dimers) to more complex 3-D nanoparticle crystals.
In the new work, the scientists have added more complicated double-stranded DNA structures. Unlike the single strands, which coil in uncontrollable ways, these double-stranded structures are more rigid and therefore constrain the interparticle distances.
Additionally, some of the strands making up the double-stranded DNA molecules have complicated structures such as loops, which pull the bound particles closer together than when both strands are exactly parallel. By varying the type of DNA device, between looped and unlooped strands, and measuring the interparticle distances using precision techniques at Brookhaven’s National Synchrotron Light Source (NSLS) and at the Center for Functional Nanomaterials (CFN), the scientists demonstrated that they could effectively control the distance between the particles and switch the system from one state to another at will.
The approach resulted in two-configuration, switchable systems both in dimers and nanocrystals, with a distance change of about 6 nanometers — about 25 percent of the interparticle distance. By comparing kinetics in the two systems, they found that the switching between states is faster in the simpler, two-particle system. The dimers also retain their ability to return to their initial state more precisely than the 3-D crystals, suggesting that molecular crowding may be an issue to further investigate in the 3-D materials.
Press release: Switchable Nanostructures Made with DNA…
Abstract in Nature Nanotechnology: Switching binary states of nanoparticle superlattices and dimer clusters by DNA strands