Disassembly of Dna-gold nanoparticle aggregates using DNA strand displacement

Abstract

It is known that the color of colloidal gold nanoparticles is highly dependent on the inter-particle distance. This property, combined with the rational assembly of gold nanoparticle aggregates by using DNA strands as linkers, lead to the production of simple colorimetric biosensors for detecting DNA in solution and in paper format. An important advantage of these colorimetric biosensors is that they can

produce outputs that can be read by naked eye, providing a means towards portable and instrument- free sensors. Also, due to the discovery of aptamers, the operation range of these biosensors can be

extended to the detection of other molecules than DNA. Despite the advantage of being instrument- free, colorimetric biosensors lack the accuracy and complexity of instrumented bionsensors.

Therefore, an instrument-free biosensor with the ability of performing complex or accurate measurements would be highly desirable. Currently, DNA is also being researched as nanomaterial for self-assembly of structures, nanomachines and molecular computation. One of the mechanisms used in these applications is the DNA strand displacement, which consists in hybridizing two complementary DNA strands, displacing one or more pre-hybridized strands in the process. This mechanism provides important properties: control on the hybridization kinetics, enzime-free DNA reactions, isothermal hybridization (can be designed to operate at room temperature) and allows the design of sequentially triggered DNA reactions. In this research, preliminary results will be presented verifying that it is possible to disassemble DNA-gold nanoparticle aggregates in solution and in chromatography paper substrate using strand displacement mechanism. Disassembly of two kind of aggregates were considered: First, aggregates where DNA-modified gold nanoparticles are linked directly. Second, aggregates where DNA-modified gold nanoparticles are linked by using a DNA bridge.