Polyvalent DNA-Nanoparticle Conjugates Stabilize Nucleic Acids

Abstract

Polyvalent oligonucleotide gold nanoparticle conjugates have unique fundamental properties including distance-dependent plasmon coupling, enhanced binding affinity, and the ability to enter cells and resist enzymatic degradation. In this chapter, the authors quantify the enhanced stability of polyvalent gold oligonucleotide nanoparticle conjugates with respect to enzyme-catalyzed hydrolysis of DNA and present evidence that the negatively charged surfaces of the nanoparticles and resultant high local salt concentrations are responsible for enhanced stability. They examine the stability of the DNA on a nanoparticle surface as a function of surface coverage and provide an explanation for why these structures resist enzymatic degradation. Enzyme-catalyzed DNA degradation can be modeled as a 2-step reaction that involves the association of the enzyme with the substrate, and the hydrolysis of the nucleic acids. The enhanced stability observed for DNA-gold nanoparticles could result from a decrease in rate of either of these two steps.