Impact of Sequence Specificity of Spherical Nucleic Acids on Macrophage Activation in Vitro and in Vivo.

The effects of spherical nucleic acid (SNA) gold nanoparticle conjugates on the activation of macrophages in vitro and release of cytokines in vivo were explored. Herein, we show that G-quadruplexes, the formation of which is enhanced on gold nanoparticle surfaces, elicit an increase in cytokine release from mouse and human macrophages and induce the upregulation of activation receptors as well as NO2 production in vitro. Moreover, these G-rich SNAs can induce cytokine release when injected intravenously, though there were no severe, long-term effects observed. These results further reinforce the notion that nucleic acid sequence and structure play an important role in how SNAs interact in biological milieu and highlight a key design parameter.

The Impact of Protein Corona Formation on the Macrophage Cellular Uptake and Biodistribution of Spherical Nucleic Acids.

The effect of serum protein adsorption on the biological fate of Spherical Nucleic Acids (SNAs) is investigated. Through a proteomic analysis, it is shown that G-quadruplexes templated on the surface of a gold nanoparticle in the form of SNAs mediate the formation of a protein corona that is rich in complement proteins relative to SNAs composed of poly-thymine (poly-T) DNA. Cellular uptake studies show that complement receptors on macrophage cells recognize the SNA protein corona, facilitating their internalization, and causing G-rich SNAs to accumulate in the liver and spleen more than poly-T SNAs in vivo. These results support the conclusion that nucleic acid sequence and architecture can mediate nanoparticle-biomolecule interactions and alter their cellular uptake and biodistribution properties and illustrate that nucleic acid sequence is an important parameter in the design of SNA therapeutics.

Nanoflares as probes for cancer diagnostics.

Patients whose cancer is detected early are much more likely to have a positive prognosis and outcome. Nanoflares hold promise as a practical diagnostic platform for the early detection of cancer markers in living cells. These probes are based on spherical nucleic acid (SNAs) and are typically composed of gold nanoparticle cores and densely packed and highly oriented oligonucleotide shells; these sequences are complementary to specific mRNA targets and are hybridized to fluorophore-labeled reporter strands. Nanoflares take advantage of the highly efficient fluorescence quenching properties of gold, the rapid cellular uptake of SNAs that occurs without the use of transfection agents, and the enzymatic stability of such constructs to report a highly sensitive and specific signal in the presence of intracellular target mRNA. In this chapter, we will focus on the synthesis, characterization, and diagnostic applications of nanoflares as they relate to cancer markers.

Spherical nucleic acid nanoparticle conjugates enhance G-quadruplex formation and increase serum protein interactions.

To understand the effect of three-dimensional oligonucleotide structure on protein corona formation, we studied the identity and quantity of human serum proteins that bind to spherical nucleic acid (SNA) nanoparticle conjugates. SNAs exhibit cellular uptake properties that are remarkably different from those of linear nucleic acids, which have been related to their interaction with certain classes of proteins. Through a proteomic analysis, this work shows that the protein binding properties of SNAs are sequence-specific and supports the conclusion that the oligonucleotide tertiary structure can significantly alter the chemical composition of the SNA protein corona. This knowledge will impact our understanding of how nucleic acid-based nanostructures, and SNAs in particular, function in complex biological milieu.