Regulating The Assembly And Growth Of Gold Nanoparticles By DNA And Their Further Applications

In the middle of1990s, two leading groups achieved the utilization of oligonucleotides as noncovalent linkers for controlling the assembly of DNA-functionalized gold nanoparticles (DNA-AuNPs). However, the traditional strategy has its own shortage with limited parameter in regulating the assembly of gold nanoparticle. To endorse this challenge, a strategy for gold nanoparticle (AuNP) assembly driven by a dynamic DNA molecular machine is revealed here. Combining with this machine, the assembly of DNA-functionalized AuNPs was regulated by series of DNA strand displacement reactions. The association rate of the AuNPs could be regulated by adjusting the concentration of catalyst-strand. The versatility of the dynamic DNA molecular machine was further demonstrated by constructing two-component "OR" and "AND" logic gates. This new strategy may find broad potential applications in terms of building up an "interface" that allows the combination of the strand displacement-based characteristic of DNA with the distinct assembly properties of inorganic nanoparticles.To further proof the versatility of newly estabilished method in regulating the assembly of gold nanoparticles. The capability of our DNA molecular machine-driven strategy in controlling the association rate of DNA-AuNPs was compared with traditional strategy which has great applications in different fields. Our new strategy showed its superiority to the traditional strategy in tuning the aggregation rate of DNA-AuNPs no matter there was pre-incubation treatment or non-incubation treatment or not, since its two components (complex and catalyst strand) can be individually optimized to facilitate the running of DNA molecular machine. We believe our strategy will provide more convenient and flexible options in designing DNA detection system and building complex nano-device.Furthermore, we showed the robustness of DNA molecular machine in other applications, such as SNP detection. Single-nucleotide polymorphism (SNP) detection based on the assembly of DNA-AuNPs driven by DNA molecular machine, was established and optimized. It was highly efficient, worked at room temperature, and was easy to handle. What’s more, a single-base change on target strand was unambiguously discriminated for either mismatches or insertions and deletions (indels). Our strategy was applied to genotyping a mutation in the breast cancer related gene BRCA1in homogeneous solution. Although we had made some achievements based on DNA-regulated assembly of gold nanoparticle, all of these works were involved AuNP functionalization with various sequences after the AuNPs were synthesized,thereby the DNA did not influence the AuNPs morphology. As we known, systematically controlling the morphology of nanoparticles, especially those growing from gold nanorod (AuNR) seeds, are under-explored, as the AuNR and its related morphologies have shown promises in many applications. Herein we report the use of programmable DNA sequences to control AuNR overgrowth, resulting in gold nanoparticles varying from nano-dumbbell to nano-octahedron, as well as shapes in between, with high yield and reproducibility. Kinetic studies revealed two representative pathways for the shape control evolving into distinct nanostructures. Furthermore, the geometric and plasmonic properties of the gold nanoparticles could be precisely controlled by adjusting the base compositions of DNA sequences or by introducing phosphorothioate modifications in the DNA. As a result, the surface plasmon resonance (SPR) peaks of the nanoparticles can be fine-tuned in a wide range, from visible to second near-infrared (NIR-Ⅱ) region beyond1000nm.