Building Polyvalent DNA-Functionalized Anisotropic AuNPs using Poly-Guanine-Mediated In-Situ Synthesis for LSPR-Based Assays: Case Study on OncomiR-155.

DNA-functionalized gold nanoparticles (DNA-AuNPs) hold great promise for numerous biomedical applications, especially the building of well-defined nanosystems. Previously reported methods for the preparation of DNA-AuNPs all rely on the use of DNA-bearing free thiol or disulfide groups at their 3'/5' ends. But here we report a novel polyvalent DNA-AuNPs conjugation approach by in-situ fast synthesis of AuNPs at the polyguanine (G ) strands. As confirmed by both TEM images and gel electrophoresis analysis, many poly G strand can form an individual anisotropic AuNP and so each AuNP functionalized with a dense layer of DNA, resulting in the formation of polyvalent (p)DNA-AuNPs. The general applicability of this novel approach was further verified in hybridization test and UV-Vis spectroscopy results show that pDNA-AuNPs conjugation is more attractive in biomedical diagnosis and specific sequence detection like microRNA-155 by using an extra-strand poly G with "sticky end" that are complementary to the target sequence.