Читать книгу DNA Origami - Группа авторов - Страница 36

One applications of DNA origami structures is the development of plasmonic structures that control plasmonic interactions by arranging AuNPs in precise positions. Since DNA origami can create a structure with a size of 10–100 nm, DNA origami used as a template enables precise placement by controlling the distance and orientation of AuNPs and examination of its physical properties. Attachment of AuNPs to DNA origami was carried out by selective hybridization of a DNA‐AuNP conjugate to complementary strands arranged on the DNA origami structure. Liedl and coworkers constructed plasmonic structures with chirality, in which AuNPs were placed precisely on DNA origami [94]. A cylindrical DNA origami structure 100 nm in length was prepared to arrange the AuNPs in right‐handed and left‐handed helices (Figure 1.12a). A DNA strand was bound to the AuNP (10 nm), and a complementary DNA strand was bound to the DNA origami structure. The AuNPs were precisely placed in nine locations on the right‐handed and left‐handed DNA origami. In these plasmonic structures, a circular dichroism (CD) response was observed in the plasmonic absorption region of the AuNPs due to plasmonic interaction between AuNPs and their chirality. Positive and negative Cotton effect signals were observed in the right‐handed and left‐handed helices, in which inverting spectra were observed (Figure 1.12b,c). In addition, when AuNPs with a larger diameter (16 nm) were introduced, the CD signal intensity increased 400‐fold due to the increased interactions. Using DNA origami as a scaffold, the 3D spatial arrangement of AuNPs was accurately designed and the CD spectra were simulated, which was in good agreement with the experimental results. Therefore, this study shows that plasmonic materials with predicted physical properties can be designed and constructed.

Figure 1.12 Helical AuNP plasmonic structures constructed on a DNA origami. (a) Left‐handed (LH) and right‐handed (RH) helical structures (diameter 34 nm, helical pitch 57 nm) with 9 AuNPs (10 nm) bound to the surface of a 16 nm diameter DNA origami. (b) Left‐handed (LH) and right‐handed (RH) CD spectra (left) of the helical structure of AuNPs (10 nm) and its simulated spectra (right). (c) Left‐handed (LH) and right‐handed (RH) CD spectra of a spiral structure of AuNPs (16 nm) (left) and their simulated spectra (right). (d) Surface‐enhanced fluorescence from two AuNPs‐bound DNA origami tower structure standing on a glass surface. Using a tower structure with two AuNPs (80 nm), the DNA strand to which the dye was bound transiently emits light that repeatedly binds and dissociates to the complementary strand DNA placed in the gap between the AuNPs.

Source: Kuzyk et al. [94]/with permission of Springer Nature.