Baptist, Anna

Heuer-Jungemann, Amelie

Nickel, Bert

Ober, Martina F.

Wassermann, Lea

arXiv

The silicification of DNA origami structures increases their mechanical and
thermal stability and provides chemical protection. So far, it is unclear how
silicification affects the internal structure of the DNA origami and whether
the whole DNA framework is embedded or if silica just forms an outer shell. By
using in situ small-angle X-ray scattering (SAXS), we show that the
net-cationic silica precursor TMAPS induces substantial condensation of the DNA
origami, which is further enhanced by the addition of TEOS at early reaction
times to an almost 10 % size reduction. We identify the SAXS Porod invariant as
a reliable, model-free parameter for the evaluation of the amount of silica
formation at a given time. Contrast matching of the DNA double helix Lorentzian
peak reveals that silica growth also occurs on the inner surfaces of the
origami. The less polar silica forming within the origami structure, replacing
more than 40 % of the internal hydration water causes a hydrophobic effect:
origami condensation. In the maximally condensed state, thermal stabilization
of the origami up to 60 {\deg}C could be observed. If the reaction is driven
beyond this point, the overall size of the silicified origami increases again
due to more and more silica deposition on the DNA origami. DNA origami objects
with flat surfaces show a strong tendency towards aggregation during
silicification, presumably driven by the very same entropic forces causing
condensation. Our studies provide novel insights into the silicification
reaction and hints for the formulation of optimized reaction protocols

arXiv.org e-Print Archive

In situ small-angle X-ray scattering reveals strong condensation of DNA
  origami during silicification

Silicification of DNA origami structures increases their stability and provides chemical protection. Yet, it is unclear whether the whole DNA framework is embedded or if silica just forms an outer shell and how silicification affects the origami’s internal structure. Employing in situ small-angle X-ray scattering (SAXS), we show that addition of silica precursors induces substantial condensation of the DNA origami at early reaction times by almost 10 %. Subsequently, the overall size of the silicified DNA origami increases again due to increasing silica deposition. We further identify the SAXS Porod invariant as a reliable, model-free parameter for the evaluation of the amount of silica formation at a given time. Contrast matching of the DNA double helix Lorentzian peak reveals silica growth also inside the origami. The less polar silica forming within the origami structure, replacing more than 40 % of the internal hydration water, causes a hydrophobic effect: condensation. DNA origami objects with flat surfaces show a strong tendency towards aggregation during silicification, presumably driven by the same entropic forces causing condensation. Maximally condensed origami displayed thermal stability up to 60 °C. Our studies provide insights into the silicification reaction allowing for the formulation of optimized reaction protocols

PubMed Central

In situ small-angle X-ray scattering reveals strong condensation of DNA origami during silicification

SAXS raw data for "In situ small-angle X-ray scattering reveals strong condensation of DNA origami during silicification

Open Data LMU (Ludwig-Maximilians-Universität München)

DNA origami can be coated in a layer of silica to improve chemical and thermal stability however; it is unclear if this is a surface or interpenetrating layer. Here, the authors use in situ small-angle X-ray scattering to study silica deposition and observe internal silica formation resulting in DNA origami condensation and structure shrinkage. Silicification of DNA origami structures increases their stability and provides chemical protection. Yet, it is unclear whether the whole DNA framework is embedded or if silica just forms an outer shell and how silicification affects the origami's internal structure. Employing in situ small-angle X-ray scattering (SAXS), we show that addition of silica precursors induces substantial condensation of the DNA origami at early reaction times by almost 10 %. Subsequently, the overall size of the silicified DNA origami increases again due to increasing silica deposition. We further identify the SAXS Porod invariant as a reliable, model-free parameter for the evaluation of the amount of silica formation at a given time. Contrast matching of the DNA double helix Lorentzian peak reveals silica growth also inside the origami. The less polar silica forming within the origami structure, replacing more than 40 % of the internal hydration water, causes a hydrophobic effect: condensation. DNA origami objects with flat surfaces show a strong tendency towards aggregation during silicification, presumably driven by the same entropic forces causing condensation. Maximally condensed origami displayed thermal stability up to 60 degrees C. Our studies provide insights into the silicification reaction allowing for the formulation of optimized reaction protocols

In situ small-angle X-ray scattering reveals strong condensation of DNA origami during silicification

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