Mechanical Stability of DNA Corona Phase on Gold Nanospheres

Abstract

Noncovalent adsorption of biopolymers on the surface of gold nanoparticles (AuNPs) forms a corona phase that drastically diversify AuNP functions. However, mechanical stabilities of such corona phase are still obscure, hindering the application of biopolymer-coated AuNPs. Here, using optical tweezers, we have observed, for the first time, that DNA corona phase adsorbed on a 5 nm AuNP via two (dA)21 strands in proximity can withstand an average desorption force of 40 pN, which is higher than the stall force of DNA/RNA polymerases. This suggests a new role for AuNPs to modulate replications or transcriptions after binding to prevalent poly(dA) segments in eukaryotic genomes. We have also revealed that with increasing AuNP size (1.8–10 nm), DNA corona becomes harder to remove, likely due to the larger surfaces and flatter facets on bigger AuNPs. These findings provide guidance to design AuNP corona that can withstand harsh environments for biological and materials applications.

Mechano-Electron Spin Coupling Modulates the Reactivity of Individual Coronazymes

“…This leads to the inhibition of electron transfer through the stacked bases as the force intensifies, resulting in reduced coronazyme reactivity. Our previous research 34 indeed indicated that the DNA corona begins to undergo partial destabilization at a tensile force of 13.9 pN. Alternatively, the applied force removes non-specific absorption between DNA and AuNP, making electron transfer less efficient, which reduces the AR→RF turnover rate.…”

Catalytic Relaxation of Kinetically Trapped Intermediates by DNA Chaperones

“…To test whether this kinetic trapping occurs, we sandwiched a dual hairpin (HP1 and HP2, as shown in Figure 1A, see Table S1 for sequences and Figure S5 for schematic HP structures) between 1558-bp and 2391-bp dsDNA handles for attachment to two optically trapped beads. During mechanical unfolding, 26 this DNA construct was stretched by moving the two trapped beads apart, which increased the tension in the DNA construct, causing two DNA hairpins to unfold. Indeed, we observed two rupture events in the stretching FX curves (red) in pure buffer (10 mM Tris and 100 mM KCl, pH 7.4), as expected (Figure 1B).…”

Amalgamation of DNAzymes and Nanozymes in a Coronazyme

“…(a) Schematic of an optical-tweezer setup. The corona DNA connects to two DNA handles, which are tethered by 1064 nm laser-trapped beads through the biotin/streptavidin links (see the Supporting Information and ref for details). (b, c) Examples of FX curves for the AR and DNA hairpin interactions.…”

“…The catalytic efficiency k cat n / K M equals 0.15 ± 0.01 s –1 μM –1 , lower than that of natural peroxidase HRP (∼2.84 s –1 μM –1 ). Surprisingly, adding the DNA corona to the AuNP significantly enhanced the peroxidase reactivity (Figure c, red; see Supporting Information and ref for detailed preparation). The saturation reactivity for the AuNP@DNA is higher than that of the original 5 nm AuNP.…”

“…In contrast, catalytic reactions are carried out by DNA templates in DNAzymes, which are most promising among all biomaterials because of their fully programmable structure and versatile interactions with many ligands, ,, including metals. Similar to the well-known protein corona, the decoration of DNA on nanoparticles readily forms a DNA corona. − The noncatalytic roles of the DNA corona , during nanozyme catalysis remain unclear since controversial observations exist among DNA-based biohybrid nanozymes: some studies suggest that DNAs inhibit the catalytic activities of parent nanoparticles because of their hindrance to surface sites , while others suggest that DNAs could enhance catalytic reactivity by facilitating substrate adsorption. , …”