Post‐Assembly Stabilization of Rationally Designed DNA Crystals

Abstract

This manuscript reports an effort to stabilize self-assembled DNA crystals. Owing to their weak inter-unit cohesion, self-assembled DNA crystals are fragile, which limits the potential applications of such crystals. To overcome this problem, another molecule was introduced, which binds to the cohesive sites and stabilizes the inter-unit interactions. The extra interactions greatly improve the stability of the DNA crystals. The original DNA crystals are only stable in solutions of high ionic strength (e.g., ≥1.2 M (NH4)2SO4); in contrast, the stabilized crystals can be stable at ionic strengths as low as that of a 0.02 M solution of (NH4)2SO4. The current strategy is expected to represent a general approach for increasing the stability of self-assembled DNA nanostructures for potential applications, for example, as structural scaffolds and molecular sieves.

Enhancing DNA Crystal Durability through Chemical Crosslinking

“…All DNA crystals presumably require relatively high cation concentrations for stability due to the high density of negatively charged phosphate groups in the oligonucleotide backbones. These cation requirements can severely limit potential applications of DNA crystals . The covalent interactions introduced by NOR crosslinking appeared to sufficiently rigidify the lattice to overcome the repulsive forces associated with the decreased ionic strength and any concomitant changes in Debye length.…”

“…These cation requirementsc an severely limit potential applicationso fD NA crystals. [37] The covalenti nteractions introduced by NOR crosslinking appeared to sufficiently rigidify the lattice to overcome the repulsive forces associated with the decreased ionic strength and any concomitantc hanges in Debye length. However,w ec annotr ule out other factors, including cation sequestration as ar esult of crosslinking or the positivec harge imparted on the N7 position upon alkylation, as other sources for lattice stabilization.…”

“…The high cation concentration might also limit potential applications if accessory or guest molecules are not compatible at these cation concentrations. One recent approach to decrease cation dependence for crystal stability has been the addition of DNA strands to convert double helices into triple helices at decreased pH . Finally, DNA crystals must be resistant to nucleases present in cellular environments or serum to be useful as delivery vehicles or for in vivo sensor and diagnostic applications.…”

“…One recent approach to decrease cation dependence for crystal stability has been the addition of DNA strands to convert double helices into triple helices at decreased pH. [37] Finally,D NA crystals must be resistantt on ucleases presenti n cellularenvironments or serum to be usefulasdelivery vehicles or for in vivo sensora nd diagnostic applications. Severals tudies have examined the resistance of DNA origami structures to nucleases in solution or those present in serum.…”

Stimuli‐Responsive DNA Self‐Assembly: From Principles to Applications

“…More recently,t he triplex and i-motif units have been incorporated in more complicated, highero rdered DNA architectures, such as nanocages, nanotubules, DNA origami,a nd even macroscopic crystals. [26][27][28][29] Mao and co-workersd eveloped as trategy to reversibly control the assembly and disassembly of aD NA nanocage by incorporating pH-sensitive triplex parts into the sticky end re-gions of the component tiles formingt he nanocages (i.e.,t etrahedrons). [26] When the solution was slightly basic (pH 8.0), the tripletsd issociated owing to ad eprotonation of Cb ases, resultingi nd isassembled DNA tetrahedrons.…”