Light‐Responsive Colloidal Crystals Engineered with DNA

Abstract

A novel method for synthesizing and photopatterning colloidal crystals via light‐responsive DNA is developed. These crystals are composed of 10–30 nm gold nanoparticles interconnected with azobenzene‐modified DNA strands. The photoisomerization of the azobenzene molecules leads to reversible assembly and disassembly of the base‐centered cubic (bcc) and face‐centered cubic (fcc) crystalline nanoparticle lattices. In addition, UV light is used as a trigger to selectively remove nanoparticles on centimeter‐scale thin films of colloidal crystals, allowing them to be photopatterned into preconceived shapes. The design of the azobenzene‐modified linking DNA is critical and involves complementary strands, with azobenzene moieties deliberately staggered between the bases that define the complementary code. This results in a tunable wavelength‐dependent melting temperature (Tm) window (4.5–15 °C) and one suitable for affecting the desired transformations. In addition to the isomeric state of the azobenzene groups, the size of the particles can be used to modulate the Tm window over which these structures are light‐responsive.

Advances in Application of Azobenzene as a Trigger in Biomedicine: Molecular Design and Spontaneous Assembly

“…For example, these modified DNA sequences can be used as light‐responsive linkers to connect with other nanostructures to control their interactions. Mirkin and co‐workers [ 36 ] incorporated azobenzene switches into the sticky ends of DNA. UV and visible light irradiation caused azobenzene moieties to adopt cis and trans configurations, respectively, to achieve dynamic regulation of pairing between sticky ends of DNA.…”

“…Reversible trans ‐to‐ cis isomerization or cleavage of azobenzene components plays the basis of the foundation for these interesting functions. [ 3,18,30,31 ] Isomerization of azobenzene under light irradiation [ 32 ] or reductive cleavage of the AZO group under a hypoxic environment results in many exciting functional effects, including release of the payload drug, [ 12,33 ] in situ activation of prodrug, [ 34 ] molecular reorientation, [ 35 ] regulation of macromolecules, [ 6,36 ] and changes in macromechanical properties. Isomerization also provides a potential method for research of high‐performance organic (opto)electronic materials.…”

DNA-Grafted 3D Superlattice Self-Assembly

“…Mirkin’s group incorporated azobenzene-modified linking DNA to synthesize light-responsive NPs lattice [ 68 ]. The photoisomerization of azobenzene molecules as a driving force was employed to modulate the reversible assembly and disassembly of lattices with different crystal types.…”

Adaptive Nanoparticle‐Polymer Complexes as Optical Elements: Design and Application in Nanophotonics and Nanomedicine

“…Azobenzene-modified DNA applied as bonding element between NPs enabled two processes: i) photoinduced assembly and disassembly of crystalline nanoparticle superlattices and ii) photoinduced patterning of colloidal crystals. [169] Lin et al fabricated arrays of plasmonic nanocubes (86 and 63 nm) with different edge lengths that were assembled, using DNA. Their arrangement physically and spectrally encoded two sets of patterns that could be changed by mapping the absorption intensity of the substrate at different wavelengths.…”

“…Azobenzene‐modified DNA applied as bonding element between NPs enabled two processes: i) photoinduced assembly and disassembly of crystalline nanoparticle superlattices and ii) photoinduced patterning of colloidal crystals. [ 169 ]…”