Selective, Controllable, and Reversible Aggregation of Polystyrene Latex Microspheres via DNA Hybridization

Abstract

The directed three-dimensional self-assembly of microstructures and nanostructures through the selective hybridization of DNA is the focus of great interest toward the fabrication of new materials. Single-stranded DNA is covalently attached to polystyrene latex microspheres. Single-stranded DNA can function as a sequence-selective Velcro by only bonding to another strand of DNA that has a complementary sequence. The attachment of the DNA increases the charge stabilization of the microspheres and allows controllable aggregation of microspheres by hybridization of complementary DNA sequences. In a mixture of microspheres derivatized with different sequences of DNA, microspheres with complementary DNA form aggregates, while microspheres with noncomplementary sequences remain suspended. The process is reversible by heating, with a characteristic "aggregate dissociation temperature" that is predictably dependent on salt concentration, and the evolution of aggregate dissociation with temperature is observed with optical microscopy.

DNA-Based Soft Phases

“…In most of the cases the interaction of micron-sized particles is not mediated by a linker sequence [135]. Usually the particles are directly covered with complementary sequences that bypass the need of having a third component in solution.…”

DNA‐Assisted Monolayer Immobilization of 2D Opaline Arrays

“…The clear supernatant was carefully decanted and its nonhybridized TAMRA dye decorated ssDNA concentration was determined using UV-vis absorption spectroscopy. The surface DNA density on the substrate was determined from the difference between the amount of non-hybridized TAMRA dye and that added initially [44].…”

“…The DNA surface density on our carboxy/sulfate bifunctional microspheres was determined to be on the order of 1.5 × 10 -2 ssDNA nm -2 , following the method reported by Rogers et al [44] The near order-of-magnitude difference in carboxy functionality content (1.075 × 10 18 COOH nm -2 ) of the carboxy-modified latex microspheres of Rogers et al versus our bifunctional (carboxy/sulfate) microspheres (3.47 × 10 17 COOH nm -2 ) might justify the comparable reduction of DNA grafting density from 1.9 × 10 -1 to 1.5 × 10 -2 ssDNA nm -2 . Figure 2 illustrates the route utilized for grafting ssDNA oligomers onto glass or silicon substrates, the latter of which were covered with their native oxides.…”

“…Similarly elevated dissociation temperatures have been reported previously for DNA oligomers attached to various nanostructures. [44,59] On the other hand, the lack of complementary A′B′ DNA linker produces featureless dissociation curves with weak dependence on temperature and salt concentration. It is worth noting that the lack of DNA linker results in removal of more than 50 % of microspheres from the corresponding 2D-opaline-array monolayer (even at temperatures as low as 5°C), signifying the profound importance of DNA hybridization at the particle/substrate interface.…”

“…[43,44] The DNA-assisted attachment of colloidal microspheres onto substrates along with their corresponding flow-induced detachment was also investigated with a view to improving DNA-microarray technologies. In this contribution, DNA hybridization has been extended for the first time into the field of opaline-based photonic crystals in order to selectively immobilize a single layer of 2D opaline arrays onto various substrates, while at the same time being able to remove multilayers.…”