title: Directing assembly of DNA-coated colloids with magnetic fields to generate rigid, semiflexible, and flexible chains.
abstract: We report the formation of colloidal macromolecules consisting of chains of micron-sized paramagnetic particles assembled using a magnetic field and linked with DNA. The interparticle spacing and chain flexibility were controlled by varying the magnetic field strength and the linker spring constant. Variations in the DNA lengths allowed for the generation of chains with an improved range of flexibility as compared to previous studies. These chains adopted the rigid-rod, semiflexible, and flexible conformations that are characteristic of linear polymer systems. These assembly techniques were investigated to determine the effects of the nanoscale DNA linker properties on the properties of the microscale colloidal chains. With stiff DNA linkers (564 base pairs) the chains were only stable at moderate to high field strengths and produced rigid chains. For flexible DNA linkers (8000 base pairs), high magnetic field strengths caused the linkers to be excluded from the gap between the particles, leading to a transition from very flexible chains at low field strengths to semiflexible chains at high field strengths. In the intermediate range of linker sizes, the chains exhibited predictable behavior, demonstrating increased flexibility with longer DNA linker length or smaller linking field strengths. This study provides insight into the process of directed assembly using magnetic fields and DNA by precisely tuning the components to generate colloidal analogues of linear macromolecular chains.
authors: Department of Chemical and Biomolecular Engineering, Rice University , 6100 Main St., MS 362, Houston, Texas 77005, United States.
authors: Julie
authors: J
authors: Byrom
authors: Patric
authors: P
authors: Han
authors: Michael
authors: M
authors: Savory
authors: Sibani Lisa
authors: SL
authors: Biswal
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D060526:Magnetic Fields
chemical_list: D003102:Colloids; D004247:DNA