title: Entropic cages for trapping DNA near a nanopore.
abstract: Nanopores can probe the structure of biopolymers in solution; however, diffusion makes it difficult to study the same molecule for extended periods. Here we report devices that entropically trap single DNA molecules in a 6.2-femtolitre cage near a solid-state nanopore. We electrophoretically inject DNA molecules into the cage through the nanopore, pause for preset times and then drive the DNA back out through the nanopore. The saturating recapture time and high recapture probability after long pauses, their agreement with a convection-diffusion model and the observation of trapped DNA under fluorescence microscopy all confirm that the cage stably traps DNA. Meanwhile, the cages have 200 nm openings that make them permeable to small molecules, like the restriction endonuclease we use to sequence-specifically cut trapped DNA into fragments whose number and sizes are analysed upon exiting through the nanopore. Entropic cages thus serve as reactors for chemically modifying single DNA molecules.
authors: Department of Physics, Brown University, Providence, Rhode Island 02912, USA.
authors: Xu
authors: X
authors: Liu
authors: Department of Physics, Brown University, Providence, Rhode Island 02912, USA.
authors: Mirna
authors: M
authors: Mihovilovic Skanata
authors: Department of Physics, Brown University, Providence, Rhode Island 02912, USA.
authors: Derek
authors: D
authors: Stein
mesh_terms: D010582:Bacteriophage lambda / Q000737:chemistry; D001583:Benzoxazoles / Q000737:chemistry; D004279:DNA, Viral / Q000032:analysis* / Q000737:chemistry; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry*; D004058:Diffusion; D004560:Electricity; D004586:Electrophoresis; D019277:Entropy; D005456:Fluorescent Dyes / Q000737:chemistry; D007700:Kinetics; D008856:Microscopy, Fluorescence; D058608:Nanopores; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D011806:Quinolinium Compounds / Q000737:chemistry; D012996:Solutions
chemical_list: D001583:Benzoxazoles; D004279:DNA, Viral; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds; D012996:Solutions; C075296:1,1'-((4,4,7,7-tetramethyl)-4,7-diazaundecamethylene)bis-4-(3-methyl-2,3-dihydro(benzo-1,3-oxazole)-2-methylidene)quinolinium; C025651:CCCGGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific