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. 2010 Jul 12;49(30):5076-80.
doi: 10.1002/anie.201000265.

Programmable shape-shifting micelles

Miao-Ping Chien  1 , Anthony M Rush, Matthew P Thompson, Nathan C Gianneschi
Affiliations

Programmable shape-shifting micelles

Miao-Ping Chien et al. Angew Chem Int Ed Engl. .
No abstract available

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Figures

Figure 1
Figure 1
Assembly of DNA-brush copolymers into micelles with spherical or cylindrical morphologies. Amphiphile structures are represented as cones for each respective morphology, with the hydrophobic domain highlighted in red. TEM images of a) 25 nm spherical micelles assembled from initial DNA-brush copolymers; b) cylindrical morphology formed following DNAzyme addition to spheres; c) spherical micelles (green) formed after addition of In1 to cylinders. See also Figure 3S in the Supporting Information.
Figure 2
Figure 2
Reversible phase cycling experiments. a) Isothermal hybridization and invasion. The y axis shows the percentage (volume distribution) of species in Dh = 396 nm size class versus input; measurements were obtained by DLS 2 h after each input addition beginning with 25 nm spheres. The Dh value of 396 nm was chosen as it is the largest aggregate size class observed by DLS at 2 h (see Figure 3). b) Variable-temperature DLS. Plot shows Dh of largest aggregates in solution at given time points. Initial spheres (A) were treated with DNAzyme for 18 hrs (B) prior to addition of In1. DLS measurement at t = 0 min taken 1 h after addition of In1. Ramp rate: 25→60°C in 5 min. Instrument cooling time was 60 min; sample was cooled by placing in ice bath for 5 min, then rested at RT for 55 min. Second heating cycle conducted 18 h later with same ramp rate (25→60°C in 5 min) and cooling time (60 min). Conditions: particles (0.14 g L−1), DNAzyme (5 nm), In1 (50 nm), In2 (50 nm), 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris; 20 mm, pH 7.4), MgCl2 (50 mm).
Figure 3
Figure 3
DNA-directed size and phase change over time. Conditions: particles (0.14 g L−1), Tris (20 mm, pH 7.4), MgCl2 (50 mm). DNAzyme (5 nm) was mixed with particles at t = 0 min. a) t = 0 min, b) 2 min, c) 2 h, d) 1 day, e) 2 days. f) Particle size as a function of time following DNAzyme addition. Blue curve: average cylinder length (CL) measured by TEM. Green curve: Dh value of largest aggregates measured by DLS. Red curve: Sphere diameter (SD) measured by TEM. DLS data was taken at the time points shown following DNAzyme addition. Data points for CL and SD are averages of multiple measurements made from TEM images, with error bars indicating standard deviations (Figure 4S in the Supporting Information).
Figure 4
Figure 4
Sequence-selective phase shifting observed by fluorescence microscopy. a) TEM image showing bundled cylinder structures analogous to optical images. Optical microscopy images show bright field, green and red fluorescence images taken after treatment with DNAzyme. b) D-1 recognizes only fluorescein labeled particles. c) D-2 recognizes only rhodamine labeled particles. d) D-1 and D-2 together cause fiber formation containing both labels. Optical image scale bars = 10 μm. Conditions: Micelles (0.14 g L−1), DNAzyme (5 nm), Tris (20 mm, pH 7.4), MgCl2 (50 mm). Shell DNA sequences are analogous to that shown in Figure 1, with an extra three bases at the 5′-terminus. The third base from the 5′-amide linkage to the polymer backbone is a dye-labeled thymidine residue (see the Supporting Information for DNA sequences used in these experiments).
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