Inducing reversible stiffness changes in DNA-crosslinked gels
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B. Yurke Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974
N.A. Langranaa) Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey 08854 (Received 9 December 2004; accepted 25 February 2005)
Researchers have constructed a number of DNA-based nanodevices that undergo stepped configuration changes through the application of single-stranded DNA oligomers. Such devices can be incorporated into gel networks to create new classes of active materials with controllable bulk mechanical properties. This concept was demonstrated in a DNA-crosslinked gel, the stiffness of which was modulated through the application of DNA strands. Each crosslink incorporated a single-stranded region to which a DNA strand with a complementary base sequence (called the fuel strand) bound, thereby changing the nanostructure of the gel network. The gel was restored to its initial stiffness through the application of the complement of the fuel strand, which cleared the fuel strand from the crosslink via competitive binding. Stiffness changes in excess of a factor of three were observed. The ability to switch the mechanical properties of these gels without changing temperature, buffer composition, or other environmental conditions, apart from the application of DNA, makes these materials attractive candidates for biotechnology applications.
I. INTRODUCTION A. Background
The use of DNA as a structural material in nanotechnology was pioneered by Seeman,1,2 who, along with his colleagues, constructed a number of geometric objects and molecular machines.3 Recently, a number of DNAbased nanomachines driven by DNA-hybridization motors3–11 have been constructed. Work in DNA nanotechnology12,13 also includes the use of DNA in the nanoscale manipulation of nanocrystals, nanoparticles, and proteins; as a template for the growth of conductive silver wire; and in the assembly of supramolecular structures. DNA-polymer conjugates in which the DNA does not play a structural role in the complex have been shown to be useful in gene therapy14–19 and bioelectronics.20–23 The use of short DNA strands to crosslink water-soluble
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Address all correspondence to this author. Present address: Department of Mechanical and Aerospace Engineering, Rutgers University, 98 Brett Road, Piscataway, New Jersey 08854 e-mail: [email protected] DOI: 10.1557/JMR.2005.0186 1456
http://journals.cambridge.org
J. Mater. Res., Vol. 20, No. 6, Jun 2005 Downloaded: 29 Dec 2014
polymer chains was first reported by Nagahara and Matsuda.24 In their study, poly(N,N-dimethylacrylamide-coN-acryloxyloxysuccinimide) was reacted with 5⬘-aminomodified 10-mer oligonucleotides consisting of all adenine bases (oligoA) or thymine bases (oligoT) to form polymer chains with short DNA side branches. Two different cross-linked structures were produced: one in which oligoA branches from one solution of polymer chains hybridized with oligoT branches from a second polymer solution, and another in which two oligoT branches hybridized with a 20-m
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