Selective DNA attachment of micro- and nanoscale particles to substrates
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D. Schwartz Solulink Inc., 6310 Nancy Ridge Drive, San Diego, California 92121
G. Tu GenOptix, 3398 Carmel Mountain Road, San Diego, California 92121 (Received 19 September 2001; accepted 3 December 2001)
Materials formed from micro- and nanoscale particles are of interest because they often exhibit novel optical, electrical, magnetic, chemical, or mechanical properties. In this work, a means of constructing particulate materials using DNA strands to selectively attach micro- and nanoparticles to substrates was demonstrated. Unlike previous schemes, the DNA was anchored covalently to the particles and substrates, rather than through protein intermediaries. Highly reproducible selective attachment of 0.11–0.87 m-diameter particles was achieved, with selective:nonselective binding ratios >20:1. Calculations showed that at most 350 and 4200 DNA strands were involved in the binding of the small and large particles, respectively. Experiments showed that the DNA was bent at an angle, relative to the surfaces of their solid supports.
I. INTRODUCTION
Recently there has been a great deal of interest in methods of rationally assembling micro-, nano-, and even molecular-scale devices and structures. Materials formed from micro- or nanoparticulates often exhibit novel optical,1,2 mechanical,3 magnetic,4 or electrical5 characteristics. Such materials therefore have potential in applications ranging from the construction of optical filters and gratings to the fabrication of ultra-high-density magnetic storage media. The assembly of nanoparticulate materials can also be used to generate templates or masks for additional material processing.3 Additionally, the assembly of nanoparticles modified to contain a chemical or biological species can be used to form biological and chemical sensors. Finally, it has been suggested that as devices (such as III-V transistors, light emitting diodes, and lasers) are scaled-down in size to the micron and submicron regime, nanoassembly techniques may be necessary to integrate the devices themselves with host substrates.6 –9 Because of the widespread interest in assembling micron and nanometer-sized particles and devices, researchers are increasingly turning to self-assembly methods to direct material assembly. Particularly interesting
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Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 17, No. 2, Feb 2002
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has been the use of DNA molecules to assemble materials.10 –12 A number of “templating” schemes have been explored in which DNA molecules act as mechanical scaffolds on which inorganic materials can be coated. Examples include the use of plasmid DNA to direct the location and size of deposited semiconductor particles,13 and the use of linear DNA strands to template the formation of silver14 and palladium15 wires. Other schemes rely on the nucleotide sequence of the DNA molecules to direct the assembly of tethered inorganic particles. Such sequence-specific schemes rely on the complem
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