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Group Members: William Ballik Robbie Edwards Alex Klotz Gio Mitchell
DNA Nanowires Phys Group 3 Group Members: William Ballik Robbie Edwards Alex Klotz Gio Mitchell
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Introduction Carbon nanotubes: interesting properties, difficult to manufacture Biological template-DNA DNA can be plated with cobalt to create magnetic cobalt nanowires. Manufacturing is electroless
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Preparation DNA from virus treated in buffer
Palladium clusters are adsorbed onto DNA surface Molecules placed on MICA substrate or silanized glass Conditions: 50ºC, pH 6.
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Fabrication Three chemical reactions: Pd (II) + DNA bases Pd(II):DNA
Pd (II):DNA + DMAB Pd(0):DNA Pd(0):DNA + DMAB + Co (II) Pd(0)Co(0):DNA + DMAB+
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Fabrication The palladium activation expected to produce more uniform deposition of cobalt; cobalt only bonds to the palladium-coated DNA surface Palladium acts as catalyzing agent in electroless plating, with DMAB chemical acting as reducing agent If Pd activation is not done, but Pd and Co added in solution, expect aggregates to form non-uniformly
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Fabrication Metalization bath of cobalt mixed with prepared DNA
Treated for minutes or more. DNA molecules could be oriented with molecular comb: bound to silanized glass and stretched through evaporation. Final products examined with AFM and UV/X-ray spectroscopy
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Results: UVS UVS (ultra-violet spectroscopy) used to verify Pd bonded to DNA Note that in activated case (left) the “shoulder” at 260 nm—absorbed by DNA—disappears after time. Otherwise doesn’t.
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Results: EDX EDX (Energy Dissipative X-Ray) used to find spectrum of nanowire, shows presence of Co.
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Results: AFM Used tapping mode.
Produced cobalt plated DNA nanotubes ~10x35 nm in cross section Plating was 70-80% continuous in non-activated case; near 100% in activated case Random clumping of Co and Pd form nanoparticles.
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Results: AFM Images compare non-activated (A) and activated (B) samples after cobalt plating.
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Results: AFM Nanowires could be oriented by molecular combing.
Free Pd causes faster growth, but harder to control than bound Pd. Non metallized DNA proved unsuitable for Co deposition
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Comparision with carbon nanotubes
Much faster fabrication, no electric potential required Ferromagnetic Inhomogeneous surface compared to CNT Most likely lacks unique material properties. Original DNA strand acts as template for standardized and simple fabrication.
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Applications Wires can be used for nanoelectronics
Preparation process can also be used to create nanoparticles. Magnetic nanowires can be used for high-density storage.
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Is this nano? Self-assembly of particles onto surfaces
The creation of extremely small-scale memory devices: islands or clumps only a few atoms wide This is mostly chemistry, and not so much quantum effects Useful for nano properties, but formation is not primarily quantum/nano behaviour
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Questions?
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