Direct Electronic Control of Biomolecular Systems: Using Nanocrystals as Antennas for Regulation of Biological Activity
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Direct Electronic Control of Biomolecular Systems: Using Nanocrystals as Antennas for Regulation of Biological Activity Kimberly Hamad-Schifferli*, John J. Schwartz‡, Aaron T. Santos*, Shuguang Zhang†, and Joseph M. Jacobson* The Media Lab and the †Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A. ‡ Engeneos, Cambridge, MA 02140, U.S.A. *
ABSTRACT We report a means of directly controlling DNA dehybridization by radio frequency magnetic field coupling to a nanometer scale antenna covalently linked to the DNA. The method of control relies on induction heating of an Au nanocrystal, which raises the temperature of a biomolecule to which it is covalently bound, while leaving surrounding molecules relatively unaffected. Because heat dissipation in biomolecules in solution is rapid(10 nm). This confirms that Z is relatively unaffected by induction heating of a nanocrystal in its proximity. Figure 3c shows the A260 with the RFMF on and off for a fixed concentration of M as N was added. A260 RQDQGRIIYDOXHVLQFUHDVHOLQHDUO\EXWWKHGLIIHUHQFH $260) remains constant. Samples of LQFUHDVLQJFRQFHQWUDWLRQRI0VKRZ $260 increasing with concentration (not shown). These experiments indicate that the induction heating of M is sufficiently localized such that surrounding molecules are not affected.
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Figure 3. Systems to test selectivity. a, Two-phase system used to test selective dehybridization. b, Difference fluorescence spectra (after dehybridization by heat/RFMF minus before dehybridization) are scaled to the same intensity. (left) Sample that has been exposed to the RFMF. The spectrum shows a peak at 515nm due to FAM, which is present on both X and Z, and a negligible peak at 563nm, which is present only on Z. (right) Spectrum of sample that has been isothermally heated to 70°C. CONCLUSION We have demonstrated the use of induction heating of covalently bound nanocrystal antennas to reversibly dehybridize double stranded DNA on the time scale of seconds. Induction heating is sufficiently localized to permit selective dehybridization. This technique permits control of biomolecules in a switch-like manner in solution. Manipulation of DNA by itself is interesting as it has been shown recently that it has potential as an actuator[10] and can be used to perform computational operations [11-13]. Because nanocrystals can be covalently attached Y8.43.5
to proteins as well as nucleic acids, this opens the possibility of switching more complex processes such as enzymatic activity [14], biomolecular assembly [15], and gene and protein ex
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