Biological and Chemical Applications

 

  • Engineered Metallic DNA (M-DNA) and its improved conductivity
    • Studies have indicated that DNA’s electronic behaviour may vary widely, ranging from a good linear (Ohmic) conductor to a wide-bandgap semiconductor. To circumvent the debate over DNA conductivity, our lab is examining a reliable method to controllably modify the conductivity of individual DNA molecular wires.
  • Ionic jet machine (a biofuel-powered nanomachine with drug delivery applications)
  • Chemical modification of CNTs
  • Biomolecule detection and delivery using 1-D nanomaterials
  • Single-cell or multiplexed intracellular delivery/detection/manipulation with nano-probes
  • Linking of DNA strands and structures to nanoparticles for intracellular delivery, in particular for targeted delivery with therapeutic applications.
  • Sequence specific branch migration within DNA nanostructures for cell/tissue-specific release or activation of therapeutic oligonucleotides, plasmids, etc.
  • Stability & dynamics of triple helical DNA structures and their crucial role in molecular nanomachine design and operation.
  • Biomolecule-enabled, controllable self-assembly of nanocomponents and the purposeful harnessing of biofunctionality on the nano scale. Specific investigations include:
    • The wiring of redox proteins to CNTs by a self-assembling DNA link and translating the electrochemical ‘signature’ of the proteins into an informative bio-signal that can serve as a bio-sensing system.
    • The harnessing of motor proteins to drive and direct the transport of nanocomponents.
    • Example: Preparation and characterization of CNT-linker-biomolecules

 

hybrid nanostructures

 

ZnO-CNT hybrid nanostructures from DNA sequence dependent catalyst placement. (1) Sequence A is attached to carboxylic acid functional groups displayed at the ends of CNTs through amide coupling. (2) Sequence B, carrying a 20 nm Au particle as a label is hybridized to sequence A previously bound to the CNTs. (3) ZnO nanowires are grown from the Au catalyst using standard conditions, resulting in hybrid nanostructures where the catalyst was placed by sequence specific hybridization. Right, SEM images of resulting hybrid structures, scale bar represents 50 nm.

site-specific linking

 

Site specific linking of nanoparticle labeled DNA. A and B illustrate amine-terminated tip linking and C and D illustrate pyrene terminated sidewall linking. E and F demonstrate simultaneous tip and sidewall linking with different sized nanoparticles. Scale bars represent 50 nm.

B. J. Taft, Adam D. Lazareck, Gary D. Withey, Aijun Yin, J. M. Xu, and Shana O. Kelley, Site-Specific Assembly of DNA and Appended Cargo on Arrayed Carbon Nanotubes, J. Am. Chem. Soc. , 2004, 126 , 12750

1st-dish Snapshot 051st-dish Snapshot 05

 

After incubation of HeLa cells with AlexaFluor 594-labeled single-walled nanotubes (SWNT) for 12h at 37°C, living cells were observed under confocal fluorescence microscope for a carbon nanotube (CNT) uptake study. The first image shows dual confocal detection of AlexaFluor 594-SWNT (red) internalized into cells with the membrane stained by AlexaFluor 488 (green). The second image shows a series images of different z-focal scanning planes down through cells. The goal of this research is to utilize CNTs as vectors to for drug delivery into living cells.

1st-dish Snapshot 05 AL-Probe1

 

Intracellular Probing

 

DAPI-CY3-02

 

Florescent In-Situ Hybridization, or FISH

1_No Desc 1

 

Xu, J.M.

CNT - Forest For Sequence

 

Biomolecule Separation in CNT NanoForest

Kim, J.H.

HChik Thesis Fig-4

 

SEM image of (a) nanorod on AFM tip

Chik, H

No Desc 2

 

Xu, J.M.

Ref-154 CV Curves

 

Representative cyclic voltammograms for Ru(III)/Fe(III) electrocatalysis at (A) 3D NEEs, (B) 2D NEEs, and (C) Au macroelectrodes in the absence (-) and presence of (+) a DNA oligonucleotide complementary to the immobilized probe.

Ref-154 DNA Detection

 

Representative cyclic voltammograms for Ru(III)/Fe(III) electrocatalysis at (A) 3D NEEs, (B) 2D NEEs, and (C) Au macroelectrodes in the absence (-) and presence of (+) a DNA oligonucleotide complementary to the immobilized probe.

Ref-154 SEM-of-2D,3D

 

Scanning electron micrographs and schematic illustrations of 2D (A) and 3D (B) NEEs.

R. Gasparac, B. J. Taft, Melissa A. Lapierre-Devlin, A. D. Lazareck, J. M. Xu, and S. O. Kelley. Ultrasensitive Electrocatalytic DNA Detection at Two- and Three-Dimensional Nanoelectrodes. J. Am. Chem. Soc. , 2004, 126 , 12270.