Synthesis and characterization of electrochemically active nanomaterials
Biological processes are adept at creating nanoscale structures under mild conditions using precise molecular interactions in a bottom-up approach. We have developed new systems and techniques that utilize the ideas of self-assembly, templating, and molecular recognition prevalent in biology, in an attempt to control surface features at the nanoscale. Electrochemical Dip-Pen Nanolithography (EDPN) is a technique to prepare nanostructures of conducting polymers from the monomer unit, using the AFM tip as the size template. This process provides significant control over size and placement of the nanostructure on a surface. We have also designed monomers for spin-coating to decrease the effect of molecular transport on the resulting size of the nanostructure. The polymerization of aniline, pyrrole, and 3.4-ethylenedioxythiophene, along with characterization of the patterned material, will be discussed.
Our laboratory has designed a DNA wrap assay that detects DNA as a consequence of a nanoscale conformational change. To decrease the current detection limit below 100 pM, we have utilized a dendritic architecture to increase the amount of ferrocenes per reporter molecule for detection. The properties of ferrocene metallodendrimers are suitable for this application because they are stable over the potential range and the electrochemical signal of each ferrocene is additive, i.e. there is no electrochemical interference between ferrocenes of the same molecule. Our synthetic approach to these metallodendrimers is described.
The delivery of DNA into the cell for transfection is a major hurdle to advancements in gene therapy. We have synthesized and characterized linear and dendritic polymers to elucidate polymer structure-activity relationships with DNA, which would provide insight into the stages of DNA condensation. The DNA-polymer structures formed, ranging in size from 100--300 nm, were investigated using AFM. We have illustrated that both the charge and hydrophobicity of the polymer is important for association and condensation of DNA at a mica surface. We have also demonstrated the first neutral DNA vector, containing a PEG chain for solubility and non-specific interactions, a nucleobase for specific base pair interactions, and a long alkyl chain to provide hydrophobicity for organization of the DNA-polymer complex.
0794: Materials science
0490: Organic chemistry