| Summary: | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009. === Includes bibliographical references. === Nano-science has exploited the hybridization and de-hybridization phenomena of DNA which are one of its fundamental functions. In particular, conjugates of gold nanoparticles and DNA (Au NP-DNA) have been extensively explored for their potential in biological applications such as DNA delivery for gene therapy and disease detection. However, DNA strands are known to adsorb onto the Au NP surface, which can severely limit the hybridization ability of Au NP-DNA conjugates. Therefore, methods of chemical modification of Au NP surfaces and evaluating DNA conformation via Ferguson analysis of gel electrophoresis are proposed in the thesis. Conjugates of DNA with Au NP of different sizes and coverages are evaluated with Ferguson analysis to characterize important parameters such as hydrodynamic size and zeta-potential. Surface modified Au NP exhibits enhanced stability and hybridization specificity in the system, which infers the effectiveness of those methods towards biological systems where non-specific adsorption is problematic. To confirm the validity of the concept, Au NP-antisense DNA experiments for gene silencing are performed in the work. Antisense DNA is designed to inhibit ribosomal activity on mRNAs and cooperatively works with Au NPs to enhance physical blocking mechanisms. However, the result shows that Au NP-DNA conjugates can enhance in vitro gene expression depending on DNA sequence and coverage of the conjugates. Suggestions are made for further investigation on proof and improvement of the translation enhancer concept. === by Sunho Park. === Ph.D.
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