Bio-Inspired Assembly of Nanomaterials for Applications on Nanoelectronics and Biosensors

142 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.Recent development in nanostructured material synthesis and engineering has made huge impact on a number of fields including nanoelectronics, photonics, biology, and medicine. A main reason for such an impact is that every nanomaterial, such as metallic nanoparticles (NPs), quantum dots (QDs), carbon nanotubes (CNTs), and magnetic nanoparticles has unique physical and chemical properties that can be used for various applications. For practical use of nanomaterials in various applications, however, it is necessary to assemble nanomaterials in controlled manner and manipulate their behaviors. This control of nanomaterials can be accomplished by functionalizing the nanomaterials with biopolymers, such as DNA. In this work, DNA has been used along with nanomaterials to demonstrate their usage in diverse applications.Precise control of the position of and distance between nanomaterials is one of the key challenges in nanoscale science and technology. A methodology to site-specifically control the distances between nanomaterials has been demonstrated using phosphorothioate modified DNA as a template along with a bifunctional linker. A bifunctional linker binds to a phosphorothioate modified position on the DNA and provides an anchor point for nanomaterials assembly. As nanoparticles can be covalently bound to those anchor points on DNA, they can be precisely placed at accurate positions of a DNA template. Since DNA can work as 1D, 2D, or 3D templates due to its programmable properties and miniature size, nanoparticles can be assembled on those DNA templates forming assemblies with controlled distances. Furthermore, as bifunctional linkers can be easily modified, this methodology is versatile and can be used for other molecules. Controlled conjugation of multiple proteins on DNA has been demonstrated as well.The interface between nanomaterials science and biology offers a grand opportunity for biodetection of various analytes. The target recognition capability of DNA, especially functional DNA, provides a novel way to use nanomaterials as a signal transducer for biosensing. Particularly as DNA can interact with AuNPs in labeled or label-free ways, different kinds of colorimetric sensors can be developed. Herein, lead (Pb2+) targeting colorimetric sensor using lead specific DNAzyme and AuNPs based on label-free method was designed which has detection limit lower than fluorescence based sensor. Furthermore, colorimetric uranyl (UO22+) sensors based on uranyl specific DNAzymes and AuNPs were developed using both labeled and label-free methods and their general properties and performances were compared. Even though DNAzyme with identical sequences were used, the two sensors showed differences in the advantages and disadvantages, versatility, limitations, and potential applications. This work provides a general guideline for the choice of detection methods for colorimetric detection of various analytes.Finally, high resolution patterning of DNA using electrohydrodynamic jet printing method has been demonstrated. This modified ink jet printing method, using electrohydrodynamic force instead of conventional thermal or piezoelectric forces, enables to print high resolution DNA features smaller than 100 nm at high speed in non-contact mode. It has been shown that the e-jet printed DNA is active and their potential applications have been discussed by demonstrating DNA aptamer-based biosensing and DNA-directed nanoparticle assembly.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD