Electrical and Magnetic Control of Nanostructures for the Biochip Applications

Abstract

In this dissertation, we report ways to modulate nanostructures using electrical and magnetic stimulation and their possible applications in biochip application. First, we report the development of nano-storage wires (NSWs), which can store chemical species and release them at a desired moment via external electrical stimuli. Here, using the electrodeposition process through an anodized aluminum oxide template, we fabricated multisegmented nanowires composed of a polypyrrole segment containing adenosine triphosphate (ATP) molecules, a ferromagnetic nickel segment, and a conductive gold segment. Upon the application of a negative bias voltage, the NSWs released ATP molecules for the control of motor protein activities. Furthermore, NSWs can be printed onto various substrates including flexible or three-dimensional structured substrates by direct writing or magnetic manipulation strategies to build versatile chemical storage devices. Since our strategy provides a means to store and release chemical species in a controlled manner, it should open up various applications such as drug delivery systems and biochips for the controlled release of chemicals. Additionally, we report the development of ultra-fast enzyme-linked immunosorbent assay (ELISA) method through the utilization of magnetic capture and release cycle. Our system is largely consisting of two components

array of primary antibody labeled nickel patterns on the substrate and superparamgnetic nanoparticles functionalized with secondary antibody. Upon the application of cyclic magnetic field, the superparamgnetic nanoparticles are actively captured and released from the nickel patterns. When the superparamagnetic particles captures antigens present in the solution and deliver them to nickel patterns, interaction between the primary antibody-antigen- secondary antibody prevents the superparamgentic particles being released from the nickel patterns during the capture and release cycle. Through this mechanism, it was possible to detect the presence of antigen within 5 minutes. Since our strategy provides a means to reduce the detection time significantly, it should open up various applications such as development of ultra-fast biosensors and cargo delivery in biochips.