Our ability to precisely manipulate size, shape, and composition of nanoscale carriers is essential for controlling their in-vivo transport, biodistribution, and drug release mechanism. Shape-specific, "smart" nanoparticles that deliver drugs or imaging agents to target tissues primarily in response to disease-specific or physiological signals could significantly improve therapeutic care of complex diseases. Current methods in nanoparticle synthesis do not allow such simultaneous control over particle size, shape, and environmentally-triggered drug release, especially at the sub-100 nm range. In this dissertation, we discuss the development of high-throughput nanofabrication techniques using synthetic and biological macromers (peptides) to produce highly monodisperse nanoparticles, as well as enzymatically-triggered nanoparticles, of precise sizes and shapes. We evaluated thermal nanoimprint lithography (ThNIL) and step and flash imprint lithography (SFIL) as two possible fabrication techniques. We successfully employed ThNIL and SFIL for fabricating nanoparticles and have extensively characterized the SFIL fabrication process, as well as the properties of the imprinted biopolymers. Particles as small as 50 nm were fabricated on silicon wafers and harvested directly into aqueous buffer using a biocompatible, one-step release technique. These methods provide a novel way to fabricate biocompatible nanoparticles with precise size and geometry. Furthermore, we developed an enzyme-degradable material system and demonstrated successful encapsulation and enzyme-triggered release of antibodies and nucleic acids from these imprinted nanoparticles; thus providing a potential means for disease-controlled delivery of biomolecules. Finally, we evaluated the bioactivity of the encapsulated therapeutics in-vitro. The development of the SFIL method for fabrication of biocompatible nanocarriers has great potential in the drug delivery field for its ability to create monodisperse particles of pre-designed geometry and size, and to incorporate stimulus-responsive release mechanisms. This research provides the potential to broaden the study of how particle size and shape affect the biodistribution of drugs within the body. / text

Integrated photonic circuits require small photonic elements. Recent progress in nanowire synthesis and nanofabrication enables us to investigate the potential of nanowires in novel integrated photonic devices. This thesis explores light manipulation on two material platforms – metallic nanostructures that support surface plasmon polaritons (SPPs), and periodic dielectric arrays for mode engineering. In Chapters 2 and 3, I will show that chemically-synthesized metallic nanowires are attractive candidates to support SPPs and enhance light- matter interactions. The first model device consists of a single quantum emitter in close proximity to a highly crystalline Ag nanowire. When the quantum emitter is optically excited, its emission rate is enhanced by a factor of 2.5, and 60% of the emission couples into the Ag nanowire, generating single SPPs. In addition to optically exciting SPPs, we demonstrate an optoelectronic device that generates and detects SPPs electrically, paving the way for seamless integration between electronic and plasmonic elements in a single circuit. In Chapter 4, I present a general strategy to create stretchable and flexible photonic devices. Flexible photonics has garnered a lot of interest because mechanical properties can be exploited to generate highly conformal devices with novel optical characteristics. We fabricated Si nanowire photonic crystal cavities and transferred them into polydimethylsiloxane (PDMS). The composite photonic crystal cavity supports high quality factor (Q) modes in the telecommunication range. We achieve mechanical reconfiguration of the cavity by stretching it, and observe tuning of the resonance wavelength over 67 nm, 134 times the resonance linewidth. The above demonstrations, when taken together, underscore the promise and potential of nanowires in integrated photonic circuits. / Chemistry and Chemical Biology

Josh Folk explains how the traditional rules of physics don't make sense at the quantum-mechanical level - and how those discrepancies can be turned into opportunities.

<p>Research on alternative energies has become an area of increased interest due to economic and environmental concerns. Green energy sources, such as ocean, wind, and solar power, are subject to predictable and unpredictable generation intermittencies which cause instability in the electrical grid. This problem could be solved through the use of short term energy storage devices. </p><p> Capacitors made from composite polymer:nanoparticle thin films have been shown to be an economically viable option. Through thermal vapor deposition, we fabricated dielectric thin films composed of the polymer polyvinylidine fluoride (PVDF) and the ceramic nanoparticle titanium dioxide (TiO₂). Fully understanding the deposition process required an investigation of electrode and dielectric film deposition. Film composition can be controlled by the mass ratio of PVDF:TiO₂ prior to deposition. An analysis of the relationship between the ratio of PVDF:TiO₂ before and after deposition will improve our understanding of this novel deposition method. </p><p> X-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy were used to analyze film atomic concentrations. The results indicate a broad distribution of deposited TiO₂ concentrations with the highest deposited amount at an initial mass concentration of 17% TiO₂. </p><p> The nanoparticle dispersion throughout the film is analyzed through atomic force microscopy and energy dispersive x-ray spectroscopy. Images from these two techniques confirm uniform TiO₂ dispersion with cluster size less than 300 nm. These results, combined with spectroscopic analysis, verify control over the deposition process. </p><p> Capacitors were fabricated using gold parallel plates with PVDF:TiO₂ dielectrics. These capacitors were analyzed using the atomic force microscope and a capacohmeter. Atomic force microscope images confirm that our gold films are acceptably smooth. Preliminary capacohmeter measurements indicate capacitance values of 6 nF and break down voltages of 2.4 V. </p><p> Our research on the deposition process will contribute to the understanding of PVDF/TiO₂ composite thin films. These results will lead to further investigation of PVDF/TiO₂ high density energy storage capacitors. These capacitors can potentially increase the efficiency of alternative energy sources already in use. </p>

A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

DNA has been widely studied in a variety of solvents. The majority of these solvents consist of either aqueous or organic components. The presence of ions or salts in these solvents can further alter DNA properties by changing the melting point or helical structure. The size, charge, and concentration of these additional components can all affect the behaviour of DNA. A new class of solvents, known as ionic liquids have recently gained popularity. Ionic liquids are comprised of entirely of ions and can be liquid at room temperature. Due to their low volatility and ability to dissolve both polar and non-polar substances, they are generating high levels of interest as ‘green solvents’. Although the interaction between DNA and ionic liquids has been characterized, the potential of this interaction is still being studied. It was discovered that when DNA mixed with DNA intercalating dyes was added to ionic liquids, there was a large reduction in fluorescence. Although this fluorescence drop was believed to occur to removal of the dye molecule from the helix, the strength of this interaction has not been researched. In this thesis, the interaction between different intercalating dyes and different ionic liquids was evaluated. We reasoned that perhaps the difference in interaction could be used as a method of separating the DNA-dye complex, which has previously never been accomplished. For example, it has been established that both DNA and cationic dyes have an affinity for ionic liquids. The relative strength of this affinity is undetermined, as well as the comparison to normal aqueous mediums. Although ionic liquids can drastically alter the stability of the DNA duplex by either raising or decreasing the melting point depending on the ionic liquid chosen, we found that the DNA actually has a higher affinity for the aqueous phase. Conversely, intercalating dyes prefer to partition into the ionic phase. The relative affinities of the two components are strong enough for their respective phases that the complex can be split apart and each component can be extracted, allowing for separation of the two.

Elongated nanostructures have attracted a great deal of interest due to unique optical, electrical and physical properties. In particular, silver nanowires and nanobeams have proven to be top contenders for a variety of applications. Due to their nano-sized dimensions, however, electrical access to individual nanowires is difficult and expensive. Here, a simple and economical procedure was designed to electrically contact small elongated structures using common facilities available at most universities. A common lithographic procedure is used to pattern gold pads and electrodes on top of nanowires already dispersed on a substrate. This process is tested by first characterizing, using a 4-point-probe measurement, a novel nanobeam created by fusing silver nanodisks. The resistivity of the nanobeams was found to be as low as 2.7x10^−8 Ω·m, which is only slightly above that of bulk silver. These measurements corroborate modeling done by another group that the nanodisks align to create a nearly continuous crystal rather than disjointed grains. In the second application, Joule-heating was used to actualize a reliable weld between silver nanowires synthesized using the polyol method. The nanowires were situated in series between two metal pads, and a procedure was designed to use electrical current to break down intermediate layers without destroying the nanowires themselves. In the last enterprise, individual silver nanowires were isolated between two gold pads and then using the same electrical recipe used for welding nanowires, the contact resistance was reduced to a negligible portion of its original value. It was found that due to the reduction in contact resistance, the 2-point-probe resistivity of the nanowire was similar to those conducted using 4 probes. The invented procedure can thus allow accurate resistivity measurements of individual metal nanowires to be done with only 2 contacts rather than 4, thereby simplifying contact fabrication and allowing appropriate contacts to be deposited on nanowires as short as 4 μm using standard photolithography.

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